lt1 running like poo after rebuild
#1
lt1 running like poo after rebuild
hey guys, i just got my lt1 back in my 94 Z. went to fire her up tonight and it idles like crap (400 rpm) and it dosnt rev. if i ease into the gas it will just stumble and fall on its face. not to mention that it sounds like its running off 6 cyl... most of the time... so i put a scanner on it and the IAC didnt move from 128 (whatever that means) and the weird thing was the timing was at 20 deg. total adv. at 400 rpm. but when you put your foot on the gas to try to rev it up it would fall to around 10, and sometimes zero.
i know that a very good possibility is that the opti is taking a **** on me but i am on a very limited budget and that amount of money really isnt in the cards. plus when i pulled the engine the opti was working fine.
i am in a very tight spot. dad needs his garage back lol. any help is greatly appreaciated.
i know that a very good possibility is that the opti is taking a **** on me but i am on a very limited budget and that amount of money really isnt in the cards. plus when i pulled the engine the opti was working fine.
i am in a very tight spot. dad needs his garage back lol. any help is greatly appreaciated.
#2
I'm in the same boat. I fired up the LT1 with a new tune and rebuild and it runs crappy so I changed the opti and it helped but still extremely rich and pops through the exhaust when holding a steady RPM such as 2300. I began to think my valves were set to tight but I've ran through them twice and once with it running so it's not that.
#3
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I never hooked my scanner up with my chip out, but it seems like it's running in Limp Mode (PCM took a dump). But mine ran around 800-900 RPM in limp mode and ran like **** just as you described (the chip wasn't seated right). If it's JUST a rebuild (all stock), and your PCM is fine, then I guess it could be something in the spark control area. Coil, opti, spark control module.
Unplug your PCM, see if that changes how it runs. If so, then the PCM should be fine (still could be bad), if not then it's a fair bet the PCM is a goner.
Unplug your PCM, see if that changes how it runs. If so, then the PCM should be fine (still could be bad), if not then it's a fair bet the PCM is a goner.
#5
sounds exactly what my car is doing, i just sent back the opti because the spindle was jammed into the opti throwing the timing off, i would say your might have your timing checked out, possibly the opti. You might be running in safe mode, so maybe tune out your VATS, there is a diagram in the FAQ's bout how to bypass it.
#6
well, i tried the unplugging the pcm thing and it killed the engine. so we know that is in good working order. but i was talking to one of my buddies who is a GM tech. and he said that the timing should be a zero. and he told me how to properly align the dowel key for the opti. so tomorrow i will rip er all back apart and hopefully that will fix the problem.
but before all that i am going to check into the tuning out the VATS thingy.
thanks guys
but before all that i am going to check into the tuning out the VATS thingy.
thanks guys
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Well, I meant unplug the PCM and THEN start it heh. I guess I'm not 100% sure how PCMs work in comparison to ECMs. My ECM I can unplug my whole chip assembly, but the ECM is still connected. I don't know if there's a limp code inside the ECM's circuit board ot what :\
Sorry I can't be of any help.
Sorry I can't be of any help.