1990 EGR Headaches

[Rouphis]

I a ran KOEO test, and got code 31 both as a hard fault and a memory code. KOER test also showed code 31. No other codes present.

I replaced the EVP sensor, disconnected the battery, started the truck up, drove it up to operating temp.

I ran KOEO and KOER Tests.

KOEO: 11 With code 33 in memory
KOER: 33 As a fault.

I got out my mittyvac and pulled a vacuum on the egr valve. It leaked down quickly. No change in the engines state.

Where should I go from here? Junkyard hunting?

-Rouphis

 

[v8318cid]

The codes indicate that the valve isn't opening/closing properly or is operating intermittently. As such, sounds like the diaphragm in the egr valve is shot. If it has never been replaced, its probably time. Even if the diaphragm hasn't failed, the valve itself is probably choked with carbon and will have trouble opening/closing even under normal conditions. A failed egr valve can cause unpredictable engine performance, and if you're in a state with emissions inspections, it can cause your truck to fail inspection. Save the evp sensor that you replaced and swap the valve. I'd suggest you stay away from junkyard parts in this case since the replacement probably won't be in much better shape.

 

[Bryan22]

When you applied vacuum to the valve, you should have noticed the engine almost die. The valve is shot. Get a new one from the parts store. Getting one from a bone yard is a bad gamble.

 

[Rouphis]

New EGR Valve Fixed It.

Thanks
-Rouphis