[JamesM3M5]

Hi all,

Have a friend with a 335Xi Auto, all stock, 29k miles. He said that the engine will cough and stumble when quickly going to WOT from low RPMs - standstill or up to about 15-20MPH. If he is rolling faster than that or rolls on the throttle moderatly fast there is no hesitation. No hesitation when in Map 0.

He's coming in on Friday to get new plugs put in, still on the originals. Aside from plugs, is there anything else I should look for or change in his settings to help reduce or eliminate the stumble?

[Castr_85M]

Is he running the new aggresive maps? These misfires are becoming a plague.

[enrita]

your friend has to log his car .

[stratplaya06]

Doing the plugs is a no brainer. Only took me about fifteen minutes start to finish and it got rid of all of my rough idle/high rpm misfiring issues.

Order the bosch equivalent plugs online and get the schwaben socket and you can do the whole job for well under 100 bucks.

[Joshboody]

check trims and AFR. I had similar issue when going too rich. Some OL map adjustments and it was fine afterwards.

[JamesM3M5]

OK thanks for the tips. I already bought a Snap On socket years ago, and I have Bosch plugs on the shelf. If the plugs don't cure it, I'll try some OL changes.

He's on the standard 7-11 or 7-29 maps (can't remember which). Not interested in the aggressive maps on this car, since he's already done with his tinkering/testing/tuning days from a past life (Honda Si turbo). This is his DD. I may be able to convince him to go further in the future...

[enrita]

Just log the car and post them here and send logs to vishnu.

[JamesM3M5]

Originally Posted by enrita

Just log the car and post them here and send logs to vishnu.

Yes that will be done as well.

[OpenFlash]

Originally Posted by JamesM3M5

Hi all,

Have a friend with a 335Xi Auto, all stock, 29k miles. He said that the engine will cough and stumble when quickly going to WOT from low RPMs - standstill or up to about 15-20MPH. If he is rolling faster than that or rolls on the throttle moderatly fast there is no hesitation. No hesitation when in Map 0.

He's coming in on Friday to get new plugs put in, still on the originals. Aside from plugs, is there anything else I should look for or change in his settings to help reduce or eliminate the stumble?

Hesitations up to 20mph when going WOT?

Lol, sounds like traction control. Have him press the DTC button and re-test.

[scottro]

Originally Posted by alofoque

Is he running the new aggresive maps? These misfires are becoming a plague.

Agreed. I was having misfire issues with the aggressive maps and went back to the 7-29 maps and they went away.

For what it's worth, the aggressive maps were trying to push 16 psi on my completely stock car, and that's typically when the misfires happened. Going back to 7-29 maps it never exceeds 14psi and I don't see the misfires anymore.

[Jeff@TopGearSolutions]

More boost doesnt necessarily cause misfires.

You should read into the misfires. Are they 1 cyldiner or multiple cylinders?

Spark plugs, fuel injectors, bad coils, or even fuel pump problems can cause misfires.

I dont know how many more threads we can have about misfires so here it is for people to search.

Hesitation bad idle rough not smooth cold start misfires plugs spark problem search injectors fuel pump coil packs replace

[scottro]

More boost doesn't necessarily cause misfires, sure, but you can't keep increasing boost indefinitely and not expect some symptoms.

It appears to just be Cylinder 2.

[Jeff@TopGearSolutions]

Originally Posted by scottro

More boost doesn't necessarily cause misfires, sure, but you can't keep increasing boost indefinitely and not expect some symptoms.

It appears to just be Cylinder 2.

So either swap plugs or swap coilpacks and see if the problem moves, its not the increased boost.

Logs would also determine what is going on. I dont condone raising boost indefinitely, not sure where i said that.

[OpenFlash]

Originally Posted by scottro

More boost doesn't necessarily cause misfires, sure, but you can't keep increasing boost indefinitely and not expect some symptoms.

It appears to just be Cylinder 2.

