M42 Head Gasket Blown, Project Thread

Author Topic: M42 Head Gasket Blown, Project Thread  (Read 10433 times)

bmwman91

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Re: M42 Head Gasket Blown, Project Thread
« Reply #15 on: June 15, 2020, 01:07:44 AM »
So I got it fired up today. Mechanically, it runs correctly and does not make any odd noises or give any other indication of a major problem. However, it is not currently running correctly. When I started it, it immediately wanted to idle at ~2000RPM. After doing that for a couple of minutes, it would drop to ~1500RPM for a moment, rev back to ~2000RPM and then just keep quickly oscillating like that.

I think that I have ruled-out the AFM (MAF conversion) and TPS since disconnecting those did not really make a difference (the engine would stumble briefly and then resume the previous behavior). I had checked the ICV a month or so ago and it was moving freely when 12V was applied, so I don't think it is stuck open, and I will check again tomorrow. When the engine is revving up to 2000RPM, the AFM output does rise to ~2.25V, which means that metered air is getting in somehow...so it is not a vacuum leak at least. I think that the only sources of a leak like that could be either the ICV, or the TB itself.

Back when I got a spare TB and cleaned it, I used acetone. Some of you may have noticed that the M42 TB (and maybe other engines too?) have a slick gray coating that looks like it was dripped or smeared into the bore. Whatever it is, acetone dissolves it, and when I was done cleaning the TB I could see slivers of light around the perimeter of the throttle plates when I held it up to a light. So, I guess the gray stuff was (maybe?) a sealant intended to produce a zero-clearance fit between the throttle plates and bores. When I noticed the newly created gaps, I wondered if it would be enough to cause enough air to leak by that it might cause issues at idle, but the gap around the perimeter was only ~0.002" (0.05mm) based on checking with some feeler gauges so I figured it would be fine.

I believe that the engine changed from a steady 2000RPM idle to oscillating due to either a switch from open-loop to closed-loop idle control, or some other switch in the software based on coolant temperature. I only ran the engine for 2-3 minutes since I don't want to get it fully warmed up until I am ready to drive it to get the piston rings seated.

Anyway, has anyone else had experiences with leaky throttle bodies? Is a gap that small enough to get the engine to idle at 2000RPM?

06/05/2011 - 212,354 miles
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bmwman91

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Re: M42 Head Gasket Blown, Project Thread
« Reply #16 on: June 15, 2020, 03:03:48 PM »
Update. Yeah the TB is a non issue. The one thing that I had assumed could not be the issue, turned out to be the issue lol. It is the ICV.

The car was running fine on it 7 months ago, and I have no idea how sitting for that long could have caused it to die. I did blast it out with brake cleaner, but I doubt that hurt it. Basically, it operates smoothly and does not stick. When I hook it up to my adjustable power supply, the following seems to be the case:
1.7-2V: vane starts to move
3.5V: vane is fully closed
7V: vane is fully open

I am not sure what the normal behavior is supposed to be, but it sort of seems like maybe the return spring is weakened or broken. Either that or there is something going on with the ECU or tune. I got the oscilloscope on the ICV terminals while it was running and the PWM signal is present, so it is not like the signal is stuck ON. I'll try a used ICV to see if that helps, or maybe suck it up and buy a new one.

06/05/2011 - 212,354 miles
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DesktopDave

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Re: M42 Head Gasket Blown, Project Thread
« Reply #17 on: June 18, 2020, 06:23:21 PM »
I'll have to check out the R3v thread. From what I've read here...you should get some sort of medal or something for your persistence. Keep at it, you've gone further beyond with the NA M42 than anyone...with the possible exception of Warsteiner...you're so very close to the ideal M42!
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bmwman91

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Re: M42 Head Gasket Blown, Project Thread
« Reply #18 on: June 18, 2020, 10:05:17 PM »
Ha, thanks. Yeah I can't believe I am still messing with this thing! Warsteiner was a lot more hands-on with his build, since I farmed out the really specialized work to MM. But, yes, I am hoping that it will be the ideal M42 when it is all done!

