I got a weird one. I'm fairly car literate and I'm usually able diagnose and know the problem to pull in to my local independent shop and tell them this and this need to be fixed and replaced. But this has me stumped.

I have a 2016 Q5 2.0 engine that went bad with carbon deposits yada yada... So I stepped up got a new motor from Power Engines it came all crated up they were super helpful pleased with them. My mechanic moved all the bits and reattached them to the new engine from the old. Everything had been working just fine on the old engine up until I put it in storage for close to two years due to a compression issue (Carbon ring deposit blow by)

Well here is the problem granted this info is incomplete and secondhand. The mechanic gave me the keys I drove it ten, to fifteen miles and had to have it towed back. The whole time it had a skip a tumble in power it hated slow acceleration between 1600-2000 rpm kind of missing and not solid power. Well the dang High pressure fuel pump apparently broke loose. Mechanic thinks it was pumping air and not fuel and that the low pressure fuel pump wasn't providing enough fuel. He ended up replacing the High pressure twice (for a total of three the original plus two replacements) then the low pressure fuel pump once and spark plugs. He said twice the high pressure fuel pump blew, and the low pressure was fine but replaced.

Well I got the keys back and something isn't right there is still a power tumble similar to the original problem, but the weirdest thing is I can floor it and it will not speed up. It does it between 40-50mph once it got stuck at 40 twice another around 46 or 50mph five times I've seen this but it's not always. If I usually back off and reengage the pedal it will then gain speed but just so weird. What am I missing what did my mechanic do wrong..?? Where do I start in trying to diagnose..??

53 minutes ago, crashoverride said:

Where do I start in trying to diagnose..??

Connect it to diagnostic code reader.

26 minutes ago, cliffcoggin said:

Connect it to diagnostic code reader.

and after that shows nothing...???

Real world trouble shooting and diagnostics has to occur

20 minutes ago, crashoverride said:

Real world trouble shooting and diagnostics has to occur

OK, then do so, and tell us the results of such things as compression tests, injector tests, CO emission, and oil consumption. It would also help to know of modifications that have been made and ECU mapping. The only actions you have mentioned are three fuel pump changes without telling us the reason. Was the fuel pressure tested before changing the pump?

14 minutes ago, cliffcoggin said:

OK, then do so, and tell us the results of such things as compression tests, injector tests, CO emission, and oil consumption. It would also help to know of modifications that have been made and ECU mapping. The only actions you have mentioned are three fuel pump changes without telling us the reason. Was the fuel pressure tested before changing the pump?

You missed the part that it’s a NEW ENGINE. with just fifteen miles on it.

So obviously no engine modifications have been made. Nor could oil consumption be noted. Furthermore having the fuel pump blow the bolt off and the next deform. All within the first fifteen miles.

Clearly "YOU" will not be able to provide any assistance. But thanks anyways.

Good morning Josh,

Let me start by pointing out that you are in grave danger of discouraging others to help and advise you due to the unfortunate attitude you display in your last paragraph.

Only you know the absolute facts about the circumstances you find yourself in, and other’s interpretation will be based solely on your ability to clearly convey those facts in a written form.

The use of capitals (and particular bold capital) in the context you use them - on this forum and most others are taken as a demonstration of frustration against those who are trying to be constructive, and that is both rude and unacceptable.

You emphasise NEW ENGINE (your caps), and Power Engines, but don’t quantify what you mean by ‘new engine’. Could this be totally ‘new’ à la ex VAG, stripped and fully reconditioned and fully bench tested, or simply removed from a scrapped vehicle, given a power wash down, wrapped in clingfilm and sold as ‘new’ I.e. new to you.

I think it would be worth you walking back to the first bus stop Josh, and giving yourself a chance to reconsider what you write.

Thanks and kind regards,

Gareth.