[austinth0rnt0n]

Hi guys,

Since the weather here in Charlotte got cold last week (20s-30s), I have been experience a rough cold start in the mornings. I would immediately think glow plugs/ module, but I am not getting any codes. I even checked with Protool.

I noticed that my driving home yesterday at highway speed (11/21) and my voltage was reading ~13.8V which I thought was kind of low. The next morning (11/22) in accessory mode it read 11.6V. Then came up to 14V at idle. However, it actually started fine this morning (no stumble) and read 14.6V ish while driving to work this morning at highway speeds.

I checked the battery voltage a few hours after I got to work and it's sitting at 12.2V.

I am wondering if it could be a bad battery since I've read that can cause a rough start without throwing codes. However, a friend of mine said it could be the voltage regulator. No codes, no other issues while driving.

Do you guys now of anything to test/try to help narrow down my issue?

[kpm]

Originally Posted by austinth0rnt0n

Hi guys,

Since the weather here in Charlotte got cold last week (20s-30s), I have been experience a rough cold start in the mornings. I would immediately think glow plugs/ module, but I am not getting any codes. I even checked with Protool.

I noticed that my driving home yesterday at highway speed (11/21) and my voltage was reading ~13.8V which I thought was kind of low. The next morning (11/22) in accessory mode it read 11.6V. Then came up to 14V at idle. However, it actually started fine this morning (no stumble) and read 14.6V ish while driving to work this morning at highway speeds.

I checked the battery voltage a few hours after I got to work and it's sitting at 12.2V.

I am wondering if it could be a bad battery since I've read that can cause a rough start without throwing codes. However, a friend of mine said it could be the voltage regulator. No codes, no other issues while driving.

Do you guys now of anything to test/try to help narrow down my issue?

Assuming voltage is not your problem.....A few years back at this time of year, I was experiencing similar momentary roughness at cold start that became a longer stumble as temperatures got colder. Similarly, no error codes were coming up. It turned out to be a failed thermostat that was not allowing coolant temp to go above 72 deg C when 88C is normal. This failure was the culprit that eventually took out the glow plug controller and finally brought on some codes(GPC communications error was one of them). Before any codes appearred, the GP Controller was showing subtle erratic behavior(i.e. once bringing on the glow plug light at start with 4 deg C ambient). The importance of a working thermostat is well documented in this forum as well as its failure causing other secondary problems(glow plug failure and regen issues included).
Start with the easy stuff like the fairly simple process for pulling up the coolant temperature parameter on you dashboard menu(found in these forums or online) and monitoring through a drive.
Best of luck!