Stumble at 2000 rpm, worse under load
 

Finally got the car out of the garage after the transmission fix. Now it stumbles badly at 2000 rpm. When I pulled away first time it seemed fine but a mile or two out it started to stumble badly anytime I pull through 2000 rpm. When standing still and revving up slowly, it cuts out exactly at 2k. If I pull away in manual and keep it above 2k revs it pulls strong and clean.

The only thing I changed on the engine were the spark plugs, so those are on my list of suspects. That or a vacuum leak as the whole thing was apart with the engine out. Tomorrow I will run it cold and see if it is there or not. Other than that using a smoke generator. Since I re-timed the engine and the CPS and solenoids were out that could be an issue but seems far fetched.

I tried with the MAF disconnected and no change. Also, no codes, the engine runs super well otherwise.

Anyone have any similar experience or thoughts on why it happens at 2k exactly?I wonder what changes in the engine management at 2k?

Which motor?

If 3.0 prime suspect it's the disa valve i think that's right about where it flips from low to high rpm and if it doesn't you'll get really poor performance at that transition.

Which motor?

If 3.0 prime suspect it's the disa valve i think that's right about where it flips from low to high rpm and if it doesn't you'll get really poor performance at that transition.

I looked in your signature or says 4.4 so not disa. Does your scanner let you chart your O₂ sensor values or fork l fuel trims to get more input?

If you have the old spark plugs throw those in and see how it behaves. Where did you buy the plugs and what plugs did you get?

Where do you get this information? DISA valve opens at ~3800 rpm...

The plugs came from FCPEuro. (NGK BKR6EQUP) Pretty sure they are the same that I had in there before. Not sure if I still have the old plugs, need to check scrap metals bin.

Just now I remembered that I replaced the engine speed sensor with a Delphi, also from FCP. However, if that sensor causes a problem I'm pretty sure it would throw a code.

I run INPA and ISTA on my laptop. Not sure if either can record data?

I'm delighted the trans repair works but this is a bit of a pain. I'm stumped it affects the running exactly at that engine speed. Anyhow, tomorrow I will do some more checking when I have daylight.

When you say standing still cuts out exactly at 2000 rpm is that in gear or neutral ?? Throttle body and cam sensor connectors could be someplace to check. Codes might come up after driving some more. Are you using a scan tool that will read all the codes?? Haha didn't type fast enough! ;) unlikely it's spark plugs especially if it cuts out when not under load.

I did overhaul on 3 m62 and every one had rough running after reassembly. Every time it was cps. Watching cam angle live with scanner showed inconsistent cam angles between banks i found and fixed the issue before driving enough to know if it was at a particular rpm

At stand still I tried both and in neutral it just cuts out. In gear with my foot on the brake it starts to heave and buck quite a bit. I think INPA being the BMW software, it should find any code, right?

Interesting, I did have the CPSes off. Maybe I should double check that they are plugged in right. Though I would have thought a CPS problem would come up with a code immediately....

Out of 8 or so failed cps I've only got a related code once. Usually just crappy running. On 3.0, it'll stall but with 4.4 it keeps running just badly


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