RPMs limited?

[bfam4t6]

Well, I thought I sorted this out yesterday, as right after replacing a newly found leaking fuel line, the car was able to rev to redline again while in park.

I let it sit a few hours, went to drive it, and while driving the RPMs were once again limited to about 3000RPM, whether in Park or Drive, it didn't matter.

Plugs and wires are around 2 years old. Could this just be a distributor cap? As a seemingly intermittent problem, I'm assuming it's something electric.

The he check engine light is on, but it has been for over a year. I do not currently have access to a scanner for updated codes, but...

The last time I pulled check engine codes it was a vacuum leak and O2 sensor. I have one of the down pipes of the exhaust disconnected at the manifold...long story, so I don't THINK I need to be worried about an O2 or clogged cat. I've had that code for over a year, and the limited RPM problem just started a week ago after the car sat idle for about 10 days.

The vacuum leak I'm pretty sure is just a small hole somewhere in a line under the intake. I put smoke through it a while back, and a small amount leaked out from somewhere under the intake. Again, this problem has been there for around a year, and all I've noticed prior to this week is some hesitation when accelerating from a stop. I'm guessing the car is running rich. Most of my driving is highway, and it seems to perform great there, besides the new limited to 3000RPM issue.

Any ideas? I know it sounds like the car has a lot of issues, but this seems like an isolated new issue to me. Maybe that's just wishful thinking though lol

[NE32]

Can you do a stomp test?

[unity]

Yes, stomp test:

https://www.bimmerforums.com/forum/s...e-pedal-faults

[bfam4t6]

I have tried so many times to do a stomp test! I tried it a bunch when the engine light first came on, and I was never able to get it to work. I think my car was built too early by a few months. It's a 1988, and if I remember correctly off the top of my head, it was a February 1988 car.

edit: yeah, I just followed that link to shogun's guide, and it says it works for 89 and newer models, unfortunately.

[SergeBMW]

Does it only rev up to 3000rpm in neutral as well or just when driving? Is your E32 built in the US? I think some Canadian spec E32s had EML for the M30 engines.

[bfam4t6]

Yes, it's limited in neutral as well. At first I was worried I may have damaged something in the transmission when recently working on the driveshaft, but that doesn't make any sense since it does it in neutral too.

I used to have an old 1976 Mercedes 450 SEL that would do the same darn thing. 85 out of a 100 times you'd drive it, you couldn't push the motor passed about 3500RPM, which sucked, cuz it limited the top speed to about 72mph. Every once in awhile though, I'd start the car, and shed purr all the way to redline. It would usually last until I shut e car off again. Then it would typically revert to its limited state. I had a BMW mechanic actually explain to me what was causing it, and it was basically some $200 electronic part that was kinda hard to find and was specific to that year due to changes in injection systems. Anyways, this reminds me of that. I feel like there's a 30 year old circuit board somewhere that's acting up.

[shogun]

Vacuum leaks have influence on the fuel pressure regulator. http://www.nmia.com/~dgnrg/hose_map.jpg
Vacuum hoses under intake https://www.bimmerforums.com/forum/s...ghlight=intake
Does the engine have EML or not? EML = the throttle valve has no bowden cable and the throttle valve has an electric motor to adjust the throttle.
You have to check the fuel pressure , see shop manual https://www.bmwtechinfo.com/repair/main/

Circuit boards of the Motronic are not a major problem.
Edit: I remember one rare case in the E34 forum, an E34 owner from Canada could only drive max. 120 kmh, he tried a lot to solve the problem. He suspected the Motronic to be at fault, I send him one of my chips for the M30 Motronic and he also used a new (used) Motronic and the problem was solved.

[bfam4t6]

Thanks Shogun, I appreciate the help. I'm sorry for being away for a couple weeks, but I just started a new job. So, life has been a little extra crazy, and I haven't further investigated this problem at all until now.

To to answer your question, no, I do not believe it has an EML. My throttle has two cables running to it.

My my plan is to order new intake gaskets, and just replace every inch of vacuum line that I can get my hands on while I'm down there. This seems like the cheapest and most logical place to start, considering I already had a leak code.

It's still an intermittent issue, as I have continued to drive the car. Living in Kansas City, we have very volatile weather. It can literally sleet and snow and then be 75 degrees Farenheit and sunny in the same weekend. It's not a perfect pattern, but it SEEMS to me that the car tends to perform better in colder temperatures. A few times the past two weeks, the car has gone to redline. It drove just fine. Most of the time, the RPM has still been limited. Sometimes to around 3,400 RPM. Although, the last time I drove it the other day, it was more like 2,800-2,900RPM.

Obviously, it's something that needs to be fixed. My bank is being a pain in the rear about checks from my new job, so as soon as that is all cleared up, I'll start ordering gaskets and narrowing down the list of possibilities again.

[shogun]

In case the stomp test does not work, try to get a code reader which works on the E32 old system. Simple and easy is the Peake fault code reader, it is basically the same as the stomp code = only gives you engine/emission related data, nothing for central chassis electronics etc. Sometimes they are available in the auctions used. Or find a shop which can read fault codes and then start repairing based on these fault codes.