Anyone Know Chevy TPI? I hope so..

[alyssasdaddy]

OK everyone....

This is my problem maybe you can help. I am a mechanic but some reason can not figure this one out. Maybe I just overlooked some things that I should not have.

1987 Chevy Camaro Iroc Z 5.0 TPI California Car

What I did was rebuilt everything, Engine, Transmission, and Brakes as well as Paint and Body. The problem is High Idle no matter what I do it always goes back to 1500 - 2000 rpms. I have set the base idle to 500 rpm with the IAC disconnected and aldl connector in diagnostic mode. Set the TPS to .54volt. The car runs very well, transmission shifts perfect, no misfire, no intake leaks (sprayed FI cleaner at all points that may leak).

When the engine is at a low idle it runs kinda like it has a big cam installed but the cam I used is the one that was with the engine. The Rockers are adjusted (Pretty sure but if that may cause then I will go back through them) Timing is right where it says to put it. (I am using the FSM).

After I set the base idle and adjusted the TPS sensor it ran great RPM where it is supposed to be and fairly clean idle. But the next day back up to 1500 - 2000.

Any ideas?

I know this is a ford forum but the people over at thirdgen have not responded. Seems slow over there plus I am a brand new user there.

I wouldn't mind pouring gas all over it and setting it on fire.. But its my fathers and he had it since 87 from the showroom floor.

 

[James86]

Don't older GM's have a MAF as well? That could need cleaning if there is one, otherwise couldn't the TPS or Idle passage be gunked? A friend of mine has a 1986 Camaro with the 305 with "tuned port" (which is what I think you're talking about), but I haven't really looked at it too often since he usually drives his Dakota for a DD.

This motor right?

It looks like it has a MAF and stuff, but I'm not terribly familiar with GM stuff.

 

[James86]

I know a lot of people with GM 4.3's had issues with their MAF sensors going bad, so you may have just put it all back together and a sensor went bad.

 

[alyssasdaddy]

The motor in Image exactly.

Mas air flow testing was putting out correct data.. But I didn't try the unplug that thing and see if the problems changes yet.

I was also told that this car has whats know as "keep alive power" to the ecm so whenever I adjust and shut it down and restart it could be losing its data. (Shot in the dark)

I am actually going out to try the Mas right now..

 

[alyssasdaddy]

Ok so I checked all my connections, Found a ground off on the back of the engine from the harness. Also found another plug that was burnt against the exhaust manifold. Took car of both not sure what the random plug is for yet.

Codes popped up..

33 Mass Air Flow sensor High GM/Sec Indicated
22 Throttle Position sensor signal voltage low
36 Maf Sensor Burn Off Function Fault
34 Another Mass Air Flow Code.

As for the TPS (22) I am assuming that since the engine idle is too high at the given value it is causing this?

Maybe the Mas 33 is because of the same thing?

34 I am thinking is also due to the High RPM?

So that just leaves 36 would 36 cause this problem? But I am open to suggestions at this point. I will be checking all the codes according to the FSM flow charts. Hopefully I get some some success out of all of this.

Could all of this be caused by a ground wire off from the engine harness?

 

[James86]

Try cleaning the MAF with MAF cleaner. If it's not getting an accurate temperature/air flow reading, it isn't going to tell the engine how much air is coming into the motor, and most of your codes seem MAF related. Try cleaning it first, and maybe check for some other damaged/disconnected wires. Worth a shot.

 

[James86]

Also found another plug that was burnt against the exhaust manifold. Took car of both not sure what the random plug is for yet

Is your O2 sensor(s) hooked up? I know on my other friend's old Buick Century it was the most random looking single wire just hanging off the firewall. When I asked what the hell it was, he said O2 sensor. Google shows that 82+ Camaros at least had a single lead O2 sensor, and since you said it was by the manifold, might be that. Was the plug still intact or was it just a burned off wire when you found it, because the plug end might help determine what it was for.

 

[James86]

I'm not trying to sound like I'm pulling stuff out of my ass, I'm just trying to help on something I'm not terribly knowledgeable about

 

[alyssasdaddy]

The O2 Sensor is plugged in, As for function I do not know. I have not made it to that point. Today I will be going to the county fair so I wont be doing to much work on it.

Tomorrow I will be looking for where that plug goes.

 

[James86]

Ever figure it out? Kinda curious...