richard_gomm
28-06-2009, 12:24 PM
Hi all,
firstly thanks to everyone whos helped with this problem on the other posts (back in october.) Its still not fixed but I think I'm much closer now. As theres been so many false leads I thought it would be easier to post new (plus didn't want to bump an octover 2008 post back up :-)
The problem is basically white smoke on startup on a passat B5.5, I know its common and I've read through the other posts and will try to build the results into this one.
The car is a Passat 1.9 TDI 130bhp AWX Engine 2002 reg.
The white smoke only comes out on a cold start, by that I mean engine left over 8 hours. The outside temperature doesn't seem to make much different (maybe slightly less smoke on a hotter day) Its a dark white, maybe white/blue smoke and smells very sickly and strongly of diesel, the smoke lasts about 10 - 20 seconds, a little gentle reving gets rid of it quickly. The car always fires on the first crank whether engine is hot or cold, however it will run rough for a few minutes before settling out.
Outside temp at this time of the year, ranges from 10 - 20 degree C.
So far the car has had the following work:
glowplugs replaced and wiring checked - all show btwn 11.6V and 12.3V
new wastegate valve
new turbo (old one was on its way out)
one new injector and complete injector harness replaced (due to a missfire)
compression test - good
new MAF
service of all filters & fluids
Coolant sensor replaced and checked to be showing the correct temp.
Inital thoughts from myself and the mechanic is that the smoke smells of unburnt diesel and various ideas were thrown around which resulted in the compression test, which was fine, and then the replacement of the turbo.
Since none of that fixed the problem we started looking at the glowplugs. All were replaced and the wiring checks out. I went out when the engine had been left for 15 hours, outside temp was around 16 C and plugged VAGCOM into the car. I turned the ignition on but didn't crank the enigne. Glowplug light came on and immediately went out (lit for less than a second) VAGCOM showed the glowplug status as 01010000 - which according to the label is Pre Glow not required. I then cranked the engine and watched the smoke come flooding out. THe amount of smoke is enough to see clearly in the rear mirror and be blown across to the fron tof the car before dispersing. Gently reved the car to around 3000 revs and the smoke increased before going after around 20 secs.
The latest test that I ran last night was that I disconnected the Coolant Temp sensor to force the glowplugs on for the 20 seconds. I had to remove the sensor to get to the connect so I lost a lot of Coolant (it was down at Min after) I then left the car overnight.
This morning I've gone out and put the sensor back in the hole but didn't connect the wiring.
Turned the car to ignition and the glow plug came on for a good 20 secs, I then cranked the car and for the first time there was NO smoke!! It still ran rough for a few minutes but no smoke.
What I did forget though was to refill the coolant tank before starting the car so the test might be invalid.
Basically my thoughts / questions at the moment:
1. The coolant in the top of the engine was lost when I pulled the sensor out last night. Is it possilbe that the coolant is seaping through somewhere overnight and only getting burnt on the enigne start? The car isn't using any large amount of coolant, I haven't had to top it up for over a year.
2. What sort of temp range does the ECU switch the glowplugs on? I've tried changing it to a longer glow period but it doesn't make any difference. THe light comes on and goes out straight away.
3. Can I know rule out stem valves as it didn't smoke this morning?
4. Would retarded timing be affected by the glowplugs being on longer? Would retarded timing give white wmoke?
I've filled the coolant back up so I'll try again tomorrow, this time starting it will had sat all night with a full coolant tank.
thanks again everyone
Richard[/SIZE]
firstly thanks to everyone whos helped with this problem on the other posts (back in october.) Its still not fixed but I think I'm much closer now. As theres been so many false leads I thought it would be easier to post new (plus didn't want to bump an octover 2008 post back up :-)
The problem is basically white smoke on startup on a passat B5.5, I know its common and I've read through the other posts and will try to build the results into this one.
The car is a Passat 1.9 TDI 130bhp AWX Engine 2002 reg.
The white smoke only comes out on a cold start, by that I mean engine left over 8 hours. The outside temperature doesn't seem to make much different (maybe slightly less smoke on a hotter day) Its a dark white, maybe white/blue smoke and smells very sickly and strongly of diesel, the smoke lasts about 10 - 20 seconds, a little gentle reving gets rid of it quickly. The car always fires on the first crank whether engine is hot or cold, however it will run rough for a few minutes before settling out.
Outside temp at this time of the year, ranges from 10 - 20 degree C.
So far the car has had the following work:
glowplugs replaced and wiring checked - all show btwn 11.6V and 12.3V
new wastegate valve
new turbo (old one was on its way out)
one new injector and complete injector harness replaced (due to a missfire)
compression test - good
new MAF
service of all filters & fluids
Coolant sensor replaced and checked to be showing the correct temp.
Inital thoughts from myself and the mechanic is that the smoke smells of unburnt diesel and various ideas were thrown around which resulted in the compression test, which was fine, and then the replacement of the turbo.
Since none of that fixed the problem we started looking at the glowplugs. All were replaced and the wiring checks out. I went out when the engine had been left for 15 hours, outside temp was around 16 C and plugged VAGCOM into the car. I turned the ignition on but didn't crank the enigne. Glowplug light came on and immediately went out (lit for less than a second) VAGCOM showed the glowplug status as 01010000 - which according to the label is Pre Glow not required. I then cranked the engine and watched the smoke come flooding out. THe amount of smoke is enough to see clearly in the rear mirror and be blown across to the fron tof the car before dispersing. Gently reved the car to around 3000 revs and the smoke increased before going after around 20 secs.
The latest test that I ran last night was that I disconnected the Coolant Temp sensor to force the glowplugs on for the 20 seconds. I had to remove the sensor to get to the connect so I lost a lot of Coolant (it was down at Min after) I then left the car overnight.
This morning I've gone out and put the sensor back in the hole but didn't connect the wiring.
Turned the car to ignition and the glow plug came on for a good 20 secs, I then cranked the car and for the first time there was NO smoke!! It still ran rough for a few minutes but no smoke.
What I did forget though was to refill the coolant tank before starting the car so the test might be invalid.
Basically my thoughts / questions at the moment:
1. The coolant in the top of the engine was lost when I pulled the sensor out last night. Is it possilbe that the coolant is seaping through somewhere overnight and only getting burnt on the enigne start? The car isn't using any large amount of coolant, I haven't had to top it up for over a year.
2. What sort of temp range does the ECU switch the glowplugs on? I've tried changing it to a longer glow period but it doesn't make any difference. THe light comes on and goes out straight away.
3. Can I know rule out stem valves as it didn't smoke this morning?
4. Would retarded timing be affected by the glowplugs being on longer? Would retarded timing give white wmoke?
I've filled the coolant back up so I'll try again tomorrow, this time starting it will had sat all night with a full coolant tank.
thanks again everyone
Richard[/SIZE]