Hi guys, I have an 87 z28 with a 305 TPI which has not been running correctly since I purchased the vehicle. First off, the car still shakes a little at idle after I fixed a vacuum leak. The car also occasionally hesitates when I really get on it. Finally the car is running rich as I get pretty poor gas mileage and there is a strong smell of fumes outside the car. I am thinking that I might have a bad fuel injector and also the O2 sensor might need to be replaced or MAF sensor might need to be cleaned. I'm also pretty sure that the previous owner had recently given the car a tune up: distributor, plugs wires, ect. I am wonder if anyone can lead me in the right direction to fix these issues. Thanks in advance.

 

Is it throwing any codes? A datalog will tell you what your sensors are reporting. You can test for leaky injectors by attaching a fuel pressure gauge to the schrader valve on the fuel rail, priming the system to full psi, and pinching the return line. If they are leaking, you'll lose pressure. You can test the electrical part of the injectors by using a multimeter to measure the resistance across the terminals. They should all be very close to each other.

 

Service Engine Light is not on. Thanks for the info.

 

I wouldn't assume that the previous owner did anything. I would pull ALL plugs, check condition and gap, check plug wires for continuity and impedance, check injector impedance hot and cold, check o2 sensor resistance, etc. This should get you headed into the right direction. Do you have a fuel pressure gauge? If you do you might check fuel rail pressure after the pump shuts off to see if it's holding pressure. If not it could be a leaky fuel injector or fuel pressure regulator which could be your problem too.

 

350IROC89, reading your post, you seem very knowledgeable. I also have the poor running engine and found the prom is for a 305 with 19lb injectors. Do you know how to get ahold of a prom for a manual 1988 z28, 350 sbc with 22lb injectors? I spoke with hyper tech and they can get me e chip if I could even get the 4 digit letters on a correct prom but i don't have the correct prom. can you please help

 

contact Tuned Performance on these boards. He can certainly help you out somehow.

 

Send me a pm , apyp is the closest thing to a 350 manual so would need a custom tune.
the apyp for aluminum heads manual transmission but has vats and a different fan switch for a/c.
easy for diy to make timing and vats as well as fan switch changes moates.net has equipment if you want a diy approach.