Engine dies - but why?

[iamdub]

Interesting. I was curious enough about this to go look at mine, and it's not there on my L59. And the oil dipstick on mine is closer to the firewall.

View attachment 407506

You got me!

I forgot I was in the GMT800 forum. Again.

 

[PG01]

You got me!

I forgot I was in the GMT800 forum. Again.

Not gonna lie, I had to check where I was when u posted that pic….lol

 

[Just Fishing]

So was just out messing with it. I pounded, pulled and twisted on pretty much anything under the hood I could get at. It never missed a beat. I pulled one of the PCM connectors off and noticed something I've never seen before. There's some kind of oil in here. To me that's not normal.

oh, you need to smell that stuff to see what it is.
If you don't know, then it's time to start sniffing fluids and compare!

 

[Just Fishing]

It also makes me wonder if you got some oil in that PCM somehow...

 

[Fless]

As noted before, oil can migrate through an electrical harness from a failed sensor seal.

 

[Jobi-Wan Kenobi]

So ended up having trouble with it again today after work this morning and was supposed to be going somewhere with it but ended up leaving it sit for the afternoon (this after making a trip into town from work). Started fine when I returned a few hours later. On my drive home the engine very briefly cut out for the first time. But there is a registered code P0335 for the crankshaft position sensor now. Now we might be getting somewhere.

 

[Jobi-Wan Kenobi]

Apparently though a new sensor requires a relearn process with a scan tool and I don't have one. So don't feel very good right about changing the sensor.

 

[wjburken]

So ended up having trouble with it again today after work this morning and was supposed to be going somewhere with it but ended up leaving it sit for the afternoon (this after making a trip into town from work). Started fine when I returned a few hours later. On my drive home the engine very briefly cut out for the first time. But there is a registered code P0335 for the crankshaft position sensor now. Now we might be getting somewhere.

Crank Shaft Position Sensor you say? Hmmm……

Now you have something to work with.

 

[Fless]

A CASE relearn isn't necessarily "required" after changing the sensor, but it's recommended. Not doing it might show random misfires, or not.

 

[Jobi-Wan Kenobi]

I had seen a couple things where the relearn wasn't required for AC Delco sensors. Is this actually true? I would think not.

 

[Fless]

It's not required for ANY brand sensor, just highly recommended. If you replace it, use an OE sensor and see how it runs, and plan to have the CASE relearn done when you can. It shouldn't be urgent, but have it done later on to be sure. It's a 5-minute hands-off procedure with a capable scan tool.

 

[iamdub]

+1 for not required but highly recommended. I recall reading at one time of a procedure for relearning it by performing a particular driving cycle. IIRC, it was a factory-outlined procedure.

Best method is with a bi-directional scanner. If you're friends with anyone at a shop, maybe they'll hook you up or charge actual labor time. Hell, a case of beer would be a generous payment for the 5-minute job.

@Jobi-Wan Kenobi, did you clear that code and does your scanner show freeze frame data?

 

[Jobi-Wan Kenobi]

@iamdub I did find stuff in a few places too about a drive cycle that's supposed to do the relearn. I didn't find anything concrete thought that it works for this vehicle platform. I don't know anyone with access to a scan tool that can do the job for me. I don't have my own just yet but am working to figure out just what it is that I want. The code wasn't present today, but I wondered if it cleared last night after key off (unless it cleared sometime today even). Right now I'm just working off a ELM327 bluetooth adapter and a phone app.

 

[Fless]

Take a look at this thread; there's a link to a list of members here who have Tech 2s and are willing to help. Would be good to know what part of the country you're in.

Tech 2 Owners Map

There are quite a few members that have a Tech 2 and there are always people who wish they had one to use so I thought I would post this thread to try and help each other out. If you own a Tech 2 and would be willing to help out another forum member that might be local to you then post up your...

www.tahoeyukonforum.com

 

[Jobi-Wan Kenobi]

I'm in northern Wisconsin (Rhinelander area) and looks like @George B is the closest but really not that close. Google puts him about 4 hours away.

