Hard starting when cold problem solved

[boatman10]

I knew my hard-start-when-cold problemwas not a fuel pressure problem I checked it with a gauge.......also squirting gas down the intake plenum did not help at all so it was not an injector timing issue [that would be caused by a bad CAMSHAFT position sensor] AND ALSO NOT a bad temp sender telling computer I had a warm engine when it was cold giving a lean-cold-start[notoriously inexact temp gauge worked n it works off same sensor}

it HAD to be, In my case, the crank sensor.
....and its known to cause this situation and it was a recall on the 2001-2003 8.1Ls in pick up trucks, I'm not sure they recalled in workhorses if they didn't it was an OVERSIGHT.

I got mine 26$ delivered on EBAY.......you just need a crank sensor for a 8.1L most the parts places do not list one for the workhorse but a 8.1L IS AN 8.1L they all have the same sensor........and it does not matter if its a single oring or a two oring sensor both with work.

I carefully pulled it out threw the doghouse with PB blaster and a little pry bar then a big pair of channel locks twisting it slightly as I pulled UP.

now it starts cold at the turn of the key.

these CPS's do not throw a code til they are about dead.

there is a 'relearn' procedure for the computer.

warm up engine TO OPERATING TEMP n do a 'relearn' for the computer.....with foot on brake take warm engine to 5000+rpms, computer shuts down motor and you will see tach bounce from 4500-5000....let off throttle.... then n all sensors are 'relearned'.

foot MUST be on brake the whole time, engine must be warm n slowly take engine UP in rpms.

[pbucha]

Great info, great diligence in finding the problem.

[pasdad1]

Doesn't pulling the ECM fuse or disconnecting the battery also force the computer to "relearn" ?

[edgray]

Great post and info. Thanks. I always thought the engine RPM was limited to around 3,000 in Park or neutral to protect engine from damage while "unloaded". Does the brake applied disable that governor???

[boatman10]

the rev limiter chips out at 5000rpms on the 8.1

do not be afraid to do this process....taking a big block up to 5K for seconds when warmed up is not extreme....it just seems like it to us old folks.

AC actuators are reset with battery disconnect, not rpm dependant sensors.......otherwise 'how do they know?'

[AKIQPilot]

My '02 W22 rev limits out at 3000 when in park. Not sure about what it does in neutral.

[boatman10]

definitely chipped out at 5K.......maybe they have changed the relearn on other newer engines.

i am also told that relearning on the CPSensor is not a 100% necessary operation.....it seemed to run fine with no check engine light before i did the relearn.

some looking around i see scangauge 2 is supposed to do it, as other fancy scanners can.

also there was a disconnect battery n then a somewhat involved procedure involving brake pedal n other things on the GM 6.0

looks like alot of guys just pop in the CPS and drive on with no issues......not throwing a code of course would be a good sign.....mine did not throw a code....then i did the process anyway.

also research shows doing the relearn like i did on a 8.1 that chips out at 3000 will accomplish the relearn.

more research shows just driving the vehicle the ECM will relearn on its own after 100mi.

i see also SOME CARS will throw a check engine light after a CPS replacement, tho they will run fine and after 100mi the light will reset itself, but most shops go thru the process cause the cannot return a vehicle to a customer with the light on.

[Fyrflie]

Thanks to this post by Boatman, I may have averted a problem.

After reading his post and determining that my motor fell into the category of a possible faulty CKP, I thought, for $45, why not replace the CKP as a preventative measure. Essentially perform my own recall.
I recently have experienced hard starting when cold symptoms.
I was able to remove the CKP without issues. But I did find oil in the electrical connector. Impending failure?

And while I was working on the coach I decided to check for any possible codes in the ecm. Using my $20 WiFi OBD2 dongle and connecting to my iPad via The Engine Link app, I found that my TSS (transmission speed sensor) is bad.

All of this and no CEL.

My hats off to all who have offered valuable information on this forum.
Happy Thanksgiving to all.

[wa8yxm]

One word of caution... GM made a few "little changes" from year to year on the 8.1L.. One of those changes was the Crankshaft Sensor (Between 04 and 05) I know this because when the 2005 Engine in my Rig was killed (Yes it was murdered by a road hazard) we replaced with an 04.. The difference appears to be more cosmetic than anyhthing else but the oil seals were different so we used the 04 sensor.

[boatman10]

say the seal difference on the CPS was an improvement to facilitate removal and are interchangeable.

the receiver hole in the block is the same.

i used the new style in my swap out.