86 2.8 difference in Idle

[blazerin]

this is a problem that has my brother stumped!also myself so I thought I would ask you'll for some help. It is a 86 S-10 Blazer 2.8 4X4 Initialy the intake was leaking so he replaced the intake gaskets and reassemled it and everything was allright . then he told me that he pulled the dis. and reset it . For what reason unsure but after this when you grab the shifter to put it in gear the Idle climbs pretty good,enough it will bark the tires when it drops into gear . He replaced the IAC , MAP , The check engine light is on constantly . Also he told me that the damn thing thinks it is in 4 whell all the time . he told me that it has code 22 well with all these problems I'm thinking it could be ECM . He also told me that his Hanes manual says that this code could be the ECU or the Isolation valve . Isn't the ECU located in the dis.?

[blazerin]

This is a 86

[MT-2500]

First thing.
Base time should be reset.
Also there may be a idle relearn procedure on it.
A Good service/repair manual should led you threw it.
Is it a s-10 or s-10 Blazer or a Blazer.
Carb or TBI fuel injection.
Code 22 may be a tps problem or adjustment.
MT

[blazerin]

My brother has drove this for approxematly 2 weeks now since this problem has accurd.I still tend to believe he does have the timing off.

[blazerin]

It is fuel injected,throttle body.

[MT-2500]

Originally Posted by blazerin

My brother has drove this for approxematly 2 weeks now since this problem has accurd.I still tend to believe he does have the timing off.

There is one way to find out.

[blazes9395]

TPS can and will give you a bad idle. Of course, like MT mentioned if timing is off, theres only one way to find out, and correct it. If you have a SES code 22, then you'll have to get that fixed for sure.

Before you check and adjust for idle, you have to verify your timing. To set the proper idle for this engine, you have to ground the diagnostic terminal(like when you get it to flash for the codes), wait 30 seconds and disconnect the IAC motor, while the key is on. What your doing here is when your grounding the diagonistic terminals, the ECM sets the IAC motor to fully closed position, once you disconnect the IAC valve the ECM has no control over idle, and thus allows you to set your base idle.
Turn the key off, unground the diagnostic terminal, and start it up. At this point you have to locate the set screw on the throttle body and set to proper idle. After you get it close, you have to then adjust the TPS sensor to the proper output voltage. I don't quite remember but I think its around .45 volts. You can do this two ways, one with a scanner, and the other with a voltmeter. You probe the proper wires turn the key to the one position, while the sensor is slightly loose on the throttle body, you move it until you get the proper voltage readout for idle. Tighten screws back up and your done setting the proper idle voltage for the TPS. You then again follow the procedure for getting base idle above, it should be close, but check to make sure. After your done, reset the ECM, plug the IAC motor back in, and your idle adjustments are done.

You have to also make sure you have no vacuum leaks, there are no SES codes(otehr than 22 in this case), and your timing is set.

Good Luck!