hey heres my issue: when i go WOT im perfect but when i let off the gas im hitting 18-20 or LEAN on my PLX wideband... and also it happens when i down shift. or tap the accelorator for a quick second. the funny thing is this only happens this extreme when my lights are on. when i turn them off its not that bad. please help? not sure if my altinator has got something to do with it. thanks for reponses in advance.

 

That sounds normal to me. You're saying that when you're off the gas, you go momentarily lean, right?

 

not momentary. it STAYS lean till i pop it outa gear bc its scares me to leave it like that...its never done that b4 till now. im worried that something isnt right. its not like a quick spot of lean its all lean.

side question... what A/F ratio should ur idle be around?

 

bump

 

Idle should be around 13s to 14s.

I still don't understand what is going on. When you are cruising at a constant rpm your AFRs start going lean?

 

Change your fuel filter.

 

Believe it or not, it also could be your spark plug wires. It's happened on my car.

 

hmm my idle is around the high 12s...not that much of an issue there. no when im crusing its fine...i get 13-16 range. pending how i use the gas pedal... but when i go hard and then let off the gas it happens or even sometimes when i down shift. it always happening in declining of rpms.

 

ok so fuel filter and wire change..? possible solutions ?

 

lol if your car is decelerating its not using that much fuel, if any at all? so the afr should read lean...am i correct or am i misreading something?

 

^^ agreed unless I'm misunderstanding something here. Your car only needs to be running rich when it's under boost, when it's decelerating it should be running lean as hell. And on initial tip in it might go a little lean momentarily but should be rich well before you build any boost.

 

i understand that its saposed to be leaner when decelerateing... thats obvious, but im stating that its even more leaner then it normally has been... like 20s... and till my meter reads LEAN and its not a momentary thing it stays like that ALL the way till i decide to pop in in neutral. hense title...EXTREMELY LEAN.

 

and it only acts that way when my lights are on.

 

If you are under deceleration, running extremely lean is normal. If you are not running lean under idle, cruising, or heavy throttle, then I think you can relax.

 

ok, it just struck me as odd and out of the ordinary that it would just go crazy lean, i never have seen it like that b4..i just thought it would be too lean. i mean i seen it breifly hit 19s and drop...but this it just stayed lean the whole time.

 

So basically I was correct back on post #2. This thread is great

 

Your fine, this is absolutely normal

Under boost you should be in the 10's 11's depending on your setup
Idles should be 13's, cruise the same

When you left off the gas you should be at 20 or LEAN....thats normal

If you go lean in throttle...now thats what u need to worry about

 

Perfectly normal. When you put your foot back into the gas it will richen back up. It's decelleration fuel cut.

 

question: cruising around in 3rd under very light load ~2500rpm, my AFR goes to 15-16 and the EGT rises accordingly. Throttle (lower AFR) or lifting (lean) lowers the EGT. Is this an issue with my map or a normal situation also?

Dan

 

No comments? I'm thinking this is normal, but the EGTs near 1750 make me uncomfortable. I had no idea how hot things could get coasting.

 

I think that's too hot. I'll see 1500 degrees max at cruise. I'd be worried about harming your apex seal springs at that temp......where is your egt probe placed? Mine is about 6 inches down the downpipe, if yours is in the manifold that may account for the temp difference.

 

Thanks for the reference. Mine (plural) are in the exhaust manifold itself. Dual EGT, front and rear sensors (see group buy). Perhaps as more people install this setup we can compare readings.

 

Why don't you richen up the cruising range to 14-15 and see how your EGTs change?

 

as soon as i can get a couple hours off from work while it's still light out!

 

Thats nothing...My friends FC on deceleration goes into the 80s...due to such a HUGE difference in his injector size. (550 primary 1600 secondary). Your fine