I just bought an '87 Z28 off a guy at my wife's work. He said it was his sons project car that has been sitting in the driveway for way to long and nothing being done to it. So the wife told him to sell it and I bought it real cheap. The last oil change was due back in December of '03 (if that helps to know how long it's been sitting). The headers were pulled half way off to change to new ones and the spark plug wires were disconnected.

I put on the new headers and changed the spark plugs as well as new oil and filter. The car starts right up, but runs a little rough. I drove it one day to work to get some of the old fuel out and it did ok but would die if I left it in Drive. I would have to put it in Nuetral if I was at a light for more than 5 seconds. When put in Nuetral, it would idol fine.

The next day I go to get in it and it idol'd fine while it was warming up, but when I put it in drive and go to push in the gas pedal the car immediately bogs down like if it's choking or something (absolutely no power until I pull my foot off of the gas pedal). If I hit the gas, it bogs. When I let go of the gas, it idols smooth.

Does anybody have any idea of what could be wrong? I bought this car for a dialy driver to get me back and forth to work and am in desperate need to get it running. I bought a new Distributor cap and rotor as well as a new fuel filter to install this weekend. Anything else I should change out or check to get this thing running right? I appreciate any help I can get.

Thanks!

 

Original engine? TPI? Anything else been changed on it? Any codes?

 

I don't know if it's the original engine. The VIN # says it's a 305, but the guy told me it was a 350? I have not gotten under the car to get the # off of the block to find out for sure. And it is a TPI. The Check engine light comes on only if I rev the engine alot, but goes right back off within minutes.

 

Not good for fuel to sit in the tank and lines for years and then run it.

Gunk in the fuel can clog filters and injectors.

If you look on the block back behind the distributor on the driver-side you should see a 5.0 or 5.7 cast in large letters into the block. You may have to pull some wires to the side and clean some grease off to read it.

 

Not all case castings will have the "50" or "57" included. However, all will have a cast number. That will tell you everything you need to know.



Regardless, the engine doesn't really matter at this point. The more useful piece of information would be they type of fuel/induction system. '87s V-8 were either a carbed or TPI system. Knowing which will aid the diagnosis.

EDIT: Since it has generated an error code, you should try to retrieve whatever codes are stored. That may provide a clue.

 

Pull your codes, they should be stored. If you need help there's a tech article here.

 

You should change the Fuel Filter first and foremost.

 

My car was doing the same thing your is and turned out to be one bad fuel injector.

 

Let's try to avoid diagnosis by buying replacement parts. It can get expensive and time consuming. Pull your codes first, it's free.

 

Thanks for the help guys...I will pull the codes tomorrow when I change out the fuel filter, distributor cap and rotor. I will update as soon as I find out.

 

Okay...I just finished changing out the fuel filter, distributor cap and rotor. The engine still starts up fine, but wants to die/or bogs if I press on the gas. I pulled the error code and it is a "45" which means "oxygen sensor rich". What does that mean? And could that really be the reason the car is running so crappy?

Thanks again for the help guys!

 

triple check your plug & wire install.
check firing order, and for cracked plugs.

 

Could a bad set of wires cause this? That's the only thing I didn't replace because the auto parts stores around here don't have them in stock?

 

doubt it, it definetly sounds fuel related imo. Dump a stp fuel stabilizer in the tank, can't hurt. Maybe theres a lot of condensation in the tank.... Very dirty injecters or tired fuel pump most likely.

Could go get a pressure tester and check the pressure at the regulater rail.

 

O2 sensor rich could be caused by misfire or a few cylinders not firing properly. Listen to 305 sbc. Check the basics first.

 

With the engine running, pull the connector off each injector one at a time and see if your able to give it any throttle.

 

Okay...Plugs look good, installation looks fine. I put a new set of wires on just now and used the Chilton manual to set them up per firing order on the distributor cap. Still idols fine, but bogs if you hit the gas.

I pulled each connector off of each injector one at a time and I was still able to give it gas. It would bog down quite a bit, but then would rev up after a second.

Anything else I should check? Thanks for the help guys!

 

sorry...double post.

 

You may want to post on the TPI board, there's a little more expertise there with your induction. I'm a carb guy myself.

 

Rent/buy a fuel pressure tester and check the pressure at the rails when it bogs down. Definitly sounds fuel related to me.

Have you run anything through the tank at all (fuel additive)?

 

Yes...I've ran some Lucas fuel injector cleaner through it already. I'll rent the tester next weekend when I can devote a full day to playing around with the car.

Another thing I noticed today was that if I gently pushed the gas down it would bog down, but if I mashed the gas it would rev up (not very good, still ran crappy, but reved up none the less). Does this explain anything?

 

Okay...I just tested the fuel pressure and it seems fine. It holds at 40 psi with the key on and idles at about 37 psi. When it bogs down, the pressure jumps to about 45 psi and then goes back down just below 40 when it stops bogging. I don't know what else to do?

Recap: Car idles fine when first started, but as soon as it warms up...the idle starts jumping and the car boggs bad when the gas pedal is pressed. Get a code 45 (oxygen sensor rich). Car is a V8 with TPI.

Already done: New Spark plugs, New wires, New fuel filter, New Rotor, New distributor cap, Cleaned IAC, Tested fuel pressure, and Tested TPS voltage (good).

Anybody have any other suggestions? Maybe a new Oxygen sensor? PLEASE HELP!!