I had my exhaust sorted yesterday and everything was fine and dandy until about half way to work, I noticed that off throttle and then back on again the car seemed quite hesitant and that on light throttle the car felt jerky, but under any more than that it felt fine and pulled fine.
When I got to work the car was very jerky in the car park and was struggling to idle. The revs were down around under 500rpm and it was really chugging. I flicked through the onboard computer and at idle it was showing 0.6 gallons per hr! Normally when warm it is at 0.2. I also struggled to re-start it once I had turned it off.
I did a quick google and read Mikes thread about the CTS and also another thread about the EGR.
The EML is not on and the car runs fine when cold as I checked at lunchtime (at idle was fine, trip computer showed 0.3/0.4 gallons per hr) and it started fine and on the journey home it was fine when cold. What I also noticed was that once the car got up to temperature (around 5-7 minutes) it still drove fine. It must have been 15 minutes in to my journey when I felt the hesitation come back as I was trundleing along at thirty. Once back on national speed limit I accelerated and it pulls fine and is happy around 60mph in fifth.
When I got home the computer said at idle I was at 0.6.
I'm going to order at new CTS tomorrow and give the EGR a clean - how do I do this please?
Someone suggested it could be an oxygen sensor? Is that worth checking as well? If so where do I find it and how do I check.
The work done on the car was having a thread on the manifold/down pipe drilled out and replaced as the nut had stripped it.
My journey to work is around 13 miles each way and a mixture of national speed limit and 30mph stuff, if that is relevant oh and the car is a 2001 Vectra SRI.
Thanks in advance for any help as I am a mechanical duckwit!