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KOKO trouble

B

blumpkin

idi expert
Messages
64
Reaction score
125
Location
Ontario
I tried to do the obd2 koko procedure, did key on full throttle waited 45secs,..key off for 45 secs.
When trying to restart it would not idle without a little throttle, clouds of unburnt fuel smoke. i hel throttle at 800-1000 manually for at least a minute,. Then i revved the engine to 2500 or so and it cleared itself and has returned to proper idle.
Why did it react in this manner?
 
a quick update, i took the truck to town drive ability is fine,. but sitting idling in parking lot after 5 mins or so it suddenly gave burp and started idling really rough with clouds of smoke, again unburnt diesel smell,. i revved it to 2500 for about 5 secs and it cleared itself and now again its perfectly fine.
Omg i should have let the sleeping dog lie,.
 
ak diesel driver said:
Assuming you're trying to set timing?
Click to expand...
No,. was talking with my son and he asked about koko,. truck has been running fine for 2 years,.
I got hime and put a cheap scan tool on it,. its running between 167-173f
it has new thermostats,. and has always run cool,.
As soon as the temp rises to over 172 it tries to do relearn and will not idle,.just stalls, restarts fine but if temp is over 172 it runs rough, missing and spewing unburnt fuel clouds,. if i rev it it clears up and settles down if temp is beliw the threshold it runs drives fine.
I have been trying to find away to exit the relearn,. and just leave it be,.
 
what scan tool are you using? also what year truck was this again? if obd2 system, you might want to look into one of those blue tooth scan tool thingys and a good paid app for your phone. something like car code or torque pro that will give you the TDC offset reading. if it's sitting at 0.00 that would be why it's wanting to do a relearn. youll want to loosen the IP nuts leaving one snug so you can get the actual IP timing as close to 3.5 deg as possible. then let it do the relearn process and see where the offset settles at. factory spec is between 0.25 and 0.7 iirc. you can go as high as 1.9 and be ok but check to see where it's at before trying to let it relearn.
 
NVW said:
It needs to be above 170F to relearn, that may be where the problem lies when it gets warmer?
Click to expand...
yes,.. i have been saying this all along,. i am quite familiar as to why it is doing tis,. what i am not familiar with is why its retarding the timing so bad,. and i am looking for a solution to stop it going into relearn at 170,. i want to exit the program,. yet i cannot find the info necessary,.
I,m thinking that it may be the different pmd that maybe has a different resistor,. i,ve changed a couple along the way,. in 4 yrs,.
So the next path i am on,. is to see what it takes for the ecm to learn a new resistor value,. again info i can't seem to find,..
I am kicking myself for not leaving things well alone
 
Try installing a new Delco temperature sensor. The one by the Thermostats and see what that does.
Have You cleaned the ground connections at the back of the right side cylinder head/intake manifold ?
 
thanks for everybody's replies,.
Just a refresh,.. Truck has been running perfectly for 2 yrs,. on a whim the boy and i decided to do a koko,. now i have the trouble,..
Does anybody know how to exit the koko relearn program? as soon as it sees 170 ish it tries to relearn,. pretty sure you need a resistor to do relearn,. I't not a temp sensor problem,. i towed the trailer on monday and it was running between 190-205 ish,. all sytems good,.
AS i will say again,. its been runnng fine for 2 yrs,.
 
When you commanded the relearn in the beginning, it cleared the setting it had stored. as far as I know there is no way to undo the command other than allowing it to follow through with the relearn. there may be some timing issues like a worn timing chain where I have heard others have had no issues until a relearn was triggered and the problems start. verify with you scanner that the actual IP timing is at or close to 3.5 degrees and not jumping around aggressively at idle and all accessories like the ac is off. if the timing is slightly off due to wear overtime, this may be causing your issue. also I recall the stepper motor in the IP can cause this issue.

one thing to note, don't use a snap-on scanner to read timing, they don't read the numbers correctly. find someone with a GM tech 2 will be your best bet.
 
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