Car Running in "Limp Mode" on Start Up

[Burnall4]

Hi everyone, new here and I am just throwing this post up (I know before I searched) I will do a more detailed search of the old thread when I have a little bit more time, here is the problem:


Symptoms:

1. Car is cold and go to start it
2. For the first thirty seconds the car idles rough, like it has a HUGE vacuum leak, shakes the motor/car toward the end of the thirty seconds and tries to choke itself off.
3. If you hit the gas in this time the idle gets worse, sputters harder
4. If you you let the car sit for the 30 sec (avg. time) it smoothes itself out and is perfectly fine, you can drive it all you want.

Side Symptoms:

1. Car can bee driven for hours, minutes etc... when you shut it off and go back to start it depending on how long its been sitting there the same symptoms as the ones for mentioned occur on different levels of severity. But some times you can just jump in it and go?!
2. If you are driving the car immediately after starting it, you can mash down the gas and it goes no where, then as the 30 sec draws to a close you can as if the "exhaust gas" or some sort of pressure is released and you are off and going.

Thoughts:

1. it seems as if the car is running in "limp mode" closed loop/open loop.
2. It could be coming from the emissions, and the ecu not recognizing the Catalytic converter is warmed up enough to go?!?! (had experience with this in my STi)
3. Something with the cold start system is not reading properly
4. There is a small/medium vacuum leak some where adding to the problem

Ideas:

1. Replace all the "tune up" items, starting with o2 sensor
2. ECU reflash/Re-program


Help:

Please


thanks for taking the time to read this!


Burn

[nicknikolovski]

Sounds like a fuel pressure problem or a vacuum problem to me. If you have a fuel pressure gauge, check that you are getting approx 3 bar supply pressure when the engine is running. Also check around the throttle body and intake manifold for any vacuum hoses that are loose, cracked or removed.

[colin86325]

What do the spark plugs look like?

[Burnall4]

Sounds like a fuel pressure problem or a vacuum problem to me. If you have a fuel pressure gauge, check that you are getting approx 3 bar supply pressure when the engine is running. Also check around the throttle body and intake manifold for any vacuum hoses that are loose, cracked or removed.

I checked for vacuum leaks the old fashion way carb cleaner...I need to check again, visual and carb cleaner. There has to be some sort of vacuum leak along with something else that is going on, I haven't checked fuel pressure yet.

What do the spark plugs look like?

haven't checked yet, what specifics are thinking of? Fuel, oil, or carbon build up?

[AcSchnitzer318is]

Ahhh yet another poor suffering soul.  Sorry to have to welcome you to the club.  There are a little over 10 of us dealing and searching for the solution to this problem.  Other threads are:

HERE

HERE

AND HERE

[nuvolarossa]

other than lambda sensor, fuel pressure, vacuum leak, and spark plugs, how is your camshaft sensor?

[Burnall4]

I talked to my friend who is a BMW master tech and he suggested this...


"sounds like the ECU is trying to find a sensor and can't so it just cuts it out of the loop, here is what you do..."

He basically said "take the o2 sensor out and leave it out, reset the ecu and see what happens, if it does not improve replace all of your vacuum hoses. If that doesn't work , try your CPS, TPS, ICV, Check valve etc... and if that doesn't work bring it to me..."

he said there is a common Vacuum hose under the Intake Manifold that they call the aorta, it has 4 vacuum hoses going into it that commonly goes bad. He also mentioned this is not that uncommon for the m42. So I will play around with it this weekend and see.


Funny thing is, started it up this morning (it was cool outside) not a problem, same thing happened the other day when i woke up super early to take my sister to the hospital, not a problem in the world. Started up and drove like a dream from the start. The outside temp was definitely cooler than any other time, by like 10-20 degrees.


Hmmm....

[Jtuner]

Do you get a popping through the intake?

[Burnall4]

YOu know, I am not sure if I do, when I go out to my car tonight after class I will check. I got the "popping" on my 325is from the intake which was a vacuum leak.

reading all the threads I have noticed some commonalities

1. Our problem is Temp sensetive either outside or car/motor
2. Our problem is also time sensetive, how long the car sits, to driving time
3. No one has replaced their ECU completely with a new/used one


Hmmm....still working through some stuff in my head before I tackle the car. I am going to consult the manual. Tonight.

