99 5.3L Chugs under load when cold

[FrankB43015]

My 99 Silverado with 5.3L 2wd 170k miles chugs when I put it under load, but only when cold. It starts fine, idles fine, shifts fine, but put a little more gas to get it up to speed faster and she chugs and sputters. Once I've driven awhile and she's warmed up, all is fine. EGR looks fine, plugs look fine, MAF just cleaned... no codes showing either.

[FrankB43015]

I got two codes today, a 102 and a 336. The guys at Advance think it may be a dirty crank position sensor.

[j cAT]

Originally Posted by FrankB43015

I got two codes today, a 102 and a 336. The guys at Advance think it may be a dirty crank position sensor.

frank the DTC 102 is usually air getting into the intake from some vaccum leak or a leak in the air ducting that the maf is in... ....could also be PCV, hoses , dip stick not seated and oil fill not seated, etc....

when cleaning the MAF only MAF cleaner is to be used ....other cleaners will damage the MAF electronics....


DTC 336 is the crank shaft position sensor CKP....this CKP is located behind the starter.. it has 3 wires dk blue/white, yellow/black, and light green....since you engine does run fine after warming up of I would say the sensor is bad ,, as I have seen this temperature variation to cause the CKP to act up....


other issues could be:sensor dirty, the reluctor wheel is damaged, the engine is worn and the crankshaft moves around too much,wires, connectors, computer, etc...etc...


after you replace this the computer needs to be cleared and then it will need to relearn itself....



DTC 335 is the camshaft position sensor CMP....


you got two sensors tracking the engine rotation....

good luck

[FrankB43015]

Thanks for the advice. I think if I go through all the trouble to get to the cps to clean it, I might as well change it out. I'll let you know how it goes.

[ukrkoz]

pardon me my ignorance and please educate me. how do you get OBD1 codes on OBD2 vehicle?

[FrankB43015]

Originally Posted by ukrkoz

pardon me my ignorance and please educate me. how do you get OBD1 codes on OBD2 vehicle?

Talented, I guess. These are the codes showing up on the computer.

[j cAT]

Originally Posted by ukrkoz

pardon me my ignorance and please educate me. how do you get OBD1 codes on OBD2 vehicle?

these DTC'S are part of the PCM diagnostic's in franks 5.3L 1999 vehicle...as well as my 2000 5.3L ....

[ukrkoz]

Originally Posted by j cAT

these DTC'S are part of the PCM diagnostic's in franks 5.3L 1999 vehicle...as well as my 2000 5.3L ....

if you say so. i have complete list of all P, B, and C codes for GM vehicles with OBD2 and am quite surprised they have 3 digit no letter codes either(not on the lists).
most confusing is that they do have "P" OBD2 codes for the same condition:
P0335 Crankshaft Position Sensor A Circuit Malfunction
P0336 Crankshaft Position Sensor A Circuit Range/Performance
P0337 Crankshaft Position Sensor A Circuit Low Input
P0338 Crankshaft Position Sensor A Circuit High Input
P0339 Crankshaft Position Sensor A Circuit Intermittent

then why would they have 336? btw, we all share same engine.

well, what do i know. GM never stops to surprise me in their ways of confusing things for regular joe.

appreciate letting me know.

[FrankB43015]

It worked! I changed the crank position sensor ($50) in about 20 minutes. The biggest pain was putting the starter back in. She now runs like she is brand new. Thanks for the help j cAT!

[j cAT]

Originally Posted by FrankB43015

It worked! I changed the crank position sensor ($50) in about 20 minutes. The biggest pain was putting the starter back in. She now runs like she is brand new. Thanks for the help j cAT!

I'm happy that this was the fix...this posting will ,,, in the future, help others with this type of failure...


good luck ..

[j cAT]

Originally Posted by ukrkoz

if you say so. i have complete list of all P, B, and C codes for GM vehicles with OBD2 and am quite surprised they have 3 digit no letter codes either(not on the lists).
most confusing is that they do have "P" OBD2 codes for the same condition:
P0335 Crankshaft Position Sensor A Circuit Malfunction
P0336 Crankshaft Position Sensor A Circuit Range/Performance
P0337 Crankshaft Position Sensor A Circuit Low Input
P0338 Crankshaft Position Sensor A Circuit High Input
P0339 Crankshaft Position Sensor A Circuit Intermittent

then why would they have 336? btw, we all share same engine.

well, what do i know. GM never stops to surprise me in their ways of confusing things for regular joe.


appreciate letting me know.

The PO was omitted as this is redundant....