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

High idle

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Old Jun 10, 2023 | 04:26 PM
  #16  
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Re: High idle

I got the part number off the injectors and they are mostplus 24lb I wonder if that's the problem?
Old Jun 10, 2023 | 05:40 PM
  #17  
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Re: High idle

Running 24 #/HR injectors (if stock GM Multec) programmed at 24.9 #/HR 94 and up) in place of the 93’s 22 #/HR is going to cause the engine to run rich, at least initially. But the feedback from the O2 sensors should cause the ECM to use the long term fuel trims (LTFT) to correct the rich condition.

And, there's a limit (~15%) to how much a rich condition can be corrected. Faulty O2 sensors can cause problems, as can additional A/F ratio problems that need correction.

And…. too much fuel doesn’t cause high idle. Too much air causes high idle.

The engine sounds like a real Frankenstein creation. Need to go through it in total to reverse all the stuff the previous owner screwed up.
Old Jun 10, 2023 | 05:47 PM
  #18  
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Re: High idle

Yeah I think I need to get a scanner it's throwing codes again
Old Jun 10, 2023 | 06:35 PM
  #19  
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Re: High idle

I'm stumped it idled good the other day right after I pulled the vac off the top of egr cant find anymore vac leaks is there a way to test iac wires ?
Old Jun 10, 2023 | 06:58 PM
  #20  
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Re: High idle

There shouldn’t be any vacuum applied to the EGR valve at idle. If there is, the EGR vacuum solenoid is leaking. If the vacuum lifts the pintle on the EGR valve at idle, it’s going to cause a rough idle, maybe even cause the engine to stall. For now, cap off the EGR vacuum line at rpthe intake manifold. Takes the EGR valve out of the equation.

Check the vacuum lines on the passenger side of the intake manifold, towards the back. 1 for the HVAC controls, and 1 for the fuel pressure regulator vacuum compensation.

Also, forget about my comments about the injectors in post #17. Don’t know why I suddenly thought you had a 93 with the 22# injectors. Mind is still a bit clouded by pain killers from a hip replacement 4 days ago.

Old Jun 10, 2023 | 07:04 PM
  #21  
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Re: High idle

I'll check I ran the part numbers on the injectors they are like 40 bucks a set also there's an old opti spark laying in the hatch area its weird whatever it did the other day the ses light went out and idle dropped to about 750 in park it has a new maf not sure its correct for the car or not
Old Jun 10, 2023 | 07:33 PM
  #22  
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Re: High idle

Originally Posted by Twiford
I'll check I ran the part numbers on the injectors they are like 40 bucks a set also there's an old opti spark laying in the hatch area its weird whatever it did the other day the ses light went out and idle dropped to about 750 in park it has a new maf not sure its correct for the car or not
If that opti is Original GM and has a Mitsbishi Optical Sensor in it "keep it and rebuild it" its worth more than Gold!
Old Jun 10, 2023 | 07:45 PM
  #23  
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Re: High idle

Not sure it has a brown front car is idling not check engine light went out too
Old Jun 10, 2023 | 07:55 PM
  #24  
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Re: High idle

Whatever is setting that light is causing the high idle wonder if it's bc I disconnect the battery
Old Jun 10, 2023 | 08:33 PM
  #25  
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Re: High idle

Part # references:

1993-1997 F-Body Part Number Collection
Old Jun 10, 2023 | 08:37 PM
  #26  
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Re: High idle

Originally Posted by Twiford
I'll check I ran the part numbers on the injectors they are like 40 bucks a set also there's an old opti spark laying in the hatch area its weird whatever it did the other day the ses light went out and idle dropped to about 750 in park it has a new maf not sure its correct for the car or not
Do NOT buy injectors for $40 per set (of 8?). They’re going to be cheap Chinese counterfeit crap.

The strategy here is to diagnose the problem, find the cause, then buy parts. Buying random parts in the hope you get lucky and buy the right part is something I won’t do. You don’t need my help to do that.
Old Jun 10, 2023 | 09:06 PM
  #27  
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Re: High idle

The injectors were in the car when I bought it I just looked up the part number on it. Today I was running the car seemed like it was surging them ses light went out and it idle fine fans were coming on then I shut it off for awhile and it's back to same thing so I'm gonna get everything to scan the pcm
Old Jun 11, 2023 | 11:31 PM
  #28  
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Re: High idle

Sounds like an intermittent problem. I sometimes have the same. Best is to try to do a scan while the engine is running bad.
Old Jun 13, 2023 | 01:08 PM
  #29  
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Re: High idle

Update the tps sensor was bad replaced it idles great now.
Old Jun 13, 2023 | 01:28 PM
  #30  
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Re: High idle

If the TPS sensor voltage is outside the acceptable range, it sets a code. I asked about scanning the PCM in post #2, You didn’t answer. Probably could have sorted this out 5 days ago. I can’t understand the reluctance of people to scan the PCM. Really just wastes the time of the people trying to help you.



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