Hey guys, here's the deal. I did an ECO swap into my '98 Cavi. When we were finally able to fire it up, it wouldnt start. To make a long story short, we ended up swappin out the PCM and the fuel pump (the pump had what appeared to be black sand completely clogging the strainer). At that particular time, all we had was my friend'd Walbro 255 sittin in his shed waiting to be installed in his car. So we put it in mine.. the car started and ran just fine. BUT... here in lies the problem. At lower RPMs (mainly between 2k and 2500), if I give it sudden throttle, it wants to stumble a lil and jerk around before it'll smoothly accelerate. The lower the RPM, the more noticeable the stumble. It clears up around 2500 and up. So far, me and Mr. Winstel have changed out the MAP sensor and tinkered with a few things. Its been chalked up to the fuel pump bein to big and flooding the injectors, and then that theory was disproved by Mr. Higgins. Its even been dismissed as the car bein too far outta the powerband, and the stumble is it struggling to gain power. I'm not too sure about that, 'cause it never did that with the 2.4 in it.. it just had dull acceleration, it didnt buck around like it does now. I am up for any and all advice. TPS, IAC motor, anything.. my personal opinion, based on what Higgins said, is that its just the time it takes the PCM to process that there's too much fuel, and close off the injectors to keep from flooding.
R.I.P. JessE Gerard 7.11.87 - 1.25.08
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Have you checked to make sure the fuel pressure is right? It could be your pressure regulator got crap in it and is stuck or something. I guess it might be possible that the fuelpump is outflowing the regulator and causing higher than normal pressure but that usually has to be one hell of an upgrade...
Check your fuel pressure.
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'96 Cavalier Good ol' Pushrod 2.2
-24X,000 miles on factory build
-Some oil loss between changes, me thinks it be rings.
if the pump was clogged may want to check the fuel filter too maybe even injectors
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
I already thought about the fuel filter. It was changed during the swap, so its still relatively new. In fact, this problem has been going on since we actually got the car mobile, which would've put the filter at havin absolutely no miles on it.. just a few minutes of idle time. As far as injectors, no we havent checked them.. but its funny you mention that, 'cause I was contemplating that being the issue just a matter of minutes ago. And we checked the FPR for any type of issues, and it appears to be acting normal. We were thinking of adding an adjustable FPR, but we cant seem to find one that actually lets you dial BACKWARDS. They all seem to go up. The only thing we havent been able to check is the fuel pressure itself. My friend's fuel gauge doesnt have an adaptor for the Schrader valve on the fuel lines. And pending my work schedule (which is hellacious), I havent had time to go pick one up. But thanks you guys for your help, and if anyone has anymore ideas, theories, or suggestions, please send 'em my way.
R.I.P. JessE Gerard 7.11.87 - 1.25.08
The Radiation Nation Facebook Twitter Twisted Metal Alliance
Well first this post is in the wrong section. Should be either maintance, or performance, not tuning.
It could still be possible that there is sand build up in the fuel filter or even the pump. Just because you replaced it does not mean it will not build back up. If there is stuff in the tank it can suck it up. I have never installed a Walboro pump in a J, but I have read plenty on it. I know there was a certain one for our cars. I'm wondering if the one your friend had for his talon is the correct one for the J's. Do you have a part number for it? Also if I remember correctly while installed wasn't there some small modifactions that needed to be made? Someone who has installed one can you verify that?
FU Tuning
Your going to have to get fuel pressure readings for us to diag.
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