[924er]

hello guys I've been avoiding this issue always heard N54s were choppy idlers but recently it been getting worse and annoying even the wife noticed it so I'm thinking there is a problem.

I have about 34k on my N54, recently noticed my car shakes when I'm parked at a light. it starts after about 10-15 sec on idle. RPMs are smooth at 600. it only goes away if u rev or drive then comes back at idle after 15sec. I tried putting in N doesn't help. no misfires, plugs have 4k.

I did some research and someone on the forums said it was their low pressure fuel sensor and it also never threw a code.

anyone have experience or this or any advice on where to start looking?

here are some logs just in case.
mods are DCI, VRSF FMIC and Cobb AP stage 1 drive

http://datazap.me/u/moswissa/stage-1...=0&data=1-6-22

thanks!!

[Ingeniator]

Originally Posted by 924er

hello guys I've been avoiding this issue always heard N54s were choppy idlers but recently it been getting worse and annoying even the wife noticed it so I'm thinking there is a problem.

I have about 34k on my N54, recently noticed my car shakes when I'm parked at a light. it starts after about 10-15 sec on idle. RPMs are smooth at 600. it only goes away if u rev or drive then comes back at idle after 15sec. I tried putting in N doesn't help. no misfires, plugs have 4k.

I did some research and someone on the forums said it was their low pressure fuel sensor and it also never threw a code.

anyone have experience or this or any advice on where to start looking?

here are some logs just in case.
mods are DCI, VRSF FMIC and Cobb AP stage 1 drive

http://datazap.me/u/moswissa/stage-1...=0&data=1-6-22

thanks!!

Add lpfp and hpfp to your pid list. Also it could be dirty intake valves. You may need a walnut blasting if you haven't had one.

[924er]

I'm probably due for valve cleaning but 34k is still pretty low.

I notice my car doesn't shake when it idles around 7-800RPM but sometimes my car idles at 600-650RPM and that is when it begins to shake.

I don't have deep pockets to replace both HPFP and LPFP when my car isn't throwing any codes and is running fine otherwise. If it is that I'll live with the shaking for now and wait for it to fully fail

Is there a way to check HPFP AND LPFP functionality thru datalogs???

Thanks

[Ilma]

My idle roughness cleared up after intake valve cleaning.

That was about 20,000 miles ago and it is starting to come back once in a while now.

Had my original cleaning at 30,000 miles and everyone said it was too soon....but once the intake manifold was off it was a different story.

[carlsontheflyer]

34k miles may seem low, but I am willing to bet it's due for a valve cleaning job. I had mine done at 35k and the valves and intake were heavily gunked up. So much so that at 35k miles it probably should've been the second cleaning.

My car is at 51k miles now and ocasionally at idle it does the same thing as yours. And on top of that, sometimes it idles at 650ish and other times at 800ish. It's a manual transmission, so it's always in neutral. And this varying idle seems to be completely independent of any external factors, such as temps, weather, humidity, altitude, etc. I've had everything checked and rechecked and I am beginning to think it's due for the next walnut job.

[els_86]

Sounds like the classic HPFP problem to me. Definitely not the intake valves as they would not be dirty enough at 34k miles to make this happen to definitely cross that off your list of possible things.

Does it just happen on startup at idle? Does it hppen when driving? Also, if you drive for a while (after it warms up) and let is idle does it do it? Any signs of reduced power on acceleration?

[BlueBimmer]

try putting in some of that Chevron Techron stuff - it is amazing and may fix your issue for $12! You'll also notice better mpgs and a smoother run up the rpms.
BMW uses it too!

[924er]

I wouldn't be surprised if my valves are dirty at 35k. If that's the problem I can live with it until I save money for a walnut blast.

It does not shake upon initial start up or while driving. It does shake when fully warmed up at a stoplight after about 15 sec when idle drops and stays at 600rpm. I'm getting smooth idle on the RPM gauge but the car is shaking


My car still pulls very nice no sign of reduced power..

I just used techron a few full ups ago.

Why does my car idle differently at times? This morning I drove it to work and idle was 750 no shakes at all. Sometimes it's 600 and that's when the shaking starts.

[924er]

Btw my car has normal cranks. Build date was post HPFP failures.

[Ingeniator]

Originally Posted by Ingeniator

Add lpfp and hpfp to your pid list. Also it could be dirty intake valves. You may need a walnut blasting if you haven't had one.

Originally Posted by 924er

I'm probably due for valve cleaning but 34k is still pretty low.

I notice my car doesn't shake when it idles around 7-800RPM but sometimes my car idles at 600-650RPM and that is when it begins to shake.

I don't have deep pockets to replace both HPFP and LPFP when my car isn't throwing any codes and is running fine otherwise. If it is that I'll live with the shaking for now and wait for it to fully fail

Is there a way to check HPFP AND LPFP functionality thru datalogs???

Thanks

I was telling you to add the hp-fuel pressure and lp-fuel pressure to your data logging requested points(pids). You will probably have to switch to single data point display if you have 6 on there now. Cobb has a bandwidth issue. You need to log an idle of your fuel pressures and a WOT run in 3rd gear preferably with a shift.

