The Strangest Thing

[Zardos]

I don't know how to explain this, but my car last week somehow lost 60 rkw.

What started it all was , As i take off from the light the car would seem to hesitate a little bit and then she was fine. She would pop a hell of a lot also between gear changes.

So i took the car to my local turner and go him to have a look.

He threw it onto the dyno and checked the following.

Mixtures (air/fuel ratio)

Timing

operation of engine components

adjust mixtures accordingly

Compression test

Removed and replaced spark plugs

Check cam timing

Adjust ignition timing

Adjust cruise mixtures.

Now what he found was that the car was out by 10 degrees. I asked him how is this possible. He could not explain to me as to how this came about.

He has corrected the problem but we are still missing 15 rkw and we still don't know how/why.

Before you start bagging him these guys have been the in game for at least 20 years and know there stuff, But this problem is a strange one.

So i thought i'll post this one up to see if any of you tech heads could shed some light on to this.

Before i forget my car is a R32 GTR and has the following mods

Turbos

PFC

Injectors 700 cc

044 fuel pump

Split fire coils

Adjustable cam gears

I'm either thinking either boost leak or Exhaust as to why we can't get the 15 krws back.

Any help would be great guys

Cheers

[madbung]

When was the engine built?

It's not hard to lose 15kw over time with normal wear and tear..even easier with some harder use.

[FineLine]

could you have jumped a tooth on the timing belt?

[madbung]

Same dyno? Fuel used?

[VB-]

how much pwer is it making all up? by those mods, your probly making enough power that 15kw could be put down to different time/different day/different atmospheric conditions/slightly diff fuel (dodgy batch)

im assuming its on the same dyno?

[Zardos]

The engine has got 60,000 kms.

Same dyno , different day. But the fuel that was in my car had been sitting there for two weeks.

The missing 15 rkw is not that much of an issue, You are correct in what you are saying VB.

But i would really like to know how can i have lost 10 degrees of timing. That has got me spooked .

Has anyone experienced

[BAMR33]

Someone mucking around with the crank angle sensor and not marking where it should go back.

[_x_FiReStOrM_x_]

Either timing belt has skipped, or the adj. cam gears have loosened and turned. Because the CAS is run off a camshaft, any change in cam timing usually directly results in a change in ignition timing.

Edit: sorry just re-read that you had cam timing checked... this is a strange one then.

Edited July 13, 2008 by _x_FiReStOrM_x_

[VB-]

was it out 10* in the computer or was it mechanical?

[Zardos]

was it out 10* in the computer or was it mechanical?

ummmm i'm not to sure, but the turner did asked if i had played with the hand controller.

I said to him that i never touch the setting on the pfc only ever have it set to monitor, which is the case.

I will ask him tomorrow about whether it was out on the computer or the was it mechanical.

[Zardos]

was it out 10* in the computer or was it mechanical?

I rang him and asked him where it was out and he said mechanical.

hmmmmmm This is really bugging me,

[VB-]

loose bolt?

[Zardos]

loose bolt?

I think that's possible, what i'm going to do is order some new inter cooler piping to replace all the old piping. once all fitted I will check it again on the dyno and still what reading i get on the dyno.

[VB-]

why the new piping?

[SXR]

check the harmonic balancer

[James_03]

I rang him and asked him where it was out and he said mechanical.

hmmmmmm This is really bugging me,

Where exactly did he find it out mechanically? Was the actual CAS out or where the timing gears out with the balancer at TDC?

I would say its related somehow to the adj cam gears you have, who installed them?. Two small things to check:

1. Mark it first and remove the CAS, check the half moon locator is still on the end of the cam shaft inside. If this is missing you can still set the CAS timing and generally it will stay OK for a bit as the rubber seal on the end of it is enough to hold it, but once its under load or driven for a while it will come out again, sometimes it will come out again quickly other times not.

Whilst you have it out, move the shaft in and out, there should be no play in it at all, neither side to side, take care when doing this but.

2. Then make sure you are running the top timing cover, or have spacers behind the CAS and the main CAS bracket. Otherwise this slowly flogs it out depending on how tight the bolts are done up, and will eventually cause the CAS to fail, and will do lots of weird and wonderful things with timing right up to this point.

Probably not either of those things but minor oversights I have seen happen that cause people a head-ache, incl myself lol.

Edited July 14, 2008 by James_03

[nizmonut]

take your cam cover off, start her up give her a free rev to 7000 rpm then snap the throttle shut, then watch the slack come on the cambelt, i lost 15 degrees of timing in a matter of minutes, cause the tensioner wasnt done up tight enough.

[VB-]

check the harmonic balancer

hey ray, is the drive gear for the cam belt on a rubber damper? i've heard of them slipping on older cars but didnt know if skylines were like that?

[Zardos]

The reason why i want to change my piping is that i have had trouble in the pass with one of my pipes come off time to time

James, I don't know where exactly he found where the timing was out.

What you said dose make sence since the last things that was installed was the adj timing gears along with the inj & fuel pump.

I need to go back and have a chat with the guys .

SXR , i too would like to know as to why to check the balancer?

nizmount , i take it that there is not ment to be any slack in the timing belt?

Thanks guys for the insite and help

[Zardos]

Just a quick update, I have since found that my radiator is leaking and it looks like I need to get fixed.

Since my radiator is custom made and that it will cost a bit more to get it repaired I have decided to ditch it and buy a new one and go for an ARC type. I’m thinking maybe a 36mm will be enough. Or will a 55mm one be a better choice?

Once I sort this out I’ll continue to work out what went wrong originally with my car and post the results up.