Tired of This Car Already

[Our03z4]

Update on my 08 Z4 3.0si coupe. I've been having a lurching feeling under 3k rpms, bouncy rpms on start up and sometimes the car doesn't want to up shift 4th to 5th. Shifts in manual mode fine but still has the lurch. Drives fine if I keep it under 3k the whole time but as soon as it goes over, game on it's been triggered for once I go back under 3k rpms.

I took the car to the bmw shop and it had no codes. They recommended a trans flush, filter, pan, and seals, also did a diff fluid change. $900 later still broken. So I thought maybe plugs and coils, changed them, still broken. Maybe it's the vanos solenoids, cleaned them, still no dice. Ran injector cleaner, no help. Checked the hose clamps and for breaks in the intake with no issues found.

Please, any advice at all would be a huge help! At this point I'm pretty ticked at myself for buying this turd.

[Vanne]

Checked fuel trims/px?
Stock tune? If not, I'd look at going to a stock tune and seeing what's what. Checked the MAF? Suprised there are no codes, esp when it's not shifting 4 to 5..

[Jsinghzzzz]

A little while back, I had the MAF changed because previous owner used an oil filter and that "supposedly" destroyed the MAF. One of my throttle position sensors were out as well.

When the problem happened I couldn't rev the engine past 3k without a lot of bucking and never got a check engine light either.

I know you have a 3.0si, but I hope that this helps.

[Our03z4]

Originally Posted by Vanne

Checked fuel trims/px?
Stock tune? If not, I'd look at going to a stock tune and seeing what's what. Checked the MAF? Suprised there are no codes, esp when it's not shifting 4 to 5..

The car is totally stock. Almost thinking I should take it to Bmw to have them reprogram everything or just buy an Ess ecu tune. The shop checked everything an nothing was out of line. Thank you for the reply!

[Our03z4]

Originally Posted by Jsinghzzzz

A little while back, I had the MAF changed because previous owner used an oil filter and that "supposedly" destroyed the MAF. One of my throttle position sensors were out as well.

When the problem happened I couldn't rev the engine past 3k without a lot of bucking and never got a check engine light either.

I know you have a 3.0si, but I hope that this helps.

The previous owner had it in to the same shop for a cam shaft position sensor which caused a check light. Car runs great over 3k. But if you do run it over 3k it sets something into motion that when you come back down below 3k it has issues. It's either drive hard 100% or below 3k 100% of the time. Drove 160 miles today with no issues until I had to pull out fast and went above 3k. Cruising after 3k sucks so had to drive it like it's hot the rest of the drive. I will check the Maf. Thanks for your reply!

[Z4M_Coupe]

I recommend getting a new MAF, it should (the Z4 MAF's fail & throw no codes too) and I hope it fixes it. Cheers

[Our03z4]

Originally Posted by Z4M_GT3

I recommend getting a new MAF, it should (the Z4 MAF's fail & throw no codes too) and I hope it fixes it. Cheers

I found a new one local to me so I'll give it a shot tomorrow. Can't hurt. Thanks for your advice!

[3002 tii]

You should hit up the N52 forum on e90post, a lot of good info there.

[garz747]

Have you changed the fuel filter? This will cause problems over 3000 rpm if flow rate is restricted.

[Our03z4]

Originally Posted by garz747

Have you changed the fuel filter? This will cause problems over 3000 rpm if flow rate is restricted.

The issue is under 3k. Going over 3k triggers what ever the issue is for when it comes back down. Runs great at high rpms.

[Our03z4]

Well unplugged the MAF, seemed to make a very slight difference at start up and triggered a cel almost instantly. Drove a short distance to see if there was a difference to no avail. Back to square one and another possibility off the list.

[Efthreeoh]

Try running it with the MAF unplugged (it will trigger the SES light). The stored engine maps should make it run better, which will let you know if the intake system is operating to spec. Also, I'd have a smoke test done to see if there is a vacuum leak somewhere.

When you say the shop didn't find any codes, did they check the car with a BMW scan tool or just OBD2? Any issue like you have needs a scan tool that records the engine running parameters to find out how all the systems are operating. It sounds like the fuel injection system is running lean or rich somewhere in the RPM range.

