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Username Post: '94 K2500 TBI Idle Control        (Topic#365505)
Che94 
Newbie
Posts: 10

Reg: 04-04-21
06-13-21 06:23 AM - Post#2821556    

I've thrown a bunch of parts at my '94 350, eventually fixing the true problem with a new fuel pump...the other new parts included the idle control valve and TBI rebuild kit, which pretty much amounts to new gaskets.

The truck runs fine, or at least, normal now with the possible exception of running "rich" when idling, based solely on my subjective "smell" of the exhaust gases. The idle speed is OK/normal(?).

I have to admit I haven't smell tested the exhausts after the engine has gotten up to operating temp.

Any comments or thoughts?






 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25483
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
06-13-21 06:59 AM - Post#2821559    
    In response to Che94

Is timing set to zero? TBI can be forgiving up 4 degrees of timing. Any more timing and a new eprom chip is better.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
Che94 
Newbie
Posts: 10

Reg: 04-04-21
06-13-21 07:19 AM - Post#2821560    
    In response to gchemist

Timing is set to zero.



 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25483
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
06-13-21 05:30 PM - Post#2821578    
    In response to Che94

Is the O2 sensor original? Are there any codes? Check for vacuum leaks. Most emission hoses should be replaced due to age.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
Che94 
Newbie
Posts: 10

Reg: 04-04-21
06-14-21 04:10 AM - Post#2821585    
    In response to gchemist

  • gchemist Said:
Is the O2 sensor original? Are there any codes? Check for vacuum leaks. Most emission hoses should be replaced due to age.



No codes but the O2 sensor is probably the original. So far as emission hoses and vacuum leaks, I replaced a couple of hoses and don't "hear" any leaks but will double check those possibilities.

Thanks...

Note: I realized after the OP I had put the question in the wrong (73-91) forum category.



 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25483
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
06-14-21 06:52 AM - Post#2821590    
    In response to Che94

It's okay. I'll move your topic. Square bodies had TBI until '91. If you need a troubleshooting guide, send me a message or email. I'll send you a TBI PDF file for troubleshooting.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
Sabino 
Member
Posts: 161

Reg: 07-16-05
06-15-21 06:46 AM - Post#2821625    
    In response to Che94

I’d check if you are getting into closed loop at idle. If you don’t get into closed loop it defaults to some, I think, rich setting. If you don’t have scanner memory is there are some pins on ALDL you can jump which will cause the CEL to flash differently in closed loop.
I had a “lazy” O2 once which changed fast enough to get into closed loop when driving but not fast enough to make criteria for closed loop at idle. It was causing me to fail emissions at idle.

65 Belair 350
68 Camaro 327
93 Suburban 5.7L TBI


 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3947
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
06-16-21 10:50 AM - Post#2821671    
    In response to Che94

A common problem for a rich idle on these trucks is a bad coolant temp sensor.
See the thread in the link for discussion and testing information.

https://www.chevytalk.org/fusionbb/showtopic.php?t...

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
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