[e30beater]

im dealing with this too. i have to keep on the throttle for a minute or so just for it to idle or it dies. (i feel like a dumbass in my high schools' parking lot, lol) a mechanic suggested that the mass air flow sensor was the problem, so i bought one off Fredk. i sprayed some o2 sensor cleaner ( or something like that,) in my exsisting m.a.f.s. and it helped a little until i turned it off and let it sit. it makes me think that the m.a.f.s. is the problem, so i cant wait until my new(er) one comes in.

i cant even go past 1/4 throttle before it starts shaking and stuff (no transision, just automaticly), i always have to shift to a lower gear ( 1st or 2nd) to get up even a small incline, (those two gears hardly have any problems, first is almost normal, but after higher rpms in 2nd and all gears on up, it like my car has turned into a huge back massager)  i don't even use the highway anymore, i can't accelerate to the speed limit in time to merge. and i can't have the A/C on and let the car idle, cus it will slowly drop rpms then die.

ive fixed the vacuum leaks i had when i first bought it, (i only saw 2 hoses comming form the m.a.f.s., i replaced both).

any ways, i guess that in that huge post i was trying to say to mess with the m.a.f.s. a little bit,and please keep posting what you do, and if it helped or not, so i have an idea of what to try next : )

[Burnall4]

I don't know if its necessarily the MAF, there are some reasons I say this but I am not going to expand, until I know for sure my hypothesis is right. I will update, I really think it has to do with a sensor/ecu/vacuum problem. yes the MAF, is a flap door "sensor" but thats not the type of sensor I am talking about.



Any other ideas?

[Burnall4]

Here is some tech info on the engine, to answer some questions, some might have, found on this website http://www.esatclear.ie/~bpurcell/318isengine.html



Dimensions (nominal) : 84mm/3.31" bore x 3.19" stroke
Displacement : 1796 cc
Camshaft : Duration: inlet 252 exhaust 252 Lift: inlet 10.2 exhaust 10.2
Lobe height: 1.8755-1.8803"
Con-rods : Max. weight variance without bearing shells: 4g/14oz split equally between big and small ends
Crankshaft : End play: 0.0031-0.0064"
Thrust on cylinder 4
Cylinders : Max. ovality: 0.01mm/0.0004"
Max. taper: 0.01mm/0.0004"
Cylinder head : Height = 140mm/5.512"; minimum height = 139.55mm/5.494"
Firing order : 1-3-4-2
Fuel Pressure : 43 psi
Oil pressure : 1.3-2.0 Bar/18 psi @ idle, 4.0-4.3 Bar/57-62 psi at 6250rpm
Oil Filter : Hengst E88H D24 in-bowl type
Oil Type : I would recommend a 5W40, 5W50 or 10W50 fully synthetic (the text book says 15W50) as the tappets seem to prefer a lower viscosity oil
Output : 134 (cat) -136 (non-cat) bhp @ 6000rpm; 127 ft-lb @ 4600 rpm
Pistons : Clearance: 0.0004-0.0016"
Piston rings : Gap: Top & bottom compression rings = 0.0080-0.0160" ; oil ring = 0.0080-0.0180"
Compression pressures : 10-11bar (143-156psi):
Torques : Big ends: Step 1 = 23Nm/17 ft-lbs, Step 2 = +70 degrees
Camshaft sprocket: 13-17 Nm/10-12 ft-lbs
Camshaft bearing cap bolts: 13-17 Nm/10-12 ft-lbs
Crankshaft damper: 300-320 Nm/217-231 ft-lbs
Cylinder head: Step 1 = 30-35Nm/22-25 ft-lbs, Step 2 = +90-95 degrees, Step 3 = +90-95 degrees
Exhaust manifold: 22-24Nm/17-18 ft-lbs
Flywheel: 82-94 ft-lbs
Intake manifold: 13-17Nm/10-12 ft-lbs
Main bearings: Step 1 = 20-25/14-18 ft-lbs, Step 2 = +47-53 degree turn
Viscous fan coupling (LH threads): 40-50Nm/29-36ft-lbs
Timing chain tensioner: 23-27Nm/17-19 ft-lbs
Valves : Seat angle: 45 degrees
Valve stem to guide clearance: 0.020"
Inlet: Solid, stem diameter 6.975mm/0.2756", head diameter 33mm/1.299"
Exhaust: Sodium filled, diameter 6.975mm/0.2756", head diameter 30.5mm/1.201"
Seat diameter: inlet = 31.6mm/1.244", exhaust = 29.1mm/1.146"
Seat width: 1.4-1.9mm/0.055-0.075"
Valve clearance : None, automatically compensated by hydraulic tappets



