car running great then bad stumble at 4000 rpm
 

My 7 has been running the best ever! The next day I go for a drive and it chokes when I give it any more than a nudge on the throttle. The stumble is most noticeable between 3000-4000 rpm. I can ease it up to redline if I dont goose the throttle. If I give the throttle a push its like shutting the key off and I get a little backfiring.

Ive spent the last few days studying the "f" section of my manual, searching for any pertinent info on the forum and I am at a loss.

Ive have checked all of the obvious and common items on the car that could cause this problem and found nothing evident.

Would appreciate any and all ideas for troubleshooting this malady.

Thanks!

-Chuck

hmm...isnt the secondary injector switch on point at 4000rpms? Something must be up with your fuel supply. Check your fuel pressure somehow.

I havent checked my voltages for the fuel pump for the 2 levels it runs at. Cant you jumper the diagnostics box between f/p and ground too get the fuel pump to run at the higher voltage?

Is this the classic 3000 RPM hesitation? My R1 had a bad case of the full fledged 3000 RPM hesitation. If you are still on the stock ECU that could be it. When I tried researching it a while back the consensus was poor grounding. I tried to improve the grounding with a homemade ground kit and it might have helped slightly. Utlimately though, the only thing that completely got rid of that hesitation, studder, and jerk was the PowerFC.

If it is the 3K hesitation, I'm sure someone has had better luck getting rid of it by now without replacing the ECU. Of course... it might be something else entirely. Good Luck!

Ive had the car for 5 years and have overcome that particular issue. Appreciate the feedback though.

I would say its probably your coil. I had the exact same problem you're discribing.

Ceylon.

Have you checked for any codes from the ECU? Jump TEN and GND at the diagnostics box and see what you get.

I had the same problem and it ended up being the ECU that was bad. It would throw code 51 for the fuel pump relay, but the relay and wiring turned out to be fine. If you have a spare ECU around it's worth a try to swap to see if it corrects the problem.

Here's the how-to for pulling ECU codes:
http://www.fd3s.net/engine_codes.html

Already tried to see if there were any codes - nothing. I have a spare ECU but I dont know if its the right one. I was also thinking that I would do a connect / disconnect of the ECU wiring harness.

Thanks for input!

Any and all ideas greatly appreciated.

-chuck