CEL after ~25 minutes of driving

[jnever1]

Hello,

Tuesday, I replaced KS. I did not replace the harness, but I did clean/tighten up the terminals. I tested the lines with a multi-meter and found no unreasonable resistance across the wires.

After a roughly 20 minute test drive, CEL came on. ~5 minutes later, it went out. Checked ECM for codes... 55 (all is well).

Today, I replaced both O2s (direct fit NGKs). Again, after ~25 minutes of driving (highway), CEL came on. I parked, turned off car to check codes...again, light off, code 55.

The car runs beautifully, smooth as warm butter. Throttle response, shifting, power... it drives as near to new as a '95 with 170K could. No sluggish behavior what-so-ever, CEL light on or off.

The light disappears either after continuing to drive or when the car is cycled off and then on again.

Fuel pump was replaced less than 6 months ago. Starter/Battery cables < 1yr. Radiator, <2 years. Fluids have all been flushed/replaced within 1 yr with full synthetics where possible. EGR/PCV were supposedly cleaned ~2 years ago during a tune-up (plugs, wires, etc.). I have my doubts about the quality of the work since I found a piece of a pipe cleaner inside one of the hoses attached to my intake (rubber, flexible 4" from filter box to throttle body) when replacing KS. They were also responsible for the radiator replacement since it had a considerable leak after service that wasn't there when I brought her in. Since then, I've done all my own work.

The only modification I have done was to replace the stock filter box with a stillin conical filter. I cleaned and re-oiled the filter when I replaced KS. This filter has been on my Q for > 4 years without incident.

I understand that the EGR system does not come on until about 20 mins of driving. Is this my culprit? This car was originally sold in California.

Thanks for your consideration.

[hoov100]

EGR temp sensor or the EGR solenoid. The EGR valve opens while cruising after the car is in it's normal temp operating range.

[jnever1]

On a third test drive, the CEL illuminated after 22 minutes. Engine temp gauge showed normal, but I understand the gauge is hardly precise. On a fourth test, basically the drive home from the third test drive (> 30 minutes), the CEL did not illuminate. I'll look into the temp sensor and solenoid. Thank you. :-)

[jnever1]

Disconnected EGR temp sensor and cleaned/adjusted the connections. Did the same for EGR and Can solenoid. Took the solenoids off and gave them a little tapping love with a 3/8" ratchet. Hooked everything back up and gave her a good 60 mile test drive. No CEL! I'll keep an eye on the solenoids and scope out some eventual replacements.

Thanks for the help. Q is good as she's going to get until I win the lottery. lol.

[reyrey9350]

any car with a maf sensor can not run a oiled air filter it ruins the maf sensor,the oil itself.

[N/A Q45]

What I was going to say^ lol. But you are losing hp by having your intake suck in the very hot under the hood air- not what you ever want aside from maybe winter. The hotter the air promotes a better chance of knock which is the last thing any engine wants - I'm not saying this is your problem but it is a problem all on its own.

[Q451990]

Ditto on the air filter.

The brush is actually in there from the factory. I have found it in both an old hose, and it's replacement. I can only assume it's to try to limit any oil movement through the PCV system... kind of a poor man's catch can?

Heath

[N/A Q45]

Ya I've also found that wire brush in the Q and my 240.