Hey guys, the G40 is back. However I'm having trouble with the timing set up and fuel at high revs. If I set the timing correctly the car runs great about town but then leans out to Stoich at high revs where as if I retard the timing from the correctly timed position then it misses when driving slowly but keeps the air/fuel the right side of rich when on boost.
I spoke to Darren at G werks and he said get a fuel pressure gauge as it could be the fuel pump which I replaced in 2004 or the map I have but the map was fine with my old dizzy.
P.S. the dizzy was replaced in 2007 just before it came off the road. Cars been back on the road 6 weeks now.
Any ideas. I thought about getting a rolling road set up but the guy asked if theres a fuel mixture adjustment?
- Jimmy B
what chip do you have fitted?
and how do you know its lean? i.e. do you have a wideband fitted?
You saying it leans out to stoich on full throttle at high revs, or partial throttle?
If you haven't got a wideband you can't really tell what the fuelling's doing. And it's unusual for minor timing tweaks to make such a difference to the AFR - unless you're really swinging the dizzy around massively.
Are you setting the base ignition timing correctly? Is the dizzy the right part?
The chip is an SNS Green injectors PSD chip. No I'm not using a wideband, just a narrow band. I tried to time it on the top pulley because my toothed pulley has no notch or anything so I just tried with the top one but I'm not sure if thats right or not?
I've been told its a G40 part yes. What should the car idle at when warm? Is it about 950rpm?
- Jimmy
Sorry it leans out into stoich on full boost.
should be 5+/- 1 degree advance on the top pulley.
what pullies are you using they should have a notch
I'm using the PSD toothies
how do I know if its 5+/-1 on the top pulley?
you get a timing gauge where you can dial in advance.
If you are timing by the top pulley (not ideal in any case) with a static gun you'll be on tdc.
QuoteNo I'm not using a wideband, just a narrow band.
then you really have no idea what the fuelling is doing, a narrowband just isn't accurate, at all. Mine seems to show around 14:1 at high rpm/high boost but when remapping and we had the wideband connected it was really around 12:1 and 11:1.
should I get a rolling road set up do you think?
Get the ignition timing set properly to start with, then if it still runs badly take it to a rolling road that'll do you a power run with AFR plot. Speaking of which, John Sleath would do that for you at the G40 RR day in a few weeks...