Okay, so here it is. Ive had this problem for the past month. Im almost wanting to trade for a geo because its making me so mad. Ive had a lot of help from the geniuses on here Its all came down to this and it leaves me at this. Theres talk about MAF problems or failing/failed injectors.

The car starts up somewhat normal. It idles perfectly fine, doesnt die or surge. When given gas while its cold it'll die, but after warm its really choppy. It sounds like a helicopter and has no pull whatsoever. It runs around 2800 rpm at 55 and only gets 8 mpg. WOT is completely fine though. Beat an lt1 TA yesterday.

I only have the money to fix one. So what shall it be, injectors, or MAF?

 

MAF problems will set error codes in the ECM. Do you have any?

Did you measure the resistance of the injectors? What are the numbers?

 

Hi i agree with Cliff you will get codes if the ecm sees the maf values are wrong. as for the injectors if you have good wide open throttle power then the injectors should be fine. I would check the throttle position sensor with a multimeter with ignition on the top and middle wire should give 0.54volts d/c wide open throttle 4.5 volts d/c. If something is not right the ecm will adjust settings to try and overcome what it sees as incorrect. this can give problems so start by disconnecting the battery and re connecting it after at least 10 secs.
The car should start and idle at around 1,200 rpm for a few moments and slow to around 600rpm.
If the idle screw has been adjusted you will run into all sorts of problems with hard starting and idle problems.

If the tps sensor shows ok maybe do a base idle adjustment as per service manual ... if you don't have one let me know and i will post the steps online.

Try the tps adjust tuning and reset faults stored by disconnecting the battery first. sounds like a simple fix

 

I have a code 33. A fuse was replaced in the dash by a local mechanic and it was cleared up for about a week. Then it all came back. But the mechanic said I should take it to a vette specialist. And I know none anywhere near me. But it seems like its starving for fuel, or getting to much. And the flooding? Could the maf cause all that? What a terrible part.

 

Doesnt hurt to try.. could you post the steps? That would be great.

Thanks.

 

Ok here goes

Do this with a warm engine and hopefully disconnected battery to clear any stored trouble codes.

First thing to do is allow the car to set the iac valve position you do this by putting a paperclip in the top right two diagnostic terminals under the dash with ignition off.
1 Now turn ignition on and wait at least 30 seconds and while ignition is on (and engine off) pull the square plug of the IAC valve then turn ignition off and remove the paperclip.
2 disconnect the timing bypass wire (a single connector near the fuel pump relay and wiper motor)
3 start the vette and set the idle with a torx bit to achieve 400 rpm in drive with handbrake on
(or 450rpm neutral with manual transmission)
4 double check the timing 6dbtdc
5 double check the throttle position sensor 0.54 volts d/c
6 double check idle 400 rpm.
7 turn of engine and reconnect the timing bypass wire and reconnect the square iac valve connector.
Now the car has the base parameters set so the ecm can run the engine with the info stored in the ecm chip.

8 you are done
Start the vette it should go to a high idle of 1,200 rpm for a little while and slow to around 600rpm.

Don't worry to much of any uneven idle as the ecm will re-learn the engine management. Take the vette for a good drive with normal stopping at traffic lights, with medium acceleration at first then some rapid full throttle acceleration. After a few minutes you will notice a smooth idle and no flat spots during acceleration.

Now if you are still having issues you will need to diagnose that and when its fixed, do the base idle setup again as it will be off if you have vacuum leaks, injector problems etc.

Good luck

 

Okayy, got it!!.. I was going up town for a job and decided to pop in the auto place. With 3 of us and 5 min of looking and tinkering, we fixed the terrible throttle. It was a tps adjustment. Now its smooth all the way down.

They didnt even charge me.

And thanks guys.. the multimeter helped me find a shot injector leading to a flooding problem. Should be running perfect be next week.

 

the multimeter helped me find a shot injector leading to a flooding problem. Should be running perfect be next week.[/QUOTE]

Don't make the same mistake I did and only replace the bad injector. Mine lasted another 500 miles and another went bad. Save a lot of wrenching and replace them all.

I've got 2 of GMs finest with 500 miles on them at an over the counter cost of $145 each. If you want to go the "only replace the bad ones" route I'll send you the 2 for $50.

 

Don't make the same mistake I did and only replace the bad injector. Mine lasted another 500 miles and another went bad. Save a lot of wrenching and replace them all.

I've got 2 of GMs finest with 500 miles on them at an over the counter cost of $145 each. If you want to go the "only replace the bad ones" route I'll send you the 2 for $50.[/QUOTE]

Nah, I like to replace everything when do replacements. Just so I know everything is new. Thanks though.

 

hello, i have a c4 1996 lt1. it starts right up and runs good with all power. after i drive it for about 20 mins or until it gets hot it cuts off. wont restart untill it sits a bit. i had the optispark done last year and done fuel filter and fuel pump. i have no engine light on and am stumped as to what is wrong with it.

 

Since he hijacked the thread to ask his question, this is in answer to c41996 (just so nobody gets confused since this has nothing to do with the subject of the original thread):

Check your ignition module to make sure you've got THERMAL (NOT dielectric) grease under it. The best way to do that is to remove the module, clean off all the grease under it and put new THERMAL grease under it.

 

This is the same problem I had with my L98. It was a heat soak problem that would disappear after a half hour or so after engine shut down and then run perfectly for another half hour or so. The way it was explained to me was that the multec injectors weren't designed for Ethanol fuel which deteriorates the coil seal causing continuity problems when they heat up. Talk to Jon at FIC.

 

cliff, on your advise i changed the icm and low and behold it solved the problem. thank you for your advise!