I have 1991 Chevrolet Camaro Z28. It has a 5.7 c.i.d Tuned Port Injected motor with a 4L60 auto. transmission. For more than a year, the "Service Engine Soon" comes on and stays on until I shut off the car. I have had two e.g.r. valves replaced because that's according to the mechanics who supposedly diagnosed it -said that was the problem and the service engine soon light is still there. The second egr valve was replaced over a month ago. Evidently that is not the problem. Is there anybody out there who for sure knows or has had this problem before corrected. . I am also experiencing driveability problems, the engine is running rich and idling very rough causing my cat converters to fail at 83,700 mi-that is present odometer mileage. The car seems to run very hot-the electric cooling fans come on at 225 degrees. I replaced the thermostat with 160 degree thermostat and hasn't run any cooler. Is there a way to make this car run cooler? I would like greatly appreciate an immediate response. Thank you.

 

Try a new MAP sensor ($35) but first look all around the engine at the little vacuum hoses and plastic lines, make sure none are leaking.

The temprature is normal... for city driving and sitting at idle for extended periods of time. The fans are programmed to come on at 224 F. Short of burning a new prom with lower fan temps you'll have to live with it (or wire the fans to be on all the time)

check your fuel pressure and also check for yourself to see what code ('s) the computer is throwing.

 

It doesn't need to run any cooler, sounds like that part of it is working fine. As long as it runs below 200 on the highway and the fan cycles on and off when sitting still, it's doing what it's supposed to do. I'd suggest leaving the cooling system settings alone.

What codes does it have stored? It's kind of pointless to just throw $300 parts at a car without even knowing what's wrong with it, or even what it thinks is wrong with itself.

80-odd thousand miles is a reasonable lifetime for a cat. I would not consider needing to replace it to be a sign, by itself, of some deeper problem.

What makes you think the car is running rich?

 

To Morley:
The computer codes, according to these technicians, said it was a Code 32-related to the EGR valve. I do not know how to operate a diagnostic scanner so I don't know for sure. I am just relying on what these techs have told me. I am planning to take this vehicle to another shop tomorrow and find what they tell me- it hard find someone who is honest these days. I also forget to mention that this car idles very rough. I had the cat converters replaced by a muffler shop and they told me that cats failed because it is probably running rich causing the biscuits inside to disintegrate and create a loud rattling sound. What tool do I use to measure the fuel pressure. What should the fuel pressure reading be on a stock tpi engine?

 

You can obtain the codes yourself; all you need is a paper clip. Do a search on this forum for posts by Vader and the words "paper clip". Then look up the codes on teh tech data page on this site, and go from there. Keep in mind, the computer won't tell you "this part is bad, replace it"; what it will do is tell you if something that it sees is either out of tolerance or not in agreement with everything else it sees. For instance, it will give you a "Bad CTS" code if the engine has been running for 10 minutes and the coolant temp hasn't reached 120°; this doesn't mean that the CTS is bad, but rather that it knows that what it's seeing is garbage. Likewise, if it sees high TPS voltage (wide open throttle), low RPM, low MAP (high vacuum, indicates low engine load) and low MAF readings (very little air flow into the intake) it knows that these 4 things can't possibly all happen at the same time, and will set a TPS code. Or, if it gives you "Rich O2 Sensor", that might not be because the O2 sensor is bad, but rather it could be a stuck-open injector.

Remember also, the ECM will attempt to compensate for what it thinks it sees, in certain areas. So for example if the O2 sensor is bad in such a way that it's always giving readings that say "I'm lean, I'm lean", the ECM will attempt to fatten up the mixture; if it's successful at doing this, and is then happy with the O2 sensor's wacked indication, then you car will drink gas like a broken hose and smell like raw fuel, even though the ECM thinks everything is cool.

EGR problems are particularly difficult to diagnose. The system has changed several times over the years and is notoriously failure-prone.

You use a fuel pressure gauge to check fuel pressure. It should be around 37 psi at idle normally, and about 43 psi at idle with the regulator's vacuum line disconected.

