Running problem And I'm confused...??? Please Help!

[zBusterCB87]

Hi everyone,

CAR-A:
I have a 1990 Chevrolet Beretta INDY, But I striped down the parts and made it a regular Beretta over time...
It had a 3.1L V6, and it had an extremely bad running problem... It missed all the time, and it would hardly stay running, and the main bearings were going bad...

CAR-B:
Then I have a 1988 Chevrolet Beretta I had replaced its 2.8L V6 with a 3.1L V6 from a 1992 Buick Regal because the 2.8 block randomly cracked across the back...lol This car ran great after the Buick engine went into it, no problems, I had taken the computer and E-Prom from CAR-A because the 2.8 E-Prom would not run the newer engine...

----------------------------------------------------
Here is what I did the last 3 days:
- Took the engines out of Both CAR-A & CAR-B
- Put the engine from CAR-B and put it and everything that goes with it into CAR-A, And I put CAR-A's computer back into it, cuz it waas in CAR-B running the 3.1 engine there...

I bought all new gaskets and parts for what needed replaced and such...
- All the sensors and electronics are the same from CAR-B, they all worked.

-----------------------------------------------------
My running problem:
- Ever since doing the job, CAR-A now idles like it has a radical cam installed....? I do not understand...? This engine ran great in CAR-B...rofl
When I mash the pedal, it is fully responsive and will spin the wheels from a dead stop on flat wit the z26 rims....
Sometimes there is a slight pause in taking off, but the car has all its power...

When in higher RPM's it runs fine, just idle id goes back to running like it had a radical cam again....rofl
The engine used to not do this in CAR-B, now it runs like this in CAR-A...

-----------------------------------------------------

The only things that are were not moved with the Buick engine but from the engine that was failing was the throttle body and, nothing else...
I cleaned the throttle body, and replaced the vacuum solenoid with one from the Buick engine already, no luck...
I did not replace the other thing on the throttle body because it was to hot to touch, it was the other thing that apparently seances the throttle plate movement...?
I will change it out with one that I know works, but later...

-------------------------------------------------------
Actually that throttle plate thing is all I have left to change out and test...

Does anyone have any ideas as to what could be happening...?
Sometimes this running like when I say like a radical cam engine, can be like rough idle, I don't have any shop manual for this cars and I cant find much anywhere or anything else much that could be wrong with the car...

Thank you all for your help everyone...
I'd be less frantic about this but I gotta go again in one more week and the cars gotta work (I already spent 1 week changing the engine out from the 88 Beretta cuz its just too rusty to drive anymore, its not safe in that viewpoint), because I wont want to go to school and take chances again...rofl

EDIT:
This morning when I go to start CAR-A it revs up to 3,000 RPM...lol (cold)
This isn't good...
update: I double checked vaccume lines and they are fine except for by the cruiz controll...
Here is what I found: a line goes across firewall to driver side of engine to cruiz controller, a T goes to cruiz and that's all fine, then the pipe continues on toward the front of car and I look at the end and it's been crimped and wraped with electrical tape, this might be an issue...??
I took a piece of aluminum because the egg is not the old vaccume one from the older beretta, it's the new electronic one, but anyways I blocked the opening to see if my EGR is stuck open, I dontthink it is, the car still revs like mad...rofl
Car is still cold, I don't want to run it till it's hot, because then I can't work on it...lol
Anyone have any suggestions...?
Thanks for help, idk what else to check, everythings the same, minus what I looked at and idk what's happening...

[zBusterCB87]

Hi everyone, sorry this thread is taking up space now...
But I found the issue, or so I think...
I can't test it cold because it takes forever to cool down, still...fail...lol
But the rough idle supposedly got fixed...? I changed the TPS...

But I still have yet to see if the random high revv (3,000 RPM) happens again...
My vaccine hose is still broken, I re crimped the end and taped it again like how I found it, it did not seem to make a difference open or closed...

The last thing I did was disconnect all the plastic vacuum hoses and fill all the throttle body ports with brake parts cleaner than ran the engine with the hoses disconnected..
It turned black as black...lol but I think that helped somewhat because the bad idle went to slight miss then after cleaning vacuum system and reconnecting everything it went to a hardly noticeable missing...

But it still missis slightly...lol
Would anyone happen to know of anything else I could possibly do to make it run perfect...?
Because the other Indy (a 3rd beretta) we have that we keep as a show car only, it runs perfect...

Thanks in advance all

[90GTZHO]

Why cant people post stuff like this in the Diagnostic section?