Revs flaring between gearchanges when cold

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Matt230
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Revs flaring between gearchanges when cold


Hi all

First post after returning to Caterham ownership.

One slight issue with the recently purchased 7 which has only showed itself since its been colder.  When the 7 is cold it revs out between gearchanges and in gear when lifting off the throttle feels like its running on for a few seconds.  When warm there is no issue. 

Car is a 1.8, with Emerald, roller barrel throttle bodies, forged pistons, verniers, uprated cams.

Recently had it rolling roaded and a bit more fuel put in at the top end.but produced a healthy 193bhp with filter on.  Wasn't aware of this cold issue as was warmer when taken over there. 

Assume it mapping as if the rollers were sticking surely this would happen when warm too?  IACV?

Thanks

Matt 

Alan Reeves
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I recently had a re map and it was done with a still warm engine. It would not tick over on start up until it was warm. Went back and modified the map.

they like to do a map session with a cold engine ...

apologies for strange words etc, predictive stuff and fat fingers...dont i ever learn to check it....

 

ScottR400D
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Sticking throttle cable when cold?

 

Matt230
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The other point is that i did disconnect the battery briefly to fit the battery conditioner.

Would the throttle cable stick when cold but not warm?  one to check but im not sure how the cable works on the roller barrel, ill try and have a poke around later today

Really pleased with the car, cant wait to get it on the track!

Matt

98 Supersport with 'R' upgrades. 193 bhp
Wrightpayne
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Not sure if the same with an emerald, on standard K’s a throttle position sensor (TPS) reset sometimes cures problems.

Ignition on but dont start, press throttle pedal five times to the floor, ignition off.

If that doesn't work I’d be checking anything that moves for sticking - cable, linkage, butterflies on roller barrels etc

Ian

ScottR400D
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Just a thought about the cable, it would be easy to check. 

If it’s been lubed up and the oil/grease causes it to slide less freely when cold but eases when hot I guess it could do. 

But as I said, easy to check, just press and release throttle, engine off, when cold. Mine shuts off very quickly. 

ScottR400D
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Just a thought about the cable, it would be easy to check. 

If it’s been lubed up and the oil/grease causes it to slide less freely when cold but eases when hot I guess it could do. 

But as I said, easy to check, just press and release throttle, engine off, when cold. Mine shuts off very quickly. 

robert green
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Cable my first thought. Check the simplest things first!!!

Matt230
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Finally had a chance to get in the garage and have a look at this.  It is either the cable or the roller barrels.  I took the filter off the barrels and a few seconds after the throttle is released the barrels ares still closing which is why the revs flaring between changes. 

The  cable is clean and has a clear route, i cant see where it attaches to the barrels.  Im pleased its mechanical but i cant quite work out what to do from here.....

 

Matt

98 Supersport with 'R' upgrades. 193 bhp
SM25T
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Or the pivot of the throttle pedal. Disconnect the cable from the top of the pedal and see if the pedal moves freely. Clean and lube if sticky. Then pull on the free end of the cable and see if it still happens at the roller barrels.
paul jacobs
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I have this same problem on a Cosworth 2l. 220bhp Duratec, fitted with roller barrel throttle, but not certain if it is a mechanical  problem, which should  be easy enough to check, maybe a stronger spring, or likely to be software, as some developers build in this 'rev hang' to burn up excess fuel when cold because of emissions legislation.  I would say it is worth speaking to a rolling road specialist about it if you can't sort the mechanical side.