Rough cold start

[matuva]

Hi all,

like says the title, we have a pickup, a 1996 K1500, experiencing very rough cold start.

She does start almost easy, but smokes white as hell ( smells fuel) for 30 seconds to a minute. Engine shakes, runs like if some cylinders misfire, then it goes more stable clanking, and then after a minute, finally run stable and fine. :???:

Here are the codes I found with my scanner:



This engine has been re-ring, + new rod and main bearings. We have no idea of the health of other components such as IP, etc... The mechanic is suspecting valve train, but I'm more enclined to think about the IP / stepper motor.

Any opinion?

 

[ak diesel driver]

try unplugging the CTS in the tsat housing. do you have a clear line on the IP return?

 

[THEFERMANATOR]

Pull the glow plugs out and spin it over before you start it to see if fuel comes squirting out of any of the cylinders. Could be an injector leaking fuel in when it sits, and then takes am inute or so to heat up and burn it out.

 

[matuva]

OK will test all that.

My apologize, I just realized I didn't tell you that I never succeed timing this truck. Whatever is the position of the pump, to the left, to the right, the scanner always read +2.02 value for the TDC offset.

We ended timing the pump "at the ear", like an old DB2, but sure it is not properly timed.

CPS or OS may be?

 

[ak diesel driver]

I've had a couple of CPSs go bad and never had an OS go bad

 

[bison]

OK will test all that.

My apologize, I just realized I didn't tell you that I never succeed timing this truck. Whatever is the position of the pump, to the left, to the right, the scanner always read +2.02 value for the TDC offset.

We ended timing the pump "at the ear", like an old DB2, but sure it is not properly timed.



CPS or OS may be?

Advance piston stuck past the point of no return,.... stepper is unable to pull/push it free as the connection to the piston is a spring loaded valve(fuel pressure controls the movement of the piston.
Solution.
1)take stepper motor off the IP( take 2 torx bolt out and move stepper to pass side to unhook from the advance rod.) and manually push the rod back in( needs a little persuasion, if unable to push it back get other stepper.)
2) remove the top cover on the IP and turn the cam ring back to the dr side.
Re-install cover and stepper, turn IP back to base setting and time IP as per manual

 

[bison]

Hi all,

like says the title, we have a pickup, a 1996 K1500, experiencing very rough cold start.

She does start almost easy, but smokes white as hell ( smells fuel) for 30 seconds to a minute. Engine shakes, runs like if some cylinders misfire, then it goes more stable clanking, and then after a minute, finally run stable and fine. :???:

Here are the codes I found with my scanner:

View attachment 42261

This engine has been re-ring, + new rod and main bearings. We have no idea of the health of other components such as IP, etc... The mechanic is suspecting valve train, but I'm more enclined to think about the IP / stepper motor.

Any opinion?

IP problem,....could be failing stepper motor or sticking advance piston.
I had that on my 98,...only in cold freezing weather though and only with first start in the morning
Replacing the IP solved the problem