Hi guys
I've fitted an AEM wideband to my car and am concerned it's running too lean. The car seems to be running ok itself and has no lack of power on boost, but it's a bit spluttery on part throttle. I've replaced the fuel pump and filter today just in case not enough was getting through.
Initial startup: 15 - 17
Partial throttle at low revs: 17 - showing ---- on the gauge (too lean for it to measure?)
Full boost: 12 - 12.5
Overrun: 13ish
The ignition timing is spot on 6 degrees and the CO pot reads 568. It idles around 950rpm but cuts out when you come off the throttle and put the clutch in to stop. I was having these idle issues a couple of weeks back with my new throttle body but thought I'd sorted them. A gt inlet has been fitted since then which could have changed things.
Any ideas? I've fitted a new coil, leads, plugs, dizzy cap, rotor arm, throttle body, inlet manifold, injectors, chip, fuel filter, and fuel pump recently and it's still not running right!
Cold start you'd expect no leaner than 13:1 really 'til it warms up. From reading about your spesh alarm I'd be checking all the wiring as a starter for 10.
Fantastic, my favourite job :D It's weird, cold start was 10.5 - 10.9 before I changed the fuel pump today.
How should I check all the wiring? Use these values?
http://www.polog40.co.uk/forum/index.php/topic,211.html
Cheers
Bit of an update. I decided to take it out on a run yesterday to see how it behaved once warm. Here's the values I've noted down:
Cold start: 10.5 - 10.9
Overrun: 13.5 - 14.5
Idle: 14 - 15
Partial throttle - 14.5 - 15.5
Full boost: 12 - 13
When it's warm it runs fine and only ever goes lean when you come off the throttle in gear. At this point the gauge reads --- but if you put the clutch in then it stabilises back to 14-15. Is this right? I had a thought that the ECU is cutting fuelling at this point so of course it will run lean? The car itself runs perfectly and pulls hard on boost.
AFRs sound good to me, maybe a touch lean on wide-open throttle, but nothing to lose sleep over. And you're right, it'll go full lean when off throttle in-gear as it cuts injections. In those scenarios the road wheels are turning the engine over, so no need for it to fire the injectors and waste fuel. No fuel = no combustion = no danger.
If it's only misbehaving when cold replace the blue temp sender and/or check the wiring for it.
Thanks Andy, I've driven it over the past couple of days and everything seems fine really. I'll swap out the blue temp sender for a new one when I get chance but it's behaving itself for now :)