Need some help with my lt1 motor
Thread Starter
Cruising
Joined: Jan 2011
Posts: 13
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Need some help with my lt1 motor
I have a 1992 sonoma gt that has a 96 lt1 put in it out of a 96vette it has been runnin great and now its runnin like crap and not gettin as hot on passenger side as the driver side... i replaced the plugs on it and checked for wire problems but nothing there.. checked all my injector fuses adn i have power going to all my injectors on drivers side but it still runs like its on 4 cylinders if u take it on the road and get on it it will coem out if it somewhat but still aint right... the passenger side gets hot but not as hot as the drivers side and u can see the steam out of drivers side exhaust but not passenger side.. it has tru dual exhaust with flowmaters and no cats what is the problem any suggestions????? Or any one in the area who can come help me out im suppose to be trading it this week but now its runnin like crap plz help
Le Mans Master
Joined: Mar 2001
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From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps
Cruise-In III Veteran
Cruise-In IV Veteran
St. Jude Donor '12
Tripple check the injector fuses - there are 2 of them. One for each bank.
Borrow a set of "noid" lights and check your injectors are firing.
Now get an inline spark plug tester and make sure you are getting spark.
do a search, someone just posted an ICM check while its in the car.
I'm going to go out on a limb and guess ICM/coil or opti.
Good luck - do the checks first before throwing parts at it.
Borrow a set of "noid" lights and check your injectors are firing.
Now get an inline spark plug tester and make sure you are getting spark.
do a search, someone just posted an ICM check while its in the car.
I'm going to go out on a limb and guess ICM/coil or opti.
Good luck - do the checks first before throwing parts at it.
Thread Starter
Cruising
Joined: Jan 2011
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ok so i took into my brother in laws mechanic shop hooked it up to computer and its misfiring on cylinder 4 only.. so we did noid light test and checked plugs wires what not everything is ok.. its not throwin any code lights either except the one thats always been on from tranny shift kit in it.. and it does not do it all the time i drove it there and back and when its out on the road it runs fine and dandy 90% of the time then all sudden BAM it does it for a little bit and quits again but while its misfiring u can push gas past half throttle and it will kick out of it and go like hell again.. Not real sure where to go from here... i was thinkin 02 sensor also p but idk and it unlikely that the opti sensor only f-n up cylinder 4 right?? the misfire counter didnt have any history on any cylinder misfire except 4 and its was alot like a plug wire grounded or somthin but its not IM LOST LOL any more ideas??
Instructor
Joined: Jan 2003
Posts: 165
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From: Marianna FL
i just checked my FSM for my 92 lt1 corvette and there is no code for a miss on #4. the car has 1 coil, the computer is not smart enough to know what cyl is mis-firing. i bet he scanned your computer with the wrong settings.
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Thread Starter
Cruising
Joined: Jan 2011
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i know i said its not throwin any codes we were watching the cylinder fire history on his computer while hooked upand running and it shows u each cylinder and how many times it fires and misfires in a certain amount of time and the number 4 cylinder is the only one that is misfiring but hell idk maybe your right
Thread Starter
Cruising
Joined: Jan 2011
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ohhh and i also found out when my fiance took it to work a cple weeks ago right before it started doin this she put 87 octane gas in it.. its a built lt1 with cam and what not so its always had 93 or higher in it i draind that gas out and put 93 back in it and still didnt work anyone ever use that seafoam treatment?? im thinkin of doin that see if it helps any.. maybe somthein gunkd up from ****ty gas???
Burning Brakes
Joined: Oct 2009
Posts: 773
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From: Minneapolis MN
Since the engine & computer is from a 1996,that means its obd2.Obd2 will show misfires when hooked up to a scan tool.1995 & earlier will not.Concentrate on cylinder #4.Check for injector pulse on that cylinder.Pull that spark plug & inspect.How old are the spark plug wires?Is cylinder # 4 spark plug wire rubbing on anything?Check whats going on with that cylinder & post back
Thread Starter
Cruising
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no it isnt smoking the head gaskets are ok i just put new plugs in it 2 days ago and did noid light test on injectors and hooked a inline wire tester on it and its gettin good spark.. could the injector on cylinder 4 be plugged and showing that its firing and just not firing anything?? i also could not see where the plug wire is grounding out anywhere and like i said it doesnt do it when u first fire it up it will run great for about a minute then starts acting weird and if u push gas past half throttle it kicks out of it and goes like hell i did the seafoam thing to it but it didnt help any either not sure what else to check.. im going to make it dark in my garage and look for a spark somewhere and pull the new plug out today and see what it looks likei tell yall what i come up with... any other ideas what it could be let me know thanks!! could it be a02 sensor or some kinda of sensor makin it do this??
i think this is what i shall try next because nothing seems to be working