droptopped_ta

I need everyones input on this...i've racked my brain to figure out whats wrong with my car...and i've nickledimed myself to the point of thinkin about investing in a match and a gallon of gas for my car. Anyways...heres the problem and what i've done so far.

My car reached 110,000 miles...and it seemed to have a slight hesitation/miss at redline when shifting (4L60E car)

I thought i'd freshen up the ignition so i put a new set of NGK iridium plugs, MSD 8.5mm wires, and an MSD coil on the car. To my surprise this didn't fix it.

I put the car on a scan tool only to find that it showed nothing code wise...however the O2 sensors fluctuated weird so the mechanic suggested i change them. I changed them and the car seemed to run fairly good...however that did last. About a month ago my car decided to start missing on me....it was still driveable but it was bad at launch at the track, and the hesitation made for bad reaction times etc....however it wasn't as bad at high RPM.

The problem progressed so my buddy told me that it had to be the EGR valve...so i replaced it.....along with the EGR solenoid.

NO LUCK

The car started missing really bad.....even smells a little bit rich?..... thru all rpms...i can tell that it has a severe misfire as my corsa exhaust sounds really funny...so i knew that i better look into an optispark.

I also changed my MSD coil again because i could see slight electrical arc between the epoxy part of the coil and the metal square ring it sets in. My new coil did the same thing? I also checked all the plug wires for burns and arc ? No luck there.

Last thing i did was the optispark....this weekend. I replaced the whole unit with a new GM unit...and its just as bad as it was? I'm really not sure what to think. I could use any input you guys have.....because this is making me sick. I also switched the coil wire because the MSD wire seemed to arc off the water pump housing?

Anyways....any ideas are greatly appreciated...i definetly need everyones help. NICE WEATHER..AND A CONVERTIBLE THAT DOESN'T RUN...errrr



95 Pontiac Trans Am Convertible
4L60E rebuilt with 2000rpm stall and revised line pressure
Eiback coilover springs
Edelbroch strut tower brace
Paxton fuel pressure guage
CSI electric water pump
MSD spark plug wires
NGK iridium plugs
MSD coil
ASP underdrive pulleys
Corsa Catback Exhaust and offroad pipe

SLeeper94Z

dude my car was acting just like your try this unplug your 02 sensors and drive for awhile see if it clears up thats what was wrong with mine i bet all my money it was the opti but it was an 02 sensor

droptopped_ta

I replaced both sensors recently..... i purchased new GM units.....but i'll give it a try.

Thanks, Nick

SLeeper94Z

no problem, i did too replace both of mine a month ago and the right went that fast, hope you figure it out

mbc9ie

i have had the same problem, i just removed the EGR valve and AIR pump, and it has made it better.. only noticed one pop at 5500 rpm. at a red light you can notice the car loading up on fuel... i believe my cars problem is MAP sensor related teh signal from the PCM to the MAP sensor is not working. (and no codes) so my thought being the MAP sensor controls (as well as the MAF sensor) fuel load..

i think and i could be wrong.. that the map is giving the car to much fuel and the egr valve is resirculating the gas vapors, and unburn gas fuems back into the engine... and i believe thats where the back firing comes from...
to much fuel in the system....

i have a haynes manual and it tells you how to use a volt meter to check all the sensors and etc.. try it and see what yours says...

jason

droptopped_ta

As soon as i get this thing figured out...its going down the road. I think i need something with more engine compartment room....more storage...and with a hardtop lol. If i get this thing figured out by next month i'm trading it in on a new GTO...err soo mad. Anyways, i really appreciate everyones input. I'm going to test out everything you guys suggested and see where it gets me. Hopefully if i find out whats wrong..it'll be of help to you guys...or the other way around.

thanks again, Nick

Bersaglieri

Where in Ohio are you? I have a similar problem, I am going to try cleaning the MAF and check the coil module. Maybe you should get it checked with a laptop program for a more detailed report.

