1999 S70 GLT

[Grantkat]

I ran into an issue this week and it has me baffled. Last week half way through accelerating from a stop, the car hesitated, surged hesitated and surged, then was fine and drove well the remainder of the week. for the next few days it ran fine. Monday morning while driving at 40 MPH, the car hesitated, lost power, accelerator unresponsive. I came to a red light and the RPMs were jumping between 800 and 1200 up, down up down. The accelerator remained unresponsive and the car was hesitating and surging, then again all the sudden it was fine and ran well. Here is what I have so far:

No codes thrown.
I ran a smoke test, - no leaks
Got into VIDA - I ran 4 ETM sweeps - all of them registered less than 1%
after the sweep tests I started the car and the idle was too low like 700 or less with very minor drops to maybe 650. but then steadied at 850
I hooked up VIDA to look at numbers while running. everything looked fine. while I was hooked up it the RPM dropped slightly one time.
then I got 2 codes - ECM-917F and ECM 959F
I wrote them down (lucky decision) and kept them on screen after stopping. I tried to look them up and when i returned to the screen they were gone. no codes set. no codes in history. I connected again and looked up faults - no codes..

Thoughts?

[scot850]

They are both throttle pedal position codes. I'd check the ETM and give it a clean. Use throttle body cleaner and cotton buds and a soft cloth. Soak the buds/cloth and use those for cleaning. Refit and see if you get any improvement. If it it pretty clean it could be the ETM failing or the throttle position sensor. Do the usual checks for loose or corroded connectors, and split vacuum pipes.

I'm sure others will chime in.

Neil.

[Grantkat]

it hasnt acted up again, but soon as i get some decent weather I will pull it and inspect and clean