taking very long to start
12-28-2010, 08:44 AM
#1
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taking very long to start
hi there,
i have 2008 Q7 3.0 TDI with BUG engine and JXX tranny and 25000 miles on clock the problem is when i drive the car for an hour or two the car is perfect it runs like new but when i switched off the ignition and start again after 10 min,20 min,30 minutes car starting is perfect but when it sit more,i mean say an hour or more then try to start the car it take very long say 15 to 20 second to start.take a comperession test it gave me 22 BAR.luckily had another car in my garage replaced both fuel rail and engine speed sensor but no effect and car also not throwing any fault nor any MIL on dash,if some had this kind of issue before or what next i have to check?Greatly appreciation for any help
Regards shazoo
i have 2008 Q7 3.0 TDI with BUG engine and JXX tranny and 25000 miles on clock the problem is when i drive the car for an hour or two the car is perfect it runs like new but when i switched off the ignition and start again after 10 min,20 min,30 minutes car starting is perfect but when it sit more,i mean say an hour or more then try to start the car it take very long say 15 to 20 second to start.take a comperession test it gave me 22 BAR.luckily had another car in my garage replaced both fuel rail and engine speed sensor but no effect and car also not throwing any fault nor any MIL on dash,if some had this kind of issue before or what next i have to check?Greatly appreciation for any help
Regards shazoo
12-28-2010, 01:04 PM
#2
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Sounds like a typical faulty fuel shut off valve but I dont know how our system works. Take a read through this V8 TDI service manual to get a rough idea.
V8 TDI
Did you try to leave ignition on without start for 15 seconds then try and see if it starts immediatly? because then you would know better if it is a switching delay in some component as opposed to a fuel delivery delay.
I suspect its a switching fault but it could be the very action of turning over the engine that encourages it to move.
Enough theorising... Please let us know the outcome.
V8 TDI
Did you try to leave ignition on without start for 15 seconds then try and see if it starts immediatly? because then you would know better if it is a switching delay in some component as opposed to a fuel delivery delay.
I suspect its a switching fault but it could be the very action of turning over the engine that encourages it to move.
Enough theorising... Please let us know the outcome.
12-28-2010, 02:00 PM
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I dont know too much about the new Turbo diesel motors, does the TDI engine use spark plugs or glow plugs?
This may be old school, but with the older diesel motors, you have to let the glow plugs (as opposed to spark plugs) heat up before you start the engine, hence turn the key on, wait approx 10 - 15 seconds then start the vehicle. I would hate to think diesel motors today are still using glow plugs but I know thats how the old diesel motors work. If the new TDI motor doesnt work the same way, dont flame me for this post I'm just explaning how the old school diesel motors work.
I had a Audi A3 loaner car that was TDI, and I did just that, turn the key, waited 8-10 seconds ( I cant remember if it had a Ready indicator) and then started the car. I dont know if I had to do that, I'm just conditioned to since I have owned an older diesel fueled vehicle in the past.
Anyone else with insight on this?
According to the manual this engine does use glow plugs (page 29) which would explain the need to turn the key on first for applrox 5-10 seconds then start the vehicle.
The reason it starts right up after you've been driving frequently is the glow plug is still hot and does not require the same amount of time to heat up as oppose to when it's been sitting for a couple of hours.
This may be old school, but with the older diesel motors, you have to let the glow plugs (as opposed to spark plugs) heat up before you start the engine, hence turn the key on, wait approx 10 - 15 seconds then start the vehicle. I would hate to think diesel motors today are still using glow plugs but I know thats how the old diesel motors work. If the new TDI motor doesnt work the same way, dont flame me for this post I'm just explaning how the old school diesel motors work.
I had a Audi A3 loaner car that was TDI, and I did just that, turn the key, waited 8-10 seconds ( I cant remember if it had a Ready indicator) and then started the car. I dont know if I had to do that, I'm just conditioned to since I have owned an older diesel fueled vehicle in the past.
Anyone else with insight on this?
According to the manual this engine does use glow plugs (page 29) which would explain the need to turn the key on first for applrox 5-10 seconds then start the vehicle.
The reason it starts right up after you've been driving frequently is the glow plug is still hot and does not require the same amount of time to heat up as oppose to when it's been sitting for a couple of hours.
Last edited by Savior Six; 12-28-2010 at 02:35 PM.
12-28-2010, 03:58 PM
#4
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According to the manual this engine does use glow plugs (page 29) which would explain the need to turn the key on first for applrox 5-10 seconds then start the vehicle.
The reason it starts right up after you've been driving frequently is the glow plug is still hot and does not require the same amount of time to heat up as oppose to when it's been sitting for a couple of hours.
04-05-2011, 01:35 PM
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SAME PROBLEM
I have something alike...
1- No matter if engine is cold or hot, I need to wait 2 more sec after glow plug light turn off to start normally...
2- If I turn right after glow plug's light turns off...it takes about 3-4 secs for the engine to start, and feels like low battery...
same issue with my fried's 08 TDI...
Not sure what's the problem with it...I guess it could be some fuel delay or bad glow plugs, I'm not sure!
1- No matter if engine is cold or hot, I need to wait 2 more sec after glow plug light turn off to start normally...
2- If I turn right after glow plug's light turns off...it takes about 3-4 secs for the engine to start, and feels like low battery...
same issue with my fried's 08 TDI...
Not sure what's the problem with it...I guess it could be some fuel delay or bad glow plugs, I'm not sure!
04-07-2011, 09:10 AM
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hi Anthony you are quite right there is something wrong with your glow plug related electronics or check your fuel injectors.it will take 1 to 2 second even a new engine.my case is little different in my country the diesel availabe here contain sulphur more than 500 ppm so this is the big reason for Common Rail diesel engine to wear the Block and promoting late starting type issues in the areas where a diesel say 50 ppm or less than that is not availabe.i think help this
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04-07-2011, 02:13 PM
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hi Anthony you are quite right there is something wrong with your glow plug related electronics or check your fuel injectors.it will take 1 to 2 second even a new engine.my case is little different in my country the diesel availabe here contain sulphur more than 500 ppm so this is the big reason for Common Rail diesel engine to wear the Block and promoting late starting type issues in the areas where a diesel say 50 ppm or less than that is not availabe.i think help this
04-11-2011, 01:35 PM
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