Hi All

I've got a problem with the gear changing on my S type R.
It's fine under acceleration, but when moving along at any steady speed between 25 - 40, the gears box seems to quickly jump in and out between 3 - 4 and 4 -5 (depending on speed). I had it reflashed but makes no difference. Any ideas please?

 

What's the mileage and have you had the box serviced? They are not really sealed for life units.

Also engine problems, like a misfire can affect the gearbox.

It might even be something as simple as a failing battery.

Have you checked for codes?

What mods have you done for the extra 150hp?

 

550hp? Bit optimistic I think...

 

If you truly have 550HP I think you just found your answer!

We have no experience with any STR making this much power.
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Have you checked the fluid level?

The zf6hp26 shifts very weird when the fluid level is low. I had a BMW 550i that had a pan leak that the first shifts in the morning felt like someone who didnt know how to drive a stick was driving the car. It is MUCH more pronounced in the lower gears.

Take care,

George

 

Thanks guys.
The engine doesn't misfire at any rev when not in gear, and there seems to be no sign of the problem under acceleration.
The mileage is 52,000
All electrics seem to work fine.
The jag dealer (last week) reflashed the gearbox and topped up the fluid - tells me it only took 1/2 litre and that there were NO codes at all on the car.
The extra HP was achieved at new (I haven't modified the car) by Paramount Performance and this is their claim along with the modification system. Maybe it's not true. All I can say is that this car is very noticeably faster than my previous stype r.
I haven't switched on the extra boost system (located in the boot) yet.
Any other ideas would be very welcome.
Thanks again

 

Should explain the extra HP a bot more. As it stands, the claim is that the engine modifications allow the engine to produce 550HP. The extra boost system (methane/water) is located in the boot and I haven't switched this on yet. I have had the car 3 weeks.
Thanks

 

All paramount supply and fit are a pully, air filter and exhaust in total about 40hp extra, as far as I'm aware no one has managed to crack the ecu yet to do a remap

 

I think you mean methanol and not methane. In any case, this will not get you 150HP extra or anywhere close, maybe 1.5HP.

Despite what your dealer did, I'd go for a full transmission fluid change. Are you sure this is not a case of the torque converter lock-up issue?

 

Since you have had a dealer reflash the TCM can you go back and drive the car with someone from the dealer? With no codes it's hard to decide what the problem is.

Outside of the TQ problem mentioned by Mikey not sure what could cause it? But if it is the TQ you should be getting a code for that.

Here is a TSB for something close and it does say to reflash the TCM but I would have the dealer verify to what revision the TCM was flashed too. It should be written on your invoice.
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They can read out what is flashed in, too.

I never knew PP even claimed such a ridiculous figure. You'd need a twin-screw...

 

All of us STR guys NEED a twin screw!!!

I don't know if I will even have the car when it comes out! I have been waiting since I purchased the STR 4.5+ years ago and I am now over 92K miles and I am getting very hungry for an XFR!!

Just wish they would drop in price like the STR did.
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A Twin-screw STR would be glorious... avos should be shipping xjr/str TS kits within 6 - 12 months from now I believe...

With that said, an XFR would be a better way to go really; with mods it would be faster still than a TS STR imo...

2010's are starting to creep into the 30k range; they'll be affordable soon enough...

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this doesnt happen to be this car which also claims to be 550hp paramount car, is it?

 

Thanks for the on going help gentlemen. The car is back in the Southampton dealers tomorrow so they can have another go reflashing - I'll take the technical bulletin with me (thank you tbird6) and I've also been in touch with other jag specialists in the area and they seem to think if the reflashing doesn't work it's either a solenoid or the TQ as you've said on the site.
With regard to the 550hp issue, as you can probably tell I'm don't really know much about cars ... so I don't really know how true this is. Guys on the site seem pretty knowledgeable (much more so than I!) so maybe it isn't 550. I'm only going by what I was told by the seller and research I did from the previous sale, which supported the re-mapping claim. I can only say that this car is quite definitely noticeably quicker than my previous str. Also, yes, it is a methanol/water boost system that I haven't tried yet. What exactly does it do? If it only increases the power by 1.5hp what is its purpose? (Again, I was told differently). Anyway, the car is what it is and I'm pretty happy with it.
The video clip is not of my car. Mine is black with Cosworth type grills in the bonnet, lowered suspension, sideskirts and spoiler and 19" wheels. I'll try to put up some photos soon for anyone interested.
Thanks once again for your help so far

 

I'd hazard a guess it's about 450hp max.

That extra 50hp will be noticeable.

As far as I'm aware no one has managed to remap a s type yet.

As for the water injection see here http://en.m.wikipedia.org/wiki/Water_injection_(engines)

 

The link provided by police gives an excellent explanation on the basics of water injection. The key is that the water will stave off detonation caused by high compression, allowing the engine to make more power. The problem is that the type-R engine in stock form does not have high enough compression to cause detonation, so really your injection sytem is a solution in search of a problem.

Possibly if the supercharger was being seriously overdriven it could be put to use.

 

Wouldn't the methanol be forced in under pressure and thus lose pressure and provide cooling (same principle as aircon)?

(This wouldn't apply to the water as it's almost incompressible as I recall.)

I can't see it adding a lot of HP, though.

 

The evaporation of the fluid does provide cooling but with the typical concentration of methanol and it's low volume during injection it contributes virtually nothing additional over using straight water.

The primary reason for mixing either methanol or alcohol is to avoid freezing, a carry over from the aircraft industry.

 

Er, you have me puzzled now. In this car the methanol mixture is only intended to be sprayed under boost. Freezing is nowhere near occurring then - right?

 

Right. The concern is actually with the liquid freezing in it's storage tank. Big problem with aircraft cruising for hours at 35K feet, not so much with summer driven cars.

I think it's more a case of monkey see, monkey do.