LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Running rich problem

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Old Sep 13, 2005 | 12:42 AM
  #1  
cmking26's Avatar
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Running rich problem

Car is tuned for mods in sig but its running too rich. I can smell gas in oil and exhaust burns my eyes out. I already bought an adjustable fuel pressure regulator and turned it down to 37psi idle. If I swapped out 30lb inj. for smaller injectors would that help at all? I need some kind of fix so I can break in engine for a dyno tune.
Old Sep 13, 2005 | 01:05 AM
  #2  
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Re: Running rich problem

does the car ever enter closed loop? Are the front o2's brand new? Did you at least get a bolt on tune?
Old Sep 13, 2005 | 01:38 AM
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Re: Running rich problem

PCM is tuned for my mods. Don't know if its entering closed loop. I just ordered new o2's.
Old Sep 13, 2005 | 01:53 AM
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Re: Running rich problem

Did you put the new o2's in yet?

Where at in IL do you live? If your not to far, are can swing bye and we can put my scanmaster on it, and see what she's doing.

Mike
Old Sep 13, 2005 | 01:54 AM
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Re: Running rich problem

New o2's are not here yet. I'm 45min south of chicago off I57.
Old Sep 13, 2005 | 01:57 AM
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Re: Running rich problem

sent u a PM.
Old Sep 16, 2005 | 05:20 PM
  #7  
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Re: Running rich problem

Got new o2's in and it didn't help any. How about going with smaller injectors would that help at all? I need to do something this is running so rich I can't even breath around the car.
Old Sep 16, 2005 | 11:00 PM
  #8  
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Re: Running rich problem

There's no reason it should not be able to run, tuned correctly, with a 30# injector. Something is telling the PCM to add fuel the engine doesn't need. Exhaust leaks can be a major cause, and also misfires. When you get the scanner on it, look for long term fuel corrections (BLM's) approaching 160. That will be a sure sign you've got a "false lean".

Adjusting the fuel pressure is not a good way to try and tune, and swapping the injectors will not cure the "false lean" problem, if that's what it turns out to be.

You can also see a rich condition if the coolant temp sensor is showing too low a temperature, causing cold start enrichment; or if the MAP sensor is showing a high pressure, indicating the engine is under load when it isn't.
Old Sep 17, 2005 | 09:20 AM
  #9  
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Re: Running rich problem

Car never exceeds about 175 or 180 tops. I have a new map sensor. There is an exhaust leak but its after the o2's .
Old Sep 27, 2005 | 03:51 PM
  #10  
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Re: Running rich problem

Originally Posted by Injuneer
There's no reason it should not be able to run, tuned correctly, with a 30# injector. Something is telling the PCM to add fuel the engine doesn't need. Exhaust leaks can be a major cause, and also misfires. When you get the scanner on it, look for long term fuel corrections (BLM's) approaching 160. That will be a sure sign you've got a "false lean".

Adjusting the fuel pressure is not a good way to try and tune, and swapping the injectors will not cure the "false lean" problem, if that's what it turns out to be.

You can also see a rich condition if the coolant temp sensor is showing too low a temperature, causing cold start enrichment; or if the MAP sensor is showing a high pressure, indicating the engine is under load when it isn't.
What would cause the map sensor to show high pressure when there is no load? Should it just be replaced or is there something else that needs to ba addressed?
Old Sep 27, 2005 | 04:15 PM
  #11  
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Re: Running rich problem

Bad tune, misadjusted valves, faulty sensor, bad wiring.
Old Sep 27, 2005 | 04:20 PM
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Re: Running rich problem

I am still stumped on this. I had the valves adjusted at the machine shop, the map sensor is new, and theres no exhaust leak. I do have a 160 stat and fans come on early so it only runs at 170-175 usually really cool. Would putting this car on a chassis dyno even help me fix this problem? Anybody around Kankakee County wanna come by with a scanner and help me?
Old Oct 5, 2005 | 04:19 AM
  #13  
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Re: Running rich problem

Still need help on this.
Old Oct 5, 2005 | 09:42 AM
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Re: Running rich problem

I have pretty much the same scenario, including a PCM4less tune for my mods. Really running rich, with no exhaust leaks, brand new GM O2s and the (for now) original injectors.

So I'm gonna piggyback my deal on this thread as well, if you don't mind.

Regards,
Brian T
Old Oct 5, 2005 | 02:13 PM
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Re: Running rich problem

Sounds similar to my problem. LT BLM's drop to 108 on left and about 111 on right at idle and deceleration. They gradually return to normal from idle to 1800 rpms. Fuel pressure drops to 0 over about 3 hours sitting time. Got new injectors on the way. If that doesn't fix it, I'm at a loss.



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