Strange fuel/engine/electric prob
Discussion
Just come back from holiday and missed my car loads having not driving it for about 10 days. Went out for a quick drive this afternoon. Not much petrol, so stopped to get BP Ultimate first. With full tank, everything was fine. The car has been running very rich recently causing it to be a little lumpy at idle when cold and drop revs to about 500rpm at some junctions/roundabouts when slowing down.
Anyway, about 15 miles later, when pulling away in first at a mini roundabout the car 'kangarood' a couple of times - momentarily (maybe half a second at most) the revs completely dropped away and acceleration stopped before forward progress continued. No wanring lights came on, no strange noises, temperature fine.
About 1 mile down the road, it happened again, and then the engine died completely. After coasting to a stop, i tried restarting - it wouldn't though. I disconnected the battery using the battery cut off switch in the passenger footwell to reset the ECU. Once connected again, i tried restarting - the engine turned over, fired for about half a second then died.
It did this a few more times, then after about 5 minutes of trying fired up and settled into an idle. I cautiously headed for home. Though only managed to travel a further 3 miles before the engine cut out again - the revs just dropped away to zero from doing 30mph in 2nd and coasted to a rest again.
This time, i tried to restart, the fuel pump whirred and engine turned over, but it would not fire up. Tried using throttle also, but nothing. Called RAC.
Just moments before they arrived (they were only about 10 minutes - great service) i tried to start and it fired up. RAC man inspected the engine, base idle screw, distributor, etc, but couldn't diagnose problem. We even made sure the petrol i had put in was infact petrol - it was. RAC man followed me home - only 2 miles - just in case it cut out again. But it didn't, it behaved fine.
Question is, what could cause this?
One of my theories is that i had left the car with maybe 1/8th of a tank of petrol in it when i went on holiday and the gases had caused an air lock?
Stepper motor will also be inspected very shortly. but i would be suprised if this alone would cause the (intermitant) problem - i do clean it fairly regularly.
Perhaps it is linked with the rich running and the dropping of revs occasionally when slowly down for junctions etc.
I would appreciate your thoughts as there doesn't appear to be anything obvious - to me anyway - which could cause this problem.
Cheers
Anyway, about 15 miles later, when pulling away in first at a mini roundabout the car 'kangarood' a couple of times - momentarily (maybe half a second at most) the revs completely dropped away and acceleration stopped before forward progress continued. No wanring lights came on, no strange noises, temperature fine.
About 1 mile down the road, it happened again, and then the engine died completely. After coasting to a stop, i tried restarting - it wouldn't though. I disconnected the battery using the battery cut off switch in the passenger footwell to reset the ECU. Once connected again, i tried restarting - the engine turned over, fired for about half a second then died.
It did this a few more times, then after about 5 minutes of trying fired up and settled into an idle. I cautiously headed for home. Though only managed to travel a further 3 miles before the engine cut out again - the revs just dropped away to zero from doing 30mph in 2nd and coasted to a rest again.
This time, i tried to restart, the fuel pump whirred and engine turned over, but it would not fire up. Tried using throttle also, but nothing. Called RAC.
Just moments before they arrived (they were only about 10 minutes - great service) i tried to start and it fired up. RAC man inspected the engine, base idle screw, distributor, etc, but couldn't diagnose problem. We even made sure the petrol i had put in was infact petrol - it was. RAC man followed me home - only 2 miles - just in case it cut out again. But it didn't, it behaved fine.
Question is, what could cause this?
One of my theories is that i had left the car with maybe 1/8th of a tank of petrol in it when i went on holiday and the gases had caused an air lock?
Stepper motor will also be inspected very shortly. but i would be suprised if this alone would cause the (intermitant) problem - i do clean it fairly regularly.
Perhaps it is linked with the rich running and the dropping of revs occasionally when slowly down for junctions etc.
I would appreciate your thoughts as there doesn't appear to be anything obvious - to me anyway - which could cause this problem.
Cheers
Only 4 things I can think of.
1)Try Richards ECU device - well worth the experience/knowledge gained if you suspect sensors.
2)That pesky temp sender for the ECU has an Intermotor replacement part - see www.intermotor.co.uk and for the price is worth changing without a doubt.
3)My Lotus 912 engines dizzy had a break up of the reluctor ring causing exactly the same sort of probs as you describe - so check that all is well inside the dizzy.
4)Go to Maplins, buy the £19.99 Auto-Range Dual Display Digital Multimeter with PC interface and connection cable. Plumb the meter into the O2 sensors and data log for 10 mins from cold.
