RV8 light throttle hesitation - where now?

[CaptiV8ed]

Stealth cam now in, rolling roaded and yet I still have a part throttle hesitation. Floor it and its great! The RR session has allowed me to rule out anything to do with ignition, air leaks and lambda probs. The tuner was of the opinion that a sensor was giving an intermittent dodgy signal possibly upsetting the fuelling. I borrowed a fault code reader which showed nothing. Today I have measured the voltages throughout the range of the throttle pot and reset base idle, also cleaning stepper (it was anyway!)



Where now? I've considered AFM voltages for tomorrow but can anyone think of anything else to look at?



Car is a 99 Chim 500.



Nick

[GreenV8S]

CaptiV8ed said:

The RR session has allowed me to rule out anything to do with ignition, air leaks and lambda probs. The tuner was of the opinion that a sensor was giving an intermittent dodgy signal possibly upsetting the fuelling.

How did you rule them out? The tuner's comments seem to suggest he suspected incorrect fuelling, but did he actually check it?

[tinker-27]

if you are running a bigish cam it will cause hesitation the only way to cure some of these problems is to go to throttle bodies

[CaptiV8ed]

The ignition issues were ruled out by the Sun analyser, the fuelling with and Air / Fuel meter. It was good throughout the range. What strikes me as odd is that it wasn't doing this even after I fitted the new cam. It has only started since I had to dismantle things again. A stealth cam isn't particularly lairy....

[GreenV8S]

CaptiV8ed said:

The ignition issues were ruled out by the Sun analyser, the fuelling with and Air / Fuel meter. It was good throughout the range. What strikes me as odd is that it wasn't doing this even after I fitted the new cam. It has only started since I had to dismantle things again. A stealth cam isn't particularly lairy....

If you've proved that the fuelling is correct then surely that rules out anything to do with the ECU, sensors etc.

[CaptiV8ed]

Thing is, it's intermittent. So perhaps a sensor is throwing occasional duff signals, enough to momentarily upset things, but still be within spec hence no fault codes??????????????

[GreenV8S]

CaptiV8ed said:

Thing is, it's intermittent. So perhaps a sensor is throwing occasional duff signals, enough to momentarily upset things, but still be within spec hence no fault codes??????????????

Your best chance to trace it was to run it on the rollers and see what was happening to the fuel, AFR and spark when the problem occurs. It's possible to do this on the road, but much easier on rollers.