Author Topic: Reviving the e30, issues (Read 3010 times)

spanish_pants · « **on:** December 02, 2011, 04:48:23 AM »

It�s been a while since i�ve been on the forum but since i�ve decided not the scrap the e30...

I�ve got a few things i have to deal with on the car. One of them is that i�m getting a strong smell of gasoline from the exhaust and the car goes through some coolant.
On the thought that it might be a blown head gasket or a crack i pulled the plugs and changed the oil. The oil came out fine, there was no coolant in any of the cylinders, no bubbles from the expansion tank or oil mixed in with the coolant or pressure in the tank when cold.
If i fill up the coolant to the cold line with in a few days it drops about and inch and half and stays that way so i�m guessing i might have i leak in a line somewhere. I still want to have the engine pressure tested just to be sure.

The plugs were a normal color except for plug #1 wich came back with what look like coal like chunky black deposits on the tip. I�m not sure what this might mean. But i also get a smell of gasoline from the exhaust when the car is running. Could it be related?

On the good side the MarkD chip which i bought 3 years ago and didn�t work on the car, now works. Looks like it was an issue with ecu compatibility.
I changed out the ecu from my non-cat car to an ecu from an e30 with a cat. Works! As soon as i get an o2 sensor welded in i�ll run the new chip permanently.

This brings me to another question regarding the airflow meter...it�s been tampered with. It was adjusted by a previous mechanic so that the car would pass emissions. He said he adjusted it so it would run lean.
Is it possible to adjust it to its factory settings?

Thanks in advance

spanish_pants · « **Reply #1 on:** December 04, 2011, 09:43:05 AM »

Here is a picture of the spark plug from cylinder #1. You can make out the crusty crystalized deposits. The other plugs looked to be fine.
Taking into account the strong smell of gas at the exhaust, and the fouled plug, could it be a stuck valve?

DesktopDave · « **Reply #2 on:** December 04, 2011, 10:33:41 AM »

I'll bet from looking at that plug that you're running rich on that cylinder. If your compression is good I'd check the injectors & coil. A bad coil can damage the driver and vice versa. Don't run the good DME for long until you've checked the coil...a bad coil will eventually destroy the DME.

Alternatively, you might have a bad coil and/or damaged coil driver in the bad DME. If you have some time, open it up & take a look at the driver transistors at the right side of the board...they're under a steel clip & plastic insulator. Usually it's easy to tell if they're bad...they will look visibly burned-out. PM me for some pictures if you're ion doubt. If the DME is bad, would you sell it for a few bucks? I'm looking to resurrect one of mine that died the same way...

Yep, the AFM can be adjusted. Pop off the plastic cover (it's only a bead of silicone sealing, most likely). Adjust the clock wheel one notch at a time. It's not a process for the faint of heart, I'm afraid. I'd be tempted to try it out if I had an EGO setup though.

Here's a writeup for the Bosch AFM:
http://www.gomog.com/articles/EFIflap.html
It's an earlier model (I'm betting off an LH-Jet system) but they're all very similar. Ignore his description of the CO pot screw, it's only effective if you plug those two wires together on the firewall for non-cat cars.

spanish_pants · « **Reply #3 on:** December 04, 2011, 10:58:30 AM »

Hello Dave, thanks for the reply!
Currently i�m running Mustang injectors on the car and replaced the wires with new 8.5mm Magnecors. If it is a bad injector then i�m going to need to buy a couple of new injectors as backups.
If it�s a coil then i�ll pick up a few of them from the junkyard this week when i go.
When i have a moment i�ll take the DME out and take some pictures as i don�t have a clue what to look for. If by any chance it is damaged i�ll happily send it to you, if you don�t mind paying the shipping from Spain.

The motor idles a little roughly and sounds rough on start up. As well when i rev the motor i can hear a small rattle from the area of the first cylinder. It doesn�t sound chain related.

Apart from the problems you mentioned, what else would cause a rich situation on a single cylinder?

DesktopDave · « **Reply #4 on:** December 04, 2011, 11:14:18 AM »

To be totally honest, I've only seen plugs like that on my bikes. FI solves so many problems. The mid-80s Honda V4's I run have a nightmare quad-carb setup that is very difficult to tune...reading plugs is an unfortunate requirement.

Hopefully it's just a bad plug. If it's internally shorting I'd guess it'd look like that too. I suppose it could be an intake problem too, but that's a very slim possibility. Too much fuel, too little air or too much oil...just eliminate the possibilities one by one. I'm no expert, either...I'd strongly recommend taking it to a pro & getting a 2nd or 3rd opinion.

NGK has a decent writeup here, give it a read...I trust their opinions, NGK makes my plug of choice.

DesktopDave · « **Reply #5 on:** December 04, 2011, 08:35:51 PM »

I found this classic writeup on the AFM too...excellent work from this Porsche nut...theory, design, model subtypes, lots of excruciating detail. He doesn't recommend changing the spring tension, but I'd say go for it. It's clearly designed to be tuned a bit.

spanish_pants · « **Reply #6 on:** December 12, 2011, 03:05:59 AM »

Thanks for the links Dave, great write ups.

The car will be going to the shop next week so i can get an experts opinion. In the mean time i took advantage of the fact that it�s a long holiday here and tinkered with the car.

I discovered that the tiny rattle i had is coming from the throttlebody. I mentioned this to my friend only to discover that his does this as well.

As of yet i haven�t taken the DME out or tackled the AFM. I may try during the Xmas holidays. Ideally in order to reset the AFM to factory settings, a picture of an unmolested unit would help. I�ll see if any forum members can help.

I then decided to tackle the rich running cylinder and fouled plug. I removed and cleaned all the plugs and added some dielectric grease. I ran two bottles of gasoline treatment and ran the tank almost dry. I then filled up with 98 octane and added some injector cleaner to the tank.
When i removed the plugs they were all clean, including the one in #1 cylinder. Also, the strong smell of gasoline from the exhaust is now gone.
I also decided to replace the airfilter while i was at it, since i can�t remember the last time this was done.

Yesterday on the drive home i decided to give the car a run up to 6000 rpm and i noticed a large cloud of smoke out of the exhaust. I shifted up and again ran it up to 6000 rpm and again a cloud of smoke.
Naturally i was a bit worried so i pulled over. I couldn�t really find anything wrong visually. The car ran as well as before, so i tried to replicate the events that led up to the smoke. I couldn�t get it to happen again.
Perhaps the high reving may have loosened all the crud in the motor and sent it on it�s way.

Anyway, as i said the car is going to the mechanics sometime this week for a thourough check up.