Help please, my v8s thinks its an automatic

[LeggitS3]

Afternoon all,

I hope someone can give me a hand with this one as I'm running out of ideas.

The car was idling at about 3,500 and not ever coming down. I've had a service and changed the speedo sensor which wasn't working and giving a dodgy reading to the ecu according to the diagnostics. Also changed the stepper motor as well just in case.

Now when stationary the car goes back to the correct idle after about 10-15 seconds which I can live with. The big problem is that when you change down gears it goes to about 3,500 and if you change e.g. from 3rd to secon when rumbling along it will keep going under its by itself. When in neutral and freewheeling it also stays at about 3,500 with no intention of ever coming down.

So essentially I have managed to get it to go back to idle when stationery (albeit it takes longer than i think is normal) but the revs won't drop off at all when in motion.

Exra's to throw into the mix are that being HarryW's old motor its not standard so I have a Tornado Chip and also a cold air induction system and fast road cams.

Any thoughts much appreciated!

Cheers

Leggit

[Barkychoc]

You could rule out the stepper motor by disconnecting the cable when the idle is normal - you need to disconnect it while the engine is running. There should be no change when you disconnect it - but once disconnected it can't raise the idle speed.

Check the hose between the airflow meter and plenum - any leaks here are not metered through the airflow meter (as its after it) so can upset things significantly.

I would be inclined to go back to where you had it serviced if thats very recent though.

ETA - just read your thread again - where did you get the new stepper from - I got one off ebay and it was hopeless - I ended up putting the old one back in.

Edited by Barkychoc on Sunday 10th May 17:23

[LeggitS3]

Thanks Barkychoc,

It was a TVR car parts one so hopefully ok but I'll check that.

It may well be the air induction system leaking as its easy to get air in after the sensor as the air intake pipe has to be disconnected everytime you open the bonnet. I'm also wondering if the air flow meter is duff.

It's going back to the garage but as they had it for 4 weeks I'm not sure they're any further forward with ideas so thought I'd see if anyone had any thoughts / experiences.

[Barkychoc]

LeggitS3 said:

the air intake pipe has to be disconnected everytime you open the bonnet.

Not quite sure what you mean here - unless the arrangement has been changed from original?
The bit of pipe I'm referring to is quite short - 3 inches or so - between the airflow meter and the aluminium part on the engine (plenum chamber).

Edited to add pic below - the big black bit of pipe.

Edited by Barkychoc on Sunday 10th May 22:17

[GreenV8S]

LeggitS3 said:

the air intake pipe has to be disconnected everytime you open the bonnet.

That doesn't sound right.

[HarryW]

GreenV8S said:

LeggitS3 said:

the air intake pipe has to be disconnected everytime you open the bonnet.

That doesn't sound right.

It might go behind the NS headlight . It added about 15 secs to the opening the bonnet malarky but ensures the intake is always cold, it added a double digit hp gain which was a fair trade off for 15 secs I thought .
No idea why its sticking at 3k5rpm though.

[GreenV8S]

HarryW said:

GreenV8S said:

LeggitS3 said:

the air intake pipe has to be disconnected everytime you open the bonnet.

That doesn't sound right.

It might go behind the NS headlight . It added about 15 secs to the opening the bonnet malarky but ensures the intake is always cold, it added a double digit hp gain which was a fair trade off for 15 secs I thought .
No idea why its sticking at 3k5rpm though.

Funnily enough I had a similar setup with a stretchy convoluted tube (and a right old pain *that* was). But it's not standard, which is why that seemed wrong to me. (If the intake is being disconnected downstream of the filter you have to be sure you get a perfect seal, otherwise you'll pull in grit. There's quite a big pressure difference across the filter and it will suck air in through any gaps.

[LeggitS3]

Morning all,

Thanks for the comments. After determining no air leaks from anywhere I had a feeling about the ECU so took it to bits, found a dry solder joint which I redid and when plugging it back in found a dodgy connector into the ecu, stripped the plug, refixed and now she thinks she's a manual again.

Hi Harry, you're definately right about the perfomance gains, drove a standard v8s the other day and what a difference!

Cheers

Leggit

[HarryW]

LeggitS3 said:

Morning all,

.............

Hi Harry, you're definately right about the perfomance gains, drove a standard v8s the other day and what a difference!

Cheers

Leggit

Hopefully the difference was in all areas and not just grunt

[LeggitS3]

handling and stability is possibly the most noticeable part.

[HarryW]

LeggitS3 said:

handling and stability is possibly the most noticeable part.

Did you wind it on a bit as suggested.

[HarryW]

LeggitS3 said:

handling and stability is possibly the most noticeable part.

YHM btw

[Stephen Pook]

Hi Leggit.

I've just read your thread. I sometimes got the high idle problem but it was an intermittent thing. It was annoying when it happened though. Glad to hear you've sorted it out.

Hope you are enjoying the car. It always proved v reliable for me including trips to London (in traffic) and from Brighton to Bath a couple of times. Always had admiring glances and comments not to mention shocking drivers of other performance cars who were not expecting the acceleration from what appears to be an older classic type of car!

Enjoy.

Steve.

[HarryW]

Only on PH can you get the last two owners and 9 years of history on line

[LeggitS3]

Evening Steve, Good to hear from you, I wasn't sure if you were still on circuit. Thanks for the heads up on the idle, it's come back again intermittently but at least idles at traffic lights etc now, it just stays high between gearchanges and when freewheeling so something isn't quite right.

The man at Austec has a cunning plan so fingers crossed for next week. Harry, I got hold of Paul! Hopefully he'll look after the old girl. She goes in on saturday and I'll collect the friday / saturday after. If you see her there forgive the filth, I haven't had a day for an autoglim session since purchase but I will.

Had a cracking drive on saturday, first time so far I've had the opportunity for a couple of overtakes and I was pleasantly surprised. After the Griff I didn't buy her for outright performance but it's certainly nice to have.

Indeed, 3 successive generations all in one forum PH is a great facilitator but I wonder if the Camaraderie exists with other cars like the Tivs?

Edited to say what happened to those wheels in your profile pic Steve? I thought they looked the bees wotsits on the car.

Edited by LeggitS3 on Thursday 21st May 00:05

Edited by LeggitS3 on Thursday 21st May 00:06

[Stephen Pook]

Hi Leggit,

Yes, a very handy forum is PH!

The 17" after market alloys are probably with Phil Reygate still. I will make an enquiry. I would say that whilst the car looked great with those wheels on the ride becomes very bumpy and twitchy. Probably great for a track but a bit severe for daily use. Still, I suppose if you wanted a 'magic carpet' ride you would have bought an old Rolls or something.

I'll let you know when I get a response.

Steve.