# Sunoco 94 responsible for limp mode & really bad engine performance



## JPinTO (Dec 20, 2001)

Hello all!

2 weeks ago, my M3 went into limp mode after a 2nd gear redline. All was well on reboot, however, performance has just been crap since. 


The motor has been suffering from Rough idle and inconsistent power through the rpm band. Not nice. A second limp mode was triggered after a 7000rpm blast in 3rd gear. 

I started thinking about the gas I've been using. Sunoco 94 is in the car 80% of the time, and consistently for the last 4-5 fillups. 

These problems started early October, so perhaps Sunoco added a winter additive that's screwing with the motor.

Well... I finally got my proof today. A fillup with Esso 91 alleviated the issues. The engine's performance is solid again, and the rough idle is gone. I'll have to keep playing with the high rpm band, since I've been hesitant to push the motor for the last few weeks. 

And it wasn't isolated to one Sunoco station--- I filled up at 3 different ones. I don't know if it's an Ethanol thing, but considering 94 was fine since April this year, I chalk it up to the winter additive.

Hopefully this will cure the cold start issue.

- JP


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## yamato (Feb 11, 2003)

Thanks for the info. I have been using only either SUNOCO 94 and SHELL 91. I have been experiencing rough idling around 550rpm and below. Although mine is not a M3, I really hope ESSO 91 is going to help, I cant wait to the next fillup! 

How rough is your rough idle?? Is it rough enough to see the steering wheell or the rear view miror to shake?

THanks!


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## rost12 (Dec 22, 2001)

Man, I've been using Sunoco 94 exclusively every since I came to Canada. I, thankfully, haven't had any problems with my M, but my father's 7er does have a bit of a rough idle... Although I was always sure it was caused by something else, I'll give Esso a try too to see if it changes anything.

Btw, nice to see you back on this forum, JP!


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## bren (Jul 1, 2002)

I always use Sunoco 94, in both of my vehicles, and no problems here :dunno:


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## Impulss (Sep 5, 2002)

JPinTO said:


> Hello all!
> 
> 2 weeks ago, my M3 went into limp mode after a 2nd gear redline. All was well on reboot, however, performance has just been crap since.
> 
> ...


I've been gassing up with Sunoco 94 pretty much 95% of the time for the last 10K miles... without any problems! I seriously doubt it's the gasoline...

If a M3 *EVER* goes into "limp" mode, take it to the dealer immediately and have them find out what's wrong with it. I have read many cases where BMWs go into limp mode and people simply restart the car and *HOPE* the problem does not return. Well, it will return, and the next time a simple restart may not return it back to normal! Limp mode is a symptom of something wrong and the only way to fix it is to take it in for BMW service so they determine what is causing it and fix it.

Off the top of my head, M3s often go into "limp" mode when there is a sensor problem or a throttle body needs to be replaced.... There is also a Technical Service Bulletin (TSB) to resolve the "cold start" issue.

My guess is that your M3 is a 2001?? They are known to have these issues... Hopefully you are still under warranty!!

Good luck!


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## Nick325xiT 5spd (Dec 24, 2001)

I suspect the real issue is that it got too cold for 94. While my Barge is obviously a different vehicle, I've found that it runs better on 93 when the weather starts getting below 40 or so.


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## JPinTO (Dec 20, 2001)

Impulss said:


> I've been gassing up with Sunoco 94 pretty much 95% of the time for the last 10K miles... without any problems! I seriously doubt it's the gasoline...
> 
> If a M3 *EVER* goes into "limp" mode, take it to the dealer immediately and have them find out what's wrong with it. I have read many cases where BMWs go into limp mode and people simply restart the car and *HOPE* the problem does not return. Well, it will return, and the next time a simple restart may not return it back to normal! Limp mode is a symptom of something wrong and the only way to fix it is to take it in for BMW service so they determine what is causing it and fix it.
> 
> ...


It's definitely the gas around here... or an ECU issue in MY M3 with the 94 around here. As I stated, these problems started at a very specific time in fall, after running the entire summer on 94. Now, it's been 3 months of driving on Esso 91, and not one limp mode occurrence since.


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## JPinTO (Dec 20, 2001)

*Well, my M3 went into a SEVERE limp mode on Friday...*

this time, it would not drive any faster than 25 mph and it took a minute at full throttle to get to that speed. I thought it would die, but fortunately I was 5 minutes from my dealer... so I made it there.

Check engine light was on, EML light on and Traction lights were all on.

So it ended up being that 2 of the throttle bodies were acting up.

So perhaps it's been something else other than the Gas all along.

- JP


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## Impulss (Sep 5, 2002)

JPinTO said:


> this time, it would not drive any faster than 25 mph and it took a minute at full throttle to get to that speed. I thought it would die, but fortunately I was 5 minutes from my dealer... so I made it there.
> 
> Check engine light was on, EML light on and Traction lights were all on.
> 
> ...


Hhaha Glad to see you got the real issue resolved. Enjoy!


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## JPinTO (Dec 20, 2001)

Impulss said:


> Hhaha Glad to see you got the real issue resolved. Enjoy!


