We we got the mods done. The L98 cam is in, the TPI heads are on and the Hooker Super Comps are in. Sounds great with the headers. Real mean sound.

The problem is that it wants to die after idling for a few minutes and if I take it for a test drive it will want to die if I try to give it any gas.

Anybody have a similar problem or have any ideas?

Thanks.

Bill

 

hows the fuel mixture

 

How do I tell?

 

You're going to need to get Winaldl to do some datalogging to check fuel mixture, also you can check your plugs too. But definitely get the Winaldl you'll need to tune that combo in now.

 

When I went through my whole swap here's what I figured out.

You'll need chip tuning to get it to run right. For a small halfway fix make your fuel pressure regulator adjustable and either get a fuel ratio gauge or download WinALDL onto a laptop and purchase the cable to hook up between the laptop and the car to see if it's running rich or lean. But the inevitable (sp)? is chip tuning, it sucks, best way is to read up on it and buy the equipment to do it yourself or you can buy some chips but they wont be perfect. You swap wasnt as drastic as mine so you might be able to get away with just the regulator or even a vacum assisted one. Bump up your IAC alittle as well for a larger cam.

 

Yeah it is very strange, the car seems like it either has a vacuum leak or low fuel pressure, because it gradually starts to run rough after you initally start it. Its so annoying because the motor sounds great, but it can't be driven anywhere! grrrrrrr. Now you guys see why my firebird no longer has TBI on it

 

I'm gonna stick with the TBI though. Just need to do some brainstorming on this problem.

I have a cable and I just downloaded Winaldl to my pc. Just need to transfer over to my laptop and hookup the laptop to the car.

 

When you start it up, does it want to die as soon as it begins to idle down to the set idle speed? Or does it run well at the idle speed and then begin to die off? What happens when you give it gas? Does it stumble? Buck? Or, does it try to crap out, bounce back up, and then run when it picks up speed? You should be able to get it to run quasi-normal as is. Tuning will help, but it should at least be able to idle with the present mods.

 

Dimented

It idles well for a few minutes and then dies. If I take it for a short spin around the block, it tries to die if I give it any gas. If I get off the gas it recovers. After a short trip down the street and back at idle speed it sat in the driveway and idled for a few minutes and then died.

Any ideas?

 

did you take off the TPS? (not sure if this has something to do with it). but you should check the voltage output. did ya replace any of the screens on the injectors or could it be possible that one or both injectors are clogged?

 

Another thing you could try is Resetting the IAC.

 

How do you reset the IAC?

 

We did a lot of grinding on that intake with the throttle body still attached, that was one of my theories that possibly a shaving was lodged up near the injector area. I would say take the TBI off and carb clean the heck out of it, maybe even take off the injectors and blow out all the passages.

 

when it quits, do you get any error code?

To Reset the IAC, do the following..
1. Depress accelerator slightly (and keep it open)
2. Start and run engine for five seconds (with accelerator slightly open)
3. Turn engine off (with accelerator still slightly open)
4. Leave engine off (key out) for 10 seconds
5. Restart engine normally and checkfor proper idle operation

Also how much milage does your car have with that IAC. Perhaps the IAC is wearing out ..

 

No error codes at all. And the car has 74,000 miles on it. The IAC is the original.

Is the IAC the device that is in the air cleaner housing coming up through the bottom?

 

And I believe IAC means 'idle air control"?

 

if your TPS has some miles on it consider replacing. use a GM only and reset to specs. that takes out the worry that TPS is defective or intermittant.

 

The ecm sweeps the IAC through its full range of motion and back to its preset park position every time the engine is shut off. Theres really not much need to adjust it as the ecm self calibrates the iac. Taht too probably wouldnt cause much trouble when driving the car, just at idle if the iac was bad. How much vacuum does the engine pull at idle? If its real low there may be timign issues or a vacuum leak, which brings up the issue, hows the timing? It sounds like possibly there isnt enough timing and the engine bogs out whenever a load is put on it. Try advancing it a couple of degrees and see if that helps. Checking the tps is also a good idea. I could be wrong but it would be unusual for that to cause major problems, though since jsut about the only things that are controlled by it are when to go into idle, the 'accelerator pump', and the throttle follower. Do you ahve the capability to data log? That might help to shed some light as to what is going on.

