Help with diagnosis

[phantom309]

I bought the suburban, it's a 99, 275,000 miles
It runs great when it's cold, fires right up no smoke soundsvery crisp, after it warms up to 160 deg or so, it will barely idle with clouds of blue smoke and lopes like an old alcohol digger. It will roll down the highway on cruise just perfectly. First thing i did was plug in a good fsd on a cooler, from my pkup so i knew that was good.
To drive it you have to give it a foot full, it chugs bad and clouds of smelly unburnt fuel smoke until it gets over 1500,. Then clears itself, and runs really nice. Power is good, motor is smooth, If i two foot it i can keep it firing on all 8 with no smoke, but thats pretty hard on the brakes.
I can bring the rpm up under no load and it cleans up a runs great at 2000
The codes its giving are

PO 1214
P 236
PO 1214pd (?)

So it seems like its going waay retarded, at anything less than 1500?
Some things i read point towards a stepper valve?

Any input would be greatly appreciated,.

Thankyou
Nick

[Yukon6.2]

Hows the timing chain?

[phantom309]

I don't think the timing chain is the culprit, it runs great cold, or with temp sensor unplugged

I unplugged the ect, and the engine runs great?
I drove a 150 miles or so today,. But its just a cover up, with the ecm thinking its -39f it has lots of advance,. Plenty of power, except for no lockup, everything works great even the cruise control,.
I don't know what to do,. Its like the ecm is out of whack?

[Robyn]

The injection pump is likely the culprit.

Check the TDC OFFSET

Any evidence that the IP has been fooled with (possibly the 3 bolts are loose)

The IP should be centered in the timing chain housing with a possible scribe mark across the IP and housing... Check to see if if there are anomalies there.


A timing chain, although possible is not likely as the thing would probably have other issues.


A possibility exists that the ECM has issues, but I would check the timing and the IP before digging into the electronics.

[john8662]

PO1214 means timing offset error. The injection pump is out of it's timing range that the computer can compensate for. The engine needs to be timed using appropriate tools (bi-directional scan tool that can initiate the time set command).

Then the pump has to be physically rotated to see get the timing in range.

Sounds like it's really retarded timing by the description, most likely due to a severely worn timing chain. See if you can get it in range with the timing adjustment, if not it'll need a chain.

John

[phantom309]

I appreciate the advice,. Again,. Why would a timing chain just suddenly stretch overnite? My 94 has over 500, 000 kms and the chain is a litle sloppy but the stepper has a huge possible range of adjustment,.
I'm just about done with this obd2 crap,. I thinks its going to go to auction
I've asked a fee different experts but nobody really seems to know why,.

Thanks again