Learn to diagnose this stuff yourself; it will save you wheelbarrows full of $$$$ over the time you own the car, and you'll always have a car that runs as good as it can. Get a Chilton's specifically for this car, or better yet a factory service manual (printed by Helm Inc. www.helminc.com ), it will show you where the different parts are, what they look like, etc. Get specific information, post it here and ask about it, there's lots of people who can help.

 

I might also add....

Posting "My mechanic says..." is about as unreliable a troubleshooting method as there is. It's almost a total waste of time posting that sort of thing, especially when it comes from a mechanic you can't trust, telling you stuff you don't trust, and you're asking here because you don't trust what he tells you. It's a little like the Islamic countries where they try to apply their religious laws too strictly, and end up with a law that says a doctor can't go into a woman's tent to examine her, he must diagnose her from outside the tent.

It's just a car, it's not rocket science. If someone as dumb as me can handle it, then it's within the grasp of just about every human with an IQ above around 25. Don't be intimidated by the task, just read how to do it, and go do it.

 

You should be able to get a fuel pressure guage at some of the better auto parts stores, It connects to your fuel rail on the passenger side towards the back, there is a cap on the schrader valve (looks like a tire stem valve), just remove the cap and screw tha guage on there, but don't close the hood with it in place, it isn't meant for perminant installation.
Code 32 is indeed the EGR code but since you replaced the EGR twice and it keeps coming back the problem is somewhere else in the EGR system. It could be the EGR solenoid not opening when commanded to, it could the MAP sensor is bad and unable to see the vacuum difference when the EGR does open, it could be a vacuum leak in the lines to the EGR valve, solenoid or MAP sensor.

Check your own codes. Get a paper clip and straighten it out, now bend it in a U shape with the ends about 1/2" apart. Gain access to your ALDL connector (by driver's right knee or by the fuse block) Find pins A&B, they are the top 2 on the far right side of the connector, insert the paper clip into those pins, turn the key to "ON' but don't start the car. The engine fans will come on and there will be some clicking of solenoids, this is normal.
Watch your check engine light, it will begin to flash out the codes starting with 12. It goes FLASH <pause> FLASH FLASH, it will do this 3 times, then it will begin to flash any stored codes as an example your code 32 FLASH FLASH FLASH <pause> FLASH FLASH, it will flash each stored code 3 times then move on to the next code. When it has flashed all of the stored codes it will flash 12 again 3 times, then start flashing the stored codes again.

Let us know what all codes you get and we'll go from there. If you do get code 32, start by checking/replacing the vacuum lines that go to your EGR valve, solenoid and MAP sensor. Checking the solenoid is a bit more involved and I'll save that for after you retreive your codes and check your lines.

 

I am living proof of that......I knew very little before i swapped to TPI. I just got books, read and (people and this web site helped mostly) went and did it, it's not all that hard, can get frustrating at time though.

 

The problem has been solved. It was the EGR solenoid and the connector. The egr solenoid was malfunction causing the egr to lose vacuum. The code has been erased and the light is gone and the car passed smog. Thanks.

 

when I bought my Camaro I test drove it and it was all sweet
so I bought it!
about 2 miles down the road from the guys house as I was leaving the friggin engine light comes on
and Im looking like this---> It still ran fine so I said screw it...I drove it home for the 2 hour ride looking at that light,then the next day I started to fix the little stuff wrong with the car
and noticed the air tube to the cat. was leaking..I changed that and the light never came on again...well what Im saying is it doesnt take much to have that stupid light come on.....
my other camaro I fixed the light quick,I took it out of the instrument panel

good luck...hope you find it!

 

Glad to here all is well

Did you fix that yourself, or did you have it done at a shop? I havn't done it on a TPI engine, but that is very easy on a carb'd engine.

But RB is right (like always)... learning the basics of car mechanics is easy. When you think about it, really there isn't anything hard about it, only frustrating things . Its all common sense really, once you kinda get the hang of it.