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92 El Dorado
127 Posts
Discussion Starter · #1 ·
1992 Caddy Eldo 4.9 liter engine.
45K miles with recent TB cleaning, new plugs,wires, dist cap etc.
Had the EGR system tested and cleaned.
Immediately Afterward went from smooth idle to slightly rough idle (sublime misfire).

Rechecked ignition parts and gaps. OK.


I ran the PFI Chart C-7 EGR diagnosis algorithm as per service manual.

Solenoid cycles OK, vacuum gage reads 15" in the ES02 override,
next step uses ED11 (engine RPM) combined with ES02 EGR override.
Raise RPM steady to 2000

RPM should DROP by 100+ after warm button is depressed and held depressed for a minute.(this turns off solenoid to pass full vac to EGR)

My RPM went UP about 75-85 RPM.
Repeated test several times even with a swapped out new solenoid.
Same result.

Next step in the algorithm is to remove EGR Valve and inspect since the RPM did not drop by 100.

Well, I had it cleaned before by the mechanic and operation tested with solenoid.
(but after leaving shop, the idle was no longer smooth)

So this weekend I plan to remove valve and decide whether to buy a new one.

Anybody experienced the higher idle while performing the EGR diagnostic test or have an opinion about this counter-intuitive reaction?

also, my idle in park is about 650 and in drive varies from about 550-575-600
with engine at operating temp. (190+ F).

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