E36 undiagnosable Problem

[Ur0favaf]

Hi everybody. Long time reader first time writer. I usually find all I need via google search and most of the times it's on bimmerforum but this time I'm left without a clue on how to go on nor what to look for. I basically rebuilt my '96 328 new. The engine has been replaced with a reconditioned one by a german factory. O2 sensors are new as well as vanos unit, injectors (bosch original), fuel pump, ignition coils (hella). Furthermore all rubber connections to intake manifold are new and bought from the dealer. I replaced Icv, maf and oil separator with vemo ones. Carbon filter for gasoline recirculation and main filter are also new from bmw. Catalytic converters also new.
Now to the point. I keep on getting fluctuating idle, not at startup but when stopping and engaging clutch. Furthermore at moments there is an almost complete loss of power for no more than one ore 2 seconds. When on the highway with this issue I discovered that the car doesn't go more than 80 km/h, at least I wasn't willing to try more than that with the feeling it gave me.
One diagnosis helper might be that rpms go up about 200 before decreasing whenever clutch is engaged if moving. To be clear, doesn't do that if the car is not moving.
I have a schwaben tester that haven't helped in this case and resorted to a technician with old bmw system. He did not find ANY error and now I'm completely out of ideas, and money.

I hope someone might help with ideas or maybe even knows what's up by experience.

Thank you for any help

[328 Power 04]

What do the fuel trim/adaptations look like?

How does it run with the MAF disconnected?
What is the fuel pressure at the rail?

[Ur0favaf]

Hi. With MAF disconnected it runs as bad. I looked up the fuel rail as I had suspects too but wasn't able to find a place to plug any instrument at all. Once asked the dealer technician he answered that those rails do not have a port to measure fuel pressure. I read in my searches that there should also be a screw to regulate pressure at the back end where vacuum line plugs in but that was also denied by dealership. I'm not sure if this matters but It's euro spec. maybe that's why (?)

Could you clarify the "fuel trim/adaptations" part? I'm not native speaker and even though I gained a lot of vocabulary in these years on the forum I still get lost sometimes

- - - Updated - - -

P.S I forgot to mention that cranck case pulse generator and camshaft position sensors are also brand new

[moroza]

Correct, there is no port for fuel pressure testing. Use a tee fitting to check fuel pressure at the supply hose to the rail.

The fuel trim adaptations are adjustments that the engine computer makes to tune the fuel delivery for correct O2 readings, which use O2 sensor input.

All rubber intake parts are new? Good, but that doesn't exclude the possibility of a vacuum leak. I don't think it's your problem, but if there's a smoke tester easily available, use it.

Engaging the clutch at idle should do virtually nothing to engine performance. The fact that it does is concerning. What's the history of the transmission?

[Ur0favaf]

Sadly a smoking machine appears to be a thing of other worlds here (italy). I tried. All the attachments to intake manifold have been checked multiple times either when replacing the rubber parts and/or components or simply out of desperation.
I have no way of testing the rail by myself so I'll have to resort to a technician again, I would highly prefer not to.

A quick correction on the clutch/rpm thing: at idle the problem doesn't show. Once you're moving and want to change gear it happens that rpms go first up by ca. 200 and then down.

Fuel trim adaptations is another thing that supposedly can only do someone with the right diagnostic system, right? I don't mind ask for a professional there to check as I trust the guy but how likely is it that that's off?

Transmission should be fine. Never a problem nor strange noises or unwanted slips

[R Shaffner]

Is the pedal bracket stable? That is, does moving the clutch pedal affect the gas pedal in any way? Same with the brake pedal?

[MarcoZandrini]

Get the OBDFusion app for your smartphone or tablet. Then buy an interface adapter from Amazon. iOS uses WiFi while android uses Bluetooth. Veepeak brand is very reliable. Then search this forum for threads on the app that include posting by Balidawg. The app allows you to check fuel trims and many other data streams.

[Ur0favaf]

Yes pedals are stable.

