Car is an '88 TBI car, modified to TPI with spliced harness.

Camaro will start, not quite as easily as it should, but the main issue is that it doesn't want to idle. When cold, it will surge between 750-1200, then when warm between 500-750 and eventually stalls.

I pulled the IAC motor, turned the key on, and nothing. The motor doesn't spin, the pintle doesn't move in and out like it should upon start-up.

Like I said, its a spliced harness, so I checked the wires at the splice and re-soldered them. After doing this, I had a friend turn the key on as I help the IAC, and I could feel the motor trying to spin (slight torque between my fingers), but the pintle still doesn't move. I had issues with this before (turned out to be bad fuel pump which has been replaced) and bought a new IAC. I checked both the new and old IAC motors, both do the same thing.

I'm at a loss now, anybody know what I should do? I would hate to fork over more money for an IAC, but if I must......

 

Turn on ACC, use multimeter at the IAC weatherpack harness connector. Should have current in all 4 pins. If so, go and buy a new IAC from any place that sells any brand other Duracrap..

 

Just had some free time, seems I confused the ALDL pins.

After jumping out A-B (correctly) and turning key to on position, all 3 (thats right, 3) IAC motors I have not only moved, but kept going until it shot the pintle, connecting shaft and spring clear out from under the hood.

Do I have 3 bad motors? are they all crap? or am I somehow giving this thing too much juice and its blowing the motors that easily? 2 of the 3 shafts went back as they should, I simply pulled the spring back and threaded them back in. The other seemed stripped, so its a gonner.

Now what should I do?

 

OOOOPPPPS. I forgot to tell you to turn off the switch before they shot out. That means they are working bro. What its doing is closing the port so that the engine can turn on. Sorry man. Once the engine is on, it'll begin to open and close in steps to maintain the idle. Now go ahead and put in the one that you feel is better than the other. But make sure that the gasket ring is used so that you wont have a vacuum leak.

 

Back together and working good. Thanks for your help! It just idles a little high, so I'm gonna do some research as to how to adjust the idle.

 

Yo I can help you with that. Hold on, Im gonna post 2 good sites.

 

1. http://www.highperformancepontiac.co...gta/index.html

2. http://mpikas.blogspot.com/2008/08/t...june-2000.html

And your welcome man. Im glad it worked out for you bro. let me know how it goes. I can tell you this though. It is gonna be either your "idle stop screw", or the TPS sensor that needs to be adjusted.

 

still havent got mine to work right an i have tried everything!

 

Did you do the TPI Tune Up on the links that I provided? Let me know what happens when you do the Tune Up.

1. http://www.highperformancepontiac.co...gta/index.html

2. http://mpikas.blogspot.com/2008/08/t...june-2000.html

Any troublecodes?

 

Alright, so I'm not completely out of the woods yet.....

The car idles low again, after loosening the idle screw a little bit. But unfortunately, it still 'hunts' at idle. When its cold it behaves just fine, but as it warms up, with the car in park or drive, it will surge a few hundred rpm's, and eventually stall. No problem re-starting, just staying running.

One thing worth mentioning is that I have RBob's EBL setup, which makes diagnosing these issues much easier, granted I know what to look for.

The TPS is fine, the IAC has recently been replaced (but not adjusted, thanks for the link, I'll do that tomorrow), and I don't think its a vacuum leak, as it idles where it should (around 675, not bad considering it has a fresh cam, spec'd 204/208 with .484/.505 lift @ .050).

I'm currently running VE learns using the EBL tuning software to get it where it should be, but as the O2 sensor still reads inconsistently, I think it may be a lean condition causing the confusion.

What other steps can I take besides continuing the VE learns, setting the IAC and TPI?

 

The IAC does not have to be adjusted. It is ONLY controlled by the ECM so dont worry about that. I dont know what RBob has but if your Camaro is a full blooded TPI with no tuning to the tables within the MemCal, then it may be that your loosing vacuum with that camshaft. To me it seems a bit too big. But I may be wrong.

 

I only adjusted the length of the pintle from the IAC housing, made sure it was right around 1 1/8 of an inch.

I also adjusted the TPS, it was off but still not the root of the problem.

Seems to me that the engine is running very lean (low mv on the O2, right?) at closed throttle. During cruise its right at 450mv, but at idle its around 40. Coming off throttle it jumps to 800 or so. I think the cam may be the issue, but how can I fix it? I'm sure tuning is able to do it, I'm just not a master at it.

 

OOOOOOOOOOO. Dont listen to that crap that authors write on how to adjust the IAC vavle. For one thing, you dont have to have the cone at that exact measurement because what will happen when you turn on the car? Once the switch changes from off to on, the ECM automatically plunges the cone on the IAC motor to close the port which will not let any air into the intake during cranking. With that said, all you gotta do before installing the IAC motor is hold back the spring and turn the cone "in" as far as it will go until it doesnt go in any more. You will know when the cone doesnt go any further in because it'll just spin. I dont know anything about the O2 sensor because I never had that problem. I learnd all my info from issues that Ive ran into. As for the cam, a solution that MAY work is installing a vacuum pump but I dont know much about that either.

 

Also as for the tables within the MemCal, I dont know much about that too. I jsut know that you can have the tables adjusted so that all values match up correctly, depending on what mods the vehicle has. That is exactly what a DYNO shop does. They'll charge close to $1,000 just to change values within the MemCal.

 

Well, the good news is I have all the equipment necessary to retune everything I could possibly ever need to change.

The bad news is I don't have the experience to properly do so.

 

Me neither. You know what, I think RBob does programming of blank EPROMS. Since you have almost the same intake, PM him and ask him for advice. Maby he can further help you out.

 

Already ahead of you. The software mentioned was purchased from him, he's been helping me out quite a bit. I simply needed to increase the VE tables for certain RPMs and vacuum readings, and now it stays running. Probably need to keep fiddling with it, but at least its not stalling.

 

From what I have read on the posts, it is best to tune with a laptop and with the engine running. The best software for this would be the tuner pro RT. Keep me updated.

 

this is what I have learned building a Speed Density system for my 92 Camaro, using DFI equipment. Firstly, the IAC is designed to bypass throttle plates to even out your idle. To initially set the IAC value, turn key on, wait 30 sec, turn key off, repeat 2x. This will set the 'initial' plunger value depending on how deep you screwed it in, etc. If you have tuning software, the IAC is displayed in percentage of open, it should read 80+ with key on, no start. You 'should' be able hear it cycle when key on, key off, its a worm gear and they whirrr.

Depending on your setup, cam, heads, etc. it matters little, what you want is around 5-8% open IAC, warm, at idle. To achieve this, you have to change the throttle plate stop screw in/out to add/remove air to the engine, and then let the IAC handle the granular idle. Unsure where to check the IAC value is in tuner pro RT, but in CalMap its under Target Idle Speed, bottom right hand corner gives IAC percentage.

The idle surge, honestly sounds like a vacuum leak, however, you have said there is none, so I would consider putting a fuel pressure gauge in the fuel rail to see if you are getting a drop in pressure, creating a lean condition and rough idle.

is it switched over to sequential or are you still running bank fire?

p.s. Once you get the IAC where you want it, be sure and reset 0-WOT for your TPS