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Warsteiner

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Re: M42 Head Gasket Blown, Project Thread
« Reply #19 on: June 19, 2020, 11:22:51 PM »
Dude....It's great!! All the work you're doing is totally hands on too. You'll be back up and running perfectly like day 1 in no time flat!

I had fun designing the motor I have....I have slide throttles that I never got to test!! LOL

Cheers,
~Ralph

bmwman91

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Re: M42 Head Gasket Blown, Project Thread
« Reply #20 on: June 19, 2020, 11:40:13 PM »
OK, I have finally found the cause of my high idle. After replacing the ICV (got one from roguetoaster which was in better shape than my old one) and swapping in a clean throttle body I got a hold of, there was no difference at all. I also tried swapping a spare ECU in to no avail. What DID work was swapping a slightly older revision of my custom tune in. Although it ran rich (old tune was for 24# injectors, current ones are 28#), it did idle at the correct RPM. The latest tune from Sssquid is a little bit "experimental" I think, so they will get me a corrected one soon, since I just emailed them with my findings. It must be that some bytes related to the ICV PWM signal got nuked since it was indeed the case that the ECU was opening it too much (air flow signal should be 1-1.5V at idle normally, and I was seeing 2.25V meaning that too much air was being allowed in to the engine NOT as a vacuum leak).

Anyway, I promise I will get all sorts of pictures up at some point relatively soon lol. I've been busy with work and dicking around with getting this thing running correctly lol.

(the above text is from a r3v post today...the car was idling at 2000RPM and being weird, and it has taken almost a week to determine why!)


Warsteiner, why didn't you get a chance to run the slides? I've always been curious about those. It sounds like they can be a mixed bag, although I would think that if you had the right camming linkage setup and tuning it would drive fine. I am already thinking about an RHD ITB kit haha!

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bmwman91

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Re: M42 Head Gasket Blown, Project Thread
« Reply #21 on: June 22, 2020, 10:24:35 PM »
The damn car still does not run properly. It is perhaps not a software thing after all. I am going to lay out what all I did today and hope that the good folks on here can help me figure this one out, because I am thinking that it is going to be something pretty obscure. Everything is on the table, including faults in the wire harness since I had it totally apart for cleaning & restoration.


- Sssquid sent me a bone stock tune with the only change being what was needed to properly run 28# injectors. The car started and idled properly from a cold start, and I drove it a few miles. About a minute after that cold start, it would stall coming off the throttle (such as at a stop sign) unless I have it a little throttle. The idle would sometimes stabilize if I was careful to really ease off the throttle.
- I swapped out the MAF conversion for the old stock AFM (conversion is plug-n-play) and gave tat a shot with the stock tune. The engine was still fully warmed up. It idled better, did not stall at all, and the only hiccup was a small stumble here and there coming off the throttle.
- After the engine fully cooled off, I started it with the stock tune and AFM to pull it into the garage. It would stall without me giving it a little throttle.
- When the engine was fully warmed up still, I popped in some of the other high performance tunes from Sssquid. They are basically the exact ones that he has developed and successfully run on other 2.1L M42 engines from Metric Mechanic. The car would start and the idle would oscillate between 1100-1600RPM. I did not try driving it, just idling.
- With the engine cold and the performance tunes in, it will idle steadily at ~2100RPM for a minute or two, before starting to oscillate.

I checked the resistance between terminals 43 & 78 on the Motornic plug (the two lines for the coolant temp sensor) and it came out to 400 Ohms when the engine was still luke-warm. Wiggling the wires at the sensor plug did not change the value, so there is no broken wire. I am replacing it anyway since my problems seem to have some link to engine temperature, but it seems unlikely that the sensor is bad since it is only about a year old.

