Real lean at first on acceleration

Roc87

11 Second V6
Joined
May 25, 2001
Gn just started doing this, it goes real lean when you first accelerate, it feels like no pump shot on a carb.

I just swapped plugs, tighter gap, trying a spare coil pack on the TR6. Only thing left I can think of trying is a different ecm

Other than this it seems fine

(Sorry for the glare on the screen)
 

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Post this in the chip section for Eric. He may wanna see the MAF reading. Let him know which chip you're using.
 
Tried my spare ecm, fresh tank of gas, still doing the same thing. FP rises 1:1 as it should. Filter isn't very old. I emailed the file to Eric @ TT.

Also seems like the car is more rich coasting than during a steady cruise
 
Eric is leaning towards it being the MAF. I was having a very difficult time getting the car to pass emissions a few months back, I bet whatever the problem was for that, is just getting worse. Gonna try out a friends Lt1 MAF this weekend
 

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What is psi4 measuring? It looks like you are cruising at 45mph. What does it do from a stand still when you accelerate?
 
how old is the pump?
is it hot wired?
what is your base pressure? How are you measuring it?
I didn't look at the log, what is the maf reading to, is it getting to the 255?
 
Car does idle, although I had a huge headache getting it to pass emissions due to high HC's a few months back.

I don't know what PSI4 is measuring, the fuel pressure looks low according to the transducer, but the autometer liquid filled gauge shows 40 line off.

Pumps are probably 3-4 years old, not more than 1500 miles, its a racetronix DP set up, I've tried swapping the primary/secondary pumps and it didn't help. They're hotwired directly off the back of the alternator. MAF seems to read high when throttle is closed, Eric @ TT had noticed that, but I tried a different LS1 MAF today, and although it seemed a tad bit better (Or maybe just wishful thinking) its nearly the same. It does hit 255


Other background, the 80# injectors have less than 300 miles back from Steve @ Full Throttle for cleaning, one is brand new since one of mine was flowing 10-15% more at idle-2500rpms. Tried swapping ECMs. Cam sensor doesn't have 500 miles on it after being rebuild by Scot. Primary O2 sensor is heated, but it also has around 300 miles on it, it gets its power from the EGR harness, but I can disconnect that to see if it effects anything. The FP transducer gets its power from the TPS harness...TPS is linear, but I'll swap it for one a friend lent me, and I can try disconnecting the transducer.

Only things left I'm thinking of trying is a friends translator, then a stock style MAF (no translator), then a stock coil pack/ign module. If it's still the same from there, I'll swap to a friends 60# injectors and his matching chip. From there I don't know what I'll do. I have to leave town for work, so it'll be a couple weeks before I can try all this
 
Don't forget about checking your BOV. If it's opening when it shouldn't, it will cause these exact symptoms (MAF reading too high).
I would not change the chip or injectors, that won't change your MAF reading.
 
40psi at idle with vac hose off? I'd bump that up to 43-45psi with hose off and see where that gets you. You seem to have plenty of pump. Maybe add some fuel in the chip for first gear
 
40psi at idle with vac hose off? I'd bump that up to 43-45psi with hose off and see where that gets you. You seem to have plenty of pump. Maybe add some fuel in the chip for first gear
 
Don't forget about checking your BOV. If it's opening when it shouldn't, it will cause these exact symptoms (MAF reading too high).
I would not change the chip or injectors, that won't change your MAF reading.

My first thought was it was getting a big gulp of unmetered air. The car is not even idling...
 
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