'87 325e Runs Rough, Stumbles, Stalls

[BMWtyro]

Our all-original (no mods) '87 325e with A/T runs very rough at idle, and stumbles (and sometimes stalls) upon acceleration. I increased the idle rpm to make it marginally drivable for my wife (it is her car; please see linked video below).

The air filter is clean, the fuel filter is new, the engine stalls immediately when you slap your hand over the air intake (so presumably no vacuum leaks) . . . so what is my cheapest course for diagnosis at this point without simply throwing tons of money and time at it?
https://youtu.be/kPbqxY5Oyzc?si=xwa89XUgf7brDxSO

[Cameron Sanchez]

Could be something with the icv some people clean it others say don’t or it could be something with the idle computer or the blue coolant sensor there’s a bunch of answers out there and ways to check things before spending a bunch of money just some ideas though

[BMWtyro]

Thanks, Cameron.

Please remind me where the ICV is located.

Does the car "object" to being run with coolant other than blue? I am currently using green, so please let me know if this causes a problem.

Jeff

[Cameron Sanchez]

The icv should be on the passenger side on the held on the valve cover with a bracket and by blue coolant I meant a sensor located on the thermostat housing it’s blue and can affect idle if it’s bad but if you have a multimeter you can test it to see if it’s bad before you buy one

[Cameron Sanchez]

Another follow up to the icv location it’s the thing that runs across the top of the intake with the hoses and is attached to the valve cover with the bracket

[82eye]

Thanks, Cameron.

Please remind me where the ICV is located.

Does the car "object" to being run with coolant other than blue? I am currently using green, so please let me know if this causes a problem.

Jeff

pray it isn't the icv. it's the cylindrical piece off of the afm boot with electrical connection and L shape for two hose connections. they are crucial to maintain idle and no longer available.

green coolant will eat the aluminum right out of all your coolant connections causing piles of leaks and eventual massive engine failure.

[tomstin]

The best all in one place for idle explanation and trouble shooting guide I have found is here: http://www.verrill.com/car/idle/e30_idleproblem.shtml

Vacuum leaks are probably the number one problem with idle issues. Holding your hand over the intake and it stalls is not a good test. Very small amounts of un-metered air will cause idle problems. The only valid test is a smoke test. Most shops could provide that service for a fee of course. Cracks in the intake boot, and the hose from the ICV to the throttle body are prime culprits. Look for a local independent BMW shop.

Good luck!

[BMWtyro]

Thanks, eye; I was unaware of those issues!

- - - Updated - - -

Thanks, Tom!

[BMWtyro]

Wow, great info! Thanks, Tom!

[BMWtyro]

First: Tom, that diagnostic technique you suggested doesn't seem to be simple enough for this old man to manage; sorry.

Recap: '87 325e sputtering/stalling at idle and upon take-off. Runs smoothly going down road, goes like stink when you floor it.

New info: I removed and cleaned the ICV with Berryman's B-12 spray carb cleaner: no change whatsoever. Then I checked all of the adjacent hoses; no damage found.

The idle does not change (nor does the car stall out) when I slap my hand over the tailpipe. A substantial exhaust leak is confirmed, somewhere in vicinity of the cat. Could this be the culprit?

We spent $1,800 when we took this car to a Bimmer specialist late last year; I just can't afford to do that again right now, so any further help will be very appreciated.

Jeff

[82eye]

First: Tom, that diagnostic technique you suggested doesn't seem to be simple enough for this old man to manage; sorry.

Recap: '87 325e sputtering/stalling at idle and upon take-off. Runs smoothly going down road, goes like stink when you floor it.

New info: I removed and cleaned the ICV with Berryman's B-12 spray carb cleaner: no change whatsoever. Then I checked all of the adjacent hoses; no damage found.

The idle does not change (nor does the car stall out) when I slap my hand over the tailpipe. A substantial exhaust leak is confirmed, somewhere in vicinity of the cat. Could this be the culprit?

We spent $1,800 when we took this car to a Bimmer specialist late last year; I just can't afford to do that again right now, so any further help will be very appreciated.

Jeff

smoke test it. you can diy a smoke tester. start with that as any other fix will be defeated by a vacuum leak. then get into the rest of the diagnostics. you won't find the issue slapping your hand over any orifice ... at least on the car ..

does the icv buzz when you key the ign on?

edit : fix the exhaust.

[BMWtyro]

The Sputtering / Stalling Saga Continues: New Info

I pulled the 325e's plugs, and they looked pretty bad so I replaced them with a set of new NGK equivalents to Bosch. It improved the idle quality slightly, but the problem is still present.

I didn't have much luck measuring the resistance in the old plug wires, at least not the way that the Bentley's manual suggests.

