P0335 Slow Cranking When Hot

Tech discussions on the L77 6.0L V8.
landcrush
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Joined: Sun Mar 08, 2020 10:55 pm

P0335 Slow Cranking When Hot

Post by landcrush » Sun Mar 08, 2020 11:29 pm

2012 L77 9C1. Purchased at auction with ~80k

Car runs fine and fires right up on cold starts.

However, after shutting car off after it is up to temp and attempting to restart it (ie; running into the store after driving around) it will crank slowly as if drawing too much power. It will eventually start but with a misfire and Stabilitrak fault warning light.

If I hook up jump leads it will fire up without fault.

Code P0335 and P0336 are present. Replaced. crank sensor with no change.

Possible issues/ solutions:

Stuck/ failing DOD lifters causing hard starts ?
Bad battery/batteries
Bad starter
Bad ground (Most of the police equipment is still in the trunk with wires cut)

I have everything to do the DOD delete but would like to figure this out first/ if it’s related.

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Fudgehog
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Location: Wisconsin

Re: P0335 Slow Cranking When Hot

Post by Fudgehog » Sun Mar 08, 2020 11:54 pm

Common sense, but I would always start with battery/alternator load test, and grounds. There are several grounds in the engine bay to check.

Also check underhood fuse box positive and ground (behind box and on its side nearest to firewall) for corrosion or loose bolts.

Also, if you replaced the crank sensor, sometimes a relearn is required for the ECU to learn the new sensor.

You would need a Tech2 or a tool that emulates Tech2 like the VXdiag for that relearn.

80k car shouldn't have stuck or failing lifters but it's possible. What about the idle hours?
13 Caprice 6.0L, Solo catback exhaust, 3.27 diff, VCM OTR, MSD coils plugs wires, transmission pan upgrade.

landcrush
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Joined: Sun Mar 08, 2020 10:55 pm

Re: P0335 Slow Cranking When Hot

Post by landcrush » Mon Mar 09, 2020 12:20 am

Super high idle hours, around 15k. I suspect that has taken a toll on the charging system and probably the valvetrain.

I’m gonna try and get it on a diagnostic tool this week to do the relearn but the issues were present and unchanged since I’ve changed the CPS.

On the same topic, is the second battery just for upfitted equipment or does it serve a necessary function.

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Fudgehog
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Re: P0335 Slow Cranking When Hot

Post by Fudgehog » Mon Mar 09, 2020 1:21 am

I know the system does take preference to charge one side first, but I'm not sure which one.

I have a second battery wired in, I run a smaller motorcycle battery for cheap insurance for my 1000w and 300w amps. I have mine wired inline, but still separated by the circuit breakers. During the winter months I connect the trickle charger and it charges both.

15k idle hours is a LOT. I don't want to jump to conclusions but I imagine the internal parts and lifters are not in the best condition.
13 Caprice 6.0L, Solo catback exhaust, 3.27 diff, VCM OTR, MSD coils plugs wires, transmission pan upgrade.

landcrush
Posts: 12
Joined: Sun Mar 08, 2020 10:55 pm

Re: P0335 Slow Cranking When Hot

Post by landcrush » Mon Mar 09, 2020 1:31 am

Yea I know it’s a lot of idle hours, had planned on doing a rebuild or atleast doing the cam and checking the top end.

I’m just wondering if sticking lifters would cause it to draw more power or make it harder to start. I know the misfire is probably related.

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Fudgehog
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Location: Wisconsin

Re: P0335 Slow Cranking When Hot

Post by Fudgehog » Mon Mar 09, 2020 2:55 am

Yeah I would also check plugs or just replace them, 80k with that many idle hours they're probably shot.

The factory plugs are usually rated for 100k but that's a lot of idle time.

Plugs are cheap, and make a big difference.
13 Caprice 6.0L, Solo catback exhaust, 3.27 diff, VCM OTR, MSD coils plugs wires, transmission pan upgrade.

s/c'd cav
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Re: P0335 Slow Cranking When Hot

Post by s/c'd cav » Mon Mar 09, 2020 4:13 pm

Fudgehog wrote:
Sun Mar 08, 2020 11:54 pm
Common sense, but I would always start with battery/alternator load test, and grounds. There are several grounds in the engine bay to check.

Also check underhood fuse box positive and ground (behind box and on its side nearest to firewall) for corrosion or loose bolts.


Also, if you replaced the crank sensor, sometimes a relearn is required for the ECU to learn the new sensor.

You would need a Tech2 or a tool that emulates Tech2 like the VXdiag for that relearn.

80k car shouldn't have stuck or failing lifters but it's possible. What about the idle hours?
slow crank electrical is the best place to start , make sure and do VOLTAGE DROP TESTS on the cables

also with replacing the crank sensor , it might not have even been a sensor issue , but possible the main batt cables , or the wiring for the sensor , or even the starter , since im guessing with 15k in idle hours it cooked the parts in that area

lifters wouldnt be a cause of your starting issues , so at this point they are a waste of time and money , since you dont mention any missfire codes

landcrush
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Re: P0335 Slow Cranking When Hot

Post by landcrush » Mon Mar 09, 2020 5:26 pm

It hasn’t thrown any misfire codes, but after slow cranking and the stabilitrak fault light comes on , it’s definitely misfiring. Rough idle and poor acceleration.

I assume an issue with the crank sensor will affect the misfire detection.

s/c'd cav
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Re: P0335 Slow Cranking When Hot

Post by s/c'd cav » Mon Mar 09, 2020 5:51 pm

it will yes , the computer sees the crank speeding up and slowing down during missfiring , but it can also send the wrong signal out or a confused signal if there is a wiring issue

landcrush
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Joined: Sun Mar 08, 2020 10:55 pm

Re: P0335 Slow Cranking When Hot

Post by landcrush » Mon Mar 09, 2020 6:51 pm

Any ideas as to why the issue is only when the car is hot? I’ve heard started heat soak is an issue with these

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