84 325e intermittent miss once warmed up

[Buckeye325is]

The problem: My daughter's 84 325e has a severe intermittent miss. It becomes noticeable at about 1800-2000rpm. It usually doesn't reveal it's self until the engine has run for 3+ minutes, thus causing one to think that the problem is resolved, only to have their hope of success crushed once they start to rev the engine and it begins stuttering and sputtering. Return it to an idle and it seems to go away or is no longer noticeable. I believe this rules out any vacuum leak.

What I've done: Replaced spark plugs, plug wires, cap and rotor, fuel filter. fresh gas, injector cleaner. The miss isn't on any one cylinder or constant.

Rule outs???
Throttle switch should only affect at idle or full throttle.
DME, fuel pressure regulator, crank position sensor,air flow meter; if it's one of these why doesn't it do it at start up or all the time??

When driving, it cause the car to surge, accelerating only makes it worse (no powering through the thing). The BMW dealer in Canton, Ohio; said that they don't have anyone qualified to work on it and it predates any of their diagnostics???

My daughter no longer smiles and has lost all hope, I'm desperate to return her faith in the little bimmer and myself.
Please, if anyone has an idea of what the problem might be or what to try next it would be greatly appreciated.

[allbmw]

So if you floor the car, the miss is still evident?

[Minnesota]

Distributor, coil, vacuum advance system?

[Buckeye325is]

If you floor the car the surging only gets worse.
I've replaced the Distributor, changed out the coil with a spare, no change. not sure about the vacuum advance system, how do I check it?

[allbmw]

I didn't think that a 325e has a vacuum advance system. Really I am more familiar with the 318i. Are you sure that you have adequate fuel pressure and volume? Is the miss sharp like an electrical miss, or more of lean fuel surge. It sounds like you are describing a surge.

Find a forum that has regional sections and ask for an independent mechanic in your area. The car may not diagnose itself, but it is certainly fixable.

[PorscheBMW]

I had the same problem, after i replaced $600 worth of parts someone on this form said to try the engine speed sensor (known by many names, engine reference, camshaft position, crankshaft position, engine posion...etc) its a 75-85 dollar part and I'm very certain thats what it is. i know that it doesn't act funny upon startup but when it started doing that it didn't acct up till about 5500 rpm then got worse. last tI'me i had to replace it the damn thing wouldn't even start, and I'm pretty sure that its the reason I'm on here today and need to replace it a 3tI'me in 3 years. now the whole engine cuts out and back on if i give it anymore gas than what the clutch requires. give it a shot. if my car was doing what your daughters car is doing, i wouldn't have hesitated to buy a new. thats the truth, i wouldn't give any better advice to my own kids.

[Rucsak]

Hi I'd check the fuel pressure regulator & replace the vacuum hose at the same time. The fuel pressure regulator has 2 small O rings inside that can perish, if yours doesn't have the circlip it mush have the sealed unit which can only be replaced entirely, simple job & about 15minutes. Good luck

[real bimmer man]

Hi, I experienced a similar problem with my 87 325e. Actually, mine would crank idle and accelerate with ease and then shut down and wouldn't restart. After replacing all of the parts that have been suggested, fuel pressure regulator, cold start valve, idle valves, coil, etc., the problem happened to be the ECU. Once replaced, the problem went away. By the way, never work on any bimmer without disconnecting the negative battery cable because not doing so will destroy your circuitry. Good luck

[Buckeye325is]

Finally back in the states, the Army decided my life was not complex enough as it was.
Anyway, I replaced the Crank position sensor and the Speed sensor (both on the Bell housing as suggested by PorcheBMW above. I got real excited because it ran fine, but as usual after 3-5 min. it started missing again.
Then I had to go on another mission so I took it to Midwest BMW in Columbus, OH and dropped it off for 6wks. They checked all the sensors, fuel pressure, airflow sensor, everything they could think of. Their final suggestion was to replace the ECU, (a noid light to the 4,5,&6th injectors showed a weak signal???).
Bought ECU... car ran fine for 3-5 min.; then as you guessed it, she started missing again.