An observation: when the car is in gear at idle (automatic trans), the idle smooths out and the sputtering and stalling largely disappears. Also, the thing runs like a raped ape when you put your foot into it (you're doing 70 uphill in maybe 10-12 seconds).

And one more thing: since the sputtering/stumbling/stalling has begun, the clock displays (flickering) "4.0 ME FDat". I think the car may be possessed . . .

[82eye]

start with this : Diagnostics, tips, & tricks by Jim Levie (E30 Jedi Master) (bimmerforums.com)

[BMWtyro]

Thanks, eye!

Jeff

[BMWtyro]

Somewhat encouraging progress report: I checked a couple of spark plugs, and found a fairly large degree of carbon buildup plus visible wear on the electrodes.

So I changed them (used NGK equivalent to Bosch WR9LS) and the car now runs nicely off-idle, and even at idle if the automatic trans is in a forward or reverse gear.
But . . . as soon as I put it in park or neutral (i.e., unload the engine), it is back to spitting, sputtering, surging . . . though not quite as bad as it was, and it never stalls-out.

The only other thing out of the ordinary that I notice is that there is a nearly-imperceptible "surge" at a constant speed (45-55 mph). It almost feels as though the volume air flow sensor "flapper" is not holding a consistent position, though the variation is not enough to show up on the tach.

So: do these symptoms sound familiar to anyone? Suggestions? I feel as though I am "this close" to solving the problem.

Jeff

[82eye]

what did the smoke test reveal ?
sounds exactly like vacuum leaks. they'll only get worse until they foul another component and then you'll have to chase multiple issues.

smoke test first and eliminate all vacuum leaks is the very first step.

edit : it's the cheapest place to start. vacuum hoses are the least expensive parts.

[BMWtyro]

I'll try it ASAP, eye.

Um, stupid question: what is the cheapest way for someone who doesn't smoke to generate smoke . . ? And yes, I'm serious.

Jeff

[82eye]

diy smoke tester : FIND VACUUM LEAKS FAST with this $15 DIY SMOKE MACHINE (youtube.com)

there's a few designs, they are all pretty similar.

[BMWtyro]

UPDATE: I bought a smoke pump from Harbor Freight and, after I determined that it was working properly, attached it to the power brake vacuum source and the ICV vacuum source --- no smoke was emitted from anywhere.

I could not find what I thought to be another vacuum source to which to attach it, but one would think that brake booster and ICV sources (going straight into the manifold) would produce some sort of result.

But no; I burned up one entire Swisher Sweet cigarillo on that test . . . and God, did it stink!

Jeff

[82eye]

not sure that cigar toy is gonna cut it. you might have to take it in or build a better tester.

does it stumble or surge coming off the accelerator when you coast toward a stop sign ? if it does there's a good chance it's the icv. there's no fix at the moment for them.

[BMWtyro]

eye,

To judge by the amount of smoke emitting from the tester when I test-tried it and before I hooked it up; and the amount of smoke emitting from the engine when I unplugged the tester hose from the ports afterward, I would say that it was generating quite a bit. It sucked that Swisher Sweet down to nothin' in no time!

The ICV has been removed and thoroughly cleaned inside with Berryman's B-12 Chemtool (carburetor cleaner) and tested as best I can (clicks when plugged into and unplugged from its power source). I'm certain that this isn't definitive, but it is possibly academic: where am I going to get a new one?!?

[82eye]

where am I going to get a new one?!?

that's the issue. you won't. they are currently nla for the e car. everyone is hoping someone in the aftermarket steps in and starts to produce them. i'm buying one for the i car as a spare while they are still available. you might check with blue streak electronics; they reman a pile of bosch electronics.

to further test try this : How to test E30 ICV Idle control valve (M20 Engine) | RTS - Your Total BMW Enthusiast (rtsauto.com)

some folk lock down the idle range by inserting a penny with a small hole drilled in it. the idle is determined by the size of the hole. it's not the best fix but can get the car drivable if there's no other fix available.

[BMWtyro]

Yes, I was being rhetorical.

Thanks for the test procedure tip; does that happen to be from the Bentley manual?

And do you happen to know the typical size of the hole in that penny?

Jeff

[82eye]

Yes, I was being rhetorical.

i see rockauto has one for $900.

Thanks for the test procedure tip; does that happen to be from the Bentley manual?

i think that's from a bmw tech service manual. what was called the bluebook once. i've got an ancient one for an e21.

And do you happen to know the typical size of the hole in that penny?

start small, like under 1/4 inch, and work up to where it's best for your car.

i'd do a test with a voltmeter first. i'd also check and test the tps to rule it out. the tps is a switch and are a known failure point. an o2 sensor might help as well.

[82eye]

forgot to add - e cars also have a separate idle control module that can crap out

edit : if you go through the procedures in the diagnostic link you'll find the correct order to test and rule out the various possible issues. if you do them out of order you may not catch the issue correctly.