Hello,

Can anyone please help me?

I have an A4 B7 (2007), its a Quattro tdi 170 brd engine with an intermittent throttle hesitation especially at low revs. No fault codes or lights on dash. It is driving me mad.

So far I have changed - fuel filter (when all this started), new egr valve (old one had teeth stripped and was not moving), new throttle body, tried unplugging maf, tried a proven fuel sender in tank, forte diesel treatment - no changes with any of them.

Update - I've found out its had a dpf delete too, so I guess I fixed the egr for nothing.

I am about ready to through the towel in so any help or advice is greatly appreciated.

thank you

David

Information - the previous owner had it mapped and I'm not sure what else, so when you plug in a scanner (I have a creda 123 basic type) it seems different. It is also not smoking at all anymore, I used to be able to give it a blast out and it would do the usual diesel thing (not sure if that is related), also the exhaust back box tail pipe seems to stay cold or lukewarm. It also had all the fuel pump relays replaced about a year ago due to water ingress - hence I had a spare fuel sender. It is occasionally slightly harder to start in cold weather and sometimes cuts out immediately, then starts next time. When the fault occurs you can pause, rev the car and it is usually ok for a bit - replicates a fuel starvation. It seems to go into limp mode for a few seconds then snaps out of it.

3 hours ago, Davidha1 said:

Information - the previous owner had it mapped and I'm not sure what else, so when you plug in a scanner (I have a creda 123 basic type) it seems different. It is also not smoking at all anymore, I used to be able to give it a blast out and it would do the usual diesel thing (not sure if that is related), also the exhaust back box tail pipe seems to stay cold or lukewarm. It also had all the fuel pump relays replaced about a year ago due to water ingress - hence I had a spare fuel sender. It is occasionally slightly harder to start in cold weather and sometimes cuts out immediately, then starts next time. When the fault occurs you can pause, rev the car and it is usually ok for a bit - replicates a fuel starvation. It seems to go into limp mode for a few seconds then snaps out of it.

Hi the starting could be glow plugs, if you go through the site archive there are loads of threads on the pitfalls of dubious remaps, also you could try replacing the fuel regulator valve on the end of the rail these often play around when old and are cheap and easy to fit.

Steve.

Thank you, I did the glow plugs last year. It seemed to start great for a while then go back to normal.