Long highway trip, noticed some surging and 'service engine' light

[sikbrik]

'01. Figured I should start there. :(

Took a long drive this weekend, which is unusual for me. Usually this is an in-town car. Anyway, first 200 miles seemed fine, cruise control on at 65ish, 2300rpm. On the way home, same conditions but seemed to be surging every few seconds, mostly on downhill or flat, never on uphill (or not noticeably.) Then around 350 miles into the trip we stopped at a rest stop and upon restart had a service engine light for about 15 seconds. It went out, we wwent on. Driving a bit more, light came back again for only a few seconds. Went away and no codes stored.

So do I start with a TCV or is it ETM time or something else (vacuum lines, MAF, etc,?)

Dealer tells me (prior to this) that all software updates are done. I'm at 145k miles, trans was replaced around 78k.

[acools]

Sir,

You state that no codes were stored, are you pulling codes using your own OBD II scanner or are you using VIDA DICE?
Many of the generic code readers will show no codes, but the DICE tool will pull codes.

Your TCV controls blow-off or venting of the turbo pressure. Were you under boost or accelerating when the surge occurred?
Since you mention you were going downhill or on a flat gradient, I would guess not. IMHO, this is more likely failing coils, dirty MAF, throttle body or the like.

If you don't have DICE, i would recommend a trip to a mate who is running DICE or the dealer. This should help frame your approach.
At 145K miles, have you cleaned your PCV? When you clean it, you can clean the throttle body as well.

Hope this helps,

Andres

[sikbrik]

Thanks for the reply. I'll check all of those things. It's time to clean/replace PVC so I'll clean the throttle body and MAF as well. Going to put new vacuum lines in, just because it's old. You're right, no boost at the time. It was very rythmic, not the kind of thing I'd expect from coils - not a 'miss'.

I'll get dice...using a generic reader. One thing that confused this all for me and likely for you is that there is no service engine light being thrown. It just coincidentally timed with the 'service' light coming on, so the car just seems to think it's time to change my oil. oops! I didn't realize that until I went to drive it again this morning and saw the same light I saw the other night - when not in a panic hundreds of miles from home, I clearly recognized the light for what it was. :o