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VQ35HR Light throttle hesitation

29 posts in this topic

Posted · Report post

Hey guys posting on behalf of a family friend.

Basically they have a 2007 350z with the VQ35HR engine with 50k which has developed a slight hesitation/miss on light throttle application when taking off and while going through the gears. If more throttle is applied you can not notice this slight hesitation and engine revs fine. 

I have searched through the forum but havent had any luck on finding what the cause might be.

Any help would be much appreciated.

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Posted · Report post

Suggest to your friend abandon the light throttle application on take off?

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Posted · Report post

My 07 HR does exactly the same thing. I have drop in K& N's and dual exhaust but it has done this with or without any mods.

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Posted · Report post

Suspicion has to be that the ECU is misreading airflow at light throttle openings and may benefit from cleaning the air-flow sensors .... easy to do if you are confident around cars, otherwise leave for a trusted mechanic

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Posted (edited) · Report post

My 08 HR does this too, though doesn't tend to when taking off (i.e. only when rolling and light throttle is applied in gear) - no breathing/engine mods on mine either...

Edited to add: My first thought was that the clutch is on the way out, but it's not slipping - more of a definite miss/jerk as the OP said...

Edited by JekVI

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Posted · Report post

I to think it could be something ecu/sensor related. 

 

I have read that doing a full ecu reset may help this issue. Has anyone tired this yet? 

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Posted · Report post

I have tried the ECU reset to no avail.

My car is having its 100k service tomorrow ( includes new plugs and I have requested a diagnostic to trace the problem ).

 

I will report back later.

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Posted · Report post

As BGTV8 suggested if you know your way around a bit you can pull out the MAF sensors and spray them with some sensor clean .  This may help them get any road grime off, as the sensor is typically a fine wire .

Make sure you use a proper cleaner that doesn't leave any residue on the sensor wire.  The HR's will have 2 , one on each inlet.

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Posted · Report post

Please report back as the car is scheduled for its 80k service this month and it would be good to find out what the issue is and what needs to be done. 

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Posted · Report post

My mechanic told me the throttle body on the Z's gets dirty quite easily and can be difficult to clean - I'm no expert on these things, but could it be related to this?

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Posted · Report post

Ok,  I had my 100k service ($870 ! ) , MAF sensors were spotless, diagnostic showed no problem.  Changed plugs which entails removal of the inlet manifold, so new inlet gaskets, injectors cleaned. Drove 20 k's home in traffic partly.  Tested low throttle take off 10 times. So far no hesitation or misfire.

 

Note; the spark plugs were 100k's old and I have experienced misfires occasionally on the drag strip.  Maybe 100k as recommended by Nissan is too long between plug changes ? 

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Posted · Report post

Thanks for elaborating Dindar the Grey.

 

The car has only just ticked over 50k on the clock, which i think isnt the cause of the issue. Its going in for its 80k service in 2 weeks.

 

By the way where abouts did you get your 350z serviced at? 

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Posted · Report post

The first thing i would check is the plugs, this is the most easiest, so you can start the elimination process and work your way through that.

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Posted · Report post

I am convinced it was the plugs in my case. Though it does cost around $400 just for the plugs and gaskets.

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Posted · Report post

Car is going in for service next week at Nissan. Service does not include plugs as its the 80k log book service. 

 

Would you think the cause is from the plugs even though the car has  just over 50k on the clock? 

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Posted · Report post

Mine had new plugs and a chemical injector clean. My car never misfired until I had maybe 85k on the clock.

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Posted · Report post

Sounds like a spark issue, so plugs or coils

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Posted · Report post

I would expect it to be a carbon build up in the throttle body...

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Posted · Report post

I have a 07 HR track coupe and had exactly the same type of issue a couple years ago - hesitation on acceleration , both from start and at highway speeds. a foreman from a large brisbane dealership came for a drive with me and i could replicate the problem literally on demand while he sat in the passenger seat eating a sandwich  - the clown was very quick to say my throttle bodies needed cleaning - $680 and two days in the shop later - drove out only to get down the road and problem still there, rang them back and they said..... oh that's your clutch slipping.....a waste of time  , money and work that didn't need to to be done to fix a problem that wasn't there. sounds crazy yes - but check your clutch 

 

   

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Posted · Report post

My throttle bodies were spotless, the car is automatic and a plug change and injector clean solved the problem.

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Posted · Report post

Interesting to see that there is the same issue being reported as what I'm now feeling. Though mine is a little different. There is definitely a slight hesitation on low throttle application, and a bit of roughness on and off the throttle. However this only started after I fitted my hfc's, cat back exhaust and did a 100,000km service which included plugs. The idle is smoother than what it was just before the service. I also did everything myself, and didn't find it necessary to remove the whole inlet manifold. All I had to do was undo the allen keys holding the tb's in place and it could get to the last plugs fine. 

  I'm pretty confident my issue is afr/tune related. Given I have Injen cai's, kinetix hfc's and a dual exhaust. The car will be getting tuned shortly and I'm expecting the issue to be resolved then. 

 I will post about the progress when it's done, even though this thread is a little old, it can't hurt having as much relevant info as possible in a thread for potential future searches

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Posted · Report post

Wow so this appears to be quite common on 07 HR engines onward.

mine is currently being fixed for this exact thing. 

I imitially thought it was a bad batch of fuel but 3 tanks later the miss/ hesitatin persists.  The real doozie was when coming out of a round about going straight and then accelerating, the car misfired so bad under throttle almost got whiplash. It was the last straw.

if I have the car in 3rd or 4th and speed drops round 30-35 kmh and then you accelerate,It will misfire also until you clutch in or shift down. This is sporadic but all the same annoying when it does happen.

real interesting thing that has come to light is that at some point before my ownership, the throttle bodies have been changed. This was discovered by the workshop. 

So likely the reason for new TBs being fitted previouslymay also be reason for the hesitation as at this stage a base relearn is not possible and possibly gettin new TBs from nissan. Maybe this car / ecu likes to shit TBs every few thousand Ks.

very interesting and annoying. 

3f7

 

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Posted · Report post

Sorry about OP thread hijack but thought maybe my follow up resolution may help others.

 

dealer discovered the Hitachi throttles were installed in my 07 HR 

apparently only Nissan branded ones were used on the 07+ 350 and on the 370

why they were installed / exchanged remains a mystery. As a last ditch they rebuilt the Hitachi throttles and the car was able to re-learn and has since run fine.

they implied that throttles were out of spec / balance and rebuild had reset spec tolerance etc.

Hope this helped someone.

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