# Engine vibration 1200 - 2000rpm



## MobileLPG (Aug 18, 2010)

Hi All,

Looking for some opinions please.
My 1995 R33 GTR has always had a strong vibration when revving from 1200rpm upto 2000rpm and also when the revs fall at the same point.
At around 1200 you can just feel the car starting to slightly shake, around 1500 it is stronger and at around 1900-2000rpm the whole car shakes quite heavily, however as soon as you are above 2000rpm the vibration stops completely and the engine is smooth.
Like wise once the engine falls below 1200rpm it is smooth.

I know these cars use quite a hard engine mount but have never been in another GTR to compare so just wanted to see if this is 'the norm' or should I be looking for something out of balance on the engine.
If it helps it is the same whether I am on standard tune or using my mapped Power FC, it is also the same regardless of whether I am running on petrol or LPG, the vibration never changed when I serviced the car inclluding new coil packs, spark plugs etc.

Does everyone else find this vibration is the same on their GTR's?

Thanks,
Edward.


----------



## R32 Combat (Jan 29, 2004)

Do you know if you get a mixture variation when the engine is 'vibrating'?
That would pin point combustion issues.
I'd be suprised if there was a balance issue, that would just get worse with RPM.
You could try unplugging each injector and see if it is a cylinder missfire.
If you have the blazt software, you can turn off each coil when the engine is running etc.


----------



## MobileLPG (Aug 18, 2010)

Hi Andy,

Thanks for the reply.
My wideband shows a steady richening as I climb the revs and I can adjust the mapping so that I get a steady 14.5 through the low revs and the shaking stays the same.
I removed the injector cut off altogether just to rule that out, rewired all the earths around the coil/igniter area.
The vibration is the same with the clutch pressed so mainshaft related problems ruled out.
Using my X431 I can drop each cylinder one at a time and although there is the obvious roughness of a dropped cylinder the vibration seems the same in that set rpm range.
I actualy set the fuel cut to kick the injectors back in at 800rpm so that there is no activity with the revs falling until 800rpm and the vibration is the same with the revs falling during fuel cut but always between 1200 and 2000rpm, the vibration is the same regardless of the revs climbing or falling, smooth until exactly 2000rpm where it is quite severe and then tailing off to no vibration by just under 1200rpm.

I was hoping this was a result of the stiff engine mounts used but if no one else has it then obviously I have an issue 

Thanks,
Edward.



R32 Combat said:


> Do you know if you get a mixture variation when the engine is 'vibrating'?
> That would pin point combustion issues.
> I'd be suprised if there was a balance issue, that would just get worse with RPM.
> You could try unplugging each injector and see if it is a cylinder missfire.
> If you have the blazt software, you can turn off each coil when the engine is running etc.


----------



## R32 Combat (Jan 29, 2004)

Very perplexing. I have run RB26 engine without the engine mounts bolted to the subframe and there was no vibration.
If you rev the car to 2000 rpm and turn the ignition off, does it still do it? I guess by setting the fuel cut to 800rpm is the same?

If it does, it must be mechanical!?!

What to the drive belts and fan do? Any vibration visable?


----------



## R32 Combat (Jan 29, 2004)

It's a long shot, but are one of the bits of auxillary equipment buggered? Like the A/C conpressor or PAS pump. Maybe remove the belts and the fan and see what it's like.


----------



## MobileLPG (Aug 18, 2010)

Hi Andy,

Right well if you've run them without mounts and they don't vibrate then that confirms that I have an issue  as you near 2000rpm my wing mirrors actually just start to vibrate a little then all is perfectly smooth.
Now that I know this is not a normal thing on this engine (didn't think it was to be honest with it being a straight six) I will look into it some more.
Well I have removed all aircon so that is ruled out.
If I rev the engine with my hand on it the vibration is hardly noticable but sitting in the car it feels really bad, I know the bearings in my alternator are shot as there is a very faint grating sound from the engine, but when I listened through a stethoscope the noise at the alternator is awful.
I haven't seen any vibration in the belts however now you mention it I think as soon as I get a chance I will remove the fan, rebolt the pulley and run the engine from cold to see if the vibration is still there.
I removed the cambelt cover last week and ran the engine so I could have a good listen to the tensioner and idler and all was fine behind the cover.

