Hard start & very rough engine

[maximsafety]

The reason I asked is that I'm almost having the same exact problem minus the PMD issue and stalling! Have checked everything (from the fuel tank on) except the CPS. I was thinking my IP had failed after only 1500 or so miles. So the CPS is PITA to change, how many hours & minutes and how can I know if I have a faulty CPS. When I tried to pull the codes using my GM Tech 1 scanner (when the engine would start) it came back no history of codes even though the SES light came on every time the engine started the eratic idle and black smoke!!!:mad2:

 

[matuva]

I have had to change several CPS.
Usually when they fail, they throw a DTCode, and cause no start/hard start conditions, sometimes when you succeed starting, it runs more or less fine, sometimes rough.

This time, we were a bit confused at first glance as the truck was having a PMD issue too, and the CPS failed only few minutes after we swap to the new PMD, throwing no specific codes.

The only codes we can refer to were the ones about cylinder/injector circuit contribution/balance fault.
What made me thinking about the CPS is that the truck was running like if she was not properly timed.

Changing this CPS doesn't takes long, about 1/2 hour job.

1- don't do it on a warm engine. Your hands will thank you for that.
2- locate the plug, usually hidden under the T-stats housing. Disconnect it and attach a piece of wire 1 meter long to it. Leave it here.
3- Pull out the protection plate under the engine (held by 15mm headbolts)
4-locate the sensor : it is down under on the front of the block, on the driver side, behind-under the reservoir of the power steering pump, inside a hole so it's front end can sit close to the harmonic balancer (aka damper), the one behind the 6 grooves crankshaft pulley.
This sensor has to monitor the revolutions of the crankshaft to report the PCM, and the PCM will then use this information for timing purpose. To do so, there's a notch in the damper wich causes an impulsion each times it passes front of the CPS magnetic sensors.
5- using a 13mm flat wrench, remove the bolt retaining the CPS.
6- now, it's time to have fun. Pull out the CPS. If you are lucky, it will come out.
If like me, you are working on a lowered suspension truck, laying under the engine, with light in the eyes, cause it's late and night has come, I'm sure you will wonder what have you done to God to merit this : CPS sensor was stuck. A few WD40 later, it comes out... and found that this funny power steering pump reservoir just decide kidding you and won't let you have enough place to completely remove the sensor.
Few cursing words and a beer later, you figure you get choices :

a - leave the CPS here and tell the guy lighting a match in the engine could solve all problems,​

b - remove serpentine, remove power steering pulley so you can release enough the power steering pump (yes, ask the GM engineers why do we have to do all that just to access the bolts retaining the power steering pump)
​

c - drink a second beer and think.
​

Finally, I choose the c
So, after the second beer and before the 3rd, :idea: : with the agrement of the owner, I slighlty hammered the reservoir, so I can get just enough place to extract the CPS.
7- put the new one in place, bolts, protection plate, using the piece of wire which came with the old harness, attach the new one, fish it to the top and connect.
8- wash your hands, finish the 3rd beer, smile to the owner who's looking at you anxiously, and start the engine.
9- do time set;
10 - enjoy, and no, don't take that 4th beer. 3 is enough

 

[maximsafety]

Matuva, for the first time in months you have made me smile/laugh about these engines.....Thank you!):h I have tried everything else and your awesome story of how the engine system failed is almost indentical to my woes:mad2: Thanks so much for the great narration on how to change a CPS I have got to replace mine before I commit to pulling my IP and sending it back under warranty. I just called my wife to tell her to get the beer ready. Here we go!:thumbsup:

 

[matuva]

Glad to help
Oh, BTW, it is possible that your truck won't restart after you swap to a new CPS.
Don't panic, disconnect the PCM, inside the dashboard, behing the passenger glove box, let it rest for 10 minutes, reconnect it, and she will then start.

Good luck

 

[Brooklyn Tow]

You "must" set timing when replacing CPS?

 

[matuva]

IIRC, yes, better set timing.
But without Time set, she will run though.

