EGR questions - 91 Suburban in Houston TX

91 Sub has 190K miles, runs great but won't pass Harris County, TX emissions test.

Check engine codes point to EGR valve and throttle position sensor. Have replaced EGR valve, EGR solenoid, and throttle position sensor. No other changes.

Before these new parts, I could drive 5 miles to 10 miles before the light came on -- other times I could drive all day and no check engine light. Now, the check engine light comes on almost immediately and stays on.

Replaced the catalytic converter last year, has new plugs, filters, plug wires, air filter and running temp is normal. What am I missing / what else should I check? TIA

Reply to
fireant
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Erase the codes in it and run it till the light comes back on. Pull the code(s) and post them. There are a LOT of items that can cause EGR symptoms that are not the EGR itself.

Reply to
Steve W.

Have you tried testing the components in question?

Reply to
aarcuda69062

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