I have replaced or swapped the following items while troubleshooting the oscillating idle to no avail:
- ICV
- throttle body
- TPS
- ECU
- AFM (swapped with MAF conversion)

Sensors & stuff that have been replaced within the last year include:
- Crank position
- Cam position
- Coolant temperature
- Crank damper wheel (60-2 toothed pulley)

Before the HG blew late last year, I was having an issue where the car would stumble and sometimes stall about 1 minute after a cold start, and it would go away after another minute as it continued to warm up. That particular behavior probably started around the beginning of 2019. I assumed it was the tune, but maybe not. I am unsure if it is related to my current issue since the entire wire harness is now a different one, damn near everything has been replaced and/or swapped and I can't think of anything that does not check out properly on my freshly rebuilt engine.


Prior electrical measurements indicate that this is NOT a vacuum leak. First, I have had vacuum leaks before, and they do not make the idle enter a constant oscillation pattern as far as I have ever seen on an E30. Stalling and a stumbling idle, sure, but not the oscillation. Anyway, the air flow signal at idle when it is idling either too high or oscillating is around 2.25V, which means that the ICV is being opened too much. Since I have replaced the ICV, cleaned it very well, checked the wiring connections, and verified that the signal looks about correct with an oscilloscope, I think that there is some issue with one of the inputs to the Motronic which is causing it to purposely open the ICV too much. As far as I know, the only things that are going to have an effect like this on the idle control are the coolant temp sensor, AFM, air temp thermistor and TPS.

At this point, I think that I am just going to have to yank the intake and fuel rail for some inspecting, take apart the big Motronic plug to verify that nothing got yanked when I rewrapped the harness, and probe through every connection from the Motronic plug to each endpoint. I am at a total loss otherwise. The engine runs well enough when not idling that I do not think it can be some sort of major cam timing issue or other mechanical fault.

Any and all thoughts and insight are appreciated.

06/05/2011 - 212,354 miles
Visit HERE for a plethora of 318iS stuff and some other randomness.  Would you say I have a, plethora, of pinatas?

monty23psk

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Re: M42 Head Gasket Blown, Project Thread
« Reply #22 on: June 23, 2020, 06:19:48 PM »
This is more of a long shot and while it can prove to give you hesitation, not a high idle as you have stated, but but maybe ECU is trying to figure things out, the coil packs? Have you checked those? I didn't see them listed here.
Alex  88 m5 | 91 318is | 19 Subaru Ascent
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bmwman91

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Re: M42 Head Gasket Blown, Project Thread
« Reply #23 on: June 23, 2020, 10:26:22 PM »
OK, the issue is mostly resolved. The car runs, and I had a good time driving it for 30 miles, running it about as hard as hard as I could while keeping it under 5000RPM (I am going to put more like 100 miles on it before really revving it just to be sure the rings are worn in). It turns out that it was a software issue after all. I have a corrected high performance Sssquid tune in the car, which is what he has developed across something like 8 other 2.1L M42's from MM. After driving a turbo diesel for 7 months, I have to remind myself that punching the throttle at 2000RPM isn't going to do much haha.

With that said, the idle still has issues, but they are relatively minor compared to what I was dealing with. They seem to be heavily dependent on engine temperature. I have outright removed the LLCO wire from the Motronic connector, so I know it isn't that lol. Anyway here's where the idle seems to be at now, in the order that I encountered the issues:

1) The car did the thing where it stalled after running for a minute as I pushed the clutch in coming to a stop sign. It started right back up and did not do it again (for a while).
2) Once it was warmed up, it would stumble and catch itself as I came off the throttle approaching most stops, and it would intermittently exhibit a 800~900RPM hunting when sitting at idle.
3) I drove it to visit my parents, and it sat for maybe 30 minutes. When I got in to start it, it did not want to start. As it cranked it just barely gave an indication of a couple of attempts to fire, and a little throttle was needed to get it to actually start. The temp needle was a little shy of the 1/4 mark at this start.
4) As I slowed to turn in to my driveway ~20 minutes after #3, it stalled. I again needed to apply a little throttle to get it to start, and it stalled again when I let off the gas to park. I again needed to give it a little throttle to start it.

