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LS1 engine question

This is a discussion on LS1 engine question within the General Help forums, part of the LSx Technical Help Section category; I have just transplanted a 1999 z28 LS1 into my 1971 Chevrolet C-10 and I it is a runner but ...

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    LS1 engine question

    I have just transplanted a 1999 z28 LS1 into my 1971 Chevrolet C-10 and I it is a runner but I have a problem after a minute or so of it running. It acts like it missing on a couple of cylinders. I can drive the truck and it will smooth out after a couple of minutes and drive fine until i shut the truck off and restart it. Does anyone know why it is doing this? No codes in the system and I am at a loss here.

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    Veteran 0rion's Avatar
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    have you done any trouble shooting to it at all? Checked fuel pressure and watched misfire counts to see what cylinders are missing? I guess the first question is do you have any type of scanner that lets you record or view live data? I'd probably start with the basic stuff like that. Any other info you can give us? What about if you just let it sit and idle does it recover on it's own?

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    yes it was put on a lap top, fuel pressure was too high and I have that regulated now. I am getting a high reading on bank 2 o2sensor. I swapped injectors from left side to right side to see if it would get a high reading on the opposing side and it did but switched back to the right side again. I changed the plugs. I cleaned out the IAC port and the tip of the IAC as well.....any other suggestions?

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    the truck runs like a raped ape when you crack the throttle tho it takes a little bit to get it cleared up but it will start to run fine with a little stutter I feel as it is driving but nothing like the missing I feel when it is at lower idle. I put a thermo guage on it and the number one cylinder was cooler than the rest.

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    I was thinking of getting the injectors cleaned by AZTPI but was told it wouldnt fix the problem.

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    when you say the O2 was high.....are you talking about the long term fuel trim %? and how high was it? I'm guessing you checked for exhaust leaks on that side and what not. No bent pushrods or anything like that?

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    Also, might not be a bad idea to check for an intake leak or something on that side while you're at it if you haven't already. Rule out all the small simple stuff first.

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    where's your fuel pressure at and are the injectors the stock injectors?

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    fuel pressure is good, stock injectors. The truck will run rough so I will pop off an injector wiring connector and it will smooth out. I will then put the connect back on and it will run smooth for a while then idle rough again. I've been told its a ground problem by one guy and an injector problem by another. I could buy new injectors for a premium but I am worried it wont be the fix.

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    so pressure is ~58psi? What are your fuel trims showing when you log it for that side and have you logged misfire counts per cylinder? You unplugged an injector and it clears up? That's out in left field really. I'd like to see what your fuel trims are saying on that side. It sounds like they may be real rich and I would wonder if it's that side of the motor only or if both sides are rich and the passenger side is just a little richer than the drivers side. If it's side specific I would look at exhause leaks, intake leaks on that side, injectors on that side, and pushrods/valves on that side.

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    iamsam38: AZTPI? I take it you're in the East Valley? If you need to take it to somebody I can recommend folks.

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