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Oi! So I have the new 42.5# injectors in the car now and I have been having some minor issues with it. It has a slight off-idle stumble at low throttle settings with a light popping sound and a little power loss. Also, it seems to knock at much lower boost levels than previous, I was able to run about 14psi and the knock was audible
! My thoughts: I still have the '85 MAF, but I converted to the '87 ECM. I have not yet connected the MAT senosr. Can this be causing these issues? Chip is a street chip from PT&E. Should I try and tune around it, or should I just grab a new MAF ($109!!!) and wire up the MAT and try again? Is it the tip-in stumble issue with the 009's? Could I be too lean on top and too rich on bottom? Any ideas?
 

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Originally posted by mike85gn:
Oi! So I have the new 42.5# injectors in the car now and I have been having some minor issues with it. It has a slight off-idle stumble at low throttle settings with a light popping sound and a little power loss. Also, it seems to knock at much lower boost levels than previous, I was able to run about 14psi and the knock was audible
! My thoughts: I still have the '85 MAF, but I converted to the '87 ECM. I have not yet connected the MAT senosr. Can this be causing these issues? Chip is a street chip from PT&E. Should I try and tune around it, or should I just grab a new MAF ($109!!!) and wire up the MAT and try again? Is it the tip-in stumble issue with the 009's? Could I be too lean on top and too rich on bottom? Any ideas?

I am fighting a similar problem and have been for several months now. By a very costly process of elimination, I think I've got it nailed down to the injector circuitry somewhere from the firewall harness to the injectors. If you've got an original injector harness on your car, I'd start there. I just installed a new Casper's 14 gauge harness, so I know that's good. Next I cut the injector harness plug off (engine side - male) and installed a new one. In the process, I noticed one of the wires (pink/black) was suspect, but I straightened it out and took a chance on it. Car ran great for couple of days and then started acting up again. I went back to that wire, moved it around a little bit and straightened it out again and the car ran great.

My next move is to pull the coil pack to clear the area and replace that particular wire from the new male injector plug to as close to the firewall harness as I can get.

My symtoms are/were very much like yours. Very high indicated knock on acceleration even with straight race gas and low boost.

I'm not saying that if you problem is in the injector circuitry, it will be as hard to isolate as mine has been. I'm just saying, check it out.



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TE45, 55lb Injectors, V4, port matched & mild polished heads, 206/206 Flat Tappet Cam, C-P Forged Pistons, 16 Position Max Effort, new best 03/29/02: 11.13 @ 121
 

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Oh, and by the way, Mike, don't overlook the obvious. You just put new injectors in. Did you have them flowed first?

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TE45, 55lb Injectors, V4, port matched & mild polished heads, 206/206 Flat Tappet Cam, C-P Forged Pistons, 16 Position Max Effort, new best 03/29/02: 11.13 @ 121
 

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Discussion Starter · #4 ·
Yeah PT&E flowed them before sending them to me. I have the flow sheet somewhere and they look great. The car ran great with the stock injectors/ECM/MAF/chip in place, but after the new injectors and chip/ecm, the problems started. Really hoping it's tuning or some minor parts (MAF, maybe a new O2).
 

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Hey Mike! Start from scratch with checking the connections to the injectors and work your way back. Make sure to send Zap your Turbo-Link.

We'll see you at the track tomorrow. Bring your snowsuit!
 

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Discussion Starter · #7 ·
Well, I just did the fuel filter! Found out that it was leaking out of the filter, so it's been replaced. According to Dad (best mechanic ever, IMO) it was just pissin' outta the filter fitting, and lkely would cause high boost leaning out and low RPM stutter due to starvation. He picked it up and we threw it in there and checked the connection. Got the MAT installed too, no more error codes! So everything looks OK except for the car, so I'm going to wash it now. Will keep you updated as to how she does tonite in "cruise mode".
 
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