roadhard1960
Veteran Member
My car likes to turn on the check engine light when it is cold. It has happened at least two winters in a row. Cold defined as freezing or so. Logging on to VCDS I get this. 17656 - Start of Injection Timing Regulation
P1248 - 35-10 - Control Deviation - Intermittent
So what confuses me is that if it gets 40+ or maybe a bit warmer and after three or 4 starts the check engine light will go off. I normally drive 46 miles to work. 8-9 hours later drive home. Today it was cold enough at 10F. My car is always parked in my garage at night which stays a bit above freezing when cold outside. If the car is parked for two days the garage might get a bit colder but it still has a nice dose of solar heat. The car got to enjoy the 10 degree weather a minute after driving off. I parked the car for 3 hours, later had to drive another 60 miles to one of our other offices. By then is was getting toasty at 35 F. I worked for 2 hours and headed for home. 5 minutes to a convenience store for a snack. Another half hour to pick up a non-contact thermometer at Harbor Freight. No engine light light the rest of the day. Another stop at the grocery store and finally back home.
I realize the computer resets the light if it sees 2 or 3 starts with no issues. Any ideas what might be so temperature sensitive?
More background. The timing chart shows it is slightly above the center line. Still acceptable according to the graph.
I drove home a week ago and there was a noise louder than its normal of slightly too loud. Personally I think the pump is sounding louder than it should and that has been an observation for a while. Granted I have heard a far noisier pump at a Dan GTG. It does have a fresh fuel filter which made no difference. The old filter had no signs of water and no crud draining out from the drain.
My injectors have some variation from -1.x to +.3. A bit wider range than some like. It does do some blue smoke when cold even if I pay attention to making sure the glow plugs do their job. New glow plugs and wiring harness as it was tossing that code 3 months ago. I figure if I am sending the pump off to get serviced at most everyone's favorite repair shop, I will send the injectors off to not so many favorite's digital injector testing service. Let him decide if I need to replace the injectors or not.
Other observations. Sometimes the idle is a bit lumpy. Not that often. Acceleration can be lumpy but seems to be better with lots of lead footing. My theory is that some of the lumpy acceleration is turbo actuation getting sticky. It could be that the pump is not doing a great job of adjusting timing. If I were more diligent I would look to see if there is a way to graph the timing while driving. Another observation is that I can be driving down the road and I get a tiny power drop. Not unlike someone turning the key off and on quickly. Not that frequent that the micro power drop happens.
My coolant tank was replaced a few years ago because I broke off a nipple doing a timing belt change. I never saw any dreaded coolant migration.
I had replaced the temp sensor underneath the vacuum pump and closer to the firewall a year or two ago. New water thermostat a few months ago when it got stuck closed.
I have done the three pump seals a few years back.
Car is low mileage at 386,000 miles. I have only driven in the snow once so the car is not full of corrosion. Not to say some connections might not need some shining up.
I have spent a few hours doing Google research and have not really found any answers that amuse me. DFS service could be $600-1,100. I am sure I will eventually send it off for testing and service.
Maybe in that long rambling post is some sort of clue to anyone more experienced than I.
P1248 - 35-10 - Control Deviation - Intermittent
So what confuses me is that if it gets 40+ or maybe a bit warmer and after three or 4 starts the check engine light will go off. I normally drive 46 miles to work. 8-9 hours later drive home. Today it was cold enough at 10F. My car is always parked in my garage at night which stays a bit above freezing when cold outside. If the car is parked for two days the garage might get a bit colder but it still has a nice dose of solar heat. The car got to enjoy the 10 degree weather a minute after driving off. I parked the car for 3 hours, later had to drive another 60 miles to one of our other offices. By then is was getting toasty at 35 F. I worked for 2 hours and headed for home. 5 minutes to a convenience store for a snack. Another half hour to pick up a non-contact thermometer at Harbor Freight. No engine light light the rest of the day. Another stop at the grocery store and finally back home.
I realize the computer resets the light if it sees 2 or 3 starts with no issues. Any ideas what might be so temperature sensitive?
More background. The timing chart shows it is slightly above the center line. Still acceptable according to the graph.
I drove home a week ago and there was a noise louder than its normal of slightly too loud. Personally I think the pump is sounding louder than it should and that has been an observation for a while. Granted I have heard a far noisier pump at a Dan GTG. It does have a fresh fuel filter which made no difference. The old filter had no signs of water and no crud draining out from the drain.
My injectors have some variation from -1.x to +.3. A bit wider range than some like. It does do some blue smoke when cold even if I pay attention to making sure the glow plugs do their job. New glow plugs and wiring harness as it was tossing that code 3 months ago. I figure if I am sending the pump off to get serviced at most everyone's favorite repair shop, I will send the injectors off to not so many favorite's digital injector testing service. Let him decide if I need to replace the injectors or not.
Other observations. Sometimes the idle is a bit lumpy. Not that often. Acceleration can be lumpy but seems to be better with lots of lead footing. My theory is that some of the lumpy acceleration is turbo actuation getting sticky. It could be that the pump is not doing a great job of adjusting timing. If I were more diligent I would look to see if there is a way to graph the timing while driving. Another observation is that I can be driving down the road and I get a tiny power drop. Not unlike someone turning the key off and on quickly. Not that frequent that the micro power drop happens.
My coolant tank was replaced a few years ago because I broke off a nipple doing a timing belt change. I never saw any dreaded coolant migration.
I had replaced the temp sensor underneath the vacuum pump and closer to the firewall a year or two ago. New water thermostat a few months ago when it got stuck closed.
I have done the three pump seals a few years back.
Car is low mileage at 386,000 miles. I have only driven in the snow once so the car is not full of corrosion. Not to say some connections might not need some shining up.
I have spent a few hours doing Google research and have not really found any answers that amuse me. DFS service could be $600-1,100. I am sure I will eventually send it off for testing and service.
Maybe in that long rambling post is some sort of clue to anyone more experienced than I.
