3.5l v8 efi 1983 kit car idle problems and questions

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Joker
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3.5l v8 efi 1983 kit car idle problems and questions

Post by Joker » Sun Mar 10, 2019 9:50 pm

Good evening everyone

Just signed up here as i have a kit car with the rover v8 fitted.

the car is an evolution roadster built in 2002 with all the bits taken from a rover sd1 on a 83 plate (A)

I've had the car a few weeks now and spent the weekend having a proper look over it, its got some issues and i thought this would be the best place to ask for some help.

today i replaced all 8 spark plugs and im awating a distrubutor cap and leads and a coil, it had a misfire but didnt when i bought it so changed out the plugs and its all good now, however the problem is on tickover once its hot, once i rev the engine as it comes back down to idle it doesn't drop fast like it should when its cold and stick to idle, it stays about idle about 1500rpm.

today i removed the plenum chamber, cleaned it, re sealed it, re fitted it, had all the breathers off and cleaned and checked those, unplugged the 9th injector on the plenum and blanked off the fuel pipe also. Also removed the extra air valve, cleaned it and refitted.

it has a FSE power boost valve fitted, i removed that opened it up cleaned it out didnt find anything of issue there. After much tinkering and messing around the TPS on the plenum butterfly was clicking when i moved the wires around it and was making the car run differently, i removed it to inspect it and the green wire 1 of 3 that goes into the tps just came away, so i opened it up and its pretty much knackered, i ran the car with out the TPS and unplugging the breather pipe which comes from the O/S rocker cover and the car starts up perfectly, drives nice, and when i rev it drops back to idle nice and quick like it should. Im a mechanic by trade and i know how the TPS works and with ecu's etc etc, its just confusing me because all day messing around with it, with the breather attached and the TPS on its not sat at idle, when they are removed its running absolutely fine and this doesnt make any sense to me haha.

so can i just stick a filter on the end of the butterfly breather to atmosphere, and am i going to cause any damage to the engine running with out the TPS? It's totally unplugged and not on the engine now as its broken. Out driving it pulls hard in every gear with no problem, no lack of power at any point in the rev range.

any help on the matter would be appreciated.

i did read they don't sell those TPS sensors any more so a modified one from another engine can be used.
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Joker
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Re: 3.5l v8 efi 1983 kit car idle problems and questions

Post by Joker » Sun Mar 10, 2019 9:57 pm

Pics of TPS and breather
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DaveEFI
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Re: 3.5l v8 efi 1983 kit car idle problems and questions

Post by DaveEFI » Mon Mar 11, 2019 9:00 am

The main purpose of the TPS is to enrich the mixture when the throttle opens - think accelerator pump on a carb. With it unplugged, the performance should seem a bit 'flat' on a standard setup. However the FSE reg might mask this a bit. To the expense of MPG.

If the idle speed is high, try nipping the various hoses to the plenum it identify where. If no leaks on any. A likely cause is the over-run valve on the back of the plenum opening at idle. Try increasing the tension on the spring by a couple of turns.
You can check the EAV is working by connection 12v to it on the bench and watch it close as it heats up - which will take some time.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

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