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VQ30DD LOOM INFO/MISFIRE

Tomcee93
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Tomcee93 Rookie

Tomcee93

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Hey guys, first time posting in the forum.

Firstly, I have a v35 sedan 300gt limited with a vq30dd motor.

The car runs super rich, suffers a misfire and struggles to start when hot, as well as going into limp mode.

I have changed plugs, coils, maf, cam and crank sensors, replaced pcv and all vac lines, used upper cylinder head cleaner (I know the design get dirty as hell), scrubbed all carbon deposits and resealed all gaskets, i have a spare ecu. 

All this and I still can't get it to run nicely.

Was wondering if anyone else has some ideas for me to get it to run and if not, wondering what the compatibility of the vq30dd loom is to a 35de? Kinda sick of trying to find parts for this obscure motor and worst case I'd potentially swap a 35de into it but I'm unsure how compatible the looms are and wether that is a massive job in of itself?

Any and all help would be appreciated, cheers.

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robbo_rb180 Grand Master

robbo_rb180

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With those codes I would have said Cam or Crank sensors but they were replaced. Were brand new genuine or 2nd hande?

Have you cleaned or checked cam control solenoid? I know on subaru's these will some time get gunked up or jammed with debris and filter baskets require cleaning

Tomcee93 Rookie

Tomcee93

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On 26/08/2022 at 8:05 PM, robbo_rb180 said:

With those codes I would have said Cam or Crank sensors but they were replaced. Were brand new genuine or 2nd hande?

Have you cleaned or checked cam control solenoid? I know on subaru's these will some time get gunked up or jammed with debris and filter baskets require cleaning

Sensors were new old stock.

I've not checked the cam solenoids other than a visual I section, didn't know they even have filters on them haha

White GTS-T Mentor

White GTS-T

Posted
Posted

If you're getting CAM/Crank correlation codes, and you've rulled out the sensors and the ECU, then next logical thing left is the wiring, or the mechanical timing of the engine.

Can you get an oscilloscope on the CPS and CKP signal wires to rule out timing chain stretch? Can you check the power and ground supply to the VCT solenoids? Are the solenoids actuating? Or, as suggested, are the solenoid gallers blocked or VCT gears worn? What is the service history like on the car? Does the engine rattle when started cold?

Find yourself a wiring diagram and test the resistance of the circuits between the sensors and the ECU. Check for mutual shorts, shorts to ground, shorts to power and high resistance.  Perform a wiggle test on the wiring loom while monitoring the CKP, CPS, ignition timing etc. 

What does the scan tool say about the long and short term fuel trims?

Does the scan tool log freeze frame/snapshot data when the codes log to help track down and replicate the condition?

  • 7 months later...
jaydor Newbie

jaydor

Posted
Posted
On 8/26/2022 at 11:20 AM, Tomcee93 said:

Hey guys, first time posting in the forum.

Firstly, I have a v35 sedan 300gt limited with a vq30dd motor.

The car runs super rich, suffers a misfire and struggles to start when hot, as well as going into limp mode.

I have changed plugs, coils, maf, cam and crank sensors, replaced pcv and all vac lines, used upper cylinder head cleaner (I know the design get dirty as hell), scrubbed all carbon deposits and resealed all gaskets, i have a spare ecu. 

All this and I still can't get it to run nicely.

Was wondering if anyone else has some ideas for me to get it to run and if not, wondering what the compatibility of the vq30dd loom is to a 35de? Kinda sick of trying to find parts for this obscure motor and worst case I'd potentially swap a 35de into it but I'm unsure how compatible the looms are and wether that is a massive job in of itself?

Any and all help would be appreciated, cheers.

hi i was just wondering what brand and part number camshaft sensors and crankshaft sensors as my 2003 300gt skyline has these error codes : p1806, p1135,p0345

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