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Car stumbling after superram swap

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Old 08-10-2002, 12:19 AM
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Car stumbling after superram swap

Hi everyone, I just installed a superram and accel intake on my basically stock L98. I seem to have come across a few problems. First of all, since I installed the bbk afpr, I have not been able to get a constant fuel pressure reading. Sometimes it'll read 46 with no vaccum, sometimes 51 with no vaccuum. Also, when I start the car and it is cold, it will run but stumble severely until it gets a little warmer, and it seems to smooth out. I also installed 24lb injectors and disabled egr, but I disabled egr and set the injectors for 24lbs in the chip. Any ideas as to what could be causing my problems. Thanks for any help.
Old 08-10-2002, 02:04 AM
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possibly the fact you disabled the egr, not sure but **** happens even when it's not supposed too.
Old 08-10-2002, 04:52 AM
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Try the stock fpr. There are a lot of factors that could cause the stumble, just look over your work.
Old 08-10-2002, 08:16 AM
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I just don't understand why the car would stumble when cold but as soon as it heats up it starts idleing alot smoother.
Old 08-10-2002, 10:17 AM
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Car: 88 GTA
Engine: modified L98
Transmission: 700r4
Axle/Gears: 3.27 9-bolt
It's idles better once it's warmed up because it has switched into closed loop mode, and is really only looking at the O2 sensor to decide how much fuel to add. The Superram has really changed the air delivery to the engine, and the computer doesn't know how to compensate for this in open loop mode since you haven't reprogrammed it for it yet. Do you have a MAF or SD car? If it's MAF you probably won't be able to get completely rid of it, at least I haven't been able to figure out how to yet on my car. Every time it starts cold it barely runs at about 400 rpm, and then the computer catches up and idles it up, but it's not a steady idle. It swings from 600 to 1200 and back again. Once it's warmed up it's a rock solid 725 though.
Old 08-10-2002, 10:22 AM
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The SR has a lot of reversion at low RPMs. Typically it will need the idle fuel leaned out some to run well. You can get an idea of how much by looking at the idle BLMs once it gets into closed loop.

If it is surging at idle, it usually means it has been leaned out too much.
Old 08-11-2002, 05:33 PM
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Not sure if you have SD. If so, have you tuned your VE tables?
Old 08-12-2002, 09:02 AM
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I have MAF and I have not gone into any tables yet, I just changed my injector constant and turned off egr. Thanks for your help so far guys.
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