Fuel System
Injectors: Flowrate: 170 cc/min
Test pressure: 3 Bar/43psi
Coil resistance: (@20 deg C/68 deg F): 15-17.5 Ohms
Ejection angle: 30 deg


Ignition
Motronic : Bosch DME 0-261-200-175 Software version 1.7 (US details)
Spark plugs : 16mm 3 electrode NGK BKR6EK or Bosch F7LDCR. The Champion RC8DMC can be used too. Note a 4 electrode platinum plug has been approved for the M42 engine with max. 100,000 miles life, BMW part# 12 12 9 071 003, NGK BKR6EQUP or Bosch FGR7DQP.
Installation torque 27-33Nm/20-24ft-lbs
Plug gap : As specified above, they are unadjustable (pregapped) otherwise 0.027"
Idle Speed : 850rpm

[Burnall4]

More research

http://www.r3vlimited.com/board/showthread.php?t=89925

put a 10$ inline fuel guage in. then see if it holds pressure after you shut it off. if it is dropping to 0 then the FPR or the fuel pump check valve is faulty. You can test the FPR by pinching the return line when you shut the engine off. If the pressure drops it is likely an $11 check valve. i can get the pn for you if this is the case. If the pressure does not drop then the FPR is at fault.

Does this mean you have the hard start problem? I recommend you try jumping the fuel pump relay before starting the engine in order to pressurize the fuel rail when you usually experience the hard start to rule it out… while it is a cheap, simple solution there are a number of other issues that show the same symptoms. One typical issue on the M42 is the ‘flying saucer’ check valve ($63 part number 11157501567) for the PCV system if the engine is also running rough and is difficult to start, especially when cold. To rule it out pinch the hose off when the engine is warm… if the idle smoothes out that’s it… the base seal can also leak so try some butane, propane, or ether at the base to see if the engine smoothes out.

also check crank sensor gap, and crank sensor resistance, both hot and cold. a new sensor cold is 960 ohms +_ 10%

Kowalski's post

[Burnall4]

Ok, so although this issue is almost resolved, I figure it can help someone out who might be having similar troubles.

My 1991 E30 318 has had a lot of issues lately. Outside of the suspension needing an overhaul it started to idle funny, randomly the idle would jump from 650-1500 RPM, and basically i had no idea what was going on.

I though to first clean out my throttle body and any surrounding areas. This seemed to help a little, but the problem with the funky idle persisted.

From there I checked some vacuum lines, found one to be cracked. Fixed most of the funny idle, but still issues.

Changed my throttle position sensor( this is not found in the 325's, those have ICV's{idle control valves}). that did..well nothing for me.

I just learned to deal with the problem till the car finally stopped running. It would turn over, was getting fuel to the engine. I had no idea what was going on. Car left me stranded..first time ever. Took it to a local mechanic(works on BMW's full time at a shop but he took me in as a side job.) had him look over the entire car.


Now what he is telling me is that the ECU's from the late E30's have ECU issues. Basically would have to swap out the ECU. I guess the soldering is not of the highest quality on all of the ECU's. He has seen more and more issues like this lately.

Solution for me is going to be garaging the car till i have money to fix it. Was going to sell it, but i just cannot let me baby go. Shell get a makeover after i graduate college. E36 M3 engine would be sweet.

So...if you have a E30 318 with random "not starting" issues consider the ECU. If you have a rough idle check the vacuum lines, clean your throttle body, and maybe check your throttle position switch(which mine was not working up to par, so i switched it out..but it didnt fix my main problem).
__________________



From

http://www.unitedbimmer.com/forums/e21-e30/12654-m42-318-wont-start-ecu-problems.html

[Burnall4]

I am still leaning to it being a ECU problem.... logic step by step based on all that has been done to the everyone else's car leads back to the ECU might be different from car to car, but if we are making generalization, it would make sense?!