runnability problems 02 impala

[back2life]

my buddy has a 02 impala ls with 3800 II he bought and had a tranny installed. it kept revving up and shuttin off so he has changed tps sensor,map sensor,mass sensor. also the intake was done because had leakage up top. car done lil better but did same thing again..exchanged all sensors again and replaced plenum gasket but same thing..ran better but still randomnly revs up high and sometimes cuts off. im lost now and as long as ive worked on 3800 ive never encountered this problem before. can someone give me some option/opinions?

[back2life]

anyone???

[Tech II]

Sounds like a vac leak somewhere, or an IAC problem, or a fuel problem.....

Vehicle scanned for codes?

Does it run better with the MAF disconnected?

Check for fuel in the vac line to the f/p regulator?

Check for missing o-rings at the PCV....there is a large orange one and a small black one....

This was happening before all these parts were replaced? And still happens?

[back2life]

Originally Posted by Tech II

Sounds like a vac leak somewhere, or an IAC problem, or a fuel problem.....

Vehicle scanned for codes?

Does it run better with the MAF disconnected?

Check for fuel in the vac line to the f/p regulator?

Check for missing o-rings at the PCV....there is a large orange one and a small black one....

This was happening before all these parts were replaced? And still happens?

no vac leaks (checked by me)
codes were only showing idle circuit at first,now i dunno
unplugging maf brung idle down but still was around 1000 and then would randomnly go up again or stumble nd shutoff
pcv has to be checked again...they changed plenums but problem was the same with both
yes was same thing happenin before and after
he took to dealer yesterday and they say its pcm and its $1000 for them to fix but if he brings in a new one they will program it for $80 but wont do it to a used one (we got one out of anutha vehicle installed and it would not crank) the pcm is the one in the air cleaner right?

[Tech II]

This was a GM dealer? List on a new PCM is around $1000(online $500)......

Surprised they won't program a used one(maybe afraid it will conflict with diagnosis?).......the used one you put in was probably the correct part number(was it?), but was programmed for another car, so probably wouldn't start....yes located in the air box....

Would be interested in knowing what the "defining moment" was, that pointed to the PCM....

[back2life]

i dont kno what was the defining moment that pointed to it...that was all they told him. im waiting to hear from him myself. he was looking at getting one thru my job (oreilly auto) to buy it then have them program it. he also took one out of my 01 bonneville and it wouldnt start it either. im stumped and he really doesnt have money to be playing with

[la1]

I second the suggestion about the IAC. I would get some SEA FOAM, The liquid to pour into the tank, follow the directions and a can of the squirt sea foam or sensor safe throttle body cleaner, not carb cleaner. save some of the liquid to pour into one of the vacuum ports on the intake manifold, wear protective glasses cause it will kick back if the engine stalls. Remove the iac and clean the pintle and the bore in the trottle body, there should be an "o" ring on the iac. you will need a ratcheting 90 degree small tool that will hold a bit to remove the IAC.

[back2life]

iac was replaced twice also

[la1]

did the " O " ring get replaced with the IAC ? in other words is there an "O" ring on the one in the car now.

did you check all the vacuum lines, the one that goes to the HVAC control unit, the one that goes to the MAP and brake booster and the one that goes to the fuel regulator.