TBI CEL - no codes, runs great

Hi All,

This little problem has been nagging at me for a while. I'm tripping the CEL at highway cruise conditions but it usually shuts itself off during the drive and no code is recorded. The wagon runs great, so it's not really a performance issue.

I remember the old Car Talk solution to this type of problem was to put a happy face sticker over the light.

But, it reminds me of an EGR malfunction because the computer will check the EGR operation at highway cruise, unchanging throttle conditions as I recall from my other TBIs. Any other thoughts on what this could be? I'm still not sure why there's no code recorded.

Thanks for any thoughts on this.

Had a mid 90s Suburban do the same thing. Unloaded, the light stayed off, even at highway speeds, but hang the trailer out back and the light would trip within 20 minutes. Take the trailer off and the light would go out. No stored codes.

Turned out to be a lazy O2 sensor. Guess it couldn't process the excess exhaust flow. Maybe the same thing with yours, only at highway speeds. Also check your PVC circuit. At high speed and high vacuum, perhaps its sucking in too much oil for the O2 to process.

I also agree, the EGR circuit may be an issue. Just on spec, I would check out EGR function.

Bill

convert2diesel wrote:

Had a mid 90s Suburban do the same thing.  Unloaded, the light stayed off, even at highway speeds, but hang the trailer out back and the light would trip within 20 minutes.  Take the trailer off and the light would go out.  No stored codes.

Turned out to be a lazy O2 sensor.  Guess it couldn't process the excess exhaust flow.  Maybe the same thing with yours, only at highway speeds.  Also check your PVC circuit.  At high speed and high vacuum, perhaps its sucking in too much oil for the O2 to process.

I also agree, the EGR circuit may be an issue.  Just on spec, I would check out EGR function.

Bill

Those sound like good places to check, thanks Bill. I don't know the last time it had a PCV valve, so I'll spend the $3 and get that done regardless.

-Leland