[924er]

Originally Posted by Ingeniator

I was telling you to add the hp-fuel pressure and lp-fuel pressure to your data logging requested points(pids). You will probably have to switch to single data point display if you have 6 on there now. Cobb has a bandwidth issue. You need to log an idle of your fuel pressures and a WOT run in 3rd gear preferably with a shift.

Ohh I see what you are saying. I thought u meant add it to your list of repairs lol

I have cobb v2 I don't know what you mean by single point display are I talking about the datalog list? when I get home I will log hp-fuel pressure and lp-fuel pressure on idle and 3rd hear is that correct ???

[carlsontheflyer]

Originally Posted by Ingeniator

I was telling you to add the hp-fuel pressure and lp-fuel pressure to your data logging requested points(pids). You will probably have to switch to single data point display if you have 6 on there now. Cobb has a bandwidth issue. You need to log an idle of your fuel pressures and a WOT run in 3rd gear preferably with a shift.

Since my car is exhibiting very simial behavior to the OP's car, I will do this as well. Thanks for the advise!

Can you please tell us what the normal hp- and lp-fuel pressure values at idle and WOT should be?

[924er]

Yes please elaborate !

[Ingeniator]

Originally Posted by carlsontheflyer

Since my car is exhibiting very simial behavior to the OP's car, I will do this as well. Thanks for the advise!

Can you please tell us what the normal hp- and lp-fuel pressure values at idle and WOT should be?

Originally Posted by 924er

Yes please elaborate !

It is likely dirty intake valves. As i have a stutter in my DD when the engine is warmed right up and pressures logs fine. What your looking for in your fuel pressures is that actual is meeting requested. You should add 4 points for this. You want hp-fuel actual, hp-fuel requested, lp-fuel actual and lp-fuel requested. If there are serious deviations between them or spikes they need to be looked into. If possible log the idle pressures when the car is exhibiting the stutter symptom. As for the WOT 3rd gear log. That is to check overall health of the tune and fuel components.

[carlsontheflyer]

Originally Posted by Ingeniator

It is likely dirty intake valves. As i have a stutter in my DD when the engine is warmed right up and pressures logs fine. What your looking for in your fuel pressures is that actual is meeting requested. You should add 4 points for this. You want hp-fuel actual, hp-fuel requested, lp-fuel actual and lp-fuel requested. If there are serious deviations between them or spikes they need to be looked into. If possible log the idle pressures when the car is exhibiting the stutter symptom. As for the WOT 3rd gear log. That is to check overall health of the tune and fuel components.

Thanks for the explanation!

[CaptChaos]

My idle started getting rougher over time and finally got walnut blasting done at around 65k km's (40k miles). Cleared up the idle completely. I could have done it much earlier and would not be surprised if that is what you are experiencing at 34k miles.

[Mit_Boost]

Originally Posted by 924er

Is there a way to check HPFP AND LPFP functionality thru datalogs???

Thanks

If you have a COBB AP, you can data log Requested/Target HPFP and LPFP PSI and Actual, if there's a significant difference between the values then more than likely one is failing.


**Edit -- Just saw I repeated when Ingeniator said; bottom line we need solid logs that clearly reflect fueling data

[924er]

Originally Posted by Mit_Boost

If you have a COBB AP, you can data log Requested/Target HPFP and LPFP PSI and Actual, if there's a significant difference between the values then more than likely one is failing.


**Edit -- Just saw I repeated when Ingeniator said; bottom line we need solid logs that clearly reflect fueling data

Ok cool thanks a lot!!! I'm hoping it's just carbon build up but that can wait I feel like my car is running stronger than ever after using 20%e85 it's never pulled this hard but the idle is the only thing.

I will post a log as soon as I can but how do my logs look for now? It shows 0 timing corrections does that means it's healthy?

http://datazap.me/u/moswissa/stage-1...=0&data=1-6-22

[Miller335]

Just got my valves cleaned today(Thanks Cwarren!) and I'm at 33K miles.
I was getting a bump at idle here and there also.

[Ingeniator]

Originally Posted by 924er

Ok cool thanks a lot!!! I'm hoping it's just carbon build up but that can wait I feel like my car is running stronger than ever after using 20%e85 it's never pulled this hard but the idle is the only thing.

I will post a log as soon as I can but how do my logs look for now? It shows 0 timing corrections does that means it's healthy?

http://datazap.me/u/moswissa/stage-1...=0&data=1-6-22

Log doesn't look bad. However log the timing channels not the correction channels. You have one throttle closure early in the run so the DME had something it didn't like. Also it wouldn't hurt to log wgdc by bank instead of the common one. Looking at the log again I think the throttle closure was because of over-boost on that run. Grab a few more logs and post them up when you have the pids swapped out.

[carlsontheflyer]

Ok, here is my fuel pressure log for idle. There are 2 logs, one for hpfp and one for lpfp. You can switch between them by clicking on change log button.

http://datazap.me/u/carlsontheflyer/...log=0&data=1-2

Edit: At the end of the logs the light turned green, so I accelerated before ending the log. That's why there is a spike in the end for requested and actual values.

[Ingeniator]

Something is a little wonky on the hp side. Grab the WOT log when you have a chance. Make sure to log all values. We want per cylinder timing, lambda both banks. WGDC actual both banks. Both requested/actual fuel pressure high and low. We also need tps actual to check for throttle closures. I'm sure I'm forgetting some but that would give a good snapshot.