Trackday hesitation/stutter
#1
Thread Starter
Trackday hesitation/stutter
I experienced intermittent, but repeated hesitation from the engine, following gear changes (up). My gut feel is some G-related pump struggle, but I’d appreciate any trackday go-ers thoughts on this.
The Facts:
In all cases the hesitation occurred after (but not during) a corner, and only after the next gear change. Eg coming out of a third gear bend, throttle wide open into the straight, shift into 4th, throttle wide open = immediate hesitation/stutter for a fraction of a second, then normal progress.
Observations:
I was sharing the drive with a friend – this never occurred during his laps. This is what makes me think some G related struggle, as it being my familiar car, I was inevitably carrying brisker pace.
It only happened in the afternoon, after a good number of sessions in the morning. Was I getting quicker? Was something degrading?
The problem hasn’t occurred since leaving the track, (covering well over 100miles) which is why I’m leaning away from something spark related.
In the back of my head I’ve got baffled sumps (which I don’t have) and fuel swirl pots (which I also don’t have) but I don’t know what the symptoms are present if either one of the pumps is starved, to know if my symptoms align, and are calling for one of the above
Wisdom/experience welcome..
The Facts:
In all cases the hesitation occurred after (but not during) a corner, and only after the next gear change. Eg coming out of a third gear bend, throttle wide open into the straight, shift into 4th, throttle wide open = immediate hesitation/stutter for a fraction of a second, then normal progress.
Observations:
I was sharing the drive with a friend – this never occurred during his laps. This is what makes me think some G related struggle, as it being my familiar car, I was inevitably carrying brisker pace.
It only happened in the afternoon, after a good number of sessions in the morning. Was I getting quicker? Was something degrading?
The problem hasn’t occurred since leaving the track, (covering well over 100miles) which is why I’m leaning away from something spark related.
In the back of my head I’ve got baffled sumps (which I don’t have) and fuel swirl pots (which I also don’t have) but I don’t know what the symptoms are present if either one of the pumps is starved, to know if my symptoms align, and are calling for one of the above
Wisdom/experience welcome..
#2
Member
Left handers?
Fuel pickup is on the left side and low fuel can starve the pump. There is a lag there as you have the length of the fuel lines as a damper.
Hopefully not oil pressure affecting VTEC.
Fuel pickup is on the left side and low fuel can starve the pump. There is a lag there as you have the length of the fuel lines as a damper.
Hopefully not oil pressure affecting VTEC.
#3
Thread Starter
Yes, left handers. I'm racking my brain, but I can't recal it happening after a right hander. Is there a solution to this other than keeping the fuel level above 1/3?
#5
Member
Sounds like fuel surge / starvation.
If it's not a track / race car just fill it with extra fuel. You're not looking at lap times so 10-15 litres extra fuel won't hurt.
I have a twin pump setup in mine with a surge tank, but it's noisy and extreme for a road car to go down that route.
If it's not a track / race car just fill it with extra fuel. You're not looking at lap times so 10-15 litres extra fuel won't hurt.
I have a twin pump setup in mine with a surge tank, but it's noisy and extreme for a road car to go down that route.
#7
Are you sure you have the OEM pump as replacement pumps if fitted poorly can change the height of the pick up and that might cause you issues.
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#8
Thread Starter
Originally Posted by S2Bray' timestamp='1474363382' post='24065584
As you correctly identified - that would be overkill for what is an occasional track steed.
Thanks for putting my mind at rest
Thanks for putting my mind at rest
Are you sure you have the OEM pump as replacement pumps if fitted poorly can change the height of the pick up and that might cause you issues.
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