Hi,
Totally new here and not much of a mechanic but i have mechanic friends who help me keep my 2003 Omega Estate in good condition.
Got the car in May 2015 with 157,000 on the clock, got it serviced and it flew through MOT. Did 20,000 miles and it had it's first problem in August 2016 with the EGR valve so put a good 2nd hand one on and checked it at service, all looked as good as can be cleanliness wise etc.
In sussing out the EGR problem, we had the engine smoke tested and replaced one perished pipe.
I then lost key in November 2016 and had all manner of problems as previous owner had changed codes and i only found out after paying for codes from Vauxhall they were wrong so after a lot of hassle and 2 ECU specialists, the ECU was recoded to original codes.
In March '17, i got a flash of lights while driving and realised alternator was going so got home, got a new one, got it fitted and the car started fine.
This is now the problem part, the acceleration has been dipping in and out of driving normally, withloss of torque or "oomph" as some may say, and almost going into Limp mode whereby the revs won't go over 2500 and the speedo just creeps up so slowly when accelerating.
Get up to 60-70 on a flat stretch, hit a hil land the speedo just slowly drops to about 40-50mph depending on the hill, and stays there. Dropping to 4th does very little except keep it there whereas in 5th you lose it.
3rd doesn't do much better, maybe a 1-2mph increase in speed and obviously revs are up over 3000 by now.
It has been 2 weeks since we changed alternator, it is definitely correct one and there are NO lights on dash and no faults to be found by computer as we plugged it in.
Today we found the large 2" or so diameter pipe/hose that runs to just under EGR valve was collapsing in on itself a bit when under 3000 or more revs in neutral so another of those will be got and tried this week but as a makeshift job, there is a hard piece of pipe in there to stop it collapsing but this has made no difference on the 50 mile run home.
It has had 2 lots of Redex throught it with just £10 of fuel each time, that definitely cleared injectors as the little cough it had had at 1700 revs or so stopped but this loss of power/torque is mystifying us!
The turbo has been checked and is clean as a whistle.
The only other thing i noticed today was that in neutral with accelerator to the floor, the revs wouldn't go above 4000 and the red line on the rev counter doesn't start til around 5500.
Any advice or opinions welcomed.