E30 Choking BAD on acceleration - Please Help!

[Bison Dele]

Hello,

I have a 1990 325i Convertible (E30) 5speed and I have developed a HUGE problem.

Issue: The car cranks up ok and then drives ok, but usually after a few minutes of driving it will choke and drop to no power (the car will not stall, but pressing the gas has no impact it just seems to choke out again). The only way to get it going again is to turn the car off and back on, but even if you get it going again once this problem starts it happens every few minutes. The problem only occurs upon acceleration...and it feels like the sensation of running out of gas where the pedal just drops on me.

Background: I am not sure if this repair is related but wanted to include it...about 3 weeks ago I changed two coolant hoses and the coolant gasket on the throttle body (removed throttle body), and cleaned out the throttle body with carb cleaner. The car ran smoothly for a few days before this new issue came up so unsure if that is related, but was working in that area.

The first time this "choking" started happening was a few days after previous work 1-2 weeks ago. The car coded me 1444 for no faults, so I took it down to the local mechanic who tested fuel pressure and such and said my pressure was low (the pressure was 6 rather than 30) and that I had a bad fuel pump. I was skeptical but he seemed sure so I changed out the fuel pump myself and also replaced my air intake bellows (they were slightly cracked). Those replacements did not stop the problem. FYI now I am receiving the 1222 code that says I have a vaccuum leak. I am at a loss and do not know what to do now.

Obviously need to find a mechanic since this guy was so wrong. Would love to get back on the road (I am 26yo and this is my only car). Can anyone please offer some advice on what could be going on????

Thanks in advance.
Jackson

[tjmonsen5]

Im going through the same problem right now. Car drives perfectly when its cold, but then 5-10 minutes later, it chokes out and runs like crap. I believe it has something to do with the coolant temperature sensor and 02 sensor. I need to replace them, then i will report back. I might need to replace the fuel pump also.

[Bison Dele]

Definitely let me know how it goes...As you know...its a pretty debilitating problem. I changed my fuel pump this morning and it did not appear to impact the issue, so I would be sure that's the problem before paying that expense...

Anyone else have ideas/guidance?

[thejlevie]

You could have a fuel delivery problem. What I'd do would be to tee in a pressure gauge on the rail inlet and tie the gauge to a windshield wiper so it can be seen when driving the car. Then go out a duplicate the problem and see what the rail pressure does.

If the rail pressure is normal when idling, but takes a drop after a bit of driving, the possibilities are a bad pump, restriction in the fuel return line or filter, or a layer of rust in the tank that is choking off input to the pump. In the later case, rust that collects on the inlet screen will remain as long as the pump is running, but fall off when you shut off the engine. A flow restriction can cause the pump to have to work too hard.

[Bison Dele]

Thanks tjle...

When I was working on the tank today installing new fuel pump...it did look like the tank had a good amount of rust in it, and the screen on the pump I removed looked somewhat coated in rust...

Does the fact that I put in a new pump today and the problem still occured help us narrow it down at all? Could this rust issue still occur that quickly with a new pump? Would this rust issue cause some of these symptoms?

Replaced fuel pump so seems like that is not it...could be an issue with the fuel filter or line...i replaced fuel filter only about 6 months ago though...

Any more suggestions?

[alternator]

I have same issue minus the pedal, it feels like car is stumbling or rear tires are getting rubbed against something for a minute?

I did major maintenance and this did not fix this issue so don't waste your money just yet, what I will be doing next is sea foaming engine and gas tank.

[thejlevie]

If there is a layer of rust sediment in the bottom of the tank, that could be an explanation for what you are seeing. While rust is quite abrasive and will cause a pump to fail rather quickly, the more immediate result is rust particles getting sucked up onto the pump's inlet screen and choking off flow to the pump. With the car stationary the rust tends to remain in the bottom of the tank. But with the car in motion the sloshing of gas can stir up the sediment and allow it to collect on the pump's inlet screen. It will remain there until the engine is shut off, at which time the particles will fall off and flow will be restored.

The fix for this condition is either to replace the tank or to acid clean and seal the tank (see the DIY/FAQ sticky at the top of the forum).

[Bison Dele]

After thinking more about it...do not believe that rust in the tank would be causing the issue...The new pump we put in had an open screen filter which opened on the top and bottom, so do not believe it could have completely clogged within 10-15 minutes...I could be convinced otherwise, but with opening on top and bottom hard to imagine...Am I right on that? Also spoke with my grandfather who helped me on the project, and he did not believe there was much rust at all in the tank, but rather just a little dye from gas additives...

