RPI Gems chip

Hi all,

I've had a search of the forum and not come up with anything.

I picked up my RR at the weekend and it seems a little 'sluggish' so much so that my wife didin't like driving it on the motorway, she was worried by the glacial response to throttle inputs.

So, I'm wondering about getting the PRP dual chip fitted, the description on their web site seems to describe my symptoms, I'm posting on here to find out if anyone else has had experience with this upgrade?

http://www.v8engines.com/carbs-4.htm#gems-lpg

Would a session with a TextBook show that the car was in 'limp home' mode and substantiate what RPI is saying?

I'm loathed to spend £500 at the moment on RovaCom Lite to diagnose this, would a simple OBDII interrogator show up this problem? Wondering if it was worth spending around £100 for a set up from eBay?

My RR is a 4.6 running a BiGas sequential LPG conversion.

Thanks

Tim

Hi
I run a 4.6 with sequential lpg,unchipped and it certainly isnt sluggish, it seems that you might have a diffrent problem. I personally would have it put on testbook or something similar before spending the £700+ on a chip that may hide another problem.
All the best
Mark

Okay may have a development.

I dropped my TVR off with the exhuast fabricators this morning, when he heard the RR he said 'oh, sounds like the cat's collapsed', so my question is, would a blocked/collapsed cat have a detramental effect on the performance, I know it won't help, but how bad would it be?

Thanks

Tim

I would think any restriction in the exhaust would affect engine performance as the exhaust gases cant get away. If it has collapsed then it`s got to be changed anyway so it`s a good place to start, although expensive its got to be done sooner or later.

DO you need a cat if your runing on lpg !!!!!!!!!!


all the best

peter

peter c said:

DO you need a cat if your runing on lpg !!!!!!!!!!


all the best

peter

Click to expand...

No, I don't think you do.

The exhaust guy wants £150+ to cut and shut the cats.

But tbh the exhaust isn't in the greatest condition, I can get a new Y piece and cats for around £300 so am edging towards that. Haven't found anyone that does an off the shelf decat Y piece. I know LR did one for the South African market (I think) but that's coming in at £500+!

The middle box looks shot but the back cans look okay, so am thinking new cats, Y piece and centre box for a grand total of about £350.

Anyone know of any off the shelf decat pipes? I can't be arsed to get the welder out at the moment so a bolt on option is a must.

Thanks

Tim

As you still need petrol to start up and also incase you run out of gas wouldn`t removing the cats affect the running of the engine?, also when i took my car for mot they done the emission test with it running on petrol so would it affect the mot?. It would be interesting to know as they are quite expensive to replace.

I run on both in a 4.6 and found stainless cats and down pipes for 250 on ebay worth a look as they do a cat back in stainless for about 450
good luck but reckon you need the cats for mot
Sandy

oh and sequential doesnt need the chip upgrade as it feeds direct of the main chip for each injector but i had mine done by performance chips for 200 quid made a big difference on both petrol and gas

Hi.
Yes the cats collapsed will kill the performance. You will need them for the mot and i'm afraid buying stainlees steel won't help because when i asked the bits inside are'nt stainless so they don't last any longer.
Most importantly you will (if you have them) need to make sure the oxygen sensors are put back on, mine had blanks fitted for the post cat (American market i assume) so i put them there. Bought the RR classic middle box from martin motors 4X4 for bout 100 pounds which gives a really nice note.
As for passing the mot mine has passed with no cats (Yes really) and it's been passed on gas! But i have bought some since and (allegedly)just chuck them on when mot is due . Hope that helps, oh the car is a 99' T with the Motronics engine management 4.0 and goes like the proverbial since i had the lpg injection timing opened up.

Cheers, Nick.

Thanks for the replies. I have bought a pair of cats on the Y piece and also a middle box, along with a can of Plus Gas to soak the manifiold studs in!

Do they sheer btw?

I paid nearly £400 for the two bits, but if anyone's interested there's a guy on eBay selling pre '98 cats and Y piece for £200! Sounded like a bargain and if I hadn't bought mine yesterday I would have placed an order and saved £100 - damb!

Thought it might be of use to someone out there.

Tim

Hiya

My 4.6 vogue middle box went and I got stainless centre and rears done and I as really impressed with the job. The chap offered to "straight pipe the cats " but as I dont have an lpg conversion I wasnt wanting to get into that . I asked if performance cats could be fiited , and they can but NJH is right , its stainless outers but the inside of the cats are of similar build products but made slightly more free flow which will assist BHP .

If I was running an LPG RR then it would be a diff story , I would have got the full stainless system with no cats fitted as for the mot the cats doesnt need to be there as long as you inisit it runs on LPG. For the MOT all you have to show is that you car can run within the limits set for its age of build , it doesnt confine you to run it on petrol or have Cats fitted.

Removing Cats will give big returns on power and MPG

Hope this helps

Anna

BTW if the cats are blocked it will cause huge perforamce probs and on a single exhaust 4 cylinder cars it can cause them not to start or rev up.

Anna