I still have the stock AFM in there, and it has the little extension harness / low-pass filter that BMW issued to most M42's at the time. I am replacing the CLT sensor when the new one comes in later this week, although the current one seems to Ohm-out just fine. Also, I assume that the super light RHD flywheel is not helping anything. I will still be re-checking for vacuum leaks and messing with bypassing the ICV as since the above issues are a lot more similar to ones people have with more "common" faults in these cars.


For the record, the 7.4lb flywheel is fun as shit. Effortless rev matching, no weird noises at start (some people said that the RHD flywheel sounded raspy, but I do not notice anything) and crazy good response. To hell with the noisy rattling from the transmission, BMW should have shipped these cars with light flywheels!

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bmwman91

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Re: M42 Head Gasket Blown, Project Thread
« Reply #24 on: June 27, 2020, 12:41:02 AM »
OK, as promised it is time for the photo dump of app the stuff I have done since the last set of photos.

The rear shift carrier mount was in bad shape, and sort of expensive to replace, so I opted for the beefier Turner Motorsport upgrade. It was only marginally more expensive, and it would eliminate the last of the stuff in the linkage that was making extra slop. It does not fit exactly like the original one (the angle is a little different), but it is good enough to work properly. It was listed as being E30 compatible, so who knows.






I did make one small modification to the carrier. Rather than jam the mushroomed end through the new poly bushing (teehee), I just channeled my inner rabbi and filed it down. In normal operation the mushroom serves no function and just makes removal of the carrier more of a pain.






Here it is installed on the car.




Here is the nice new 7.4lb RHD flywheel installed on the engine.




I also bought the proper crank locking tool, which is a hell of a lot easier to use than the big ½” cold rolled plate I drilled holes in 15 years ago. It was $85 at Pelican Parts. The weight of the engine was more than enough to keep things from moving around as I torqued the FW bolts to 120 ft-lbs.




Next up were the clutch disc and pressure plate. The FW and PP were dynamically balanced together and came ended up with <0.9 grams of total imbalance in the end. Cardelli Motorsports in San Mateo, CA did the balancing for me for $100 cash.






Next the transmission was bolted on. That was a super easy task with the engine up on the mobile workbench, and I got it to slide right into place. One hand to support it (so as to not load the pilot bearing excessively), one to start one of the big top bolts. And no, I did not bother cleaning the transmission. I had thought about it, but at that point I needed to get the project moving and out of the garage.




And there it was, mostly ready to go back into the car. It had a nice new ground strap as well. I replaced all of the ground straps (engine, alternator, hood) with new ones from Bavarian Restoration.




There were a few odds and ends to take care of before dropping the engine back in. Among them was purging the fuel lines that had sat for 7 months. This was pretty easy to do by looping the old feed hose onto the return hardline and hooking the battery up to the pump. If you hook the battery negative to the chassis and the positive terminal to C101 pin 13 (fuse box side) it will run the pump and have fuse 11 there for protection. I ran it for a few minutes and that was that. All flexible fuel lines up front were replaced with new ones.






Oh, and at some point I decided to cut my old flex disc in half to see how it is constructed. They are directional and need to be installed properly to put the proper parts into compression when applying engine power, leaving the other less stiff parts free for taking up vibration when engine braking. These things have some beefy fiber bundles inside (maybe aramid or glass, I did not check too closely).




Anyway, here it is plopped into the car. The main items to reinstall first are the engine mount arms and mounts and the exhaust header. That saves you from a bunch of reaching around under there, and getting the header in/out with the engine in place is a hassle. A few of the other accessories were also installed. Leaving the intake manifolds off, and having the entire firewall wiring tray out, made it super easy to get in. I almost did not even bump the engine or transmission into the car at all while tilting and lowering it in. In the past the main trouble spot has been up at the firewall where the intake manifold would hang up on the wiring tray (or the main wire loom).






