90 302 efi
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From: Williamsport,Pennsylvania
90 302 efi
hey guys I posted this in the truck forum and didn't get an answer so maybe you motor guys can help me. all electrical except coil have been replaced . egr valve cleaned . no codes being thrown. 4x4 aod ,,, It starts fine idles good and even revs good in park . but when i try to drive it it boggs down and smells like gas reall bad. if i stay on "WOT" it kinda crackles a little and when the rpms get up then it runs great as long as I stay "WOT" as soon as I let off it goes back to bogging. I pulled the plugs and they look fine. let it warm up and while it was running pulled the oil fill cap and got no smoke so i don't think its a blowback issue. is this a motor issue or am I looking at tranny ?? it shift well so i didn't think that was it. any direction would be greatly appreciated. 
Hotshot
Joined: Jul 2002
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From: Bend,OR
your tranny may be out of adjustment, when was the last time you serviced the tranny. if you smell gas real bad maybe your fpr is toast. when you pulled the plugs did they look real wet, and when you check the oil did the dipstick smell like gas?
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From: Williamsport,Pennsylvania
oil doesn't smell like gas I pulled the plugs and they looked good not wet not sheened over or black well a little but not overly. I thought maybe the regulator but from past experience they either break open or closed. but thinking about it maybe thats not the case. they are cheap and I will try that. I was thinking o2 sensor but they aint cheap and I didn't get any codes for that. as for the tranny well I have never serviced it and don't know when it was done last I just bought the truck a few months ago. I checked the fluid and it's not bright red a little dirty colored and at a good level. Isn't the tranny controlled by the computer? i think its an aod but not sure . the gear selecting is 1,D,OD .
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Joined: Jul 2002
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From: Bend,OR
no the AOD is not controlled by the computer. it has a cable that sits next to your throttle cable . Oh, you may have a clogged cat. that would explain why you must drive at wot . bang it with a hammer, dont dent it though and run it and see if it clears out if not then you probably will need a new on. hows the rest of the exhaust looken?
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From: Williamsport,Pennsylvania
well it will need a new exhaust before inspection and emissions next year my garage guy told me i'm supposed to have 2 cats a precat and another piggybacked right behind it. Muffler is almost done also but I had idea's of going with headers an H pipe "for the o2 sensor" dual cats and dual mufflers. but with emisions I might be stuck with a cat-back. i'm all for clean air but i want some power too !!! I'm nt sure ofthe emisions stuff in my state "PA" but i have seen a single cat ussed to replace both of them " according to advanced auto anyways . well i'll go fire up the hammer and give it a go !! hehe
Hotshot
Joined: Jul 2002
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From: Bend,OR
a single 3" exhaust will perform better then any dual setup you use unless you are pushing out some serious HP. And Yes the new HIflow cats are designed to replace the dual cat setup. your o2 sensor sits before the cats anyway so there is no need to relocate it either. if you go with headers look into a shortie and get a good brand like gibson, edelbrock, bassini. headers are the one item you dont want to go cheap on because it will bite ya in gaskets and time replacing them.
late
late
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From: Williamsport,Pennsylvania
ok here is a new twist now having done nothing but add some injector cleaner this thing is idling super high,, I backed off the idle screw to no aval. also talked to a few exhuast places and they all think the rough running no power issue is from a clogged cat.. I have unplugged the connector thats on the side of the throttle body but it does nothing. is that the TPS?
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Hotshot
Joined: Jul 2002
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From: Bend,OR
first off you should not mess with the idle screw its preset for a reason and will cause issues down the road. a clogged cat will cause the issues you are having. that connector on the side of the throttle body is IAC valve. if it does nothing then you might replace that as well. the tps is located on the bottom of the tb
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Junior User
Joined: Feb 2004
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From: Williamsport,Pennsylvania
well all is back where i started i didn't want to hear IAC thats 60 $$$$$$ plus 300 plus for an exhaust system,, grrrrrrr i'm really starting to not like this truck!!
almost forgot I checked for vacuum leaks and I didn't find anything but I did pull off the air box hoses and its sucking some serious air. that could mean a fuel regulator correct?
almost forgot I checked for vacuum leaks and I didn't find anything but I did pull off the air box hoses and its sucking some serious air. that could mean a fuel regulator correct?
