Brief loss of power

[mav 1]

A couple of times on Saturday I had a brief loss of power - driving through London (lots of stop/starting) and occassionally as I slowed the revs would fall to almost 0 (idle is normally around 950 RPM) and then would spring back up to normal idle.

Any idea what this could be? Maybe I need to clean the stepper motor or could it be something more serious? Both the lights at the bottom of the rev counter lit up as well (battery indicator and one other) - the battery was replaced 3 months ago.

Cheers,
Mav.

[Johno]

Check you 100amp fuse, they sometimes break but give enought to run on and can given similar symptoms.

[spend]

Sounds more like engine cutting out, unless battery is flat 100A fuse shouldn't affect it - but it seems some cars did have the fuse cutting the the alt and the fusebox.

More than likely in area of fuel pump or ign amp/coil if its cutting intermittently though I would have thought.

Dave

[mav 1]

Doubt it's the fuse, we drove 150 miles on Saturday and Sunday and the loss of power only happened on Saturday morning.

I guess it must the fuel pump - it does whine from time to time.

Thanks guys.

Steve.

[MADMAX2]

The problem is Ken Livingstone! you drive your TVR into London and he sucks the life out of you with the congestion charges and your car is having a reaction to that! try driving elsewhere lol

[GJR]

Mav,

Last time my car was on the road I had a similar problem, but the loss of power was under acceleration not as I was slowing down... the description of the problem mine had is in the link below.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

As yet it is still unresolved, but it could be an HT problem, stepper or as was suggested to me at the time by a mechaninc (non-TVR mechanic), it could be the AFM that's playing up. ie. in my case telling the ECU that the airflow was low, and as a result the ECU cuts fuel to a low speed setting.

What ever it turns out to be could you let us know as it might help to sort mine out when I get it back on the road sometime in the next 12 months.

G

[mav 1]

We didn't have a problem driving c.75 miles on the Sunday, so I think it must be the fuel-pump that has been whining. Someone on Thunder in the Tunnels mentioned that it was making a noise.

My car goes in for a service in a month or two so I will get it looked at then. I'll let you know, GJR, if I find the solution. I do have small loss of power under acceleration when I first start the car, but I had put that down to the cold - maybe it is another symptom of the fuel pump.

[thegman]

sometimes i have this is the car is very hot or cold, as the car goes from open throttle onto idle (normally accompanied by the clutch going down) the revs can dip and the car has stalled once or twice. Not causing a big problem for me really. From reading around on hear I presumed my stepper maybe needed a clean...

[bigdods]

I had something similar a few years back. Only happened once, never repeated. I was sitting in solid traffic for abut an hour on what was probably the hottest day of the year. Fans running non stop but engine temp pegged at 90 so no problems. But every now and then there was what I can best describe as a stutter, the revs would drop down to about 400 and the engine felt like it was about to die. A couple of blips on the throttle and everyhting was ok again for about 10 minutes, then it would repeat.

At the time it felt exactly like the problem I used to get on my Renault 5 GT turbo where the fuel would vapourise in the pipes when the engine got very hot. The cure was the same (rev it up a bit). With hindsight I think its more likely that the heat had caused something to go out of spec. Probably the stepper motor but could have been the AFM overheating or a cooked sender. It has never happened again so I had no need to investigate further.

[GJR]

bigdods said:

I used to get on my Renault 5 GT turbo where the fuel would vapourise in the pipes when the engine got very hot.

I forgot to mention this as it was also suggested at the time. The biggest problem is that it's so random and therefore near impossible to reproduce in the presence of a mechanic . With mime it had happened a few times at low speeds and it was annoying but not a huge concern. What really prompted me to get advice from a mechanic was when I tried to overtake a lorry on a nice long stretch of road. Had just begun to accelerate hard and pulled out when the power just died (luckly no oncoming traffic), revs dropped to near zero, battery light came on for less than a second, before it burst back into life again. With the loss of power obviously I dropped back behind the lorry and stayed there... didn't want to try that again. Everything was normal for the rest of the trip though

You could change all sorts of things on the car but you'd never really be certain that you've solved the problem because of it's random nature..... this is why I wondered if there was some ECU software around so that you could just hook the ECU up to a PC after the event and see if there is an error code associated with it ? At least then it might give you an idea of where to start ?

G

[350Matt]

I had this on mine, and two things fixed it;

Replace the fuel pump and ECU relays (the ones on the ends of leads on top of the battery) the car would occasionally turn itself off and then back on again.
Replace the ECU water temp sensor, mine was a little out of scale causing the occasional rich misfire.

Matt

[crackedfinger]

Had this - it was the ignition amp, if they are on the way out they show break down when hot. It essentialy is onlt noticable when pulling up stationary, like traffic lights or parking.

[thegman]

crackedfinger said:

Had this - it was the ignition amp, if they are on the way out they show break down when hot. It essentialy is onlt noticable when pulling up stationary, like traffic lights or parking.

was this a diy fix?

[crackedfinger]

thegman said:

crackedfinger said:

Had this - it was the ignition amp, if they are on the way out they show break down when hot. It essentialy is onlt noticable when pulling up stationary, like traffic lights or parking.

was this a diy fix?

yep - only takes 10 mins to change.

[thegman]

ok so my problem has now got worse. my symptoms:

Erratic idle and hunting when coming off power - has stalled twice
Loss of power (after a spirited drive). The first time I just carried on driving and it sorted itself out. Second time I took my foot of accelerator and the car stalled. Then it only restarted on 3rd attempt.

So.. Either a fuelling or ignition issue. My first thought was to change plugs and leads. ANybody with same symptoms?

[That Daddy]

thegman said:

ok so my problem has now got worse. my symptoms:

Erratic idle and hunting when coming off power - has stalled twice
Loss of power (after a spirited drive). The first time I just carried on driving and it sorted itself out. Second time I took my foot of accelerator and the car stalled. Then it only restarted on 3rd attempt.

So.. Either a fuelling or ignition issue. My first thought was to change plugs and leads. ANybody with same symptoms?

Maybe a wild shot(bit like a doctor without the patient) but see if you can borrow someones Air Mass Meter,its worth a try and takes 5 minutes to substitute.

Edited by That Daddy on Sunday 2nd March 19:26