After bolting on some more stuff, I turned my attention to the engine wire harness that I had completely rebuilt. The final remaining task was to trim the ignition coil leads to their final length. I took measurements of the wires, where things were stripped, etc., on the original connectors and duplicated that with the trimmed ones. All of the sheathing is new since I changed up how the bundles route from the main loom on the firewall, and getting it all neatly in place was a bit of a chore. The main 0.56” ID sheath that the 12 wires for the 4 coils ran through split into four 0.25” sheaths, and to get clearance on the ends for the heat shrink tubing and stuff I needed to slide it all up into the main one. Windex for the win, it does wonders for enabling things to slide around while also drying quickly. Anyway, I am getting way too excited about wiring lol.

I started by figuring out how exactly I wanted to route the main bundle to give it a proper service loop for strain relief, and then I played with a few different configurations for the individual leads. The one I settled on worked out so that none of the smaller looms would rub on the metal plug retainers, none of the plug ends would be subject to any movement from the chassis loom and everything could be conveniently zip tied into place and serviced in the future. This is a COP plate kit from HQ Autosport, but I made some changes to the fasteners and added some washers as spacers for ergonomic reasons (maybe I will do a write-up of how I improved upon it sometime).










OK, I will try not to type another giant paragraph about wiring. As much of a pain as it is, it is sort of fun if you are doing it right.

Once things were roughed into place, I cut the leads and sheath pieces I would need. From there it was just a matter of crimping the terminals on and putting the connectors together. As another FYI point, the rubber boots for these connectors are a real pain in the ass to get onto the 0.25” sheathing. It is the same diameter as the original sheaths, but the boots are either not intended for use on that size, or they are supposed to be REALLY snug. Getting them onto the sheath was a bitch…be warned!








Here it all is laying in place before I actually finished it up.




And here is the final setup. I am pretty pleased with the little service loop that connects the chassis to the engine. Compared to how I trimmed and routed stuff on the old harness back in 2006 when I invented the COP conversion (fun fact!), this is immensely better. Considering that shitty wiring job lasted 14 years with no broken wires or pierced insulation, this should outlive me.






And so, here it all is today. I have ~160 miles on the engine and have been driving the dog shit out of it. Damn it is fun, and despite being able to feel the car’s age, it is a hell of a lot more fun than most newer cars. All drivetrain and suspension stuff is effectively new, but it’s still based on 40 year old automotive design, so the way it handles and reacts feels a little dated. BUT, it is a go-kart compared to heavy newer sports cars, and despite being slower it has a feel that you don’t get anymore. I had mostly forgotten how much I enjoy driving this thing over the last 7 months of waiting and toiling!








Other random crap….

As you all have seen, I was chasing down gremlins as I tried to get it to run. Since roguetoaster sold me an ICV that was in cleaner shape than my old one, I decided to dissect the one I took out. I’ve never seen one opened up, probably because you have to totally destroy it to get it apart. The outer housing is staked in like 10 places (both the end, and on the sides) and one part is pressed in. Ultimately it is just a simple little electric motor. The design is sort of unique, and clearly not intended for high torque, but it works well enough. The single coil that makes up the stator interacts with the magnetized center cylinder and funky-shaped upper section that serves as a rotor of sorts. The I assume that the shape of the ferrous top is what allows it to interact with the symmetric magnetic field from the coil (I wouldn’t expect it to generate motion at first glance, were it not for the wedge shapes at the top which you can sort of see in the next pic).






This set screw (which is epoxied into place) sets the end stop for when the thing is not energized. It leaves the ICV open an amount that corresponds to the engine’s air needs at the designed idle speed, hence why unplugging it usually leaves the car idling reasonably well.




