Hows it going? Since I purchased my car 3 months ago, it hasn't been running at its peak. I'm going to be as detailed as possible; It is my daily driver and everytime I floor it from a complete stop, rather than pouncing like a lion, the car takes off catching speed slowly while vibrating severly (yes the whole car) ; once it shifts into 2nd gear, the vibration gradually smooths out and the throttle starts to respond better. If I floor it from around 30-40mph, it gives me the same slow speed vibrating effect but not as much. The owner told me when I bought the car that it had injectors that were "a little dirty" and that all they needed were to be cleaned with an injector flush; did that about a month and a half ago and it improved drivability somewhat, now I have these problems to deal with. I tried cleaning my iac valve but the problem is still there. Another detail I think I should point out is that when im driving and I gradually give the car gas, the speed picks up smoothly with no or very minimal vibration. A buddy of mine who has a '04 titan says he can "smoke me" and he can for now but I want to show him what an '89 GTA is capable of!!! Any help on my situation would be greatly appreciated and sorry if I forgot to expand on something...if you want me to explain something a little more feel free to ask! My car: '89 GTA w/ 350 L98 TPI (owner said it was rebuilt and has 40k miles), hedman headers, crane cams cam (not sure of specs), crane cams perf. rockers, flowmaster exhaust and screens removed from MAF.

Thanks in advance guys!
L8R! :Cool:

 

Sounds like an ignition miss to me. I'd put sparkplugs, wires, distributor cap and rotor on it. Since it has headers on it, check clearance of wires to headers and maybe put insulated boots on to keep the wires from burning.

 

I already put a new cap, rotor, and wires about a month and a half ago. I found out today that number 4 spark plug wire is burnt from the header at the boot and they are the cut-to-fit type !
Can this be the cause?

 

yes, the spark is jumping to the header at the boot because it is burned, this will cause the symptoms you mentioned. I have hooker 1 3/4 headers and it was imperative that i got boot insulators; they work well and the boot insulator is actually touching the header and still keeps the boot from burning. Good Luck

 

I would check the fuel pressure, timing and for vacuum leaks first. Don't worry about smokin your buddies truck. Not yet. I think those trucks run 14's in the 1/4. Thats not to far off what our cars ran back in the day.

See if you can get it on a scanner. See if it's getting any spark knock. That will kill performance faster than anything. Check your TPS.

If you have a spark plug wire grounding out it should miss and shake like a bitch, all the time, not just when you lay into it. Look at it in the dark and see if you can see any sparks. You should be able to raise the rpms in park and it should shake/buck. Make sure the distributer is in the right spot. If it's off even a tooth it can make it run sluggish or backfire.

Check the map sensor. It can cause all the things you have mentioned.

Good luck. Let us know what you find.

 

Right on! well im going to give the burnt spark plug wire issue a shot first since its the most obvious; I took a look at the wire in the dark last night and yes its arcing at the header, if thats not it then I will look into the vacuum leaks, fuel pressure and spark knock after. I really appreciate this info guys and speaking of my freinds truck (04 titan) anyone race one of these? He smoked the hell out of my freinds '88 stang gt once (excuse my language) .

Thanks
Ruben

 

Well I put in a new set of MSD universal spark plug wires with the 90 degree boots earlier and the result....no more shaking and the car now takes off much better from a complete stop; not to mention it runs much smoother and looks wayyy better than with the straight plug type! Speaking of the straight boot type plugs.... the ones I had before fitted nicely over the plugs except for no. 6 and no. 8 plugs which were burned at the boot from the header and they were only about 2 months old; I learned my lesson though! The only bad outcome of this "repair" is that the car now backfires when im going 40 mph+; Im going to check that each one is plugged in correctly on the dizzy and the plugs later on today and post an update on the result. I'm also thinking that my car might be running a little on the rich side since every time the car backfires its two or three "pops" a split second apart but I could be wrong. Is there a possibility that this is causing the backfiring?

Thanks!
Ruben

 

Double, triple check to make sure you have the firing order right. I have been a mechanic for years and its still easy to do. Next I would check your intail timing. Don't forget to disconnect the tan wire to put the computer in limp mode. I think if it was a burnt valve or a bent valve it would do it all the time and would miss.

 

Where is this tan wire located?

 

"89 with a 350. Injector cleaner!!! You can not run injector cleaner on those injectors! You will trash the injectors if you have not already.

 

The only cleaner I used for my injectors is seafoam through the gas tank and noticed a difference in the throttle reponse a little, but changing the wires (the proper ones) made it run and launch even better! I also stepped up to "premuim" grade gasoline so it could burn cleaner! Lol well I thuoght injector cleaner was supposed to clean them, what did you use?

 

 

Seafoam is great stuff. I didn't realize no one answered your last question abou the tan wire. On a TPI car I don't know. If there is still the factory sticker on the fan shroud it should tell you. Most of them were either under the passenger side kick panel inside the car or around the A/C box near the firewall.

 

On my car which is the same year, model, and engine its in the upper left side of the engine bay when your in front of the car, right in front of the blower with a cylinder type connector.