Chimaera 'misfire' - car just serviced ..................

[harricook]

Hi All

Bit of a cry for help / need reassurance type thread

I just had a car serviced (4 ltr TVR Chimaera 1998 - 31000 miles) - car went away with no misfire/fault - service was routine

The car was serviced 4 weeks ago - but today is the first chance to drive the car


It has what I can only describe as a 'light throttle misfire' - which wasn't there before the service [very confused ??] for example - as you come to go round a nice sweeping roundabout - in say 3rd gear - throttle almost non existant - the car kangaroos ??? - if you gas it - problem gone - but I can't drive everywhere with loads of throttle all the time ........ Mmmmmm maybe I can

The garage are MILES (and I mean MILES away) - and now closed over the christmas break ...... and due to the distance - the car is VERY unlikely to go back to them

Prior to me phoning them to discuss when they reopen - I wondered if anyone else had any ideas on what could have 'changed' while the car was away ???


Confused ??

Cheers - and Happy New Year to ALL !!!!
.

[Ribol]

Might be just a bit of damp getting to it, check one of the leads hasn't come adrift etc.

If you can, try starting it up in the dark and see if there any ignition related sparks flying about that shouldn't be.

If it was ok when you parked it up there can't be much wrong with it

[darkcat]

i would say its likely you have a cracked distributor cap.
I had a terrible startup misfire, and was that.

in a GOOD service, they would have removed the cap to check/clean it, and may have cracked slightly then.

nice and cheap too...

[ShadownINja]

Make sure all spark plugs are firmly in place.

[blitzracing]

Check if they changed the rotor arm, and if it was genuine Lucas (or as near can be anyway). There are some truely horrible after market parts floating around that cause some nasty misfires.

[bigdods]

I had a major misfire caused by a cracked spark plug extender. It was rather obvious whaere the problem was when I lifted the bonnet in the dark and found blackpool illuminations coming from one of the extenders. I suspect a stone had somehow bounced off it and cracked it as it had some marks on it.

So get out in the dark with the bonnet up and see if you have any arcing. As others haver said, could be a bad HT lead or a problem with the cap as well.

If nothing shows up in the dark , pull off all the extenders and cables and reseat properly anyway.

If the above doesnt resolve it then it could be a co-incidence , they do happen. Coil on the way out could have been finished off by the recent cold weather.

[paulathome]

If the car is kangarooing at part throttle, it might be also worth checking
The airflow meter connection on nearside inner wing. If this is loose
Or not making a good connection it can cause bad snatching
At part throttle. Good luck.
Paul.

[myph]

When you returned from the service did you not notice the problem then? if none of the previous mentioned items then possibly dirty fuel, have you filled up recently? some stations have run low on fuel recently so you may have picked up some contamination.

[harricook]

Hi Everyone

Firstly Happy New Year !!

Secondly - apologies for the tardy response/thank-you for your replies & suggestions.

I went down with the flu (again) after posting the thread & have just lost 2 weeks (which was NOT good) - but also about a stone (which WAS good - although I don't recommend it a a diet plan !!


So yesterday was the first time I could/was able to start the car again since posting the thread.


I’m not sure ‘light throttle misfire’ is the correct description of the problem – as what I noticed today after starting the car (car idling) was that it was ‘surging’ from 1200 revs up to 1800 revs and back to 1200 & back to 1800 etc etc etc (this is from cold)


Then when I drove it (car now warm) – car also doing similar i.e. holding say at 2500 revs – what it is doing is exactly the same – surging up to over 3000 & back to 2500

The kangarooing around the roundabout I mentioned before is not a misfire holding it back - but rather the car surging forward ..........



So my original post mislead a little - Apologies

All the best

Edited by harricook on Monday 10th January 10:45

Edited by harricook on Monday 10th January 10:46

[.Mark]

The raising and dropping of revs like that is usually indicative of the Stepper Motor needing a clean.

[Podie]

.Mark said:

The raising and dropping of revs like that is usually indicative of the Stepper Motor needing a clean.

I've never touched a stepper motor in my life, despite having had TVRs for years - I'm convinced the stepper motor cleaning is a placebo..

[blitzracing]

Thats not the stepper as such, but the ECU trying to stabilise the tick over when something else is wrong. Check for air leak in the plenum area for a start (Pipes and joints) and this really screws the setting of the mixture as well. Also check that the stepper is not loose, or an air leak past it.

Some more pointers:

http://www.g33.co.uk/fuel_injection.htm

[.Mark]

Podie said:

.Mark said:

The raising and dropping of revs like that is usually indicative of the Stepper Motor needing a clean.

I've never touched a stepper motor in my life, despite having had TVRs for years - I'm convinced the stepper motor cleaning is a placebo..

Actually this is a very good point. I've never touched it either but when I had similar problems to the OP Fernies replaced mine under warranty and all was fine. Unless they did something else too.