Help pls: N54 Hesitation/ stumble at about 2500rpm

[Chavoos]

Hi Fanatics

I have a problem on my 135i.
The car has a slight miss / stumble / hesitation on light throttle which happens usually in 6th gear (or drive) highway driving at low 2500 or so rpm. Somehow it happens more often on slight inclines. On all JB Maps.
The car doesn't throw any codes, which makes diagnosis difficult.
At WOT the car feels great, maybe it's masked with the power?

I initially assumed it was the plugs. Replaced plugs from g-drive but problem still persists.
Did logs as well and both fuel pump values are in acceptable range.

The car has backend flash and recently had a carbon clean.
The problem may have started after either one but cannot be certain.

I've done some internet research and seen that guys have had similar problems.
Some of the solutions offered:
1. Injector clean with BMW fuel system cleaner. Apparently carbon build up here??
2. Plugs
3. O rings or clamp from front turbo to cooler.
4. O2 sensors were mentioned but didn't resolve one guys problem.

I am thinking perhaps it could be 02 sensors since I am not getting the catless codes despite removing the cats, or is that just because of the Backend flash?

Please provide any insights or guidance on what the mostly likely culprit could be and what should I try.



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[SKYF]

i had the same problem, if i remember correctly the changed the ignition or coil pack.

 

[Riaan335]

Chavoos, my car does exactly the same, but not on specific revs, yet more below 4000rpm. On slight inclines it tends to do it more, but also on flat roads. My car does it intermittently. I can't replicate it every time. Also, it seems to do it more when it is hot than during the cooler mornings or evenings.

I'm gonna change coil packs next week and see what happens.
Already fitted new plugs.

Please post your findings here again if you manage to solve it.

I thought it could be octane related, but it happens on random brands fuel (95) and with or without octane booster.

 

[Chavoos]

Thanks guys , My first thought was coil pack as well after replacing plugs but why isn't there any code.
Being on an incline makes me think it could be a fuel issue.



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[Josh-ZN]

i think its a lack of octane. make sure you have your revs up before pushing too hard or on inclines else you will limp. thats what happens to me.

 

[SKYF]

@josh please eloborate when you say lack of octane. You should not be only at high revs to acccelarate

 

[Josh-ZN]

@josh please eloborate when you say lack of octane. You should not be only at high revs to acccelarate

i have always found that when i am in low revs and i press the accelerator the car goes into limp mode or it has unsteady acceleration. so say i am cruising along at 90 or 100km/h in 6th gear and i need to get going for any reason. if i push slightly too hard, the car hates it. it immediately loses power and sometimes makes an unusual exhaust tone.

since having my tune (for years now) there are 2 things i always ensure.

1) never accelerate too hard when the engine is still cold or way too hot.
2) never accelerate too hard in the wrong gear. change up and then go.

both those situations cause limp mode or unsteady acceleration for me when car is mapped.

the wrong gear situation was improved when i used OB or changed to a lower boost like map 1

edit: i had so many things changed on my car but it only does it when mapped. i never have it anymore because i have changed my driving style. i can replicate the problem 8 or 9 times out of 10 if asked. so i just avoid it and the car thanks me for it. still going strong :rollsmile:

 

[BeamerMan]

I had the same problem you are having after I changed plugs, in the States guys complain about it happening after changing plugs and have done many kms with the issue.

In the rare case one or two guys changed plugs, coils and injectors where some say it worked and others not...

Mine was bad in 6th gear at WOT but has gotten better.. The hesitation has gone away but the shake on idle is still there.

Being in the correct gear resolves the issue sometimes, I notice it most in 4th.

 

[Chavoos]

Thanks guys .

This problem was not present for the past 30000km using similar fuels and driving the same way.
I had a ethanol mix yesterday which increases octane win 95 fuel and it's still there.
Strangely it's only at about 2500rpm , keeping it steady and cruising , sometimes , and more on inclines.

Maybe I should just drive it fast all the time. Lol


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[Chavoos]

Beamer I have it with old and new plugs .

Josh, have u considered a backend flash.
May resolve your problem, if not, you can go back to stock.


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[Josh-ZN]

Josh, have u considered a backend flash.
May resolve your problem, if not, you can go back to stock.

thanks but its still on MP, so not flashing it anytime soon. i dont have the problem anymore with a change in driving style

 

[Kish2604]

Chav's...

