Long crank, no faults

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Jimmy Brooks

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Update on the truck, first I’m going to list everything I diagnosed then I’ll list everything the shop has done.

fuel rail- checked for leaks/ moisture non found, checked sensor, read psi correct, voltage read within range and moved when cold, car preformed fine.

High pressure fuel pump, built pressure fine, acted normal, car preformed normal, presssure relief valve unknown

Checked ECM for corrosion/moisture none found, checked drainage from the weather stripping at the bottom of the windshield found it wasn’t flush with the windshield. Poured multiple bottles of water into bits that were separated, water made its way to the fenders and drained out, no signs of moisture in the engine bay.

Checked coolant temp sensors, MAF sensors, voltage in range and moved when with engine rpm when cold, all read correct.

Starter/battery- jumper boosted start, car cranked faster then normal, made no difference car still cranked for an excessive amount of time.

Injectors- pulled them myself, and sent them to my mechanic to be tested, mechanic said injectors were tested and came back fine.
no smell of fuel in oil.

So I had the car towed over to the mechanic.

Mechanic pulled plugs and borescoped the cylinders, dry

Mechanic swapped fuel rail pressure sensor, still preformed the same

Mechanic pressure tested fuel rails, no leaks

They now said they are suspecting a bad ECM but need to do further diagnosing first.

Pretty wild seems like this may be one of those unheard of cases with these cars. I’ll keep you guys updated on everything.
 

f1racer328

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Thanks for the update! This is one of the more frustrating threads on here that I've seen in a long time. Hope you can get everything resolved.
 

greiswig

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They now said they are suspecting a bad ECM but need to do further diagnosing first.

Pretty wild seems like this may be one of those unheard of cases with these cars. I’ll keep you guys updated on everything.
It's not beyond the realm of possibility that the ECM is faulty, but my limited experience has been that vehicle computers tend to either work or not. And when they don't, they throw a lot of codes because so much is going wrong.

Again, my limited experience leads me to believe that once you figure it out, it will be one of those "Oh, geez, I can't believe it was THAT" kind of simple fix moments. Or at least I hope so.
 

Jimmy Brooks

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It's not beyond the realm of possibility that the ECM is faulty, but my limited experience has been that vehicle computers tend to either work or not. And when they don't, they throw a lot of codes because so much is going wrong.

Again, my limited experience leads me to believe that once you figure it out, it will be one of those "Oh, geez, I can't believe it was THAT" kind of simple fix moments. Or at least I hope so.

Agreed, the only odd thing about the PCM is some times when I tried to click on certain live values it would come up with an error on the IID tool app (not displaying N/A but a physical error message) that would kick me out of the live value mode or completely crash the app. I assume this is an issue on the IID tool side of things but not sure. But I don’t think it’s the module either.
 

Jimmy Brooks

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Indeed it is frustrating. I was doing a little research and came across this thread. https://www.freel2.com/forum/topic37673-120.html
Similar symptoms. Turned out to be cranking speed was too slow due to bad earth strap. That reminded me of a video you posted where the crank speed sounded slow to me. Might be something to consider.

Interesting… wonder if that could be my issue. The other thing is it would crank slower with the cold/rain which hypothetically with a bad ground wire would be harder on resistance. Definitely worth a look, only other thing is I did boost it with a jumper pack and heard it crank very fast but it still took a long time. If you have any wisdom on how that please share. Definitely wouldn’t cross it off the list of suspicions just because it took a while to crank with a boost though.
 

jlglr4

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No wisdom on why the jumper pack wouldn’t do the trick, or even why a slow crank would cause the problem in the first place. If the voltage is low enough to slow the crank speed, maybe its starving the spark as well - maybe the jumper is not enough to give full voltage to both. Not sure.

Another possibility is that it has more to do with the crank/cam position sensor. Maybe a weak or failing sensor is exploited more with a slow crank or voltage interruption. The ecm won’t deliver spark until it gets the signal it’s looking for to determine the firing order/timing.
 

Jimmy Brooks

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No wisdom on why the jumper pack wouldn’t do the trick, or even why a slow crank would cause the problem in the first place. If the voltage is low enough to slow the crank speed, maybe its starving the spark as well - maybe the jumper is not enough to give full voltage to both. Not sure.

Another possibility is that it has more to do with the crank/cam position sensor. Maybe a weak or failing sensor is exploited more with a slow crank or voltage interruption. The ecm won’t deliver spark until it gets the signal it’s looking for to determine the firing order/timing.
What’s interesting is the mechanic said there was a pending cam correlation sensor code. He said he swapped both the cam and exhaust sensors and there was no difference. He also said he could see the sensor communicating with the ECM via diagnostic scanner. Apparently this is why he was pointing towards ECM. He said he would swap the ECM with a junkyard ECM to see if that fixes it which would lead me to either have to get a new ECM from JLR or get mine rebuilt. That was as of Thursday and they never called back so I assume they didn’t find anything.

I’ve been busy all of today but Monday I’ll pop back in and ask for an update.

Also they did check the ground wires to the starter and all looked good.

Cam correlation code makes me suspicious though.
 

jlglr4

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I wonder if a cam correlation code could actually be due to a failing crank position sensor. The ecm probably tries to correlate the crank position and cam position. The other thing that a cam position code brings to mind is the VVT solenoid (which is apparently a very easy fix if that’s the problem). I wonder why you couldn’t see the pending cam position code on the GAP tool, but the mechanic could see it with whatever he’s using.
 

Jimmy Brooks

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I wonder if a cam correlation code could actually be due to a failing crank position sensor. The ecm probably tries to correlate the crank position and cam position. The other thing that a cam position code brings to mind is the VVT solenoid (which is apparently a very easy fix if that’s the problem). I wonder why you couldn’t see the pending cam position code on the GAP tool, but the mechanic could see it with whatever he’s using.

That what I was thinking, I found that weird too. The only thing that made me believe him about the code is that I did have 2 weird occurrences that were spread apart randomly. I would get step on the throttle to where I would be pulling in second all the way through 3rd-4th gear to around 4.5k RPM shifts and it would almost feel like the car was bogging a little or cutting power while rpm was in creasing. (Basically my foot was in one throttle position but it felt like I would’ve been feathering the throttle a little) This would be followed by a weird shift a couple of seconds after, shift would be very fast or a little slow. I would notice this behavior just by staring at the rpm gauge, and feeling power. I had just got the transmission over hauled so I assumed it was something weird. After a 30 min sit with the car locked it felt completely normal again. Still didn’t see any codes in the PCM after this though. Odd occurrence and I assumed it was just a fluke. Happened again another time but went away.

Side note I had also just reset the adoptions due to a weird ”pause” feeling shift the car developed going from second gear to third on the first 2 shifts of the day. The adaption clear fixed this but I believe the weird behavior came after the adaption clear which is why I figured it was a fluke.
 

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