I need help as I cannot find what’s wrong with my car it barely revs above 3000 rpm when under load or when driving although it revs to the limit when static, exhaust burns clean no excessive smoke or any noises from the engine, is very economical returning 55 mpg, It will only do 85mph downhill with the wind behind it. It is the Y17DTL engine with no air charger. I bought the car without road testing it and the guy refused to take it back saying it was sold as seen so I have no history of why this fault exists. I will list everything I have done to date so perhaps you can suggest some ideas!

1. Engine flushed and new oil air and fuel filters, removed the pick-up unit in the fuel tank and cleaned the plastic gauze (although not dirty and the bottom of the fuel tank was clean) siphoned fuel out at the filter head to confirm clear fuel feed to filter.

2. Took the exhaust manifold and turbo off as one unit to check that the turbo was not seized and rotated freely, I also wanted to check that the vacuum unit to the turbo boost and its linkage was not seized. All ok

3. I left the exhaust down pipe off at the manifold and took for a drive to eliminate any blockage in the exhaust system. All ok

4. Checked the cam belt timing to confirm it was not a tooth out. All ok

5. Changed the MAF sensor with the one on my daughters Vauxhall Vectra as it was the same Bosch unit which had the same part number. This made no difference.

6. I removed the EGR valve unit and gave it a good clean out with carb cleaner and elbow grease although it was not really very dirty. No difference.

7. I went to a local scrap yard who allowed me to change the MAP sensor and the EGR control unit before I buy. This made no difference no guaranties these were ok.

8. Removed the rocker cover and checked the valve clearances, some were at 30 thou, some at 35 thou and only 3 valves at the correct 40 thou although I do not believe this to be the fault.

9. I called a Company that repair the EDU units fitted at the back of the sump, they say my fault is unlikely to be the EDU unit (Will not start of cuts out is normal faults) and that I would be wasting my money to get this checked.

10. I took the car to garage, Hickleys of Taunton in Somerset who are specialists, the technician spent 3 hours on the car but was unable to find any faults this is what the report said :-

Found no DTC’s. No air leaks found, exhaust is not blocked, turbo is boosting correctly, Air flow meter correct, timing correct. No contamination found, Pump seeks ok. EGR is operating however block of EGR to try to improve performance, car is running better, advise customer to try and return if not happy.

11. The Technician suggested it could be the ECU, the fuel pump or maybe the injectors. I found a guy on eBay that re-programmes second hand ECU’s to your car at £200 and as I described the fault he thought that it was the ECU at fault and would change it and if this was not the fault he would only charge £50 for the visit and re-programming. He came down to Yeovil from London and spent over 2 hours with me and the car, it is not the ECU. He got me to hold his diagnostic equipment whilst he drove the car and said the turbo boost fault flashed up temporarily and so he spent a long time trying to locate the fault but to no avail, he suggests that the Vacuum pump is weak and not giving enough vacuum to control the turbo boost correctly.

12. I remove the alternator and stripped the Vacuum pump off and took it apart, it is a cylindrical vain pump but I could see no signs of wear, the cylinder was smooth and un-scored the carbon type brushes were clean no signs of scoring or scratches and looked unworn. I lightly greased it and put it back but of course that made no difference.

13. I bought a second hand fuel pump from a 2004 car that had only done 46,000 miles as the bottom end was knocking after running out of engine oil.

14. I have now ordered new vacuum hoses for the EGR and boost control valves and the hose to the boost unit in case these are collapsing internally.

I really am out of ideas now!

Please help!!!