I'm really beside myself... I've put too much into this car, but can't figure it out. Could it be the injectors???

I would really, really appreciate any suggestions.

[Buckeye325is]

This weekend I replaced the injectors, cleaned the C-101 connector and hosed the engine with starting fluid while running, no vacuum leaks.
Checked DME connector and reconnected new DME.
Started it up, ran fine for about 3-4min., then started in on the intermittent miss thing again.

I'm really getting desperate, surely someone out there has an idea what it could be.

Thanks.

[Buckeye325is]

Today got a tip from the tech. at MAG BMW in Columbus. Check all the ground wires on the DME with volt meter to see if there is any currenton the ground thus indicating a poor/bad motor to chassis ground. Checked them all, kept my fingers crossed, car was sputtering... but no dice. All ground wire showed <0.02volts.

Really getting desperate to get this car back on the road. Any suggestions would be greatly appreciated.

[Wapiennik]

This might not be helpful... But you said you're desperate.

I'm not a mechanic by any means, but when you mention the consistency of 3-4 minutes I think of heat finally reaching some of the components. I know that when heat develops in most anything, things begin to expand. In relation to my story below, have you ever checked the integrity of all the pulley's or anything connected to the belt that contains any sort of bearings?

I have a 96 328i. Years ago I knew little about the car. It had a funny jerk one day when driving and most noticeable when accelerating and idled poorly. I kept riding in it for a couple days cause I was too busy and poor to attempt fixing it and my serpentine belt actually broke and took two fins on my radiator fan with it. My center tension pulley (not the a/c tensioner) had seized up and was rotating off and on. During its last few days, the pulley actually wasn't making any noises.

Again, I know that might not be helpful, but you never know.

[Buckeye325is]

Thanks for the reply Wapi. Yes, I've replaced the timing belt tensioner pulley, water pump and the others "I believe" are OK as well.

Here's what happened today...

I drove her in town twice, about 10-15min. each direction. First trip, missing and bucking as usual; when I got to AutoZone, to pick up some parts for my accord and 74 Ford F250, I noticed that the idle was kinda going up and down. It would rev up for 1-2 seconds then back down, up and down, over and over. So I turned her off. On the second trip when I was driving back I noticed she seemed to be running rather smooth. Parked her and rev'ved the engine to 2K, then to 2500 rpm, NO MISS? I thought, it must be because I'm in the car and I'm just having trouble hearing it. So I popped the hood, and cranked the linkage to 2-2500 rpm, smooth as a sewing machine. Held it there and she didn't miss a beat. Closed the hood, shut her down and walked off scratching my head.?.!.?.

I wanted to drive it some more to see if it would eventually act up, but I had a half-shaft and alternator to install and a voltage/charging issue to resolve on the old truck and I was runnin' outta' daylight. It was already 21:30hrs.

Sooo, I believe this rules out a vacuum leak issue, timing being off by a tooth (I was really starting to question the expertise of the mechanic, especially since he was me), burnt valve... so what does this leave as possibilities. I really can't turn her back over to my daughter, just to have it start happening again and her loose all faith in me and the little E30.

Where do I go from here?

[JhwShark]

Buckeye,
I've read through this posting and understand the frustration. Big sorry for you and your girl. Also, BIG THANKS for your service in or with the Army!

I am no Buckeye fan, live with a Block'M" wife...yet, that does not stop my desire to help.

It seems you have replaced all incidental items, tune up as well as fuel system plus ECU. So I'm just going to list, some may be redundant , irrelevant, or completed. It is odd that your last time on return trip it was fine??? What has been the outside temperatures?

