'86 325es startup issue

[Hoon]

Hey guys, so i have a 1986 325es and whenever i start the car, my idle is pretty weak and there is a pretty prominent petrol smell. Sometimes the idles fluctuates up and down between 700-1200 rpms just briefly. The idle and smell get a bit better after around 5 minutes. This leads me to believe that the cold start valve is malfunctioning as i have replaced plugs wires cap and rotor along with my IACV.. would really love to diagnose this issue so any help is much appreciated.

Thanks Guys! -Eames

[Hoon]

Bump

[dnguyen1963]

Well, if you have unburnt petro then just follow this equation for troubleshooting

Engine running = Fuel + Fire + Air (assuming with correct compression)

You have too much fuel so check your ignition system and perform a smoke test to check the Air component. Hint - fluctuating idles often can be attributed to vacuum leaks.

[Hoon]

'86 325es startup issue

Thank you @dnguyen1963 I'm going to check for obvious vacuum leaks and depending on how that goes will probably smoke test...

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[Hoon]

so i've went and had a smoke test done, there was a minor vacuum leak from the valve cover hose that goes to the throttle body ( i believe the crankcase vent breather ) so i sealed it up. no more leaks but little to no change.. still having a minor and occasional missfire on idle and very very subtle hesitation going up the rpm range... any more info much appreciated

[Seawolf]

...still having a minor and occasional missfire on idle and very very subtle hesitation going up the rpm range...

A couple of suggestions: Bad O2 sensor causing rich mixture, and what's your fuel pressure look like ? Check the FPRV vacuum line, if there's fuel coming out of that then that's where your fuel smell is coming from and the FPRV is toast.

Let us know how you get on.

[Hoon]

Let us know how you get on.

Well it looks like I'm going to adjust my valves and see if that clears things up. God knows when the last time it's been done was :pp

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[Hoon]

Adjusted my valves and gave her an oil change with 10w40 it seems to have smoothed out quite a bit but there is still a subtle miss fire on idle... Trying to figure this thing out... Maybe corroded ground or sloppy injector? Would a faulty AFM cause this?

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[jlevie]

The odds are that you need a new OE/OEM O2 sensor. The scheduled replacement interval is 100k. The DME uses the O2 sensor data to adjust fuel trim and it remembers that trim until the DME is reset by a battery disconnect.

I don't know what ignition parts you used, but anything other than BMW OE/OEM parts are suspect. Use NGK ZGR5A plugs.

As mentioned above check the rail fuel pressure and check the components of the cold start system. If the car has over 100k on it, there is a good chance that the injectors need to be professionally cleaned, rebuilt, and flow tested. I use RC Engineering and they will give you a report showing the flow rates before and after rebuilding.

[CorvallisBMW]

Do you have the Bentley E30 manual? It has an excellent section on testing/troubleshooting the M1.1 (325e) cold start systems.

I would check your cold start injector first. Simply remove if from the intake manifold and verify that it's spraying on cold starts. You can also rent a fuel pressure tester and test for the correct fuel pressure (should be 2.5bar) right there at the injector.

I would also consider replacing your engine temperature sensor. It's a $10-$15 part that tells the engine how much extra fuel to inject during cold starts, and can often cause cold start issues.

And as jlevie said, replace your plugs too. For $2/each, you really can't go wrong.

[Hoon]

Do you have the Bentley E30 manual? It has an excellent section on testing/troubleshooting the M1.1 (325e) cold start systems.

I would check your cold start injector first. Simply remove if from the intake manifold and verify that it's spraying on cold starts. You can also rent a fuel pressure tester and test for the correct fuel pressure (should be 2.5bar) right there at the injector.

Welp im going to get my injectors flow matched by an injector shop in the area that i have used before, hopefully that helps, may look into a refurb afm and new 02 sensor... but i am thinking very hard about doing a b25 swap... i love my eta but the b25 just seems like slightly better platform to work with. So if anyone knows of a b25 for sale that is failry budget friendly, i would be interested, specifically an 87 b25!

[Hoon]

I don't know what ignition parts you used, but anything other than BMW OE/OEM parts are suspect. Use NGK ZGR5A plugs.

all parts ive used on the car have been OE, most from turners ;)

[rwh11385]

This thread is helpful for sorting out our current issues on the 325e but also makes me want to swap it out for a later i engine to avoid the headaches plus get more power...

[JeLani]

Adjusted my valves and gave her an oil change with 10w40 it seems to have smoothed out quite a bit but there is still a subtle miss fire on idle... Trying to figure this thing out... Maybe corroded ground or sloppy injector? Would a faulty AFM cause this?

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My ES 2.7 stroker/885 had that same misfire you're describing. every few seconds at its highest idle rpm it'll misfire, you can feel it blow if ur standing near exhaust. Do your accelerator choke/hesitate sometimes too? this happens to me sometimes after coming down from about 6.8k and i'll have to tap the gas.