Scratching me head...new BMW owner.

[wilholl]

Something to read from Spece30 forum:

The idle switch should close when the throttle stop is 1mm off the idle speed screw. That tells the DME that the engine is idling and accordingly what fuel map to use and to use the ICV for speed control. When the idle speed screw is correctly adjusted the engine speed should be 950rpm with the ICV disconnected and drop to 750rpm when the ICV is connected if the idle switch in the TPS is correctly adjusted. So on an engine at normal operating temperature, you adjust the stop screw for 950rpm. Then adjust the TPS so that the idle switch closes when the stop arm is 1mm off the stop screw. While you can check the TPS at it's pins, the best check is made at the DME connector. That eliminates any possibility of a faulty engine harness interfering with those signals.

The WOT switch should close at about 40% of full throttle, as I recall. When the WOT switch closes the DME shifts to a different map and ignores O2 sensor data. At 4500 rpm the DME stops using AFM data as the flap should be fully open. From there to the redline the DME uses only engine coolant temperature and rpm for fuel delivery and spark advance. I think the DME uses a different map from 4500rpm up, but I've heard conflicting opinions on that.

All of the maps are subject to learned fuel trim, which is based on O2 sensor data taken at part throttle. Since an aged, but operable, O2 sensor typically indicates a leaner mixture than actually exists and we don't have catalytic converters that can be damaged by high HC in the exhaust, there can be a slight benefit from using a aged sensor.

Understand that learned fuel trim and fault codes are stored in volatile memory and are lost if the DME looses un-switched power. If your kill switch disconnects all power, every time you turn off the switch that data is lost.

The WOT switch is important. If the DME doesn't see that data the engine will run a bit lean above 4500rpm with a consequent loss of power.

Oil can, and will, leak into the TPS. The switches are simple open metal parts and oil will interfere with their operation. I highly recommend drilling a 1/8-3/16" hole in the center of the round boss on the bottom of the TPS. That gives the oil a place to escape and makes the TPS last a lot longer.

If desired, you can plug the hose from the ICV to the throttle body (best solution) or disconnect the ICV and use the stop screw to set a higher idle. The downside is that you may have to hold some throttle in cold weather until the engine warms up a bit. The upside is that the water pump will be spinning a bit faster and be moving more coolant. That helps to keep the peak engine temp from spiking so high in a red flag situation. I liked an idle of 1200-1500rpm.

Also, I had some similar problems with my e30 sometime ago. I found that I had water in the connector for the fuel injector harness (underneath the intake manifold). As well as some water inside the o2 sensor harness connector. when I resolved the moisture issues it ran 100% better. I did adjust my TPS so that it worked when the throttle closed, this helped in smoothing the idle. It stopped hunting for idle (RPM's jumping up and down).
I hope any of this helps!

[Bggdnssnguy]

That's what I'm thinking also. I have been busy and getting my truck running for this weekend. So I'll check later this weekend for leaks. It's only thing keeping me from daily driving it.

[Ether-D]

That sounds like a vacuum leak to me.

[Bggdnssnguy]

It also sounds like your icv is sticking. Remove it and wash it out.

Will this being dirty cause the idle to be at 1,000 rpms? And have no brake pedal while in drive but a firm pedal in park? I just bought my first BMW. And I'm having this issue.

[Jdbush2010]

Updating. Slowly but surely it was getting worse and worse. So I did some searching and read that if the o2 sensor is disconnected the ecu will run on default. So the other day I was really frustrated and grabbed my knife and cut the wiring that somebody had done (wasn't very well done and didn't have a connector anywhere). Ran great aside from idling higher. But it gave me enough to realize an issue. I plan to install an o2 and correct wiring as well as a plug for easy connection and disconnection. I also plan to replace the o2 heater relay. Thanks for everyone's ideas

[Jdbush2010]

I'd wait til the new CPS gets there and then form an opinion. The used one could still be bad. Don't give up on the car. You're almost there.

I haven't fully given up but my hair seems to be getting thinner at an accelerated rate. The cps did help a ton. Also may switch back to the other afm. It's a new unit supposedly and it's a free swap. I checked the icv last night and it was filthy. I have two of them. One I got recently and one that came on the car. I put the cleaned new one on. I don't know if it matters but I unplugged the tps and it did nothing for idle or wot. I need to invest in my own multi meter soon

[Ether-D]

It also sounds like your icv is sticking. Remove it and wash it out.

[Ether-D]

I'd wait til the new CPS gets there and then form an opinion. The used one could still be bad. Don't give up on the car. You're almost there.

