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several fault codes

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May 14, 2016, 2:01 PM

Post #1 of 3 (1232 views)
several fault codes Sign In

I got a 1989 Jimmy s15 with a 4.3 throttle body.

I was downtown and when it was idling it would stumble, speed up and then stumble and slow down and sometimes die. I made it home going 70 all the way.

I was going to take the idle control valve off and clean it but it was loose. So, I tightened it thinking I had found the

Then when I started it it ran like it was supposed to but when you turn the ac on and then turned it off it would stumble and die.

I cleaned the Idle control valve again.

Now when I start it the motor stumbles and barely runs and then it suddenly speeds up and runs smooth but
to fast for an idle and immediately throws a

24 code: Vehicle speed sensor vss or circuit
33 code: MAP sensor or circuit excessive air flow
45 code: Oxygen sensor rich

If I switch it off and start it there are no codes set but after it goes through its stumbling again and speeds up
the same code appear again.

Could a bad idle contol valve cause the problem or should I look at something else.

Thanks for your help

Its a week later and I just put the new idle control valve on and now its idling right and speeds up when you
turn the compressor on. All is good now. You can close this out now. Thanks

(This post was edited by jackx on May 18, 2016, 1:39 PM)

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May 14, 2016, 3:17 PM

Post #2 of 3 (1223 views)
Re: several fault codes Sign In

For the 33 and 45 start with the MAP sensor, check engine vacuum, check for vac leaks EGR, vac lines, base gasket etc at the MAP sensor is there good vacuum, what is return /signal voltage ? A skewed signal could force a rich condition.
For the code 24 tell us is speedo working?


May 14, 2016, 4:10 PM

Post #3 of 3 (1217 views)
Re: several fault codes Sign In

Thanks. the hose on the bottom of the map was disconnected and one on the back rear was disconnected. Connected
them and now it runs and no codes. I had already ordered a idle control valve an I guess I will go ahead and put
it on. Maybe then the motor will idle up when I turn on my ac. I think cleaning it helped but I must have knocked
the vacuum lines off the map when I had my big cresent wrench in there trying to loosen and tighten it. Thanks for
your help. I need all the help I can get.

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