Did see your tank cleaning DIY guide, thanks for pointing me there.

Thank you guys for responding so quickly, would love to continue to hear your thoughts/advice so we can get back on the road!

FYI- Already mentioned this...but this issue only seems to occur once the car has heated up. If I start it cold it will run for 10min+ before the failure occurs, but once it fails once it will fail again quickly afterwards...

[thejlevie]

There could be something else going on, but if you saw rust in the tank you need to find out if this is a fuel starvation problem first. That means seeing what the rail fuel pressure is when an event occurs.

[Bison Dele]

Ok that makes sense. I will try to get a measure of that in the next couple days...need to track down a pressure gauge...Thanks.

[alternator]

Sea foam it...

[Bison Dele]

Update: I was examining the intake bellow into the throttle body yesterday and noticed that it appeared some liquid had gotten into that and the throttle body. It was only a small amount, BUT would be consistent with a minor leak from the area where I replaced the coolant gasket on the side of the throttle body a couple weeks ago. I had an issue with a seized screw so it is possible the gasket is not functioning 100%. However there is no visible leak or seap from that joint externally.

So my question is could this sort of issue cause the symptoms I am experiencing? Also, how would you rate the chances of this being the issue?

Still following up on other suggestions...

[thejlevie]

A leak at the throttle body heater would be external to the throttle body and can't cause the problems you are having.

[bimmerweez]

You could try replacing your ignition coil, when they go bad, it's get more noticeable the harder you accelerate. Check all your vacuum hoses, there's a lot of them, your engine could be running overly lean. Finally if your car runs rough only when hot, try swapping your O2 sensor, when the engine reaches operating temperature, the O2 sensor goes into close loop and starts telling the ECU how rich or lean to run the engine, could be running way too lean..

[chefthomas]

Buy a hose kit they cost about $90 and replace them all and come colored so you know which you have replaced any small air leak can cause this and for god's sake check the bottom of your throttle body boot that's where mine was and it was cracked like a smile in the coil of plastic and you could not see it till you took the whole freaking boot off!

cold start sensor coming off your fuel line could be a good place to look as well and a cheap fix..

[draccent]

Fuel filter...perhaps???

I haven't heard a word about that.

[Systema]

This sounds similar to a problem I have. After reading about it a bit, I thought it might be dirty injectors. I've got a new set of Mustang injectors sitting on my desk waiting to go in later today, I'll let you know if it solves anything.

[catchuk]

Im wondering if the op figured out the problem? I'm having the exact same issue with my 1990 325i.

[Kershaw]

You could have a fuel delivery problem. What I'd do would be to tee in a pressure gauge on the rail inlet and tie the gauge to a windshield wiper so it can be seen when driving the car. Then go out a duplicate the problem and see what the rail pressure does.

If the rail pressure is normal when idling, but takes a drop after a bit of driving, the possibilities are a bad pump, restriction in the fuel return line or filter, or a layer of rust in the tank that is choking off input to the pump. In the later case, rust that collects on the inlet screen will remain as long as the pump is running, but fall off when you shut off the engine. A flow restriction can cause the pump to have to work too hard.

Im wondering if the op figured out the problem? I'm having the exact same issue with my 1990 325i.

I would advise you to follow Jim's advice.

[tdennehy]

My 1990 325i vert is stomping a 1222. A few months ago, my ICV was sticking, and the idle was bouncing up and down. I cleaned it with brake cleaner and stuck it back in and bought a new one. When the new one arrived, I put it in. Non-Bosch.
Fast forward a few months - it was winter and I wasn't driving it as much since it rains in CA and the car leaks a little here and there, usually on the driver's seat. I started driving the car again and noticed that the car would lurch - almost as if the car was shut off and then turned back on. The CEL light would come on briefly and then go off again. At first I was afraid to drive the car, but then I quickly figured out this only happens within the first five miles of driving the car that day. After five miles, it no longer happens. Even if I drive it to work and let it sit, it will not do it until the next day, when this starts all over again. I drove it to my mechanic, however it didn't stopped by the time I got there. It only lurches 3-5 times in the morning, and then it stops.

Any ideas? It appears intermittent, even though I have determined there is a pattern.

[superj]

Yours, i bet, is a temp sensor issue. You have more than one though so find which one tells the ecu the engine temp that effects fuel delivery. Also, check the o2 sensor