Hey guys, I have an '87 350 tpi in my '91 gta. When in any gear besides neutral and accelerating under 2 grand, the car bucks like no other. As I accelerate over 2 grand, the motor smoothes out for the most part. And it idles just fine. Does this sound like a shorted injector or two or something else?

 

any changes in gas milage?,maybe tps bad or o2 sensor

 

The car has done this for as long as I have had it which is about a year now. The TPS was replaced when I first got the car. Would the o2 sensor cause it to do this?

The main reason I thought it was the injectors was because of our last try to install an MSD Digital 6al box. The mechanic for the life of him could not figure out why he couldn't get the box to run on the car (after finally getting a working box of course). After hooking up the good box and starting the car, he said the motor would just load up. Out of all the 100s of boxes he had installed prior to this, he had never seen this happen. MSD thinks that I have a bad ground in one or two of my injectors and the box's wiring was interfering with the bad ground(s).

 

The reason the TPS was replaced early on was because the car barely idled. The new TPS fixed that for the most part along with some other tweaking and tuning. Also, the car (when hot) likes to burn really rich. Sometimes so rich that I am putting out exhaust clouds when revving and there is an overly powerful smell of exhaust. I like to burn a little rich but not this much.

 

Also, the car has a mild cam and has been bored .030 over. The couple time I calculated mpg, I got about 19mpg on the highway and between 10-12mpg around the city.

 

just ohm out the injectors. it's not hard. should be around 14-15 ohms, maybe as low as 12-13 but the important thing to look for is one or more that are way off from the rest. first thing I always check when working on a TPI setup. injectors are notorious for internal shorts in the coil windings.

 

Ok I will do that tonight when I get home and update you all afterwards.

 

id say your o2 sensor is bad if it burns rich when hot,because the fuel mix is controled by o2 sensor when car warms up

 

A shorted injector is a reasonable guess.

The bucking was among the symptoms my car gave me.

In my car the problem was intermittent for quite a while which made it difficult to pin down. Once it got to where it wouldn't run anymore I was able to locate the culprit--one injector at 5.5 ohms.

 

check your CTS.