As Jeff said, just swap coils (since that is free) and see if the misfire follows the coil. If not, change plugs and you should be good to go. The aggressive maps run more boost, less timing and considerably richer AFR in the low end/midrange than the older maps. All of this demands more from the ignition system hardware which means that nothing can be marginal. But then again, all this results in an extra 30-50lbft of torque and a much quicker car. So making sure that your coils/plugs are sound seem to be a small price to pay

Again, this doesn't seem to be the case with the OP as he isn't throwing any misfire codes. Just the normal hesitation that one would expect to see when romping on it at low speed with traction control not disabled.

Shiv

[scottro]

Originally Posted by shiv@vishnu

As Jeff said, just swap coils (since that is free) and see if the misfire follows the coil. If not, change plugs and you should be good to go. The aggressive maps run more boost, less timing and considerably richer AFR in the low end/midrange than the older maps. All of this demands more from the ignition system hardware which means that nothing can be marginal. But then again, all this results in an extra 30-50lbft of torque and a much quicker car. So making sure that your coils/plugs are sound seem to be a small price to pay

Again, this doesn't seem to be the case with the OP as he isn't throwing any misfire codes. Just the normal hesitation that one would expect to see when romping on it at low speed with traction control not disabled.

Shiv

What do you suggest for addressing the hesitation when going WOT? Mine does that as well, but I've disabled traction control.

[GeorgiaTech335coupe]

Injectors starting to go bad can cause those type of symptoms. When they start to go bad, it is easier to produce the symptoms at higher boost. Went through this process for every one of my injectors one by one. Not fun.

[OpenFlash]

Originally Posted by scottro

What do you suggest for addressing the hesitation when going WOT? Mine does that as well, but I've disabled traction control.

If what you are feeling isn't traction control kicking in, the next thing I would try is new spark plugs if they havent been changed in the last 20k miles. That's far more likely the cause than injector issues (although there are recalls pending right now). Best bet would be to call your dealership, tell them your VIN and ask them if any apply to your car.

[JamesM3M5]

Problem solved:

No, new plugs did not fix it, nor was it traction control. Reset all adaptations and ECU. No better. Logged, found knock induced timing pulls at 2000-2800 RPM when whacking the throttle open from a standstill/slow roll. 2-3 hard hesitations until you got past 3k.

I tried pulling timing in the affected cells by up to 5 degrees, no help. It was anywhere from 0 to +2 in those cells, I went to up to -5. So I called Vishnu and got Robert. He told me to change to the 11-1 map. Since this car has NO other mods, I put on Stage 1 6AT. Reset all adaptations. Test drove. PROBLEM FIXED. Evidently the 11-1 maps control timing a little differently per Robert.

Thanks to Vishnu and Robert. Phone answered immediately, and gave me the tip as soon as I told him the problem and my current diagnostic and repair attempts.

[scottro]

Originally Posted by JamesM3M5

Problem solved:

No, new plugs did not fix it, nor was it traction control. Reset all adaptations and ECU. No better. Logged, found knock induced timing pulls at 2000-2800 RPM when whacking the throttle open from a standstill/slow roll. 2-3 hard hesitations until you got past 3k.

I tried pulling timing in the affected cells by up to 5 degrees, no help. It was anywhere from 0 to +2 in those cells, I went to up to -5. So I called Vishnu and got Robert. He told me to change to the 11-1 map. Since this car has NO other mods, I put on Stage 1 6AT. Reset all adaptations. Test drove. PROBLEM FIXED. Evidently the 11-1 maps control timing a little differently per Robert.

Thanks to Vishnu and Robert. Phone answered immediately, and gave me the tip as soon as I told him the problem and my current diagnostic and repair attempts.

I had the same problem, in fact still do, with 7-29 maps. Problem goes away with 11-1 maps. Installed new plugs, which did fix a misfire problem in higher boost conditions that I was having with the 11-1 maps, but did not fix the hesitation/misses immediately when going WOT.