I'm still not "experimenting" with Sunoco 94 until the spring, though!


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## Mr. The Edge (Dec 19, 2001)

how's the car been treating you otherwise?


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## rost12 (Dec 22, 2001)

JPinTO said:


> I'm still not "experimenting" with Sunoco 94 until the spring, though!


Your loss


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## JPinTO (Dec 20, 2001)

atyclb said:


> how's the car been treating you otherwise?


Other than a lady backing into it with her Lexus suv... and the throttle body issue... and my front rotors being warped... GREAT! Awesome vehicle. :thumbup:

Whatever happened to ChuckD's CSL knockoff wheels? Any updates?

- JP


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## SteveMedina (Apr 4, 2003)

JPinTO said:


> Whatever happened to ChuckD's CSL knockoff wheels? Any updates?
> 
> - JP


The wheel has been CAD designed and pictures were posted of the drawings, not the real wheel....looks like its going to be a great wheel.


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## JPinTO (Dec 20, 2001)

Update on using Sunoco 94:

Filled up for the first time in 6 months... and no limp mode occurs. But, my extremely bad idle when first turning on the car has returned. It almost stalls for the first minute unless I manually keep the revs up. Back to Esso fuel.


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## JPinTO (Dec 20, 2001)

Shoot, I have to eat my words. Limp mode triggered last night in 4th gear, full throttle at about 85mph. 

Sunoco94 m3 no likey.


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## rost12 (Dec 22, 2001)

JPinTO said:


> Shoot, I have to eat my words. Limp mode triggered last night in 4th gear, full throttle at about 85mph.
> 
> Sunoco94 m3 no likey.


I recently drove through a tank of Esso 91 on my car just as a test, no discernable differences at all.

Did you get winter tires this winter, JP?


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## JPinTO (Dec 20, 2001)

rost12 said:


> I recently drove through a tank of Esso 91 on my car just as a test, no discernable differences at all.
> 
> Did you get winter tires this winter, JP?


I got a second set of 18s and put Dunlop WInter sport M3's on them. Yourself??


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## rost12 (Dec 22, 2001)

JPinTO said:


> I got a second set of 18s and put Dunlop WInter sport M3's on them. Yourself??


Ah, you gave in!? 

17''s with Pirelli 210's here, but after experiencing both in snow I believe M3's are significantly better :/ Btw, I put my summer tires back on this friday... What do you know, it's snowing outside :rofl:


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## JPinTO (Dec 20, 2001)

rost12 said:


> Ah, you gave in!?
> 
> 17''s with Pirelli 210's here, but after experiencing both in snow I believe M3's are significantly better :/ Btw, I put my summer tires back on this friday... What do you know, it's snowing outside :rofl:


No kidding--- you didn't really think that Friday's 17F would last did you?? 

I find that the Dunlop WS M3's are very light snow tires... but they are actually quite stable in performance whether it is cold or warm out. You had the Dunlop WS M3's and then went to the 210s??


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## rost12 (Dec 22, 2001)

JPinTO said:


> No kidding--- you didn't really think that Friday's 17F would last did you??
> 
> You had the Dunlop WS M3's and then went to the 210s??


I didn't, but it's all good... The weather is still nice enough to warrant 18''s (I had to go with 17'' for winter, and I just couldn't stand them anymore)

No, I had 210s on my previous 325i and I swore by them... So I got them for the M as well, and I have been disappointed, frankly. It's probably the extra torque on the thing, but they're far from surefooted in snow, in my experience. Dunlops are on my father's car, and that thing just plows through the worst stuff with ease :dunno:


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## JPinTO (Dec 20, 2001)

Well--- the warmer weather has definitely made a change in the gas composition. Sunoco 94 is again safe in my vehicle.

My rough performance and periodic limps are gone. The S54 accelerates like a fiend again, without quivers when accelerating in the upper rpms. I must be one of the rare crazies who drives an M3 through the winter weather, so perhaps this issue is not seen by others. 

So, I suspect I'll get 6 months of blazing flawless performance on Sunoco 94, and then "mysteriously" performance woes and limps will start plaging it again. When it resurfaces in Fall, I'll get BMW to diagnose the limp reason.


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## Impulss (Sep 5, 2002)

Take it in!! They obviously didn't fix your problem the first time


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## lucyM3 (Dec 4, 2006)

*BMW M3 - engine errors*

I live in chicago which is the worst place to drive an M3 in the winter - so I got stuck in the snow this morning and my "check engine light, EML, Traction, & Tire Pressure" lights all turned on! When I finally got out of the ice...the car wouldn't go past 3000 RPM.. ..so I reset the tire pressure and turned the car off for a few minutes and eventually it started to drive somewhat normally (still feels funny) but my check engine light is still on - any ideas???


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## Impulss (Sep 5, 2002)

It doesn't have anything to do with the snow (i dont' think)

Sounds liek a common problem.. MAF (mass air flow) sensor issue. You haev to take it to the dealer to have it fixed.


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