Okay I'll look up a veepeak

[328 Power 04]

Windows laptop & K+DCAN cable & 20-pin adapter and this

https://www.bimmerforums.com/forum/s...xperimentation

[Ur0favaf]

Okay. Update. Since last time I had the car picked up with a trailer and brought to my usual mechanic to finally find out that camshaft timing on the exhaust side was off by 30 degrees. The issues stayed though and apparently cam position kept on changing in an unexpected manner in subsequent controls. Last time fixed with green markers to see eventual changes it stayed were supposed. Being not happy at all I decided to go to the dealer, a suggested one non the less and they too after 3 days of work till now have no fudging clue what is happening. Vanos functionality has been checked again with proper tools, timing is okay and fuel pressure too. Even vacuum lines are now triple checked. I'm really desperate

[Ur0favaf]

Hi guys, I'm going to copy/paste my reply to a previous, maybe dead, thread in another section. The more minds the better. I'm looking for brainstorm here 😅

So. I updated Inpa anyway based on 328 instructions and as he said scales remained the same. Was worth trying. I'm going to link two videos I just made (bad quality and bad English, sorry) to ask for your help. I want to fix this car for good but unfortunately I first went the dealership and generic professional way and that screwed me up quite a bit so now I'm chasing problems by myself. Main thing is a misfire (o similar symptoms) that comes and goes, sometimes really bad. In the videos my readings of today

Vid 1:
https://youtu.be/5nwc1HX-CR4
Vid 2:
https://youtu.be/itbT3PF8jlQ

[shadowpuck]

just to give everyone a chance to catch up - here's the other post about this vehicle and problem...

https://www.bimmerforums.com/forum/s...osable-Problem

[Ur0favaf]

just to give everyone a chance to catch up - here's the other post about this vehicle and problem...

https://www.bimmerforums.com/forum/s...osable-Problem

Right. Thank you. Didn't expect that to be true. There might be some updates from that thread but I'm not sure now. Hopefully they'll come to mind if needed

[328 Power 04]

In video 1, all the parameters were good as far as I can see, including the smoothness / balance per cylinder. It looks normal there.


Under what conditions does the engine misfire? Idle only? Driving hard? Hot? Cold? Random?

If random: do you have a readout what the data looks like when it's misfiring?

Were there any stored codes in INPA DME read out?

[Ur0favaf]

In video 1, all the parameters were good as far as I can see, including the smoothness / balance per cylinder. It looks normal there.


Under what conditions does the engine misfire? Idle only? Driving hard? Hot? Cold? Random?

If random: do you have a readout what the data looks like when it's misfiring?

Were there any stored codes in INPA DME read out?

It is random but almost never at start up when dead cold.
The most recent errors refer to track control, second throttle body actuator, but never came back after deletion and the primary throttle body sensor (replaced). I'm not sure on how much trust should i put in the dme for fault codes since it never highlighted oxygen sensors knowingly bad nor did it display anything about huge vacuum leaks and faulty coils.

[bmwdirtracer]

I've looked at both threads, and your videos. You've obviously spent a ton of money trying to make your car perfect.

I find it very confusing that nobody's done a fuel pressure test while the symptom is manifesting. In other words, you need to connect a fuel pressure gauge (using a "T" fitting) into the feed hose to the fuel rail. Use a long enough hose to run the gauge out of the back of the hood -- and tape the gauge to the windshield. Then go drive the car and when it starts misfiring, read the gauge. If it doesn't read somewhere close to 3.5 bar (51 psi), you've found your problem.

You've said that the car barely goes over 80 kph; it could just be that you accidentally misconnected the two fuel lines in all your work. At the very least, this needs to be one of the very first steps in your diagnosis...not left until the engine's been retimed, and you've been frustrated for months hunting the issue.

Start with the basics: air, fuel, spark and compression. The trouble with all the computer diagnosis you've been able to do is that it's happening at idle, and when the symptom's not manifesting. Please don't misunderstand, I am a devotee of using the diagnostic computer to find problems, but older cars like E36's don't provide the level of detail of modern cars.

All the best to you!

[MauiM3Mania]

Threads merged.

[bmwdirtracer]

Thank you Mr. Moderator. Now all the information is together.