325 Cab Not Starting - After Words of Wisdom

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MunsterScot
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Sat May 25, 2019 2:44 pm

Hi All,

New to the forum and unfortunately my 2nd post is to ask for help (My 1st posy is in the new members section).

I picked up a 1989 325i Cab about 3 - 4 months ago. Had been parked up for a while but running fine and in decent condition. Bit of work and got it through its test.

In the past couple of weeks ist started to give bother. Sometime it own't start, sometime it starts and drives fine and other times it starts, runs for a bit then cuts out. Like this morning, started fine, ran into town, cut out and wouldn't start, left for about 15 minutes and she started, drove her home and now she won't start.

Work done before problems started:
- Put Forte fuel system treatment in tank
- Put other injector cleaner in next tank
- New NGK plugs

Just before the problem seemed to start (might not be related):
- Cleaned ICV with carb cleaner & WD40
- Cleaned Air flow sensor with contact cleaner
- Cleaned air intake
- Changed Fuel filter - got garage to do this as I could get to it with the jack

Since problem started:
- New distributor cap
- New rotor arm

Tests done today (from info read from the forum):
- Power at fuel pump
- When turned over fuel pump operates
- Tested fuel pump relay and DME relay = both good
- Bridged out DME relay: ICV buzzes but won't start
- Power to coil - check using a bulb
- Check coil with multi-meter and good
- Checked main cable from coil to cap with multi-meter and good
- Removed spark plug cap 3, connected to an old plug and left it on rocker cover. When turning over = spark
- Removed fuel return line for fuel regulator = fuel coming out the regulator when turned over

So, I have spark at the plugs and fuel at the fuel rail but still won't start (couple of times it nearly did).

I'm think new fuel pump as I've read on the forum that even though the pump is working it might not be getting to pressure (I don't have a gauge to check pressure).

Or, could there be the chance it is the injectors and with the fuel cleaner and new filter crud is stuck in them?

Any word of wisdom appreciated.

Thanks.
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BenHar
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Sat May 25, 2019 7:51 pm

MunsterScot
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Sun May 26, 2019 4:55 pm

Thanks BenHar.

Update:

When out to car this morning to try and start it (had been sitting outside overnight). Started but rough and then stopped. Had another read through the Engines Trouble shoot.

Checked the blue temperature sensor - initially reading approx 2.3K Ohm.

I checked the C191 connector. No signs of corrosion. Sprayed it with contact cleaner anyway and reconnected together.

Car started bur rough and ticking over about 1800 rpm. Checked the throttle cable and had to slacken it off. I'm guessing this after cleaning the throttle body. Ticking over but still rough. Also , when pressing the throttle would almost die then pickup.

I then found out that if i disconnected the airflow meter (AFM) and the moved the throttle it would rev OK so thought the AFM might be on the way out. Stopped and restarted and after a couple if minutes started to tick over with AFM connected. Does the ECU need time to 'learn' the readings (I had the battery disconnected yesterday to charge it)?

Once warmed up the blue temperature sensor was reading about 300 Ohms so I think it is good.

Tried to start it a few during the day and it started and ticked over but sounds like it has a miss now and again (could be my imagination though).

My guess is it might have been the C191 connection starting to give problems and with disconnecting it, spraying it with contact cleaner and reconnecting it has fixed it (at least for now).

Next step: Planning on changing the fuel pump (for a cheap one as a trial) anyway as I've read it can also cause strange things to happen.

Will keep you posted if the new pump makes a difference.

Alan.
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BenHar
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Sun May 26, 2019 6:09 pm

MunsterScot wrote:
Sun May 26, 2019 4:55 pm

Does the ECU need time to 'learn' the readings (I had the battery disconnected yesterday to charge it)?
Yes, you are supposed to let it idle for ten minutes thane take it for a "spirited" drive.

Ben
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arrisbmw
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Wed May 29, 2019 7:41 pm

sounds like you've check a lot, only one component you didn't,y mention is the CPS. if that is failing could give you all the issues your having.
check out wiki on here
MunsterScot
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Thu May 30, 2019 7:05 pm

Thanks BenHar & arrisbmw. I'm fitting a new fuel pump tomorrow then I'll reset the ecu and take her for a spin and report back.

I didn't think it was the CPS as in the Wiki it says "More specifically, there will be no spark or fuel." and I had both.
MunsterScot
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Sat Jun 08, 2019 2:52 pm

Update:

Fitted new fuel pump last weekend, reset the ecu and took car for a drive and everything ok. Yesterday took the car out and about an hour into the drive it died. Eventually restarted and would cough and splutter and then all of a sudden was OK again. Later in the day a 1 hr drive and it was OK.

Idle was low so I checked the TPS. Working OK for closed throttle but not working at 2/3 open. Found dry contact inside switch so re-soldered it.

While the throttle body was off I opened and cleaned the C101 connector with contact cleaner.

Put all back together ensuring all sealed and pipes cable tied to prevent leaks. Reset ECU, let idle for 10 min (was still around 600 rpm on the rev counter) and then took for a run.

Ran fine for approx 30 - 45 min then cut out. Eventually started again. Now some times the car will rev to 2000 - 2200 on its own (should be idle). Some times it drops back to idle on its own some times it doesn't. Disconnecting the ICV no impact. Disconnecting the AFM sometimes causes it to cut out.

When it does idle I've sprayed WD40 around the pipe connections, etc. to see if there is any air leaks but no change in revs.

Also, somebody before me has been at the AFM as the cover to the electricals is slack and comes off. Could this be a cause?

Any ideas what it could be? Could it just be the ECU still learning the new settings and it will take a bit more time?

Thanks.
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BenHar
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Sat Jun 08, 2019 5:24 pm

When you checked the C101 did you pull back the rubber and look at the wires coming out of the underside?

They can get badly corroded.

Ben
MunsterScot
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Sun Jun 09, 2019 12:01 pm

Stripped it all back out again this morning to re-check the C101. Looked OK on both sides with the rubber pulled back. Contacts inside the plug also looked OK. Bit the bullet anyway and cut the C101 out and soldered wire between the two sides. Rebuilt and she started but cut out a couple of times when doing the 10 minute tick over after re-connecting the battery. Took her for a run and she ran OK. Got back home and still idle low and sounded like it might cut out. I had a read of:

http://bmwe30network.net/forums/read.php?3,9615

and adjusted the AFM slightly (last owner had already been at it) She's ticking over better now but still seems a bit low and sounds like it has a slight miss now and again but it but could be my imagination. I'll reset the ecu again and then take her for a run this afternoon and see what she is like.

I'll need to see if there is somebody close to me that has a CO meter and can set up the AFM properly.

Would checking/adjusting the valve clearance also help her idle better? I don't know the last time they were done.

Thanks.
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