I would start with the o2 sensors, they take a hell of a beating in the catless downpipes vs stock. I had an issue in the last 2 weeks were the car was backfiring under wot during the gear changes together with a lot of low throttle hesitation. turns out the one sensor was loose and tightening it up got rid of that issue. The hesitation has also almost all but disappeared...

The back end flash deletes the catless dp codes so you won't get them, did you try flashing back to stock file to see if it still there...

Keep us in the loop...

 

[Del-Bosc]

I had the same problem you are having after I changed plugs, in the States guys complain about it happening after changing plugs and have done many kms with the issue.

In the rare case one or two guys changed plugs, coils and injectors where some say it worked and others not...

Mine was bad in 6th gear at WOT but has gotten better.. The hesitation has gone away but the shake on idle is still there.

Being in the correct gear resolves the issue sometimes, I notice it most in 4th.

Shake on idle seems to be a prevailing issue also have this problem. Not sure about the hesitation do you have a N54 ? Manual

 

[George Smooth]

Hi Fanatics

I have a problem on my 135i.
The car has a slight miss / stumble / hesitation on light throttle which happens usually in 6th gear (or drive) highway driving at low 2500 or so rpm. Somehow it happens more often on slight inclines. On all JB Maps.
The car doesn't throw any codes, which makes diagnosis difficult.
At WOT the car feels great, maybe it's masked with the power?

I initially assumed it was the plugs. Replaced plugs from g-drive but problem still persists.
Did logs as well and both fuel pump values are in acceptable range.

The car has backend flash and recently had a carbon clean.
The problem may have started after either one but cannot be certain.

I've done some internet research and seen that guys have had similar problems.
Some of the solutions offered:
1. Injector clean with BMW fuel system cleaner. Apparently carbon build up here??
2. Plugs
3. O rings or clamp from front turbo to cooler.
4. O2 sensors were mentioned but didn't resolve one guys problem.

I am thinking perhaps it could be 02 sensors since I am not getting the catless codes despite removing the cats, or is that just because of the Backend flash?

Please provide any insights or guidance on what the mostly likely culprit could be and what should I try.



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When u get a chance again try replicate the problem accelerating through the rpm range using the cruise control stalk if u auto.

 

[Chavoos]

Yes Del, it's an n54 auto.

Kish I will try the stock map and see if the problem is still there.

George I can try that. The problem is not so difficult to replicate usually. What should I be looking for if the problem is identified wen using the cruise control stalk.


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[George Smooth]

Yes Del, it's an n54 auto.

Kish I will try the stock map and see if the problem is still there.

George I can try that. The problem is not so difficult to replicate usually. What should I be looking for if the problem is identified wen using the cruise control stalk.


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If you can replicate it using the stalk it may be mapping. Start going back to stock flash and maybe older versions of software on JB. I worked on a car that two version of the JB had a similar miss and once it was updated it went away. Its free to try this so would take this route first. Considering your car had a leak before the clean this could have also masked the problem prior.

 

[khumalbs]

Hi Fanatics

I have a problem on my 135i.
The car has a slight miss / stumble / hesitation on light throttle which happens usually in 6th gear (or drive) highway driving at low 2500 or so rpm. Somehow it happens more often on slight inclines. On all JB Maps.
The car doesn't throw any codes, which makes diagnosis difficult.
At WOT the car feels great, maybe it's masked with the power?

I initially assumed it was the plugs. Replaced plugs from g-drive but problem still persists.
Did logs as well and both fuel pump values are in acceptable range.

The car has backend flash and recently had a carbon clean.
The problem may have started after either one but cannot be certain.

I've done some internet research and seen that guys have had similar problems.
Some of the solutions offered:
1. Injector clean with BMW fuel system cleaner. Apparently carbon build up here??
2. Plugs
3. O rings or clamp from front turbo to cooler.
4. O2 sensors were mentioned but didn't resolve one guys problem.

I am thinking perhaps it could be 02 sensors since I am not getting the catless codes despite removing the cats, or is that just because of the Backend flash?

Please provide any insights or guidance on what the mostly likely culprit could be and what should I try.



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[I had exactly same issue and it was a faulty coil

 

[Chavoos]

She's fixed!!!
Initially We went back to stock file with JB, and stumbling vanished. Thereafter we loaded the updated version of the pump backend flash and the car is smooth again

It was a mapping issue.

Thanks.






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[Kish2604]

Thanks for the update... Glad it's been put to rest!

 

[hoosain]

iam happy we sorted the problem out:joy:

chavoos is smiling again