 

Thanks guys, your giving Chris and myself some good places to start.

The timing was set with a timing light. So it should be ok. Though we can try advancing it a few degrees.

I have a cable and a laptop and can data log. Although I am not quite sure how to hook up the cable to the car. Which holes in the ALDL do the cable wires go into. Anybody have a diagram?

Will the data logging tell us if we have a vacuum leak?

Another possibility is that we had to bore out the 4 center bolt holes on the intake (installed pre-87 heads). We could have clogged one of the injectors. One of the things we will do this weekend is take of the TBI unit and give it a good cleaning.

We will see.

Bill

 

Here is the finished product. Need to get it on the road though.

 

If you wish to test for leaking injectors, just slip a towel under each one and prime the pump. There should be no gas on the towels. Similalarly, you can observe the spray pattern with the car running. It should be a cone shaped spray and it should intensify when you suddenly blip the throttle.

Yes, data logging can show a vacuum leak by the readings from the map. An abnormally low reading could indicate a vacuum leak or some other problem. Oh, almost forgot. How was the lash set? A poorly set valve lash will cause all the same problems. This would be easily seen on a good vacuum gauge by the erraticly fluctuating low vacuum. Even if the lash was set right with the engine off its still worth while to set it with the engine running. You get much more uniform results. Heres a pic of how to hook up the aldl interface.

 

when i had my PFI V6 in the camaro, I remember that it wouldnt idle and keep on dieing, even stalled once at low rpms while i was poking around town, anyway it turned out to be the IAC. but i got a new MAF

 

Hey Bill
That ALDL cable is priceless, set it up how it shows in the picture, you shouldn't need that resistor, I didn't. Once you have the program running, the first thing you should look at is the MAP Sensor on the sensor data tab (not raw data). If that is anywhere above 40 you have a vacuum leak. Reasonably it should be around the mid 20's - low 30's. Try spraying carb cleaner around all of the possible areas and listening for a change in how the engine runs. You can also try spraying soap and water and watching for bubbles. Try running a little more timing, maybe around 7* base? Also, try making the FP a little higher by converting the FP reg to an adjustable one. It could also be your fuel pump, maybe it can just run for a little bit before it craps out? Good luck and happy holidays!!

Tony

 

Dimented,

I already have the cable, one side goes to the laptop and the two conectors on the other end from you diagram looks like one goes to the ground (A) and the other to the data (E). And then just run the car on and run with WinALDL open on the laptop?

I will give it a try.

Tony,

I will check the map data when I get it all hooked up. I will let you know what the results are.

Thanks.

 

Yes. Make sure to specify the correct serial (usually com 1) port or winaldl will not recognize the connection. As long as its all set up properly, the program will automaticly begin displaying the data.

As for the IAC, that certanly shouldnt be ruled out. If you want to see if its the IAC. The IAC can be completly extedned by jumping pins A & B on the aldl. After a few seconds disconnect the connector for the IAC. Give the min air screw on the tbi a few turns to open up the throttle blades. If the car idles and drives at P/T normally, albeit with a fast idle, then a sluggish or faulty IAC is to blame.

Im in the same boat as Jon in that I dont like the IAC all that much because of the problems/headaches it can cause. Ive found that big gains in ease of driving and idle can be found by disableing the throttle follower and taking the idle mostly out of the ecms control.

 

Lots of food for thought here. I will give it a try this weekend. Unfortunately I have to work the holiday. The planes still gotta fly.

Thanks.

Bill

 

this may sound simple, but did you disconect the timing bypass connector when you set the timing? If you don't and set it to 6 degrees it will idle and possibly run for a while till the startup spark decays out. Then you'll be left with negative timing. The amount of advance also decreases with load so if it runs when it's not under a load and dies when it is then maybe your timing is way retarded. Your car will have 20-35 degrees of timing with the computer hooked up and working properly at idle, to set the timing you have to disconect the brown wire with the black stripe, this bypasses the cpu's control over timing and allows you to set the base timing. Just somthin that popped into my head when you described your problem.

 

Yep. We bypassed it when setting the timing.

I ran the car in the garage for a few minutes today and it did not sound as if it wanted to die or anything. Did not take it for a spin though. Maybe tomorrow.

 

anybody have a source for the aldl connector?

 

customefis.com $40 ??