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EchoDeDupra
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Discussion Starter · #1 ·
I've always been told that when you let off the throttle when the car is in gear and driving, the AFR's should peg lean due to the injectors turning off or something like that.

Well, on my car, when I give 0% throttle while in gear, it reads about 14:1 afr....

Also, my car seems to run perfect some times, and then after getting on it a bit, it will start misfiring and breaking up a bit.

I've already changed/re-checked my spark plugs and generally checked for boost leaks around the intake manifold. Something I have noticed is that when I disconnect the IACV, I can still start and idle the car. I thought this wasn't supposed to happen?

I'm running a MAP ECU, with delphi 880cc injectors, and NGK 6097's (I can't think of any other pertinent mods).

Thoughts??:wavey:
 

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I don't have any suggestions as to what your problem might be, but I have the MAP ECU and 850cc injectors, NGK Iridiums, and mine does peg lean when I let off suddenly while cruising. Mine has not misfired and no breaking up either.
 

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T88 YOU
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3,567 Posts
your IACV is acting normal, on a pulse-width modulated IACV an engine will not run with it unplugged but supras use a stepper motor, it shuld not change the idle at all when unplugged (unless the compressor kicks on)... im not familiar with the map ecu so i cant help you with that one. do you have adjustments for decel fuel with the map ecu like with a standalone?
 

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EchoDeDupra
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Discussion Starter · #4 ·
I don't think I have those adjustments...

Everything was working fine until I sent my turbo out to be fixed and the car sat for a month or so :(
 

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Maybe a problem in throttle position signal that your ecu sees? Does it get 0 when you let off the gas?
 

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EchoDeDupra
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4,122 Posts
Discussion Starter · #6 ·
My wideband and Map Ecu both read 0% when I am off the gas :(
 

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i know you said you checked the plugs ... but are the gaps right??

Geno~
 

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EchoDeDupra
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Discussion Starter · #8 ·
I changed my plugs about the same time I put the turbo on. I had just put the ngk's in right out of the box, and on my first start after sitting for a month, the issue I'm dealing with now appeared.

So, I pulled the plugs and lowered the gap to .028, and the issue is still there.

I think I am going to see if I can borrow an air compressor and check for boost leaks on the intake manifold/Throttle Body. I also just got a spare IACV that I could try swapping in to see if it has any effect.

I would appreciate any other suggestions :)
 

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.028 is good... the only thing i could think of off the top of my head would be checking for boost leaks like you said.

goodluck bro

Geno~
 

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EchoDeDupra
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Discussion Starter · #11 ·
So...... dun dun dun.... (Dramatic pause)

I was able to borrow a friends Pressure Tester and we found out where this path of least resistance air leak is. I say path of least resistance because it could be masking other leaks, but this is the only one that I can here/test/etc.

And the verdict...... it's around the area of my 4th cylinder Injector Grommet. We pressurized the system, and it was clearly audible. I poured a little soapy water on them all (to narrow it down) and the 4th one blew all the water out of there extremely quick. So... it's either my O-Ring on the Injector or the physical injector grommet. Tomorrow, after work, I'm going to tear down that side of my engine again, and probably either examine the grommet to see if it is in there tight, or just simply swap the injector to another cylinder. The bracket that holds the injectors onto the car is between 1-2 and 5-6 leaving 3-4 to be at the mercy of those two. I'm going to also try shaving a little more aluminum off the brackets so when I tighten the fuel rail on, the injectors go in a little farther. I was told by the manufacturer of this fuel rail that I might have to do it (they never explained why) so I'll give it a shot tomorrow.

Thanks for everyone's help and input. I'll post results hopefully within the next 24 hours or so.
 
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