Small hesitation under load under 1500 rpm
 

Hi just got my 986 with a 2.5 and the car pulls like a champ. I have this little nagging issue though, if I let the revs below 1500 while driving, when I get back on the throttle it hesitates and bucks once or twice, then it picks up the revs and it's fine. Doesn't matter if I go light or heavy on the throttle still does it. If I don't let the revs drop below 1500 it drives perfect. No other symptoms, no CEL and no pending codes when I scanned it with my OBDII.

I was thinking of running some Techron through it to see if that helps. Anyone else had this happen before?

Techron can't hurt, but I guess my suggestion would be to not try and accelerate from 1,500 RPMs. I try to keep it above 2,500-3,000 RPMs at all times, as per many recommendations from this board.

Here's s reference for what Joe B is talking about:
http://986forum.com/forums/general-discussions/25016-lugging-engine.html

As far as the bucking AT 1500 rpm, I'd recommend going through all of the basic tune-up stuff if it has not been addressed recently: Techron, Plugs, MAF - TB - Intake cleaning, Air Filter.

Well the car shouldn't buck. But I would really suggest downshifting instead of attempting to accelerate basically from idle.


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+ 1, keep th revs up.

When this occurs the engine is not lugging, it's when it transitions from drop throttle to touching the accelerator, like coasting through traffic. I have just been consciously using a lower gear but it just seems odd to me. Perhaps it's just the nature of the beast.

Cosmo, are you still experiencing this?

This sounds like what I'm figuring through currently. The car threw a CEL the day I put it into hibernation, so I cleaned the throttle body, figuring the rough idle I was experiencing at the end of last season was from a dirty throttle body. I probably should have pulled the fault code, but didn't.
I did the 100k service over the winter. It started right up, but I couldn't drive it until just last week.
The car idles well enough, maybe a touch less silky than previously.
I'm thinking a MAF that's on its way out. The car hesitates wickedly below 2500rpm with a noticeable lack of power, and it sounds like it is backfiring through the air box until it gets rolling. It and starts to pull at 2500+ rpm.
No CEL, though.
I unplugged it and am going for a spin later to pick up my son from work. From what I understand, if the symptoms don't manifest with the MAF unplugged, then it confirms the MAF is bad.
I'll post back with a report.

Runs like a new car with the MAF unplugged.
Time to go parts shopping, dammit!

Well, never try to clean a MAF. You can use some brake cleaner or so to spray on the metal string to get it a bit cleaner, but never – i mean really never touch this thing or try to clean it mechanically. If you try that in 90% the MAF is gone and you need a new one. These things are stupidly sensible.

Regards, Markus

Mine has seemed to have gotten better with a bit of driving. When I bought the car it had just been taken out of winter storage and had the battery disconnected. It's happened a couple times recently but it's way better.

I feel its always good to update these threads with the solution. Mine was coils, I replaced all 6 (two were soaked in oil from bad spark plug tube seals). I did all the tubes, plugs and coils. Problem is completely gone now. Was misfiring at low rpm under load enough to affect drive-ability but not enough to throw a CEL.

hmmm, I would have thought misfires would be logged by an OBD scanner

Nope. I also had the same problem on a 2011 BMW 328i. Would misfire under load at low rpm. No CEL. Seems that the only misfires that are recorded are complete failures, not weak spark.