Hi all,

First off, thanks to all the posters on this site. It's been a major resource in keeping my car on the road.

I have a 1992 Z28 with a TPI 305. I have had the car for less than a year and before my ownership, it had not been driven much in the past 3 years or so. I cleaned the fuel system and it had been running pretty good but now it's running really poorly and getting gradually worse.

It's getting really bad gas milage, no power (esp. when it warmed up), the idle was really high and it stumbles on acceleration.

I started out by replacing the temp sensor for the TPI system, the 02 sensor and the ICV valve. When I tried to set the idle speed, per the instructions that I found on this site, it would not idle down to the 500 rpm in drive at all it would just die as soon as I removed the plug for the ICV. I set it as low as I could but I am seeing about 1.2-1.5K rpm. The car still feels like it's not making much power, but it's better than it was before.

From what I have read, it sounds like the EGR valve has gone bad. Does that sound right? Could it be the MAP sensor? Replacing the EGR valve looks like kind of a pain, so I would rather not do it if I can. Is there any way to test it with out removing it?

Thanks in advance,

Reed

 

Don't rely on the car's tacho for an accurate RPM.

Connect a cable from a notebook to your ECM to see what codes are thrown.

 

What I used to do with my old TBI trucks when the EGR went bad was disconnect it and plug the vacuum ports.

Instant fix. Would throw a code sometimes though.

 

I tried the paper clip trick to read codes, but it's not throwing any. It runs much better, but it still feels sluggish.

I set the idle speed with an external tach, but I don't have a cable to plug it into my laptop. What kind of info can the system kick out? Like can it give me engine coolant temp?

I also have been having an issue with the gauges. Mostly the temp gauge is acting crazy. I replaced the sensor, but it still is not reading right. It acts ok until it gets to 220 than it keeps going till it pegs out. I read the temp with a IR thermometer and it's not overheating and it never looses coolant or boils over so I think that the gauge is messed up.

 

If your engine bay grounds are getting bad it can throw your gauges wacky. Seen it before

 

You really need to have some sort of real time data scan tool to maintain these cars, A cheap aldl cable, tuner-pro software (donation based so free if you don't wanna pay) and the computer will tell you pretty much anything you would wanna know about what your engine is doing. engine temp, iat, map sensor read out, iac position,and a ton more info, its all there in real time. trying to diagnose one of these engines without it is pointless you will just end up throwing random parts at it and wasting money.

 

I have been looking for the block to fire wall ground and I am not sure if my car has it. Is it the one that comes off the valve cover on the passenger side? Theres a ground strap there, but I can't seem to find on one the block it's self.

Any one have a picture of theres?

Thanks for the help so far. I have ordered an aldl cable and I hope that helps me figure out the car some more.

 

I'm not sure where the block to firewall ground is, But i'm pretty sure all the computer grounds and maybe instruments as well were on the back of the passenger side head.

 

I did some more looking around and I can't find a ground wire attached to the head. The only ground wire that I can find is attached to the valve cover and ties to the fire wall. I tried to take a picture, but it's kind of hard to see.

I added a ground strap, off of the ac compressor support. No changes to report. Does any one have a digram that shows where all the electrical grounds are?