revs increasing when engine is hot

The Oily Bits S1 Specific Topics
1

I have an ongoing problem with my VHPD. After driving for some time, over half an hour or so, the idle on the engine can increase gradually, sometimes up to 4k revs.

Gerald at GST adjusted the butterflies but seemed to think they weren’t quite right still. Even so, you’d think any extra air getting in would express itself sooner than a long drive.

Any ideas? I was wondering if the gasket needs replacing. Or maybe the bush for the butterflies is shot, or it’s the emerald mapping. Can you get the throttle body assembly refurbished?

Thanks in advance for any advice

2

Just to add, stalling the engine slightly with the clutch drops the idle to 1k revs…

3

Try cleaning/changing the Throttle Position Sensor (TPS).

4

I replaced that, no joy :frowning:

5

Okey dokey, now clean up the wheel speed sensor on the hub on the rear hand side rear wheel. This can get quite corroded & is linked to the ECU.

Good luck

6

Okay I’ll give that a bash. Incidentally, it’s your old engine that I have in my S1!

7

Small world - are you guy I sold it to in 2005? I had it re-freshed at 25k miles, & then sold it at 36k miles. How has it lasted mileage/condition wise?

8

No I bought the car from him. The engine is still tip-top. I’ve put another 10k on it, or thereabouts, and it’s been bulletproof save for a couple of minor standard K series niggles. It did 149mph down the North Weald runway. Still going v strong and compression tests have been fine. Passes the mot after a bit of fiddling and uses a normal amount of oil. Think its on about 30k miles now?

Now going to frantically touch as much wood as I can find!

9

Pleased to hear that, & thanks for the update.

Good luck with the “revs issue”.

10

Sounds like a dirty/blocked IACV (Inlet Air Control Valve)

Under the inlet manifold.

Take it off and give it a good glean to get rid of all the muck that it sucks on from oil laden recirc gasses.

I had the same problem on my first Exige S1.

A bugger to get at… but take the air box off and the ‘boot’ divider and it is quite easy to get at!

Good luck!

11

With a Rover K VHPD :open_mouth:

Was it wind assisted (with a RR Olympic engine)?