[Jdbush2010]

Well may have spoken a little too soon. It started doing its thing again unfortunately. Last night it ran great. I'm so confused. I've never had a car be this much of a pain before

[StereoInstaller1]

Awesome. The Motronic 1.3 setup is super simple, easier than TBI even!

[Jdbush2010]

So took the crankshaft sensor off to inspect it and found the wire had been rubbed down to the core. The yellow wire to be exact. My problem was I ordered one yesterday and it wasn't to be expected until Friday. So got ahold of my guy who is parting out a couple e30's and he had just the one I needed. Granted it was an hour drive one way but the cps was brand new! Didn't have a spot of oil on it and scored it for 20 dollars.
So I installed it. Ran great then slowly got worse. Couldn't figure it out. Drove it rather hard when I was headed home because I was kinda pissed at it. Turns out she looked it. Cruising speed it was grand, never acted up once. Idled at the stop lights and all perfectly. Granted it was 1100 rpm but still better than erratic and around 500. So I'm crossing my fingers that it is all fixed. I'll keep updates

[Jdbush2010]

https://youtu.be/aaho_TA1cdI

There is the link. I'm not sure how to upload lol

[Jdbush2010]

Hey man, welcome to R3V. I too was a GM tech for a while, but the E30 was just too big a draw.

Got a fuel pressure tester? Im guessing some sore of fuel pressure issue...leaky injector, leaky FPR, bad vacuum line, something along those lines, In a GM one might assume TPS for the issue you are having, the E30 TPS is just a WOT sensor, doesn't care about nothing, it's just a toggle switch.

Best of luck, and welcome to R3V!
Luke

Thanks man! I pulled the injectors out a couple days ago and none leaked. I haven't had the chance to flow them or anything. It hold good pressure and doesn't leak off. Cold starting isn't an issue either. Within a couple cranks it's up and running. It doesn't have a cold start injector. I have a video to upload and hopefully you guys can learn from it. Makes it a bear to drive in town and it's ruined the fresh oil change...

[StereoInstaller1]

So I just recently bought my 1986 325es. I've been searching and searching and trying stuff but to no avail. Specs on the car:
1988 super Eta 2.7it bottom end
1988 2.5it head
Full motronic 1.3 harness
Intake swap
272 cam
E36 Bosch blue top injectors
Tuned ECU by MarkD
Ireland engineering long tube headers with MagnaFlow muffler

Here's the problem I'm having. It runs super rich after a few minutes and hardly wants to idle. Sometimes it's great for a little while longer depending on how hard I beat on it. When driving at minimal throttle cruising it will start to buck and miss and sputter but when I give it more skinny pedal it clears out and takes off like crazy. I don't like running it that hard must to be able to drive. It's my daily so I have no other options but to drive it.
If it acts up and I beat on it it will clear up and be fine for a short while then start again.
I have checked for vacuum leaks, no smoke test. Just the carb and coke cleaner method.
Changed both coolant sensors (gauge want working properly)
Changed maf with known working unit as well as tps, icv, icm, and fpr.
Put new plus in, and it helped some
Checked the o2 sensor and it was dirty, I was assuming it was due to running rich. The hard wires were also twisted and black taped... So I stripped them back to the good, non corroded parts and soldered and heat shrank them.
I did check the c191 and went ahead and did the fix for that for good measure.
Now I have gotten the car to run great with no problems for a couple days last week... Then it returned just as I was telling my buddy how glad I was that it was fixed. Just my luck.
So here I am not knowing what it is or how to start.
I have only tested one thing and that was the cts. Coolant sensor tested good. Had the correct resistance. Now when I checked the ecu it wasn't cooperating. Cts read I think 330 ohms whereas ecu was reading somewhere like 1400 ohms if I remember right.
Any input is nice. Sorry if it's in the wrong section, this is my first post and I'd really like to enjoy my car. I was pro gm before but love my e30. Thanks! I hope that's enough info

Hey man, welcome to R3V. I too was a GM tech for a while, but the E30 was just too big a draw.

Got a fuel pressure tester? Im guessing some sore of fuel pressure issue...leaky injector, leaky FPR, bad vacuum line, something along those lines, In a GM one might assume TPS for the issue you are having, the E30 TPS is just a WOT sensor, doesn't care about nothing, it's just a toggle switch.

Best of luck, and welcome to R3V!
Luke

[Jdbush2010]

I'd also swap your tuned DME with a stock one and see how that changes things.

I swapped the dme and the ecu with stock units with no change. If I keep throttling at cruising speeds there isn't a problem. I could do this but some of the law enforcement around here may frown upon that