Huge problem help please!

[Liquidsteel2]

I have a 1990 rs camaro, 305 tbi. I've been driving it for almost 8 months. but starting 3 days ago. It started back firing really bad when i'm driving it. Idling very rough. The RPM guage is going crazy. Changed TPS, ignition coil, ECM, not sure what else to change. I want to put it on machine, but doubt i'll make it. Said could be a timing issue, or plugged mixed up, but i haven't messed with the timing. Any help would be much appreciated. Could a bad fuel pump, or not getting enough fuel cause this?

[malletslinger]

Maybe... Have you checked the trouble codes?
Did you check to make shure the distributor isnt loose?
If it is going nuts...then it sounds like the computer may be haveing some reference issues. So in three doys you replaced the TPS, ign. coil, and ECM?!? Taking shots in the dark like that gets expensive, and if you make a mistake along the way, it will make finding the problem twice as hard.
Check the codes! If you dont know how, and you dont have a Haynes manual(which outlines how to check the codes on page 3 of Chapter 6) then tell me your email address and I will send you the pages you need(I already have them on my computer).

[Liquidsteel2]

[email protected], yeah i replaced them. My car very important. gotta make it back and fourth to work, thank you kindly for the help.

[wrightz28]

keep it simple....

Ever notice how close those plug wires are to the manifolds?

I'd be looking for burnt wires

When was the last tune up? (plugs, wires, filters, o2, cap & rotor). And yeah, after mentioning the cap and rotor, you replaced a coil with out replacing these first?

[Liquidsteel2]

Because my pockets aren't big, I bought those over time, because i was going to by 5.7 injector, Because my bottom end is a 350, I went on and put them on there, because i figured it could be those. I was wrong. Coould the Map sensor cause this?

[wrightz28]

My pockets aren't big either, that's why I don't shotgun parts at a problem hoping one will hit the mark.

Again, keep it simple, pull your plugs and read them. Check the wires for being burnt through by the exxhaust. This can be easily done by spraying water on them when it's dark, you'll see the spark arc out of the insulation instead of going to the plug.

Still no codes?

nothing on the last tune up?

[Liquidsteel2]

Yeah the check engine light is on, i took to advance to get it scan, He said he couldn't scan it, but those peeps sorry up there. Do you know, how i can get it to flash codes using a paper clip or something? I read that somewhere but i can't remember. I changed wires and plugs maybe 5 months ago.

[wrightz28]

Okay, now we're getting on the same page here.

To get codes you jump on the diagnistic connector A to B, the top right 2. And yes a paperclip iwll do fine. DO NOT do this with the car running. Put the clip in, then turn the ignition to run, not start. You'll hear the radiator fan come one, and then she'll start talking, by code 12, blink, pause, blink, blink =12. After 12 falshes three times, any other stored codes will follow.

Just because you changed the plugs and wires, does not by any means make them exempt. Right after changing them is when plug wires are the most suspect to being burrnt. What did you set the plug gap to? Have you doulbe checked and made sure the boots are secured to the plugs and distributer posts? What plugs did you use, please don't say Bosch. If so, get em out of there.

Did you check the ignition timing after the plug and wire swap?

[Liquidsteel2]

12,15,23,34,43 are the codes, yeah i used Bosch, i thought they came pregapped....

[wrightz28]

Alright, well I think malletslinger has a manual close to your year and can chime in with something a little more concrete, but off the top of my head:

12-normal, no pulse ref.
15-CTS constant low temp or open?
23-I know 21 and 22 are TPS circuit on the TPI setup, not sure about TBI?
34-definatelya MAP code, high vacuum? (vacuum leak somewhere)
43-ESC spark control system, (EGR in some systems)

I'd recommend disconnecting the battery for about 2 minutes to reset the ECM and running it again for a few minutes. I'd love to see just the 34 come back which would simply mean a vacuum issue. Check the vacuum line to MAP for the giggles of it while resetting the ECM.

And yes Bosch platinum are pregapped, but their quality has deminished in recent years. Both of my own cars and a few cars I serviced were experiencing misfires. After taking Bosch out of all them, they were all fine as the plugs were the only things the cars had in common.

When it comes down to the ignition system use good ol Ac/Delco, may cost a little more up front, but the long term savings are well worth it, especially on ignition modules.

[Liquidsteel2]

alright, just reset the computer about to run, and see what it does, I really appreciate all the help your giving me.

[Liquidsteel2]

For the time i drove, check engine code, was only 43 after computer reset, but it didn't misfire not 1 time, but it will drive good for a while, but start actin up. But didn't while i was driving. Knock sensor was loose only thing i seen noticeable, no check engine light while it was on. it feel back off. then light on. Guess that's what was causing code 43.

[malletslinger]

That'l do it...
You should find some way to keep it from falling off...
Thats great!...now dont you feel like an ass for just buying parts left and right?,lol
Its amaising how much trouble can be caused by one little thing isnt it?

[Liquidsteel2]

Thanks for the help. Nawww i don't feel like a ass, I already had those things. I just wanted everything new, when i started seeking for performance out of tbi. car is 16 years old. None of those things ever changed. Thanks alot for the help everyone. I really hope the knock sensor was it. Didn't know that could cause misfire.

[malletslinger]

I strongly suggest buying a HAYNES REPAIR MANUAL, It is full of info and is worth more than its weight in gold. They are cheap and can help a do it yourselfer save hundreds of dollars! in somecases with just one repair.
My camaro was vibrating and running badly, and one of the trouble shooting tips said to to the timming chain, so I read the section on timming chain replacement and did it myself. Parts were about $58 including gaskets and sealer. I did it myself and it made a world of difference, just like the book said... To have it done at a shop would have been hundreds of dollars!!! In a few hours, the paid for itself many, many times over