Having to replace the EGR valve every three months

Tiny
SEAN0309
  • MEMBER
  • 1993 CHEVROLET 1500
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 60,000 MILES
Hi, the truck listed above is a K1500. I have replaced my EGR valve 3-5 times. Every 3 months it goes bad. Any suggestions on why this is happening. Also my exhaust smells like fuel and when I start in up and let it warm for a few minutes the RPMs start dropping like it is going to shut off. The tachometer goes down then it jumps back up. The exhaust smells like rotten eggs which I am guessing means the catalytic converter is bad. I was wondering if the catalytic converter could make the sensor go off. Ever time I take the EGR off it has carbon build up on the piston on the EGR valve. I am getting the new ones from AutoZone I got either Duralast or Delphi. Wondering if I should get AcDelco. The fuel pump and tank are new just had it replaced a year or 2 ago.
Wednesday, February 17th, 2021 AT 2:27 AM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

It could be related to the exhaust. Did you note if there was any carbon build-up in the intake when you had the egr off? Have you tried to retrieve diagnostic trouble codes?

Start with that. Chances are there are more than one. Here is a link that shows how it's done:

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Try that and let me know what you find.

Take care and God Bless,

Joe
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Wednesday, February 17th, 2021 AT 5:40 PM
Tiny
SEAN0309
  • MEMBER
  • 2 POSTS
The only code I get is 32. When I had valve of I didn’t see carbon build up in the intake. I sprayed carburetor cleaner in it and wiped it out.
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Thursday, February 18th, 2021 AT 1:26 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

It could be a few different things. Do me a favor. Take a look through these diagnostics for the code and see if it has things you feel comfortable doing. The attached pics correlate with the directions. Actually, pic 1 is the primary set of directions.

__________________________________

1993 Chevy Truck K 1500 Truck 4WD V8-350 5.7L
Under 8500 GVW
Vehicle ALL Diagnostic Trouble Codes ( DTC ) Testing and Inspection Manufacturer Code Charts DTC 32 Powertrain Controls - ECM/PCM Without Electronic Transmission Under 8500 GVW
UNDER 8500 GVW
Exhaust Gas Recirculation System Circuit Code 32

pic 1

Exhaust Gas Recirculation System Circuit

pic 2

Circuit Description:
The ECM operates a solenoid to control the exhaust gas recirculation (EGR) valve. This solenoid is normally closed. By providing a ground path, the ECM energizes the solenoid which then allows vacuum to pass to the EGR valve.

The ECM monitors EGR effectiveness by de-energizing the EGR control solenoid, thereby, shutting "OFF" vacuum to the EGR valve diaphragm. With the EGR valve closed, and 02 sensor fluctuating normally, fuel integrator counts will be greater than they were during normal EGR operation. If the change is not within the calibrated window, a Code 32 will be set.

The ECM will check EGR operation when:

Vehicle speed is above 45 mph.
Engine vacuum is between 15 and 60 kPa.
Throttle angle between 6 and 30%.
No change in throttle position while test is being run, max. 4%.
EGR on threshold 98%.

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.

1. By grounding the diagnostic terminal, the EGR solenoid should be energized and allow vacuum to be applied to the EGR valve and the vacuum should hold.

2. The "Service Engine Soon" light should also flash while the diagnostic terminal is grounded. If the light does not flash, this may indicate that the "Quad-Driver" has been damaged by low resistance in TCC circuit.

3. When the diagnostic terminal is ungrounded, the vacuum to the EGR valve should bleed off through a vent in the solenoid and the valve should close. The gage may or may not bleed off but this does not indicate a problem.

4. This test will determine if the electrical control part of the system is at fault or if the connector or solenoid is at fault.

5. This system uses a negative backpressure valve which should hold vacuum with engine "OFF."

6. When engine is started, exhaust backpressure should cause vacuum to bleed off and valve should fully close.

Diagnostic Aids:
Before replacing ECM, use an ohmmeter and check the resistance of each ECM controlled relay and solenoid coil. For example: TCC, etc, See: Computers and Control Systems > Component Tests and General Diagnostics > ECM QDR Check Procedure (Without 4L80-E Transmission) Refer to "ECM Wiring Diagram" for coil terminal ID of solenoid(s) and relay(s) to be checked. Replace any solenoid where resistance measures less than 20 ohms.

______________________________

Let me know if that helps.

Take care,
Joe
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Thursday, February 18th, 2021 AT 5:36 PM

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