Tickover troubles!

[hioctanefueler]

I regret if this query comes under the heading of 'repeat novice question', but here goes...when I bought my V8S ealier in the year it was running a 1,500+ rpm tickover. The vendor suggested that it may well be from prolonged lack of use and as the car was otherwise in excellent condition, I went ahead with the deal.

I booked the car into a local TVR specialist, for a service and attention to the tickover. And it duly came back running fine, at 950 rpm. However after a couple of hundred miles it has gone back to the original figure, along with an occasional missfire and cutting out at lights, just for good measure!.

As the stepper motor was cleaned, timing reset and plugs replaced, when serviced, I'm now at a bit of a loss how to tackle the problem. If any kind soul has resolved a similar problem in the past I would be most appreciative to know how. Thanks in anticipation. Chris

[Barkychoc]

Is the speedo working OK - the engine drops the idle speed to the lowest level when it sense the car isn't moving any more via the speedo sender. While the car is still moving it drops it to 1200 or so until you stop.

[hioctanefueler]

Hi Chris - thanks for the prompt reply.

In answer to your enquiry about the speedo - it only becomes operational after 2/3 miles, but appears to be ok after that. From your comments it would appear that the sender unit may well be the problem. Could a high, erratic tickover (+ missfires) be caused by a faulty unit?. In which case it would be mean simply replacing the unit or is it that simple!?. Cheers - Chris

[v8s4me]

I had something similar on my V8s and it took weeks of tinkering to sort out as it was due to a combination of issues. Perm one or any combination of:

1. Using too thick a washer when replacing the stepper (try running without a washer and see if it makes any difference).
2. Break in the permanent live feed to the ECU.
3. Break in the wiring to the tune resistor.
4. Faulty sensors eg coolant temp.

After dealing with 2,3 & 4 things improved but 1 finally sorted it out.

Good luck.

[seb400]

Interestingly enough my car ran for quite some time without the benefit of a working speedo, it didn't cause me any noticable problems, although as Chris suggests it should have done!

Now it has been repaired it too takes a couple of miles before waking from deep slumber. I put this down to major lack of use, as when it was my daily driver it worked perfectly (until we took the body off with the speedo cable still attached).

Over the years I've had the car it has, intermittently, displayed the same 'high tickover' issue. I have generally found that disconnecting and reconnecting the battery (does this reset the fueling map?) cures the issue.

Steve