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Matt, Mechanical Engineer
Category: Audi
Satisfied Customers: 22758
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Can you help I have a audi allroad 54 plate, i have just

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Hello , Can you help I have a audi allroad 54 plate , i have just fitted an fully reconditioned high pressure fuel pump it has been coded to the car immobilisor and there is fuel getting to the injectors, however the car will not start when turning over it seems as if there is something missing - it does not sound like it is trying to start as it did normally before i changed the fuel pump, the pump timing has been checked
Do you think the fault could be electrical or any suggestions on what to do ?
any help much appreciated


if you think its not injecting at all then I'd consider changing the crnak position sensor as if this is faulty then it will never start injecting

so check the connections to the crankshaft sensor, unplug it and check for corroded contacts and broken wiring, and consider fitting a new sensor - do the same for the cam position sensor
If the EGR valve is stuck open then this too can effect starting so try disconnecting it to see if this helps or changes anything

Could also be an injector leaking fuel back through the overspill pipe, so not getting enough fuel pressure to tell ECU to fire the injectors, this is trickier to find and you’ll need the garage to do a ‘run back’ test to identify which one is the issue

do you still need help?
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Customer: replied 9 months ago.
Hello Matt, thank you for your reply i will rate the answer. I have not had time to try your suggestions but i will i,m going to try and find the items you mention,( crank sensor, cam sensor ) when we try to start the engine its as if there is no compression and its sounds different when turning i didnt say but its the 2.5tdi BAu engine - will that make any difference to your suggestions.
many thanks

Hello John

I'd still check what I've suggested and also I'd check that you're getting full power to the glow-plugs, they pull a lot of current so take care when checking but see if the relay is clicking when the ignition is turned on first and also check the fuse if this is OK check to see if the engine earth strap is also OK.

If the plugs haven't been changed in the last 20K then they may have to be replaced.
You can test the glow-plugs with a multimeter by measuring the resistance across the plug ( between the power connection and the body) it should be around 4-8ohms if its tending to infinity / open circuit the plug is faulty or by using a clip on current clamp, either on the supply wire to glow plugs or onto engine earth, with glow plug light on you should see 15-20amps for each glow plug fitted, 4 cylinders would be approximately 60-80amps.

Customer: replied 9 months ago.
ok will check the glow plugs as well. Would poor glow plugs account for the unusual lack of compression sounding when cranking over the engine?. When trying to start the vehicle over the last number of weeks i have had jump leads from another vehicle and have had a mains powered starter pack to help turn it over at speed.

hello John

usually a ' low compression' type of noise is a lack of fuel so I'd still say its likely to be a crank sensor or possibly the injector / s leaking back as mentioned

Matt and other Audi Specialists are ready to help you
Customer: replied 9 months ago.
Thank you for your help fingers crossed -other wise i,m going to tow it into loch ness thanks john