[Our03z4]

Originally Posted by Efthreeoh

Try running it with the MAF unplugged (it will trigger the SES light). The stored engine maps should make it run better, which will let you know if the intake system is operating to spec. Also, I'd have a smoke test done to see if there is a vacuum leak somewhere.

When you say the shop didn't find any codes, did they check the car with a BMW scan tool or just OBD2? Any issue like you have needs a scan tool that records the engine running parameters to find out how all the systems are operating. It sounds like the fuel injection system is running lean or rich somewhere in the RPM range.

Driving with the maf unplugged made no difference. The shop is a BMW only shop with the BMW scan tool. Everything looked fine on it. This only happens once the car has warmed up and has been driven moderately hard. Smoke test is a good idea.

What do you all think about taking it to BMW for a total re-programming?

[Efthreeoh]

Originally Posted by Our03z4

Driving with the maf unplugged made no difference. The shop is a BMW only shop with the BMW scan tool. Everything looked fine on it. This only happens once the car has warmed up and has been driven moderately hard. Smoke test is a good idea.

What do you all think about taking it to BMW for a total re-programming?

Reprogramming might be expensive as it takes a few hours (well for an E90 it does). But maybe, and maybe you tried this, just disconnect the battery for a few hours, to reset any adaptations. If that doesn't work, then get an estimated from the dealer about the reprogramming cost. I have two (2) N52 and both run like a charm. Both are manual transmissions though. It's hard to figure out if the auto trans is causing your issue.

It almost sounds like a Valvetronic problem.

[Our03z4]

Originally Posted by Efthreeoh

Reprogramming might be expensive as it takes a few hours (well for an E90 it does). But maybe, and maybe you tried this, just disconnect the battery for a few hours, to reset any adaptations. If that doesn't work, then get an estimated from the dealer about the reprogramming cost. I have two (2) N52 and both run like a charm. Both are manual transmissions though. It's hard to figure out if the auto trans is causing your issue.

It almost sounds like a Valvetronic problem.

Unfortunately I disconnected the battery as the first step. Even changed it just in case something was wrong with it.

Valvetronic is how I've been leaning too.

Thanks for the reply!

[Huz-Z]

Has the car been exhibiting this particular problem since you got it or is a new issue?

My first thought Is that its either bad gas, dirty fuel filter, dirty air filter or dirty spark plugs. My 3.0si (2006 that I’ve owned since 2009) is also an automatic and it’s never done this.

[KevinC]

I would find a solid local indy BMW mechanic and take it there for diagnosis. BIMRS is a solid organization and will help you find a good shop locally...

https://www.bimrs.org

[Our03z4]

Originally Posted by Huz-Z

Has the car been exhibiting this particular problem since you got it or is a new issue?

My first thought Is that its either bad gas, dirty fuel filter, dirty air filter or dirty spark plugs. My 3.0si (2006 that I’ve owned since 2009) is also an automatic and it’s never done this.

Started shortly after buying it of course lol. Shell 93 used and Bp 93 no difference, also used techron*sp. Replaced all plugs and coils with no change. Air filter looks new but already have one arriving tomorrow from ECS. I have noticed tonight oil along the head. Not sure where it's coming from, maybe the oil filter housing gasket.

[Our03z4]

Originally Posted by KevinC

I would find a solid local indy BMW mechanic and take it there for diagnosis. BIMRS is a solid organization and will help you find a good shop locally...

https://www.bimrs.org

The one I use was the first result, they couldn't figure it out and are considered the best around here. Might try the other place that is also on there that I use.

[Efthreeoh]

Originally Posted by Our03z4

Unfortunately I disconnected the battery as the first step. Even changed it just in case something was wrong with it.

Valvetronic is how I've been leaning too.

Thanks for the reply!

Just worth a shot, but have you pulled the connector to the Eccentric Shaft Sensor (ESS) to check for oil contamination?

[Our03z4]

Originally Posted by Efthreeoh

Just worth a shot, but have you pulled the connector to the Eccentric Shaft Sensor (ESS) to check for oil contamination?

I have not, I will check that tonight and report back!

[mad1stgen]

See if you can datalog the throttle body angle. The lurching you're talking about is usually a result of tb plates moving to try and compensate for a vacuum leak somewhere, or maybe even a faulty TB.
I wish cars would still have tb cables