Help required for Newbie!

[Johnniem]

Well, I bagged the 450 Chim I have been after for some time. Had a few niggles with "stuff" that Austec have sorted for me (Thanks Paul and Ann!). Before purchase I had a full inpection by Rob Ingleby who felt it was an excellent example and ran smoothly even when cold. This is partly why I was taken by it. Obviously the fact it was Aston Martin Blue helped seal the deal!

Since I have been driving her she seems "hesitant" at almost any speed. It is very difficult to explain as she basically runs very well, just not very smoothly (as she did when I first drove her). I have pootled around south london on all manner of roads and even at a constant revs on a smooth road surface (to eliminate bumps that might seem like juddering from the engine) she seems to blip or hesitate regularly. There is no backfiring and when I ask for power I get it, in spades.

Is this a stepper motor thing? I would be surprised as she was given a 12000 mile service less than 300 miles back. Any help or advice would be appreciated. Warning: I know how to fill her with petrol (regular owner feature!) and can adjust the rear view mirror (non-techie alert!)

By the way, I love this car!!!!

[TVR keith]

Fuel makes a big difference to these cars. If a lot of your driving is in city conditions the injectors tend to get a bit bad tempered.
Try Shell V Power.
Tesco 99 works well in my 450 and is a lot cheaper but I give it a tankfull of Shell every 3 or 4 fillups as I'm not sure that the Tesco stuff has all the cleaning additives.

[so called]

I had a problem with my Chimaera 4 which sounds a little similar.
Mine was misfiring but not all the time and you could feel this hesitance
in the responce. Believe it or not I found that the plug leads were touching
the foil heat shield on the underside of the bonnet and causing shorts and burning.
Soon as I adjusted the leads it was fine.
Also I had a problem of the leads touching the exhaust manifold...same problem.
Finally made purchase of new leads and made careful and correct lay of cables to ensure no further problems.
Result...no further problems.
Always kept a close eye on them after that.

[GingaNinga]

A couple of HT leads had come loose on my 500 which had the same impact as you're describing. It's now part of my regular check up to make sure they are on tightly

[chim666]

Johnniem said:

Is this a stepper motor thing? I would be surprised as she was given a 12000 mile service less than 300 miles back.

Quite possibly.

BTW - just because you car has had a 12K service doesn't mean that the stepper motor's been cleaned (not sure if it's part of any specific service anyway).

It wouldn't hurt giving it a clean anyway - see here for instructions...
http://www.tvrcc-south-wales.co.uk/stepper.asp

Edited by chim666 on Thursday 28th June 14:52

[Johnniem]

Thanks you guys. There's a few things for me to look at. Stepper motor first! HT leads next.

[Bomber Denton]

Did Rob say it had a 'strong engine'?

[Barreti]

If you are going to take off your HT leads, remove them one at a time and label both the lead and the dizzy cap. It might seem like overkill right now but it could save you an awful lot of agro in the future.

And get some V-Power in there to clean things up. I've never run mine on anything other than Ultimate/V-Power and its as sweet as Blackpool Rock

[Johnniem]

Bomber Denton said:

Did Rob say it had a 'strong engine'?

No, he did say that "it pulls strongly throughout all rev ranges". It is a great car and I love it but there are so many little niggles that require attention. I shall start with the stepper motor this weekend, check the HT leads are not loose or shorting and see what happens.

Also, I find the accelerator quite stiff which makes town driving quite jumpy as revs control is difficult. The trouble is that I have no frame of reference cos I 'm a newbie! It may be that the cable needs replacement. Who knows?

[SpudMurphy]

Johnniem said:

Bomber Denton said:

Did Rob say it had a 'strong engine'?

No, he did say that "it pulls strongly throughout all rev ranges". It is a great car and I love it but there are so many little niggles that require attention. I shall start with the stepper motor this weekend, check the HT leads are not loose or shorting and see what happens.

1. Don't overtighten the Stepper
2. Only a little more than finger tight for the Stepper
3. Hardly tighten the Stepper when you put it back
4. Be gentle when refitting the Stepper

Get my drift?

Retrieving bits of shredded stepper from the plenum after overtightening is a bo**ox of a job. I know, I've done it. Not a difficult job but easy to get wrong. Good luck.

[nikman]

Johnniem said:

Since I have been driving her she seems "hesitant" at almost any speed. It is very difficult to explain as she basically runs very well, just not very smoothly (as she did when I first drove her). I have pootled around south london on all manner of roads and even at a constant revs on a smooth road surface (to eliminate bumps that might seem like juddering from the engine) she seems to blip or hesitate regularly. There is no backfiring and when I ask for power I get it, in spades.

Bbbbbut was this 'roughness' there when Rob checked it out? If so did he say anything? And if it only appeared after you had Austec 'sort' a few things for you, why not just take it back to them and tell them what happened? It may have some direct connection with something they did/touched/disturbed. That's what I'd do before cleaning the stepper motor / changing leads etc.
Nick.

[Johnniem]

nikman said:

Johnniem said:

Since I have been driving her she seems "hesitant" at almost any speed. It is very difficult to explain as she basically runs very well, just not very smoothly (as she did when I first drove her). I have pootled around south london on all manner of roads and even at a constant revs on a smooth road surface (to eliminate bumps that might seem like juddering from the engine) she seems to blip or hesitate regularly. There is no backfiring and when I ask for power I get it, in spades.

Bbbbbut was this 'roughness' there when Rob checked it out? If so did he say anything? And if it only appeared after you had Austec 'sort' a few things for you, why not just take it back to them and tell them what happened? It may have some direct connection with something they did/touched/disturbed. That's what I'd do before cleaning the stepper motor / changing leads etc.
Nick.

Well, I cleaned the stepper motor (tightening up very carefully as suggested!) and although there is a little difference I am not competely satisfied so I will have to take her back to Austec's and get them to deal with it. She was fine when I first test drove her and Rob was very pleased with everything. It seems to be a subsequent issue, so there may need to be a little disucssion before I pay out hundreds for additional works.

Cheers all!

[ATG]

The stepper just controls the idle, yes? Can't see that being the cause. More likely it's something like an intermittent HT short, but this kind of thing can be a pig to find by trial and error, so a word with Austec followed by returning the car probably makes good sense.

Throttle stiffness ... if it is stiff, not sticky, you might try removing one of the three springs that returns the throttle to the closed position. The "weight" you feel when you push the throttle is just the result of the throttle cable pulling against these three springs. IIRC, one spring is fitted axially on the throttle's rod sticking out of the plenum, and there are two fairly strong coiled springs hooked onto the framework around the throttle rod that pull on a lever arm attached to the throttle rod itself. You could try taking off on of that latter pair of springs. I found that the throttle snapped shut with absolutely no problem with one of these springs removed, but I prefer the weight of all three.