 

[iamdub]

@iamdub I did find stuff in a few places too about a drive cycle that's supposed to do the relearn. I didn't find anything concrete thought that it works for this vehicle platform. I don't know anyone with access to a scan tool that can do the job for me. I don't have my own just yet but am working to figure out just what it is that I want. The code wasn't present today, but I wondered if it cleared last night after key off (unless it cleared sometime today even). Right now I'm just working off a ELM327 bluetooth adapter and a phone app.

It's worth checking in to to know if the app would be able to access the freeze frame data. My point was if the code and its data were saved, you could see what the CKP sensor was reporting at the time the code was set.

IMO, it's worth doing to be sure your timing and misfire detection are on point even if you don't see or feel anything amiss. If you do replace the CKP sensor, call around to a few shops and ask what they'd charge. I think the proper term is "CASE relearn" (Crank Angle Sensor Error). Perhaps a shop that knows exactly what it is and that it only takes a few minutes, and knows that you know that, would be fair about it and not try to charge their minimum fee, which is often 1 hour labor at $75-$100+ per hour. For more options, I don't know about EFI Live, but someone with HP Tuners (such as a performance shop) can perform it for you as well, no licensing needed. That is, unless they changed this. Can't trust them HPT people sometimes.

 

[Jobi-Wan Kenobi]

@iamdub the phone app is capable of doing data recording but the crankshaft sensor isn't one of the parameters it looks at. There are a few shops (no performance shops close by though) in the area I can check with. But yea I do agree regarding the fee for it. I can pretty much arrange a time to show up and just wait for it to be done because it really shouldn't take that long.

 

[iamdub]

@iamdub the phone app is capable of doing data recording but the crankshaft sensor isn't one of the parameters it looks at. There are a few shops (no performance shops close by though) in the area I can check with. But yea I do agree regarding the fee for it. I can pretty much arrange a time to show up and just wait for it to be done because it really shouldn't take that long.

Not data recording like live data ("real-time monitoring"). A freeze frame. It's a snapshot of what all the sensors were reporting at the time the DTC was set. It's a really handy diagnostic feature that is usually standard with any half-decent scanner. I mean the data is already there, in the PCM. It's just a matter of accessing it along with the DTC you're viewing.

For example, say I had high idle, persistent stalling, rich exhaust codes, maybe even lean exhaust codes, sooty O2 sensors, etc. I could check the freeze frame for the rich exhaust code and, as expected, I'd see the O2 sensor reporting low or high (whichever indicates "rich"). But, I continue scrolling through the freeze frame data and I see the coolant temp sensor is reading some obscenely low temperature. There's my smoking gun. The PCM is thinking it's super cold and dumping fuel trying to warm up the engine. The excess fuel soots up the sensors and, eventually, they're clogged and can't accurately sample the exhaust so they report it as lean, which makes the PCM dump even more unneeded fuel.

 

[Jobi-Wan Kenobi]

Last night I decided to take on cleaning up the grounds. I got the one on the engine block done and today it seemed that may have taken care of the crank but no start condition. The engine will still intermittently die but seemed to start right away just fine. Today now I cleaned up the frame grounds but now I seem to have other electrical issues worse than I already had. I made a post in the electrical forum for it.

@iamdub gotcha regarding the freeze frame capability. Yes the phone app does do it. Parameters it looks at are pretty limited though. This is for an EVAP code that's currently active.

 

[Jobi-Wan Kenobi]

Crisis averted. I ended up missing a ring terminal for one of the grounds hooking things back up after cleaning.

Back the issue at hand. We'll see now if cleaning the other grounds helps to clear up the stalling issue. Otherwise I do have an AC Delco crankshaft sensor on order that should be showing up on Monday that can get swapped in there.