Question for Piper cam owners
 

My race zs has piper 270 cams in and very light flywheel. It's always stalled when idling and runs rich low down. Top end is fine and not lean as its running a remapped ecu. Question is what's other people's running like? Thinking It will have to get a piggyback ecu to make it run better low down and so it idles better but not sure on which way to go as the Siemens unit is a pain. Help appreciated

What ecu you running? I'm on emerald K6 with 285's, throttle bodies and 3.5kg flywheel idle etc is fine

Yours is a 4 pot though right? Standard ecu, but mapped for the cams

Standard ECU and flywheel
Never had a problem with stalling and idle is smooth.

Occasionally doesn't fire but a bit of throttle sorts it and then it idles fine.

Yeah sorry jumped gun bit there. If its running lean sure you doing have a air leak ect

It's not running lean, it's good over 4k

Was the ECU remapped to take account of the cams and flywheel?
If so it should be able to cope with the tickover etc.

open the tb butterfly a little on the grub screw to raise the revs, 1050rpm works a treat

What's the best piggyback ecu to use?

Mine has started to do this since changing the thermostat. It never did it before and the only thing i removed during the thermostat change was the TB which makes me believe it is related to this. potentially a vacuum leak? ive cleaned (and yes properly cleaned) the IACV. Next i will probably remove the TB and make sure both mating faces are completely clean.

If that does nothiing i'll be investigating the possibility of the piggy back ECU may have packed in?

It passed fast idle test for the mot emissions but failed natural idle test. The examiner told me that the fast idle one was the important one so was happy to pass it.

Thing is, i would have thought that this would have been handled by the piggyback ECU. I think it was put on originally to overcome lean issues at top end but would they also not have looked into where the car was fueling rich?

I dont know, good luck anyway and if i do get to the bottom of it will let you know.