Hello again,

My 1990 Corvette with an L98 engine continues to display a SES code 32 after a few minutes of highway driving. The engine runs normally and the gas mileage is what it always has been.
I have been through this system following both the Factory Service Manual and an article from Corvette Central. the EGR works properly, the EGR solenoid works properly, I swapped the ECM since I had one, nothing seems to help clear this code and stop it from recurring.

Any suggestions are welcome. Remember it is a 90, that system is different from earlier years.

Regards,
B

 

After my top end engine refresh recently I had a similar issue on my '89. I was, frankly, relieved to see that was the only error code thrown after I had the whole top / front / bottom of the motor off for new timing chain, water pump, new gaskets, injectors, valve guide seals and springs, etc... In my case, the EGR temp sensor was bad. It would give an intermittent signal only and the wire connector at the top of the ceramic was no good. So I swapped it out for a new EGR temp sensor and that fixed it. No issues since then.

But your car doesn't have that sensor, it relies on a different method of checking the EGR system operation via the O2 sensor - checking to see if it leans out correctly when EGR is operating. There are a few possibilities (since you've swapped the ECM and it still occurs) - 1/ the EGR valve operation is either intermittent or there is buildup of carbon near the seat which is affecting the EGR flow or pintle movement, 2/ the EGR solenoid is iffy and intermittent, 3/ vacuum line leak to control the vacuum to the EGR valve, 4/ intermittent wiring or connector problem to the EGR solenoid, or 5/ the O2 sensor is giving the ECM a reading it doesn't like when the system is measuring the effects of the EGR test routine.

I'd start with the easier stuff first, checking all the vacuum lines for integrity (especially near that friggin' stupid connector / Y joint near the solenoid itself). Those crack all the time. Then I'd recommend a close look at the wiring and solenoid area - reseat connector, check for shorts, etc...

See what you get, decent starting point...

 

make sure you replaced your EGR valve with the correct one. There is a difference between the EGR valve for an automatic and a manual. Once I installed the correct one for my manual my codes went away.

 

I've had the same code myself on my own '90 for some time.

Haven't really felt like messing with it, but those guys pretty much covered it with what they said.

 

When I had work on the top of my 89 they broke the sensor wire of of this. Check it also as it is very easy to get in the way.

 

I had no idea that my EGR had failed until I did an Emission test of the car. It failed miserably do to NOx that are formed at higher combustion chamber temperatures. It really helps the engine run cleaner and better when the EGR is working properly. The unit on my C4 failed and never threw a code. I replaced the EGR and the FPR and Hundreds of dollars into replacement parts and bolted it back together.

The only item I should have stopped and figured out was when the Insulation on the EGR Feed tube slowly burned off. When an L98 starts pinging I make sure the EGR is working properly as it is can cause detonation.

I like to test it with the engine idling, I put a Hand-Vacuum style pump on the line going to the EGR and when I pull a vacuum the EGR will move up or down and the idle will change.

My other favorite is to check your knock control system, while the engine is running simply "Tap" the cylinder head or something near the engine block with a metal wrench. The idle should drop as it retards the timing showing that it is working properly.