How many miles on the engine and has any major work been done...just to get a baseline on current state of the rig??
Have you gotten to a compression test (wet and dry)?
Can you do a CO at the tail pipe and/or is the tail pipe sooty?
How is the state of fluids, oil need additions frequently? and the H2O? when you do an oil change do you smell much gas odor in the oil?
When you had the plugs replaced, what were the individual observations, consistent or varied? Pull the new ones and compare to memory.
When did the last valve adjustment occur and was the head torqued (over-torqued?) Could you have an issue at the head-gasket?
Do you have the Blue coil? Is there a Balsat resistor in line with it or any coil, has it been checked?
What has been done on the distributer? if vacuum advance is the diaphragm good?
Has the car overheated in a major way?
That is all I can think of right now.
Jon

[Buckeye325is]

I'm back...

The army decided I needed to go to Cincinnati for the week. So I decided to drive the old girl, figured she would make it or die trying. Well, she made it, bucking and stuttering all the way. I did manage 20mpg, not bad for how she was running/missing.

I did buy a compression tester and other items a harbor freight while I was there. Interesting, the name brand is U.S.General... and made in China, figures.

I don't have any knowledge of the engine history, it had more or less been abandoned for 2-3yrs, but my daughter saw it and had to have her. I replaced the timing belt..., on purchase. The car ran fine for about 9 months and this started happening.

I'll do the compression tests this next week, not certain what the number should be, need to check the Bentley Bible. The miss isn't any specific cylinder though.
I don't have a CO tester but the tail pipe is sooty black and smell like she's runnin' rich.
She uses some oil but no smell of gas in the oil.
Plugs are black and smell of gas, I think; I'm beginning to even question my own nose.
I adjusted the valves when I did the timing belt, approx. 5k mi. ago.
I haven't messed with the head, no white smoke, blown gasket or the like, She does have the old hex head bolts.
Balsat resistor??? See below for coil.
No knowledge of over heating, hasn't done it while I've had it.
No vacuum advance, she has Motronics.

So this evening I replaced the coil and FPR with the know good ones from my 325is, replaced all the relays in the fuse box and the 3others (pump relay...). Took off the distributor cap just to have a look (no carbon tracks, practically brand new. No movement of the rotor or front of cam (a friend thought it could be a worn front cam bearing allowing the rotor to maliciously move about in the cap) all looks good, feels good.
So I washed her really good hoping this would do the trick. Took her out for a short drive and she up and died on the way back... I was gradually accelerating when she just cut out the tach. went to -0-... she restarted immediately and for the next 30-45 seconds dedn't seem to have any miss, but on the hill up to my house she started obviously missing again.

Took her down to my friends house to have him take a look at her. We had been revving her and listening for about 4-5 min. when she died again while idling. Restarted easily enough, but she died again about a minute later and this time refused to start. After about 20 min. of tinkering and allowing her to cool down she finally started up (still missing, I believe because she was still warm). I jumped in and drove her home, still missing but no more dying.

I'm just glad she didn't die on me on the way to or in Cincinnati. I was going to drive her to Columbus tomorrow, but I'm having second thoughts.
It seems like she's getting worse and I'm still clueless.

[JhwShark]

OK
The miss only happens once car has warmed up.
Valves should be still in adjustment.
We now know that signs of rich conditions exists.
You have replaced a lot of stuff.
It is burning some oil...How many miles on engine?

We do not know if the car has a Balst resistor in line to the distributor? If this car has one, a white ceramic rectangular block, that can crack and when warm the internal wire can have an Open which causes misses.

Are the plugs fouled uniformly such that they all look (are fouled) the same? Is there any way to get a Smog shop readout; HC, NO, CO. Sometimes a bad catalytic converter with an Oxygen Sensor once warmed up can cause missing high NO, HC CO; all plugs would look the same as well. I use the CO meter on my old rigs that do not have sensors. If you can get a smog readout skip getting a CO meter (it already appears you will have a rich reading).
All plugs fouling also possibly shows from oil burning.
If non-uniform plug appearance, you may find a variance on the compression reading for one or more cylinders.

