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Light Throttle Hesitation - VQ35DE


GoHashiri

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Hi all,

 

I've only recently bought my '02 350z (83,000 miles) and i have noticed that under light load (approx. 5-10% throttle) the car hesitates. It seems to happen throughout the rev-range irrespective of gear, although it is really only noticable between 1,800-2,500RPM - going higher typically requires a higher throttle application. There is no EML and this occurs regardless of engine temperature. It's very annoying when cruising.

 

I have cleaned out the throttle body, gave the MAF a couple of squirts of electrical contact cleaner, then performed an ECU reset and idle relearn to no avail - however this seemed to fix the idle cutting-out problem.

 

I have read of similar issues across the board from plugs to fuel dampers to cats, although this often isn't with a DE. I'm thinking it's possibly a sensor or ignition problem; has anyone experienced anything like this?

 

My thoughts are: cam sensor, crank sensor, knock sensor, maf sensor, ignition coils. 

 

Being located in Japan with minimal language ability makes it difficult to source a mechanic's help. 

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  • 4 weeks later...

Hi all, 

 

Just an update: Last week i changed the PCV valve to no avail - it likely needed doing anyway. 

 

Probably a better way to describe this issue is surging under light throttle, irrespective of gear. I can replicate it in neutral.

 

Today i decided to inspect the ignition coils to look for oil, and, of course, there is oil in one of the passenger side wells - quite a bit at that.

 

I know i need to replace the valve covers, but seeing as they're fairly expensive, i'm going to try sealing it up with RTV temporarily. I'll buy new ignition coils and plugs now.

 

I have some questions to ask:

 

Do the OEM Nissan ignition coils have any branding on them at all? Mine don't. Which makes me suspect they've been changed for cheap one's.

 

Secondly, has anyone tried Hella ignition coils for these things?

 

And shamefully: has anyone tried sealing a leakly plug well with RTV?     

 

 

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Update:

 

Today i replaced 3 ignition coils, all spark plugs and RTV'd the leaky oil seal (plug #6 from the top). Upon checking the right-side valve cover a little more thoroughly i noticed the spark plug seal was coated lightly in oil - so both covers need to be replaced in the near future. 

 

I took the car for a 15km drive and it seems as though it's been cured; the idle is smoother, response is better and it seems to hold fine at cruising speeds. I'll need to go on a longer drive next weekend to really evaluate it - corona virus permitting. I'm reluctant to believe this could be cured from just plugs and coils, but please take a look at the plugs below to see what you think - they're not in the best shape for sure. 

 

I also ordered a MAF the other day thinking it might be this; so if anyone needs a MAF in the Aichi prefecture area HMU.

 

I'll report back later to notify everyone of my findings.

 

WhatsApp Image 2020-04-05 at 17.49.58.jpeg

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