 

[matuva]

Well well.... I'm sure now, this truck (or his owner) is cursed...
Last evening, the guy changed the CTS as I told him to do (was broken and caused erratic reving), and went a drive test of 3 kilometers.
Then he phoned me to tell : "Al, could you come home and let me know what's going on ? The engine started knocking during drive test, and is now making a strange noise"
:sosp: I grab my laptop and go. On the way I was wondering what the hell did happen again, like he is describing, I thought it has now too much advance and so rattle.

When I arrive, I asked him to start.

Glow cycle and start : :bigeyes2:

hmy1: I've never heard an engine screaming like that !!! It was like if the engine was alive, it was like a live pig you're trying to cut the throat of

I yelled the guy to shut off !

After a few seconds I tell myself : this is metal suffering somewhere.
While I was telling the guy what I was thinking about such a noise, we both look at the oil dipstick.

We pull it : dry!!! Check 4 times, still dry : we ended adding more than 3 liters fresh oil in the crankcase.

I don't understand why the OPS did not shut off the engine... and the guy sware the oil level was perfect when he did his last oil change, and so he doesn't understand either why so much oil is missing.
I answered him this is just because he doesn't check enough in the interval.

After oil added he started the engine. The engine screamed a second then ran smooth, noise free.

We let it idle for few minutes, checking gauge, shut off and check level.

We went for a road test.

After a kilometer or so, the engine was running a bit rough, then rev up and stall :toetap05: No restart...

After few investigation, we saw in the transparent bowl of the fuel/water separator that it was half empty. Obviously, air is coming from somewhere.
We bleed the fuel filter, and she restart.
We have to fix that air leak too....:dot:

What's your opinion guys (and girls ) ? Do you think the engine has suffered a lot and there are now important internal damages ?

I listen to the engine. It was not running perfect, knocking a bit, but i can't tell if this a rod knock or air in injectors...

 

[NVW]

He'll be lucky if one or more bearings are not screwed. Screaming sounds are not good.

Leo

 

[625fireman]

X2 more than likely the mains, rod bearings are at least going, going, going, will be gone soon if not already. Does he have some major oil leaks somewhere, or is the old girl burning that much oil. Granted if you dont check it, it's your own fault for grenading an engine. Glad you fixed the other problem for him.

 

[Turbine Doc]

OPS does not shut off an engine, only lift pump, but IP can still pull it's own fuel thru a dead/weak lift

 

[matuva]

X2 more than likely the mains, rod bearings are at least going, going, going, will be gone soon if not already. Does he have some major oil leaks somewhere, or is the old girl burning that much oil. Granted if you dont check it, it's your own fault for grenading an engine. Glad you fixed the other problem for him.

no major leak we can see, no oil on the floor, and the old girl doesn't smell oil smoke while running.
The guy swore that she never eat oil before,he says that's why he was so confident and neglected checking.
i don't understand how so much oil is missing...

OPS does not shut off an engine, only lift pump, but IP can still pull it's own fuel thru a dead/weak lift

True Tim, I forgot that point, and the IP is only 3-4 months old, so healthy...

 

[matuva]

He'll be lucky if one or more bearings are not screwed. Screaming sounds are not good.

Leo

X2 more than likely the mains, rod bearings are at least going, going, going, will be gone soon if not already. Does he have some major oil leaks somewhere, or is the old girl burning that ...

Looks like he is going to play with bottom end rebuild...

After we curer air leak and change injectors (8 brand new BOSCH), we will see what's going on.

Cross fingers, even though I have a bad feeling...

 

[Veg_Out]

Looks like he is going to play with bottom end rebuild...

After we curer air leak and change injectors (8 brand new BOSCH), we will see what's going on.

Cross fingers, even though I have a bad feeling...

Good luck keeping the southernmost 6.5's running. Constant job.

 

[matuva]

The truck is sitting in a garage.
The guy is a bit discouraged. We just found an air leak wich may have caused or help stalls we were fighting against.
I told you it was cursed.

The engine has to be taken out for diagnosis, constantly knocking loud now. If he is lucky, he will just neeed new bearings, but I'm afraid the crankshaft is gone.

Owner want's to make a break for now (money). SO we'll see that later.

 

[Big T]

Can't wait to remove mine with the belt and other stuff in place.