Technical Cinq Drives Itself

[NottsCharger]

This could be something simple bit like me but am baffled by my cinqs behaviour.

It had been running fine and is fully serviced, 70k but rebuilt engine 5k back.

For last few weeks the idle speed refuses to return to normal but not far off abt 950rpm and when releasing throttle it dops to say 1200 then takes a while to settle at 950. But the most alarming bit is when I pull away in first gear the cinq surges off momentarily and the accelerator pedal actually falls beneath my foot. Great for traffic light sprints but dangerous in heavy traffic.

I was thinking air leak at base of pot but would this account for cinq trying to drive itself?

 

[rallycinq]

Slipped nipple possibly, or air leak. I'd check your nipple first, and remove if its damaged.

Cheers

SPD

 

[sei16v]

Check for air leaks using trusty wd40

 

[NottsCharger]

Yes I am thinking must be air leak now, I have tried replacing ICV with a spare I had but no difference. Think air leak is most probable as I had only recently fitted a 40mm Tricker and a McKrich chip that I had from last Cinq before this problem started. Taken chip out but maybe gaskets around insulating block below Tricker aren't quite right.

No time to investigate problem need to get car back into garage, cruddy time of year for working on cars!

 

[fingers99]

If it is from the Tricker gasket, you can probably get some paper gasket material from a local factor -- alternatively FROST do it -- or use some hymolar to see you through the winter.

 

[rallycinq]

Also check the join between the two halves of the TB.

Cheers

SPD

 

[NottsCharger]

I did buy some gasket paper off ebay and made new gaskets up when I fitted Tricker, though haven't yet checked them so they could be cause. Have also had a problem with the spacer between the throttle pot top and base, the gasket was missing in places around the air intake for the ICV, I tried to fix this with some blucol sealant. I've put cinq in garage and tonight I will try to get to grips with it.

Going to classic car show at NEC on Sunday and want to take Cinq even tough I will be trying to keep up with mates Coupe 20vt an Uno turbo and a Strada Abarth 130TC!

Cheers for the advice.

 

[NottsCharger]

Well I removed the throttle pot and cleans all the mating surfaces, cut new gasket paper and used some instant gasket for good measure. Refitted and certainly cured the high idle speed.

Now drives well but still has this surge under load as you pull away, doesn't do it when you rev the engine stationary. Had me thinking MAP sensor due to effect only when under load. I tried the not very scientific manual test for checking the MAP sensor, ie. sucking on vacuum pipe at manifold end and that had no effect on the revs but left a horrid taste from pipe, yuch!

Could a faulty MAP sensor cause overfuelling as I pull away but otherwise not seem to affect its running?

 

[rallycinq]

Could a faulty MAP sensor cause overfuelling as I pull away but otherwise not seem to affect its running?

Possibly. But I would expect the exact opposite.

Cheers

SPD

 

[fingers99]

Can you describe the surging?

 

[NottsCharger]

As I pull away in first gear the throttle pedal goes down about 2cm without me touching it and the car accelerates as if on full throttle, this lasts for about 2 to 3 seconds then revs drop back and reverts to where ever my foot was on throttle pedal. There is no fouling of the pedal or cable and the nipple thingy is fine, it seems to be a air/fuelling issue. Revs up normally when stationary, only shows this strange behaviour when under load. Does it in all gears, though most noticeable in first.

What I don't understand is how the accelerator pedal can actually go down and thus open throttle flap acting against the spring without me touching it?

 

[fingers99]

I have a hunch that -- at least one -- of the engine mounts is severely knackered. See if really slackening off the throttle cable makes any difference.

Does it do the same with the McCritch chip?

 

[rallycinq]

I think that the only way this can be management is if the manifold isn't tight.

Everything else points to mechanical. I'd actually take the throttle cable off and see it it still drives itself.

Is the return spring on the correct points?

Cheers

SPD