Mr_Metal

Now that it's running... it wants to RACE at idle.
And, the warmer the engine gets... the higher the RPMs go.
I can "kick it down" w/ the throttle, but it then resumes the "racing idle".

I'm getting about 30# oil pressure, which makes me happy @ 123,xxx miles.

Any thoughts on this problem anyone?

So far I've replaced:
- Brand new:
* Starter/solenoid
* Fuel filter
* INJ 1 fuse
* 8mm coil wire

- Junkyard (used) parts:
* ECM (computer)
* MAF sensor
* MAF, Fuel Pump, MAF burn-off relays / connectors

BoostedVenge

Does this only happen @ idle? Will it drive normally when going around town? What is the idle trying to go up to? I'd check your IAC motor.

LinuxGuy

iTrader: (1)

Check your throttle position sensor (TPS) voltage - it should be 0.54v at the closed throttle position. Also I think vacuum leaks can cause some problems. Just recently, pasky had some problems with the LT1 he just swapped into his car idling at 5000RPM, turned out two of the injectors were not fully seated into the intake causing a huge vacuum leak. He said it settled down to 1200RPM, then 800RPM after tracking down a few other vacuum leaks.

Also, I don't know if it'll help in this case, but here is an idle adjustment procedure you might want to try after you get the idle down. It worked great on both of my 2.8L Camaros to get the idle back to normal, although they were only off by a little bit. (It especially helped the 89 that was stalling. The throttle plate was not even close to being open enough at idle.)

I have done the adjustment twice on the 2.8L V6 (once for each of my Camaros), and I can say the adjustment worked well in both cases. As for the 3.1L V6 adjustment, I've never had a 3.1L to adjust the idle on.

Taken from the Chilton's Chevrolet Camaro 1982-92 Repair Manual.
My own comments are added in italics.

Before you do any of these adjustments, make sure your timing is where you want it. I have found that changing timing will subtely affect the idle.

Multi-Port Injection (MPFI)
2.8L Engine
1.) Using an awl or equivalent, pierce the dile stop plug and remove it. This is the plug covering the idle speed adjustment screw (aka idle stop screw, aka minimum air adjustment screw) on the back side of the throttle body.
2.) Leave the Idle Air Control motor connected and ground the ALDL diagnostic terminal (connect pins A & B. Note: Do not remove the wire from the ALDL connector until instructed to do so in step 6.). Turn the ignition to the ON position, but do not start the engine.
3.) Wait 30 seconds, and with the ignition switch still in the ON position, disconnect the Idle Air Control connector. (This will place the Idle Air Control Valve in the park position.)
4.) Disconnect the distributor set-timing connector. (i.e. - The wire on the firewall you disconnect before adjusting timing.)
5.) Start the engine, allowing to go into closed-loop operation. Watch the Service Engine Soon light on the dash. When the light is flashing 2-3 times per second (i.e. - rapidly), the engine is in open-loop mode. When the light is flashing about once every second (i.e. - slowly), the engine is in closed-loop mode. Once the engine is in closed-loop mode, continue to step 6.
6.) Remove the ground wire from the ALDL connector (leave the engine running when you do this or you will have to go back to step 2).
7.) Adjust the idle stop screw to 550RPM in D if equipped with an automatic transmission or 650RPM in neutral if equipped with a manual transmission.
8.) Turn the ignition OFF and reconnect the Idle Air Control connector and and the distributor set-timing connector.
9.) Adjust the throttle position sensor to 0.54v at closed throttle since adjusting the idle screw has changed the position for closed throttle. Start the engine and check for proper idle operation. You will have to disconnect the battery to clear the code set from disconnecting the distributor set timing connector.

3.1L Engine
1.) Disconnect the negative battery cable. Using an awl or equivalent, pierce the idle stop plug and remove it. This is the plug covering the idle speed adjustment screw (aka idle stop screw, aka minimum air adjustment screw) on the back side of the throttle body.
2.) Ensure the throttle or cruise control cables are not holding the throttle lever from returning fully. Back the throttle stop screw out until and air gap is visible between the screw and the throttle lever.
3.) Turn the screw in until is just contacts the throttle lever; then turn the screw in an additional 1 1/2 turns.
4.) Connect the negative battery cable and connect a suitable scanner to the ALDL connector to monitor the Idle Air Control (IAC) valve counts.
5.) Place the transmission in P if equipped with an automatic transmission or neutral if equipped with a manual transmission.
6.) Start the engine and allow it to reach normal operating temperature and enter closed-loop operation.
7.) Monitor the IAC valve counts with all accessories OFF, the IAC reading should be 10-20 counts. If not as specified, repeat the procedure.

Mr_Metal

LinuxGuy

Thanks for the heads up on the idle adjustment... I'll give it a whirl and let you know how it goes.

LinuxGuy

iTrader: (1)

No problem.
I forgot to ask what exactly you meant by a racing idle. You mean it is going up and down? How high and how low does it go? Thanks.

Mr_Metal

BoostedVenge
Thanks also for your reply...
I didn't see your post or I would have acknowledged it.

Being new to the EFI, I don't know what the IAC motor is.

Call me what you want; give me a carb and a supercharger and it's on... all these gadgets/gizmos are wearing thin on my old-school patience, that's for sure.

Your help is appreciated.

Ovrclck350

First off, check all your vacuum lines. Make sure not only that they're there, but that they're routed the same way.


Next, reset the IAC and adjust your minimum idle. There's a tech article on how to do it on this site. Just go to www.thirdgen.org, click on Technical Articles, then on IAC and TPS adjustment.


The IAC is on the throttle body. I'll post a pic. On TPI engines, it's on the underside, but IIRC (I haven't looked at a V6 in a while) it's on the top. Before you do all this, take it completely out, and clean the pintle. You'll probably have some carbon buildup on it.

LinuxGuy

iTrader: (1)

Um, the procedure I posted above is for adjusting the minimum idle, I posted it because it works a little better and has the RPM settings for the V6 engines (the tech article at ThirdGen.org has the RPM settings for the V8s).

The IAC is the big round thing that sticks out of the throttle body and has a 4-wire connector. On the 2.8L it sticks out the back of the throttle body at an angle on the left side. On the 3.1L it sticks straight out of the left side.

Ovrclck350

Some people don't have access to scanners and such though.


Plus, the RPM's are essentially the same anyways. That's the same procedure I used on my V6 and it always worked great.

LinuxGuy

iTrader: (1)

Yeah, I thought the same thing when I included the 3.1L info, that's just what the book said. I would think the 2.8L method should work fine with the 3.1L.

Yeah, for me the method above worked a little better, but the one in the Tech section works well too. The biggest differences I can see is that the one above has you wait until the engine is in closed-loop and it has you disconnect the distributor timing-set connector (and of course the RPM differences).

Mr_Metal

Thanks to the support/help of the 2.8L MPFI troubleshooters on this board:
Previous Thread
Dale
camaro_junkie
FbodTrek
Ninetails
85f-bird
TomP
dcm01003
pasky
This Thread
BoostedVenge
LinuxGuy
Ovrclck350

The '89 2.8L MPFI is FINALLY running AND idling at a normal speed.
Funny thing is that AFTER I chased down 4 vacuum leaks and adjusted/cleaned the IAC... it would still idle REALLY high.

At that point, I went back to basics and:
*Re-installed the first computer that was in there when I got it
*Swapped MAF sensor w/ 2nd one I pulled from junkyard
*Adjusted the TPS

Like MAGIC, it runs like a champ now.

THANKS all :hail:

LinuxGuy

iTrader: (1)

Wahoo! That's great! Glad we could help.