A few months ago I purchased a 96 Z28 from a private seller. I didn’t know too much about the 4th generation of Camaros but I knew I liked the way they look. I love my new car and have been trying to give it the care it needs myself to familiarize myself with the car. The car came with a service manual which I use as my bible with this car. The car has a few problems that I’d like to repair but being a computer tech and not a mechanic the diagnosis process is a challenge for me. Any problem that’s come up I’ve googled time and time again with little luck on one so I came here to ask all of you.

The car has a problem accelerating after it has warmed up. Taking off from lights the car stumbles when shifting from 1st to 4th (skip shift took some getting used to) Most of the time the car recovers and shows little or no trouble at 2000RPM and higher. My dad is a diesel mechanic and has offered me some tips and allowed me to use his scanner which picked up no codes at all from the system. From what I’ve read a bad opti or even O2 sensor would throw some kind of code so I’m at a total loss. The only other info I have is that the fuel pump does seem rather loud. I have not had the chance to test for pressure in the fuel system but logic leads me to believe the more fuel demand the worse the stumble would be at higher RPMs.

If anyone can give me any insight I’d be extremely grateful.

 

I had the same type of problem it was the opti it ran fine till it warmed up then ran like crap. at the top of the page you posted your thread on is a sticky which tells how to do a test to diagnose the opti, it is easy to do and only takes a couple minutes.

 

You can buy one from fleabay or even make a skip shift eliminator, its just a resistor. If the car is running fine except for this I would try this first.

hth

Andy Schuck

 

What are you talking about here...that the skip shift is making the car stumble?

 

I dont think that the skip shift is making the car stumble, that is just when its most noticeable.

 

check the opti, GM fuel pumps whine from the first day they come out, I would also have it scanned again to make sure

 

check and see if your intake elbow is torn

 

As in between the Air Cleaner and Throttle Body?

 

yea it the rubber portion

 

check for vacuum leaks-check for a worn pcv valve. get some berryman carb cleaner and check for vacuum leaks and "false air" between the maf and throttle body. check the egr valve. you have no misfire codes? will your dads scanner allow you to access obd2 misfire diagnostics? generally if it is stumbling-obd2 will flag a code.

 

Service engine light does not have to be illuminated to have a problem.
I would change the o2s anyway

 

Do you know the condition of the spark plugs and wires? When I bought my '93 z28, the man I bought it from took it to a dealership to get it fix and they told him that it was the EGR valve solenoid but I bought it from him anyway. It turns out that the solenoid wasn't bad but the spark plugs were shot. It would run fine when you first start it but then when it warmed up, it would stumble a lot. I would check the plugs and wires too.

 

Given the info here I think I’m going to try and check for a torn intake or a vacuum leak, Beyond that Plugs and wires, They are currently an unknown and sadly the only place I have access to tools is at my dads which makes for a hot car. Also while doing the plugs and wires I’ll diag the Opti using the method in the sticky. If that doesn’t help I’ll move on to O2s. I’ll keep you all posted.