This little flag is the thing you see moving through the hose barb. The ECU sends a 100Hz PWM signal to the ICV, and this little door flaps open and closed at that rate. Varying the on/off time in that 100Hz signal is how the “average” opening amount is created by the ECU to control idle (Motronic also uses enrichment and ignition timing to control idle speed and stability).




Back when my fuel injectors were stuck shut, I tried to free them with a programmable power supply (you can program voltages and on/off times to make a pulsed output). I also had some spare wire harnesses that were cannibalized to rebuild the one in the car, so I took more parts from them and made my own little debug connectors for the injectors (and some other stuff just in case).







Phew…there it all is. Things are mostly wrapped up now, and I will make new threads for the other non-rebuild stuff I came across in this project. I’m going to cross section one of my old ignition coils for fun, and probably take apart the old MAF sensor element. Mostly I need to remember to make a DIY for how to improve the HQ Autosport COP bracket kit, and try to get measurements of the wiring dimensions. Granted, many of the measurements are useless unless you totally rebuild your harness since the stock ignition coil wire routing won’t leave you enough length to do it my way.

Thanks a lot to everyone for all of the input, encouragement and discussion over the many months since this all started! The E30 community is probably the #1 reason why I still have this stupid car lol.

06/05/2011 - 212,354 miles
Visit HERE for a plethora of 318iS stuff and some other randomness.  Would you say I have a, plethora, of pinatas?

monty23psk

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Re: M42 Head Gasket Blown, Project Thread
« Reply #25 on: June 27, 2020, 11:35:28 AM »
great pictures. I highly recommend the e30 m3 engine harness cover that goes on the passenger side. Will clean up the by even further. When I got it, it was expensive, like $20, no idea what the m3 tax is now a days.
Alex  88 m5 | 91 318is | 19 Subaru Ascent
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DesktopDave

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Re: M42 Head Gasket Blown, Project Thread
« Reply #26 on: June 28, 2020, 08:25:55 PM »
That certainly is a comprehensive read. It's almost exhausting to read it, I can only imagine what typing it all up was like. Thanks for sharing!

I'll have to check out that flywheel over at R3v...I couldn't agree more about the fun factor. A lightweight single-mass flywheel is always near the top of my upgrade list. You're running an awfully light 'wheel, but given the lightweight M42 & G240 components it must be a real pleasure to shift.
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Nick_318is

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Re: M42 Head Gasket Blown, Project Thread
« Reply #27 on: June 29, 2020, 06:35:55 PM »
Awesome updates, happy to hear its back in working order!

bmwman91

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Re: M42 Head Gasket Blown, Project Thread
« Reply #28 on: June 29, 2020, 06:54:27 PM »
great pictures. I highly recommend the e30 m3 engine harness cover that goes on the passenger side. Will clean up the by even further. When I got it, it was expensive, like $20, no idea what the m3 tax is now a days.

That certainly is a comprehensive read. It's almost exhausting to read it, I can only imagine what typing it all up was like. Thanks for sharing!

I'll have to check out that flywheel over at R3v...I couldn't agree more about the fun factor. A lightweight single-mass flywheel is always near the top of my upgrade list. You're running an awfully light 'wheel, but given the lightweight M42 & G240 components it must be a real pleasure to shift.
Awesome updates, happy to hear its back in working order!

Thanks. Yes it is a tremendous relief to have this thing running well again. It is in bad need of a full repaint job, but I guess it's a real "sleeper" at the moment. I can't believe that I have had this car for almost 15 years, and have been driving this model of car for 20 years! I will say that having a second car that is newer and more reliable helps a lot with being able to enjoy the project car.

