Almost Stalling On Acceleration

[SECURITY]

when i go to accelerate from either a standing start or between gears the car hesitates, goes lean and kind of sputters a bit then goes back to normal. if i accelerate SLOWLY it doesnt do it, and when i accelerate HARD it doesnt do it, im not sure what it is. i tried checking for leaks in the vac/cooler system with no luck.

i took a vid to see if it would help identify the problem. the gauge on the left is the wideband and you can see the pressure/vac/accelerator position on the gauge on the right.. turn up your volume so you can hear what the car is doing.

http://www.youtube.com/watch?v=xPHSLI50Kd4

cheers guys

Edited December 27, 2009 by SECURITY

[DRD-00F]

dat video be private...

[SECURITY]

oops.. fixed it

[GTR-32U]

Thats a tough one, Does it only do it under mild load ? Aftermarket ECU in the car ? maybe a tuning glitch...Are you sure its going lean in that split second and not rich ?

[DRD-00F]

well unless he has wired the wideband backwards or some crap, it's definately going lean...

It is a tough one! Maybe there's a small block in one of the injectors? Or the pump isn't getting enough voltage or something? Other then that... I was thinking a stuck throttle body but that wouldn't lean it out...

[SECURITY]

sorry, shouldve given a run down on the car

its got a vipec ecu, it does it under any load, i tried changing the tune around (the vipec has a 1-100 range) i went from 42 in the cells up to 60 and it didnt change much, im pretty sure its a mechanical issue.

[GTR-32U]

well unless he has wired the wideband backwards or some crap, it's definately going lean...

It is a tough one! Maybe there's a small block in one of the injectors? Or the pump isn't getting enough voltage or something? Other then that... I was thinking a stuck throttle body but that wouldn't lean it out...

My mistake...I didnt see the AFR ratio thing on the left...Definately sounds like some kind of fuel issue. Highly doubt its ignition ( although I could be wrong )....Has anything been done to the car recently ..like prior to this problem occuring ?...Maybe a vacuum line got knocked loose

Edited December 27, 2009 by GTR-32U

[Adriano]

Remember that a missfire will show up as lean on the AFR meter

[JonnoHR31]

missfire will usually dance between rich and lean as pockets of air then pockets of fuel pass the sensor

checked your fuel pressure?

[toddlls]

Timing is too far retarded perhaps

[OMGGTR]

mates car had a similar issue ended up being an earthing problem and coil-pack misfire dunno tho hope u find the source!

[r31 25t]

Not sure about the vipec ecu but I had a similar problem on my VH41de safari running a link ecu, it turned out to be an acceleration enrichment issue.

[SECURITY]

Not sure about the vipec ecu but I had a similar problem on my VH41de safari running a link ecu, it turned out to be an acceleration enrichment issue.

i think you might be on to something, ill have a play around with the accel enrichment tables and see where it gets me.

[STATUS]

when i go to accelerate from either a standing start or between gears the car hesitates, goes lean and kind of sputters a bit then goes back to normal. if i accelerate SLOWLY it doesnt do it, and when i accelerate HARD it doesnt do it, im not sure what it is. i tried checking for leaks in the vac/cooler system with no luck.

i took a vid to see if it would help identify the problem. the gauge on the left is the wideband and you can see the pressure/vac/accelerator position on the gauge on the right.. turn up your volume so you can hear what the car is doing.

http://www.youtube.com/watch?v=xPHSLI50Kd4

cheers guys

accel pump adjustment

[SECURITY]

can you elaborate Trent? i cant find that feature on the vipec

[JonnoHR31]

its under fuel - accel enrichment

[SECURITY]

thanks mate.. just making sure he wasnt talking about something different.

[paulr33]

when did the problem start

what changed since then

[Guilt-Toy]

this car has not been tuned yet has it?

[SECURITY]

this car has not been tuned yet has it?

not properly, i had it on a dyno after the engine was rebuilt by the engine builder but the new injectors and plenum havent been tuned in properly. i got it running pretty well using the auto tune and the m5, but this problem just started randomly though.

the accel enrichment didnt work. it didnt change at all. i think its something mechanical rather than the tune.