-Dustin-

droptopped_ta

I live outside of marietta ohio, about 15 minutes from interstate 77 along the ohio river. Its boring here lol....but its not a bad area. I'm going to go test some stuff out on my car again tonight. I'm wondering if i have a bad plug wire or sparkplug ? They're both new...but i suppose its possible. I'll keep you guys posted.
-nick-

droptopped_ta

Welp...under the suggestion of a few LT1 guys i'm removing my NGK iridium plugs, and MSD wires. I'll be replacing them with Accel 9000 series wires...which i just bought, and AC Delco plugs. I've also replaced the ignition control module and coil. First i tried swappin in another MSD coil...but it was arcing...so i removed it and have now replaced it with a Accel unit. I'm hoping the different wires and plugs are the final cure. I'm also going to have my injectors flow benched while i'm doing the 48 hour process of changing the plugs and wires. I'll keep you guys posted with whats goin on.

It also looks like i'll have a good optispark, ignition control module, MSD coil, and possibly a few NGK iridium plugs (less than 5000 miles) and Possibly some decent MSD wires (less than 5000 miles) to sell. Not sure tho...just have to wait and see. I guess if 6 of them are good....then my 98 sonoma 4.3 will be getting some new wires lol. Along with some plugs hehe.

If i don't get the cure soon.....then its going into the shop with intent to find the gremlins lol. After that......its going down the road. It's honestly a beautiful car with alotta nice things added to it. I'll also post it here forsale once i fix it lol.

thanks again for the help. -Nick-

p.s. have you guys had any other luck?

Bersaglieri

My problem turned out to be the opti, my MSD's were not the problem and I dont see why they would be. Dealer ship diagnosed my miss and some detonation as the opti. I am also running so rich I coat the rear bumper with black soot.

-Dustin-

droptopped_ta

I've finally got it running again. To be honest i'm not 100% sure what the true culprit was..however i believe it was a combination of a few things....

to give you guys an idea of what all i did....

Changed my like new MSD wires out for a set of Accell 9000's
(i think one of them was bad..or going bad...makes me mad but i'll be sending them to MSD and selling the new units when they send them to me)

Changed my also new MSD coil for an Accell coil
(didn't make a difference...both were good...will be selling the MSD unit sometime)

Changed the ignition control module
(100.00 bucks and no extreme difference..i will also be selling the take off unit)

NGK iridium plugs with 3000 miles max swapped out with OEM
($12 dollar plug swapped for a $5 dollar plug...debatable difference)

Injectors flowbenched
(very expensive process at 8 ea..but i'm glad i did it. 26.50 ea to have them cleaned but mine all came up 100% and didn't need cleaning)

Optispark
(changed out the old unit with a new GM one)

Anyways...thats what all i did...in the end i think all these things had wear on them...because now the car runs 1000 times better than it did when i bought it. I'm sure the opti was wore..and the one MSD wire may be shot..not sure. I have to run testing on it to see. I may be wrong is saying this...but when i changed to the NGK iridium plugs i thought i had made a great choice....now i'm unsure. I really couldn't justify spending that much on another plug again. The stock platinum ac delco runs great. I'd also suggest anyone thats fighting a similar problem probe the wiring to your MAF sensor and check the voltage with the key on. The middle wire is ground. The yellow is power and should be around 4-6 volts. The pink wire with the center probe at ground still...should read around 12 volts. Check this out and try bending around the wires...wiggling them etc. while your car is running. You might want to try unplugging the MAF sensor while the car is off and start it up. See if you can tell any difference because i think i had a combination of some wiring issues..and ignition issues. Hopefully all is resolved now...and a lesson is learned.

Wondering what the lesson is?...well its that i've learned that for everything i've replaced needlessly...i'll now have a part to sell on ebay lol.


Thanks again for everyones help

p.s. did i mention that i think my one manifold has a slight leak..unsure if its a slight crack or gasket.

I'll be reviewing the idea of headers....so lets here some suggestions on them..

I'm thinkin pacesetter long tubes and having them jet hot coated?

Thanks again for everyones help. -Nick-