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Visit HERE for a plethora of 318iS stuff and some other randomness.  Would you say I have a, plethora, of pinatas?

bmwman91

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Re: M42 Head Gasket Blown, Project Thread
« Reply #29 on: November 17, 2020, 03:13:52 PM »
It has been a couple thousand miles now, and I wanted to pop back in here with an update. Well, less an update than just a note. I am absolutely loving this engine and the car is more fun than ever. Whatever was wrong with the engine as it was originally built may never be known, but it is in a lot of ways a totally different beast now. It revs smoother, makes more power, makes less "hissing" noise, gets 20-30% better fuel economy, does not leak or consume oil and just generally feels more composed. Granted, I now have a really good tune for it from Sssquid, and a considerably lighter (and dynamically balanced) flywheel, but even still the engine itself is better than it was. All said, this is the sort of engine I feel like MM is probably known for building, and while it was frustrating as hell to never really feel satisfied with the original one, I am satisfied now. MM stood behind their product and reputation all along, and I would do business with them again.

I will probably never know what was wrong with the original engine that they built for me in 2012, and my only guesses are:
1) I did a lousy job of reinstalling the head after they replaced all of the valve springs (the springs they originally used were defective) and there was a pinhole leak or leaks the whole time. It seems exceedingly unlikely that a compromised HG survived 7 years of my hard driving.
2) A valve was slightly bent and not replaced when I sent the head back after the 2nd spring failed. Again, it seems sort of unlikely since they had the head totally apart to swap in the known-reliable dual spring setup (the original build used single springs).
3) MM did not correctly mark which valves came from which port, reinstalled some into the wrong locations & didn't re-lap them to the seats. This is my leading guess and I think that it would explain why so many of the issues I had seemed like they could be explained by compression loss / combustion chamber leakage.

Jim said that they did not find anything conclusive in the engine when I sent it back late last year after the HG completely failed. The cylinder bores were 0.001" out of round, which was not great, but is also not enough to completely explain the poor running. The current engine is built with a fresh block, with the bores matched to the old pistons (with new rings)...I sent the old engine back right around Thanksgiving last year, and they determined that it would be quicker to match-bore a fresh block than to try to get new pistons since supply logistics were a mess at the time. Completely machining the fresh block likely cost them more than a new set of pistons, but I appreciated the effort to turn things around fast. Anyway, if the old engine's problem was in fact #3 (poor valve sealing), they might have yanked the head apart before checking the sealing, or if it was messed up maybe they didn't want to say anything since that's sort of a head-slapper mistake. Either way, they put on their latest multi angle grind & new seats to match, so it is not an issue now (if it ever was).

Last time I spoke with MM to let them know I was pleased with the engine, they mentioned that they were developing a complete ITB kit for the M42. I think that I will give them a ring in the next week or two to see how that is coming along. Dyno data I have seen from M42's with dBilas and RHD ITB kits seem to show gains across the entire RPM range, and I would certainly be happy to get a bit more area under the curve. RHD's kit is well designed, priced well and available now, so it is one consideration. I'll see how things turn out with MM's kit. I am still very eager to get out to Missouri in the spring (fingers crossed that the COVID nonsense dies down by then) to visit Sssquid and MM. If travel is an option by then, I sort of want to get the car trucked out there for some live dyno tuning, and if the ITB kit is ready by then I can install it at MM, get the throttles synchronized and have some fun with them. Anyway, if I could hit 100HP/L I would be pretty stoked, even if that is a totally arbitrary goal.

The other item I am still thinking over is which stand-alone ECU system to go with. The "easiest" options are the PnP MS3Pro for M5x engines, and the Link E36X ECU, since both use the 88 pin connector and I would just need to move some terminals around. The other system I like is AEM Infinity 358 (can drive "dumb" coils directly) and the 508 (can't drive dumb coils, but has built-in WBO2 control and logging), with the major downside being the top-entry harness connection which would be tough to fit into the glove box and still clear the plastic cover. Motec and other motorsport ECUs all seem like they are likely to be entirely overkill for my application. I'm open to suggestions though.
« Last Edit: November 18, 2020, 12:26:57 AM by bmwman91 »

06/05/2011 - 212,354 miles
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