Thanks again,
Edward.


----------



## R32 Combat (Jan 29, 2004)

I think it's a 'back to basics' job.
All the usual questions
1) Does everything rotate freely
2) Is the cam timing correct
3) Are any of the large rotating bits out of balance/damaged. Flywheel/clutch assy, crank pulley.


----------



## MobileLPG (Aug 18, 2010)

I agree, need to spend some time checking it over.

1) Will have to do a bit more checking but as far as I am aware all is rotating freely.

2)Cam timing is fine, I checked it while I had the cover off and it was perfect, I double checked the ignition timing while I was there and was surprised to see it was already timed perfectly.

3)Crank pulley is all there...I checked that over at the same time as the timing so all appears fine there..however clutch and flywheel I have no idea...these will be getting changed quite soon though for a complete Nismo twin plate setup so that will either fix the issue or rule out the clutch/flywheel (clutch now slips 90% of the time when the turbos kick in so ready for replacement)

Edward.



R32 Combat said:


> I think it's a 'back to basics' job.
> All the usual questions
> 1) Does everything rotate freely
> 2) Is the cam timing correct
> 3) Are any of the large rotating bits out of balance/damaged. Flywheel/clutch assy, crank pulley.


----------



## MobileLPG (Aug 18, 2010)

Hello again,

Right, today I removed the viscous fan to make sure that wasn't causing an issue.
Ran the engine and had a good listen, it's amazing how much more you can hear without the fan going....in perfect timing with my vibration I get a knocking noise from the front of the engine, I have taken a video and uploaded it to youtube---

The knocking is most audible at around the 40 second mark.
***x202a;R33 GTR knocking.3gp***x202c;‏ - YouTube

Now in this video the knocking is very clear but it actually is nowehere near as loud when you are actually listening at the car (the mic on my phone seems to pick it up really well) 
The knocking starts around 1300rpm and gets worse upto around 2000rpm then completely stops and there is nothing above those revs, it ties in perfectly with the vibration I am getting.
When trying to pinpoint the knocking using a stethoscope, I cannot hear this knocking when touching the stethoscope onto -
Oil pump, Rocker covers, cylinder head, engine block below inlet manifold, engine block below front turbo.
I can however hear this knocking clearly with the stethoscope touching the cambelt front cover (upper and lower)
Unfortunately I had no helpers so there was no way I could lay underneath the car and listen at the sump/lower block and raise the revs.

Any thoughts welcomed.
Thanks,
Edward.


----------



## MobileLPG (Aug 18, 2010)

Just found a thread on here where some other members have exactly the same 'issue'
http://www.gtr.co.uk/forum/110583-engine-vibration-low-revs.html

And another-
http://www.gtr.co.uk/forum/125883-r34-dual-mass-vibration-question-1500rpm.html

Also came across someone's youtube video with the same issue, at exactly the same revs as mine
http://www.youtube.com/watch?v=bK3MQKJNZU0

It feels good to know I am not alone


----------



## R32 Combat (Jan 29, 2004)

It's odd for sure. I'd be interested to hear if you identify the source of the noise.

Could it be big end bearing noise?


----------



## MobileLPG (Aug 18, 2010)

Hi Andy,

It had crossed my mind.......:bawling:
However in the time I have had the car the vibration has stayed the same and the knocking is perfectly in time with the vibrations.
When I next get some spare time to play with the car I will run it up to around 2,000rpm and cut each cylinder one at a time and see if the knocking changes.
If I cannot get to the bottom of it then I will look at pulling the engine and doing a refresh anyway just to be safe.
I have a spare engine that I purchased with a spun bearing with the intention of building a solid forged motor a bit at a time but it makes sense to refresh this one if I cannot find any other cause.

Edward.


