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Help with 258 Mopar FI

Thanks again for the welcome back. I'm having some problems with my MOPAR fuel injection on my 258. It runs great once it's warmed up but upon first start in the morning it runs like crap. (not sure how crap really runs but its the best familyish word I can come up with right now.) As long as I keep my foot in it its ok but if I just fire up the engine and don't use the skinny pedal, it sputters and dies at least once. I can't find any vacuum leaks. I checked by spraying WD on all connections including manifolds. I'm running 92 octane as recomended by MOPAR. The engine was rebuilt recently (before deployment) with basically all new guts. It's done this since the install/rebuild. Any takers on what could be the problem? Thanks in advance for the advice.. Rich Harris

86CJ7: Mopar MPFI, Detroit locker, 31 BFG AT's(for now) 1" body lift, Got money left over from deployment and it's going into gears, a front locker, Rubicon Express 2-1/2" YJ springs, one piece axles, and 33" BFG MT's. LIFE IS GOOD!
Reply to
Richard Harris
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Isn't this just about standard running procedures with the MPI Kit? Mine also does it and I've read a lot of others have it. I either try to toe tap it through the warm up or just let it die the first time and after that it's all right.

I have heard a sound like sucking on a straw up to a certian point when starting and after that no which leads me to believe it's some kind of vacuum problem. But I have never figured it out, yet.

You could call Hesco and ask them. Maybe they've come up with something by now.

Bill

Reply to
William Oliveri

Assuming there's nothing weird like something loose, or the basic timing not set right, this sounds like the idle stepper motor isn't boosting the idle speed when cold. Could be caused by a bad ECM, MAP or temp sensor, or just a bad connection somewhere. I'd go back and be sure you've got good connections at the components, then run whatever MOPAR gave you in the way of diagnostic routines. Owners of these MOPAR EFI kits I've come across have raved about how well it performs, the Howell version too. Too bad they're so expensive, but they sure are a good retrofit item on the 258.

Oh, also, FWIW, if you're ever going to consider 35's you should consider the RE 4.5" kit rather than the 2.5.

Reply to
Jerry McG

Reply to
Richard Harris

OK, I didn't realize there was a stepper motor on the throttle body. I though fuel mixture on Multipoint Fuel injection is controlled by the computer not a stepper motor. I'd think (there I go thinking again) that I'd get a fault code if there was a problem with a sensor..No??

PS: 35's are not even in the picture. I feel they are just too big for a SWB Jeep to run. I'm sure someone will flame me for it but that's my opinion. With 31's and skill I've done some pretty good trails, Holcomb Creek and Crabb Flats at Big Bear Ca. for example. My opinion is anything bigger than

Reply to
Richard Harris

Richard Harris ( snipped-for-privacy@san.rr.com) wrote on Monday 26 April 2004

11:42 am:

I've got the same problem. Actually, mine sometimes even dies twice. I've gone to Hesco a number of times with no luck. I've done everything they've recommended, and replaced parts that might even remotely have something to do with it. No luck.

If you fix it, please share with the rest of us.

Thanks.

Reply to
Michael White

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