I'll keep watching...
Jon

[stephers]

Hi,
Have a look at the ignition control unit. It sits on the left inner fender up close to the firewall. It is mounted on a aluminum plate for heat dissapation as it is solid state circuitry. These can cause missfires, no start situations. Usually once the car is warmed up hence the aluminum plate. This sound a lot like your problem and most often overlooked. There is no dist. on these cars as the rotor is mounted directly to the camshaft. No vacumn advance. Both the advance and timing curve are contolled through the ECM. If the o ring seals are bad on the fule pressure reg. you would see fuel stains around it, I have a very hard time believing that this would be the problem. THis sounds very much like an electrical miss, not fuel related. This problem will not set any codes.
Hope this helps, Rick

[Buckeye325is]

Latest,
Messed around with the little beast for most of the day today. I checked all the plugs, they all have a greyish, almost white look to the electrode and metal dohickey, all uniform in appearance no wear, still look new. An inline plug check light didn't appear to have any misses when installed on 5, 4, 2 and 1 wires; nice strong flash.
Holding off on the compression test for a remote starter, should have by this weekend.
Not sure how to check the O2 sensor without cutting down the wires, I know there's got to be a less invasive way of testing it. Any suggestions?
I'm going to check the phone book tomorrow to see if there's anywhere local to get her smog tested, What numbers or results should I be looking for?
Also, not sure about where the balst resistor to the distributor would be. There's nothing from the coil to the distributor, or anything in the wires leading to the coil.

I did find what looked like an in-line fuse on the smaller wire coming from the battery at about the 2 foot mark in the trunk, I cut off the shrink wrap and noticed it was rather corroded up. I went to the power distro . block on the firewall and saw that it connected to 2 red wires that disappear into the wiring harness and "ahh haa" one of the red wires had been viciously mauled by a malicious mouse (guess he did more than just build a giant nest in my blower). The wire was only about 1/3 chewed up, but I was really hoping I found my nemesis. After fixing up the mouse eaten wire, I connected the red wires' terminal to the primary battery hub on the distro. block, to bypass the possibly faulty in-line fuse.

Long story short, the same as before. She ran for about 3-5min., just long enough for me to start feeling smug then she started up with the miss again. AAARRRHHHH!!!
Next, replace the in-line fuse, probably with one for a stereo amp. system. Any idea what amp. it should be? Replace the TPS, even though I'm 98% certain this is not it.

Rick, I got real excited about the ignition control module, thinking "this sounds like it could be IT". then I checked the Bentley and discovered that the ignition control unit was only used on 4-cylinder engines with TCI-i ignition systems. Still, I went and had a look, nope, none there. It's all controlled through the DME, which as stated above I've replaced to no avail.

I know it's probably something stupid simple and probably cheap, I just can't figure it out?

[stephers]

How about disconnecting the O2 sensor, leaving it in an open loop and letting the car warm up. See if the miss is still there. Just a process of elimination. Sorry about the control unit, it has been a few years since I worked on BMW's

Rick

[JhwShark]

So we need to check items that impact potential rich running conditions once the car has reached warm up. Since it only happens once at running temp we would assume it is not distributor related; however if (I just do not have a wiring diagram, post one if you have one) there is a Ballast resistor it is a low possible.

The smog test will reveal data at running temp. The smog readout will usually have data sorted by HC (unburned fuel and oil), CO (Air/Fuel ratio), NO (excessive output of Nitric compounds). It will/should have Maximum allowed(for the geography and any regulatory req's) Min output, and Measured. The measured compared to Max is the data to use in diagnosis. It is usually at low and moderate rpm's.

High NO usually means a bad Catalytic converter but could be caused by a bad O2 sensor. High HC means not a complete burn some causes can be bad O2 sensor that causes Components to inject wrong A/F mixture, vacuum leaks, or worn valves, even worn rings (lower prob in this case). High CO can be from similar O2 issue or vacuum leaks.

I'm not sure how the engine will run if you unplug the O2 sensor at its plug (Wired. not removing at the bung); but it is/maybe a way to see if it is bad

Spending the low $ on a smog test can help us determine what vector to take.
Jon