----------



## RKTuning (Nov 7, 2005)

Have you checked front crankshaft pulley bolt torque!!!!!
or camshaft pulley bolts!
Have had both cause that problem


----------



## Chris Wilson (Aug 20, 2001)

I have seen several R32 and R33 GTR's exhibit this. I have never found a GTS-t that does it. My take, for what it's worth is stock factory balance isn't great. The stiffer mounts on the GTR that have to handle the FWD torque and hold up the heavy engine. front diff assembly transmit more NVH. I built an engine for a customer that originally had this vibration, the stock and original crank, flywheel and damper were found to be miles out of balance. It was dynamically balanced to a high factor. It no longer vibrated. Damper was OE original, despite my reservations about reusing it.

I would definitely follow RK's advice and check the damper isn't loose though, as it will *ugger up the keyway and nose of the crank if it's run loose.


----------



## Madaxgt (May 13, 2010)

Did anyone ever solve why some rb26's do this? I'm 99% sure its not 'because thats the way they are' its caused by something, theyre a straight 6!! To get that sort of vibration from an I6 it needs to have a massive out of balance force to create the small-ish vibration seen. Mine does it but it never always did it, unless i didnt notice it the first few months i had it, unlikely. 

Is it likely that its the break down of the crank damper rubber delaminating? Wierd sporadic missfire?


----------



## Chris Wilson (Aug 20, 2001)

I think I have replied before, but it appears it's a combination of poor factory balance and it's only GTR's which show it, as they have much stiffer engine mounts to cope with the weight of the engine / box/ transfer box and front diff in the sump, plus the mounts have to cope with front drive train torque transfer. You never seem to get this in a GTS-t, even when a GTR engine that shows these traits is straight swapped in with a GTS-t sump fitted. A good full balance will usually see it right, even in a GTR. Factory balance is pretty naff compared to most Toyota straight sixes.


----------



## kismetcapitan (Nov 25, 2005)

to me, this screams harmonic balancer. and if one doesn't get that sorted ASAP, kiss your oil pump goodbye. ask me how I know...


----------



## edd_x2 (Jan 10, 2009)

did you get to the bottom of it ?


----------



## Madaxgt (May 13, 2010)

Still haven't solved mine. It definately didnt do it when I bought it. 

Only work I have done is replace turbos and new rear diff. Since this it has done the vibration. It could just be coincidence. However I have noticed it is much worse on a cold start than when its warm so its looking to a combustion/ignition problem...Its smooth on boost/no noticeable missfire but doesnt mean it hasnt got a cylinder with poor spark or bad mixture. 

I still sort of suspect the front pulley/harmonic balancer but thats dispelled by the hot/cold thing. I gave it a good look over and it doesnt look delaminated but its pretty hard to tell. Bolt was all torqued up. Not checked cam pulley bolts yet.


----------



## camlob (Nov 8, 2008)

Sorry to bring this up, but after reading the posts, does it mean that GTRs engine mounts are not usually changed? Just wondering if I have to change mine since I am freshening up all my suspension bushings.

Thats one of the first mods we do in Porsches, well since the engine weight is a big part of the rear end.


----------



## mattojpn (Aug 24, 2014)

Sorry to bring this up. But I have the same problem. 
Did you solved... How?


----------



## SlinkyDog (Oct 8, 2016)

Sorry to bump -- seems I have a similar problem. Anybody get to the bottom of this?


----------



## Jgtr33 (Aug 27, 2016)

MobileLPG said:


> Hi All,
> 
> Looking for some opinions please.
> My 1995 R33 GTR has always had a strong vibration when revving from 1200rpm upto 2000rpm and also when the revs fall at the same point.
> ...


No it's not normal. Car shaking can also happen when the O2 sensor is bad.


----------



## Jgtr33 (Aug 27, 2016)

camlob said:


> Sorry to bring this up, but after reading the posts, does it mean that GTRs engine mounts are not usually changed? Just wondering if I have to change mine since I am freshening up all my suspension bushings.
> 
> Thats one of the first mods we do in Porsches, well since the engine weight is a big part of the rear end.


You change the engine mounts when they are worn out or you want to upgrade them with stiffer mounts. Personally, I would change them after 100,000 miles.


----------



## 120506 (Jun 23, 2015)

Are them pulleys in the video floating/moving side to side? ? Might be an illusion but to me they looked like they had play in them as the revs went up


----------