Last edited by Lagerlot; May 12, 2004 at 03:10 PM.
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
no, that has nothing to do with the fpr. do you have a haynes manual? if not get one this will help you diagnose your problem. it will show you how to check your fuel pressure . you may also have a clogged fuel filter.
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From: Williamsport,Pennsylvania
yeah I was going to go get one tommorrow I have one for everything else I own. So far i'm leaning towards the cat. I'll change the fuel filter tommorow thats cheap and never a waste of money
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From: Williamsport,Pennsylvania
Ok here is the update!! new coil and fuel filter hehe " just got out of the shower" the preasure seems good by the way hehe . I went the cat clogged route. called an exhaust guy and he will do the whole thing for 250 so knowing this and that I need new exhaust anyway I decided to open up the cat a little . took out a bunch of ceramic stuff and a bunch of wire crap but none of my symptoms have changed except this sucker is loud. I pulled the plugs again and they show what should happen when they are working properly. no carbon now excess heat ect.... Could an O2 sensor cause this or maybe even a map sensor? i'm not getting any codes at all showing a problem. it idles good and revs good when in park and nuetral. but I did notice something different than before now when I drive the brakes seem like they are not there. I have good fluid level . i'm thinking loss of vaccuum and my engine is toasted starting to get frustated.
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From: Williamsport,Pennsylvania
ok guys here is another update ,,,, I think I have it narrowed down to timing chain !!! I set the timing and it runs good for a little bit check the timing again and it is off. when I have the light on it it advances normal when I give it gas but it will "Jump" quite a bit. With the normal advance I can see the timing line move smoothly give a little more gas and it Jumps several degrees. i'm not sure on how many cause I can't read the marks but it goes from about 1.5 inches below the pointer to 1 in. above it.
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Joined: Sep 2002
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From: Oregon: Land of the Majes
Not to sound like a total ***, but you really need to take the damn thing to a reputable shop, and let them have a look at it...you have been batting zero with it, and an EFI truck is not something you just start throwing parts at.
First of all, you have not ran a fuel pressure check, using a gauge, while driving...that will nail down whether or not it is a fuel delivery issue (regulator, primarily)....you may have clogged injectors, definitely a possibility of the cat being plugged...in that case, make a simple cut in the y-pipe, or, something similar, to check for clogged convertors...some shops have a backpressure tester....with what you have spent on parts already, you may have had it diagnosed by a shop already...
First of all, you have not ran a fuel pressure check, using a gauge, while driving...that will nail down whether or not it is a fuel delivery issue (regulator, primarily)....you may have clogged injectors, definitely a possibility of the cat being plugged...in that case, make a simple cut in the y-pipe, or, something similar, to check for clogged convertors...some shops have a backpressure tester....with what you have spent on parts already, you may have had it diagnosed by a shop already...
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From: Williamsport,Pennsylvania
hehe any input would never be taken like that not from me anyways. I have replaced the fuel pressure regulator fuel filter. I did a leak down test and it stayed at 40lbs. I opened up the cat and its not clogged hehe not anymore . "I needed new exhaust for next years inspection anyways" I do have a reputable shop that I use.He told me it sounds like a timing chain to him. He does not get into major repairs like that ,, he is only a 2 person garage and is always very busy. My truck has 170k on it and the parts I have replaced have not been costly and has for the most part been tune up stuff that wasn't a waste I m going to check the timing belt with a breaker bar and see how much play is in there. I got a few qoutes on doing it and I will just buy the pullers and do it myself.