I have an SES code and some weird symptoms - don't know where to start to correct problem.

'90 RS 305 TBI LO3 engine - no mods (yet)

The SES code is 32 - "Fault in barometric pressure sensor circuit
OR
Fault in exhaust gas recirculation valve
diagnostic switch
OR
Fault in electronic vacuum regulator valve"

The situation/symptoms:

Just installed new timing chain. Car ran rough, thought I needed to adjust timing - found out it was a loose plug wire. Also noticed a drop in the oil pressure gauge ( down to red at idle in Drive ).

Engine cold: Checked oil - full. Cleared codes by disconnecting battery for couple minutes.

After this - no codes, car ran better than ever, and oil pressure back to 30psi at idle in Drive, 40-45psi when I gun it. After 20 minutes of driving, last 10 minutes at above 65mph, SES code 32 returned while exiting highway, and oil pressure gauge reading low again at same instant SES light returned (in red at idle in Drive, at 20psi when accelerating).

I know what/where EGR is ... but not this "EGR diagnostic switch. The rest I don't know. And I'm not sure why this is affecting the oil pressure gauge???

Any input appreciated

 

This may be an old post but I was checking to see if anyone had had this happen before. The hays manual is wrong, it is an egr valve code. If it is like my car, look at the port/valve what ever you call it where the hose from the pcv valve plugs into the base fo the trottle body, I bet the valve/port is cloged up, and you are getting alot of oil in your filter. If this is not the case test for vaccume leaks on the egr valve, and test if the egr valve is working right.

It may be effecting your oil pressure because this will builed up pressure inside the engine preventing the oil from flowing right.

 

Not an old post ... thanks for reply -

I'll check PCV goods, but I don't have any oil to speak of in air cleaner.

I checked the code 32 in AllData .... its a little different than the tech article here at ThirdGen. AllData states code 32 is:

CODE 32 Vacuum switch shorted to ground on start up

Exhaust Gas Recirculation (EGR) OR

Switch not closed after the ECM has commanded
EGR for a specified period of time. OR

EGR solenoid circuit open for a specified
period of time.


EGR valve moves, and cuts engine when I push on it manually during normal operating idle. EGR hoses don't seem to be blocked, So I'm assuming I need a new EGR Solenoid, and got one today ($26 assumption - I can live with that.)

I'll post my results from replacement of EGR Solenoid and PCV check.

 

OK...
Checked PCV Valve ... all seems to be fine - rattles when I shake it, has good vacuum on it, I can see the valve getting sucked in when engine running.

Replaced EGR Solenoid - must have done something good, 'cause now the air flows out the heater and dash vents instead of just the defrost vents (thought I had a vacuum problem in the heater control).

Code 32 gone, no other codes.

BUT.... still have the very low oil pressure. Lotsa throttle, best I get is 25 PSI - at idle in Drive, in the red (0-8 psi). Pressure also drops overall as car warms up.

 

Those GM oil pressure senders are notoriously bad for accuracy. Buy a new one for $30 and problem with oil pressure will most likely be gone as well. It even cured my oil leak problem.

 

Agreed, I would start on the sending unit.

 

Replaced sending unit today ... oil pressure back up ... thx everyone!