icpr4u

I have a new to me 82 base model that will not idle. It is, as far as I can tell, all factory except the radio, alternator and maybe the antenna.

It ran really rough when I got it so I have changed the fuel pump and ran a few tanks of new gas through with a fuel system cleaner. That helped quite a bit.
It would always run poorly once it was warm and actually died a few times under hard braking or when i'd activate the headlights.

I know this screams VAC LEAK but shouldn't it at least idle?
Looks like the injectors are doing their job with a nice looking cone of fuel spray. I removed the IAC motors and gave them a quick spray w/o any change.

Anybody have tips for this newbie Vette owner?

billschroeder5842

In a word... NO.

82s are a unique beast. The CFI places different demands on the vacuum system. The fact that your car dies when braking or the lights on tells me you need to start with vacuum problems, as these systems are completely vacuum operated.

Could you also be more specific about "not idling" as in "will not run below XXX rpm and shuts off requiring a restart" or "runs rough below XXX rpm but will lope along?" There is a big difference.

Also, leave the IACs alone as they are tricky and temperamental. They do not respond well to being chemically treated.

So here is my recommendation for an initial starting point...
1) Buy a service manual and AIM (Assembly instruction manual) as these are critical
2) Look/listen for vacuum leaks- hoses, manifold bolts. Get a piece of hose, start the engine and put it to your ear and then move it around from port to connection...etc. You will be amazed at what you didn't think you never heard. Start with the driver side back of the engine- there are ports for brakes, headlights MAP sensors etc. Plug a few and see if you can locate the issue.
3) check your timing. You need to be about 12. This will also improve your idle speed.

Easy Mike

Have you checked for possible error codes stored by the computer?

icpr4u

it spit out 12 and 22 and I THINK 44

(I am away from the car and won't be able to really get at it until next Monday)

icpr4u

Thanks

I will try to get that info to you but I am basically gone until next Monday

Please Stay tuned

74 LS4-454

But since you still have access to a computer, you can check out the "sticky" in the above section. Here is the link.....

https://www.corvetteforum.com/forums...solutions.html

You can read at your leisure and this will serve as a guide line to help determine how to correct your CFI problems.....and with the help of us 82 owners, you should be able to correct them yourself or take to a tech who can help with the info gathered here....good luck.

Buccaneer

22 is a TPS issue and should be dealt with first. Check the voltage, key ON, engine OFF. Should read .524mv or just over a 1/2 v. The issue is a low reading. The ECM needs to know where idle is via the TPS. If you try and balance the TBs in "any" way, you "MUST" reset the TPS sensor back to .525mv or your idle will be off.

This is sometimes a PITA to set and you will probably have to play with the screws to get it to the voltage needed. The closer to that number the better. Also, if your TB shafts are badly worn (and at 80k they probably are) it will be hard to next to impossible to balance the TBs and that idle will change i.e. the blade position will change every time you hit the gas because of the play. One of the drawbacks to CFI.

Get the TPS correct before moving forward. The 44 is an O2 issue, it may be bouncing in and out of open and closed loop.

Best thing you can do is buy a GM service manual. Best investment you can make with the car, trust me on this.

Good luck and post up your findings/results.

icpr4u

Ok I got a chance to play with the car a little bit yesterday and here's what I found out:
The TPS is set as close as I can get it. I was using a ALDL cable and winALDL so i'm not sure how accurate that is but it was set bouncing between .47 and .63 initially. When I started it up dropped it .39v. The car was trying to idle at 500-550rpm which seems a little low.
Also, I tried adding vaccum to the EGR valve and it would not hold vaccum. Does this indicate a faulty EGR?
Still getting a MAP sensor code 34. Not really sure what to do about that
My next step is to replace the fuel filter, since I happen to have on hand and then to see if the fuel pressure is where it needs to be. Once that checks out I'll be replacing the plugs and wires along with an ignition timing adjustment/check.

billschroeder5842

First ... Do you have a manual yet?

Next, you need to dial in your TPS more at get as close to that .525 with the key forward and engine not running. Take your time, and tap-tap gently the sensor; the number will jump around a bit but ultimately settle down.

After that.. Code 34 on your MAP sensor says you have low manifold pressure and have vacuum leaks. You need to isolate these leaks starting with (as you mentioned earlier) with your brake and headlights. When you do your car will run like a totally different animal.

Unless you EGR is stuck in the open position, it will have no influence on your idle. Don't mess with it and concentrate on dialing your TPS and hunting down the leaks.

icpr4u

How long does the tps take to settle down?
I sat there and watched that thing for several minutes and it was bouncing back and forth from .47 to .63

Is it more accurate to test with a multimeter and the jumper wires?

billschroeder5842

Yes, a multi meter and jumper wires are the way to go. It took me about 15 minutes.

icpr4u

Ok that's what I'll do then.

I do have the GM service manual but I'm one of those "self taught" guys who knows just enough to be dangerous so the manual is a little difficult to understand at times

icpr4u

Still waiting on the TPS extension harness to set that so no new info but here's a video of the injectors in action.

billschroeder5842

Sorry, video is distorted and feels slo mo.

icpr4u

Yea. It is a slow mo video.
You tube might have play speed options if you care to speed it up and watch it again.
I should be able to get more time to work on her Wednesday. I'll let you all know what I find

icpr4u

Well it Idles

I got a few minutes to mess with it today. My intent was to set the TPS but my multi meter is D.R.D (dead right dare)

So I figured I would start eliminating vacuum systems from the equation. With a plugged headlight system she idles like a champ at about 600-650 in park and 575-ish in gear.

I will get that darn TPS set if it kills me.

Gonna try for a test drive to the gas station tonight to see if it will drive ok

wish me luck

billschroeder5842

As mentioned earlier, vacuum leaks are the bane of our existence. Now that you have the leakage pinned to the headlight system, you can isolate the leaks. Don't over look hoses; if the ends are cracked and not seating well, cut off a 1/2 inch.

icpr4u

Yes that narrows it down for sure
When I came back from the test ride I plugged in the laptop and using winALDL the tps voltage was bouncing all over. The idle was a fluctuating from 600-1000. Because I have a new timing light/toy I checked and it was advanced off the scale. It also was not consistent.
Sill intend on fixing the TPS setting first but it looks like I have some timeing issues to work out as well. Not surprisingly

Buccaneer

The TPS needs to be set so the ECM knows where idle is (blade angle). You do know that you MUST unplug the EST wire before adjusting the advance, right? If you don't the ECM WILL automatically counter any adjustment you make.

I would focus on vacuum issues first after you take of TPS. Hope this helps some, good luck.

icpr4u

It helps a lot. Thanks and I'll keep you posted