EGR Replacement - make sure you get a Delco

[gmbellew]

I had a high idle and surging issue after getting off the highway and/or long drives. I would also occasionally get EGR check engine light codes. I finally pulled the EGR, and it didn't seem to be in good shape. seems it is probably lazy closing after being open for extended periods of time.

I ordered a replacement ($65) from a parts house I have had good luck with and installed the new part. I immediately noticed an off-idle stumble once I hit closed loop.

hmmmm...maybe the EGR solenoid....$30 part later and I still have an issue.

it is definitely in the EGR arena, because when I plug the vac hose, I have no issues. until I cruise the highway and the ECM tries to look for the EGR and throws a code.

ok.....I have also had a couple random TPS low voltage codes in the last 6 months. one of them I even caught in aldldroid. TPS is a parameter for the EGR solenoid to open, maybe that is the culprit. so i replace the TPS ($65) and make sure the sensor harnesses are routed to avoid crossed/pinched wires. I still have the issue.

I start reading up on EGR and apparently some aftermarket parts are not correct (positive instead of negative backpressure) or are not designed correctly. I track down a Delco part (214-5073) ($100) that seems to be the correct part.

the new EGR shows up today. so I pull the aftermarket valve and do a side-by-side. I notice some subtle differences in appearance and in spring tension on the gasket. hmmmm....seems this aftermarket part isn't maybe right.

I install the Delco part, and finally all is good in the world. no more off-idle stumble. so, if you have an 87-91 5.7L half ton, your EGR is Delco 214-5073...there is NO SUBSTITUTE!

what a pain this was to track down...hope this helps somebody get to the finish line quicker than I did.

 

[AuroraGirl]

I had a high idle and surging issue after getting off the highway and/or long drives. I would also occasionally get EGR check engine light codes. I finally pulled the EGR, and it didn't seem to be in good shape. seems it is probably lazy closing after being open for extended periods of time.

I ordered a replacement ($65) from a parts house I have had good luck with and installed the new part. I immediately noticed an off-idle stumble once I hit closed loop.

hmmmm...maybe the EGR solenoid....$30 part later and I still have an issue.

it is definitely in the EGR arena, because when I plug the vac hose, I have no issues. until I cruise the highway and the ECM tries to look for the EGR and throws a code.

ok.....I have also had a couple random TPS low voltage codes in the last 6 months. one of them I even caught in aldldroid. TPS is a parameter for the EGR solenoid to open, maybe that is the culprit. so i replace the TPS ($65) and make sure the sensor harnesses are routed to avoid crossed/pinched wires. I still have the issue.

I start reading up on EGR and apparently some aftermarket parts are not correct (positive instead of negative backpressure) or are not designed correctly. I track down a Delco part (214-5073) ($100) that seems to be the correct part.

the new EGR shows up today. so I pull the aftermarket valve and do a side-by-side. I notice some subtle differences in appearance and in spring tension on the gasket. hmmmm....seems this aftermarket part isn't maybe right.

I install the Delco part, and finally all is good in the world. no more off-idle stumble. so, if you have an 87-91 5.7L half ton, your EGR is Delco 214-5073...there is NO SUBSTITUTE!

what a pain this was to track down...hope this helps somebody get to the finish line quicker than I did.

i am not sure about the 4l60e, but the 4t60e which is damn near the same thing but backwards apparently, (transaxle) has a PCM failure mode for lost TPS signals. on the truck before the transmissions went fully electronic(you have a tv cable, right?)

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https://gyazo.com/2c2e3c07357847e058e3a179a9473529
your computer is checkign the rationality of the tps, so if it has a reason to think its actual true data is incorrect, you could get the code. i would put your OE back on if it was the GM/Ac delco one


also... did you have a code 32?
#91-6-105: SERVICE ENGINE SOON LIGHT POSSIBLE FALSE CODE 32 - (Dec 10, 1990) SUBJECT: "SERVICE ENGINE SOON" LIGHT - POSSIBLE FALSE CODE 32 SERVICE PROCEDURE) VEHICLES AFFECTED: ALL 1987-91 TRUCKS WITH 4L60 (700- R4) A/T Some 1987-91 Light Duty Trucks equipped with 4L60 transmissions may experience a possible false code 32 - EGR system malfunction. The customer may not experience a change in performance or driveability with a Code 32 set. If normal EGR diagnostics do not reveal the cause for Code 32, the following steps should be taken to correct the condition: Check the TCC (Torque Converter Clutch) engagement solenoid/wiring harness for a shortcircuit. 1. Disconnect the TCC harness connector from the left side of the transmission. 2. Measure resistance between TCC transmission connector terminals "A" and "D" with a Digital Volt Ohmmeter (DVOM). Solenoid resistance must measure 20-25 ohms at 20' C (68' F). Resistance will be slightly higher if the transmission is at operating temperature. If the resistance is less than 20 ohms the TCC solenoid diode or wiring is shorted and the solenoid must be replaced. 3. With key on, using a DVOM check for voltage at pin "D" of the TCC wiring harness. Voltage greater than one volt should not be found. If voltage exceeding one volt is present, circuit 422 is shorted to voltage and the short must be repaired. Refer to the appropriate Service Manual for circuit 422 diagnosis and repair. Test operation of the TCC through the use of a scan tool connect to the vehicle ALDL connector. The following conditions must be satisfied when testing TCC operation. - Clean stored trouble codes. - Engine at normal operating temperature (above 65 C, 149 F) and in closed loop. - Constant throttle position. TPS voltage = L.3V (minimum = 1.1V, maximum = 1.5V). - Vehicle speed = 72 kph (45 mph) (minimum = 56 kph (35 mph), maximum - 88 kph (55 mph). - Brake switch closed (brake pedal not applied). - 3rd or 4th gear. CONFIRMATION The scan tool will display the ECM command for TCC engagement when the above conditions are satisfied. When the TCC engages there should be a decrease in engine speed by a minimum of 100 RPM. If TCC operation is normal it is not necessary to replace the solenoid assembly. After verification of TCC operation, check for stored trouble codes. If TCC fails to engage consult Section 10, Transmission Controls located in Fuel and Emissions Manual and section 7A of the appropriate Service Manual. General Motors bulletins are intended for use by professional technicians, not a "do-ityourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job

 

[gmbellew]

the EGR troubleshooting also mentioned something about the TCC. based on monitoring it via aldldroid, lockup appears to happening normally and I can feel lockup occurring. but I will save this for future reference in case I still have issues after highway driving. the TCC will be a likely culprit if so. thanks!