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Old 02-08-2006, 10:16 AM   #1
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Default Some new findings

Last night i changed out my FPR, my fuel pressure sit reads around 39 at idle when u rev it up it shoots to around 52 then falls again to 35 then back to 39 and holds, at any engine rpm....for those wondering i have changed my fuel pump, strainer and filter, my pressure was bad with my old pump at key on ign off.
The car still stumbles around 4000+ rpm, it feels like its not getting enough fuel. Next thing to try is put my pulley back to the 2.55 stock to see if i pull KR then.
Im wondering, maybe I have compleat exceeded what my stock PCM is capable of? Fuel tables cannot adjust for the new found power?
Im really starting wonder if maybe i dont need a compleat custom burn. I have no fuel trim level readings or anything like that as of yet. When the car misses it pulles up to 20 degrees of KR. My plugs are also gapped at 0.55. My exhaust system does not leak at all, nore do i have any broken vacuum lines..
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Old 02-08-2006, 11:31 AM   #2
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Default Re: Some new findings

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Originally Posted by SSEimatt93
Last night i changed out my FPR, my fuel pressure sit reads around 39 at idle when u rev it up it shoots to around 52 then falls again to 35 then back to 39 and holds, at any engine rpm....for those wondering i have changed my fuel pump, strainer and filter, my pressure was bad with my old pump at key on ign off.
The car still stumbles around 4000+ rpm, it feels like its not getting enough fuel. Next thing to try is put my pulley back to the 2.55 stock to see if i pull KR then.
Im wondering, maybe I have compleat exceeded what my stock PCM is capable of? Fuel tables cannot adjust for the new found power?
Im really starting wonder if maybe i dont need a compleat custom burn. I have no fuel trim level readings or anything like that as of yet. When the car misses it pulles up to 20 degrees of KR. My plugs are also gapped at 0.55. My exhaust system does not leak at all, nore do i have any broken vacuum lines..
Matt, for the record, I was bouncing up and down from around 39-42ish and up to 49 when I accelerated right after I changed the 94'* pump. I don't remember the exact numbers, though Bill might. He had the gauge while I was driving.
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Old 02-08-2006, 12:19 PM   #3
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Morty.. you weren't bouncing anything after the change.

Matt.. at WOT according to Bill and Don..that'* low pressure. Odd with just changing the pump and strainer. Maybe check the fuel filter since it'* easy to change.

Morty'* L27 didn't stumble bad until his NY driving style got the pressure down below 30psi

With the changes you made, there are many more factors to be considered and I'm sure BW will have suggestions for you.
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Old 02-08-2006, 02:48 PM   #4
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Only problem is, i cant get a reading while diving, i my fuel pressure gage wont stre out to the W/*
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Old 02-08-2006, 02:54 PM   #5
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Quote:
Originally Posted by SSEimatt93
Only problem is, i cant get a reading while diving, i my fuel pressure gage wont stre out to the W/*
umm....extend it
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Old 02-08-2006, 03:12 PM   #6
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And why are you diving with your Bonneville anyway?

No, really... Use a piece of fuel line hose to make an extension. That way you can drive (or dive) and a friend can take the readings (or other way around).
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Old 02-08-2006, 03:34 PM   #7
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Quote:
Originally Posted by SSEimatt93
Only problem is, i cant get a reading while diving, i my fuel pressure gage wont stre out to the W/*
It may sound extreme, but if you have a helper, it'* easy to remove the hood and put it back when you're done. Tie the gauge to the Strut Brace.

We really need to get this fueling thing nailed down and either identified as the problem or ruled out.

If we rule it out, we need to really consider the LIM as a suspect. Perhaps uneven flow between each port. That'* a big question mark on your car and mine.
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Old 02-08-2006, 03:49 PM   #8
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I exteneded mine to about 7 feet with a piece of air compressor hose, which is rated for the pressure and then through quick research I found it was also good for fuel.

hook it up..toss it in the drivers window and go for a cruise..
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Old 02-08-2006, 08:24 PM   #9
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Tomorrow i think i will have the hose extended, local place that does all the line work for us at work.
For some reason i want to belive its the stock PCM that cant learn fuel tables for that much more power..but im not sure..
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Old 02-09-2006, 12:32 AM   #10
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Matt and I just got off the phone from discussing administrative boring ****, but also touched on his car. Sometimes problems like this are easier to solve while you can talk it out, but I don't want to let our thoughts go un-reflected in his topic.

The major change was the LIM porting. This primarily affects airflow into the cylinders. Because he'* flowing so much better into the cylinders on the intake stroke, his stock PCM MAY not be able to adapt. His massive KR and red hot EM'* are an indication of an obvious lean condition that the Fuel Pump and FPR weren't able to solve (even though both were diagnosed as below spec). This is proof that you NEED to make sure you have ample fuel supply before making major changes, although that did not solve his problem.

In the meantime, since he planned to anyway, he'll be getting a new PCM. While it'* being shipped, he'* going to double-check his fuel pressure with a different gauge, and look for vacuum leaks.

Another thing to try later may be a MAF sensor from a 94/95.
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