Afternoon all,
Having some very frustrating problems with the A4 at the minute. It's a 2007 TDI 140 (BRE), no DPF.
I have recently blanked off the EGR at the intake manifold, and since doing that I have lost nearly all performance. When driving, the turbo doesn't boost 90% of the time, except sometimes when going uphill, where the turbo spools, it will boost as normal and I will regain all performance! If I remove the blanking plate, everything goes back to normal.
I suspected a dodgy MAF sensor, as this issue went away completely with it unplugged (with blanking plate in), and I had full performance once again, so today replaced it with a new genuine Bosch sensor, however that has made no difference at all. I disconnected the EGR vacuum pipe at the actuator end and blocked it with a screw, however that made no difference either.
My only thought could be a vacuum issue, as I believe the ECU will shutoff any EGR function with the MAF unplugged as it uses that to work out EGR flow, meaning no vacuum sent to the EGR valve, but with the MAF plugged in I believe full vacuum will be going to the valve if the plate is in as it's seeing no EGR flow. But why would this issue only be present when the blanking plate is in? If it's a vacuum issue wouldn't it be present all the time, with our without plate?
I am completely stumped as to what is going on here, why will it only boost when going uphill?!
Any help would be greatly appreciated!
Having some very frustrating problems with the A4 at the minute. It's a 2007 TDI 140 (BRE), no DPF.
I have recently blanked off the EGR at the intake manifold, and since doing that I have lost nearly all performance. When driving, the turbo doesn't boost 90% of the time, except sometimes when going uphill, where the turbo spools, it will boost as normal and I will regain all performance! If I remove the blanking plate, everything goes back to normal.
I suspected a dodgy MAF sensor, as this issue went away completely with it unplugged (with blanking plate in), and I had full performance once again, so today replaced it with a new genuine Bosch sensor, however that has made no difference at all. I disconnected the EGR vacuum pipe at the actuator end and blocked it with a screw, however that made no difference either.
My only thought could be a vacuum issue, as I believe the ECU will shutoff any EGR function with the MAF unplugged as it uses that to work out EGR flow, meaning no vacuum sent to the EGR valve, but with the MAF plugged in I believe full vacuum will be going to the valve if the plate is in as it's seeing no EGR flow. But why would this issue only be present when the blanking plate is in? If it's a vacuum issue wouldn't it be present all the time, with our without plate?
I am completely stumped as to what is going on here, why will it only boost when going uphill?!
Any help would be greatly appreciated!