Cycle log time is once per second to how many you fancy.
Bob
>> Edited by zircon450 on Wednesday 3rd August 22:18
1)Try Richards ECU device - well worth the experience/knowledge gained if you suspect sensors.
2)That pesky temp sender for the ECU has an Intermotor replacement part - see www.intermotor.co.uk and for the price is worth changing without a doubt.
3)My Lotus 912 engines dizzy had a break up of the reluctor ring causing exactly the same sort of probs as you describe - so check that all is well inside the dizzy.
4)Go to Maplins, buy the £19.99 Auto-Range Dual Display Digital Multimeter with PC interface and connection cable. Plumb the meter into the O2 sensors and data log for 10 mins from cold.
Cycle log time is once per second to how many you fancy. Bob
>> Edited by zircon450 on Wednesday 3rd August 22:18
Maplins meter will allow you do record volts over time, amps, ohms etc etc.
Fit the meter on the Lambda sensor one at a time from cold. take the data every second, whip that into your spreadsheet program and do some averages, high's lows, check how long to stabilise, does it stabilise.
Then doe the same again when the engines warm, take the readings at tickover rpm, then add 500 rpm (brick on throttle pedal) take the readings again for a couple of minutes.
Again to 2k , 2.5k 3.5k rpm - now sit back and analyse some data you cannot suck out of the ECU.
Think about all the other options for sensors etc, basically start developing some test situations and maybe start to compare with other cars that run perfectly and some cars that don't.
It would be possible to compile lots of stats from lots of cars and develop a "logical" method of testing a duff vehicle rather than swap this, swap that, or paying mega bucks for guru experience.
Bottom line is factual information from your car can provide you or a guru with valuable info, resulting in an easy fix for you maybe, or a reduced amount of expensive guru time because you can provide a whole set of info and give some clear pointers to a possible problem.
Needless to say, this is only my thoughts and at an early stage, but hopefully you see where I'm coming from.
In the future it may be known as a "BDL" Base Data Log and become a format that all of us could provide our guru guys with.
Just and idea.
Fit the meter on the Lambda sensor one at a time from cold. take the data every second, whip that into your spreadsheet program and do some averages, high's lows, check how long to stabilise, does it stabilise.
Then doe the same again when the engines warm, take the readings at tickover rpm, then add 500 rpm (brick on throttle pedal) take the readings again for a couple of minutes.
Again to 2k , 2.5k 3.5k rpm - now sit back and analyse some data you cannot suck out of the ECU.
Think about all the other options for sensors etc, basically start developing some test situations and maybe start to compare with other cars that run perfectly and some cars that don't.
It would be possible to compile lots of stats from lots of cars and develop a "logical" method of testing a duff vehicle rather than swap this, swap that, or paying mega bucks for guru experience.
Bottom line is factual information from your car can provide you or a guru with valuable info, resulting in an easy fix for you maybe, or a reduced amount of expensive guru time because you can provide a whole set of info and give some clear pointers to a possible problem.
Needless to say, this is only my thoughts and at an early stage, but hopefully you see where I'm coming from.
In the future it may be known as a "BDL" Base Data Log and become a format that all of us could provide our guru guys with.
Just and idea.
Your problem sounds identical to mine, I had a great drive up to Derby, parked overnight and started her in the morning when she ran really rough.
All the symptoms after that were the same as yours till the battery completely died from having to restart so much.
I thought alternator or the dreaded 100 Amp fuse problem, but it turned out to be the Vacuum advance tube, Lambda sensor and coil. Bloody unlucky I thought.
Like the previous have mentioned its probably a sensor associated with the ECU, good luck.
All the symptoms after that were the same as yours till the battery completely died from having to restart so much.
I thought alternator or the dreaded 100 Amp fuse problem, but it turned out to be the Vacuum advance tube, Lambda sensor and coil. Bloody unlucky I thought.
Like the previous have mentioned its probably a sensor associated with the ECU, good luck.
Thankfully i have a new coil on order as well as some other bits (flamethrower, KV85, champion eon plugs).
Gave the stepper motor a real good clean and then took the car out yesterday. The problem did not come back, though the drive was only short as bedding in new brakes (black diamond discs and pads - the car barely stops at the moment!).
It's amazing how much difference a clean stepper motor can make - idle was perfect and the engine was so smooth. I'm gonna take it out for another gentle run today to bed in the brakes and see if the problem occurs again.
I think i'll try to get a new water temp sensor just in case (Lucas SNB802) though am hoping it was just an airblock in the fuel lines.
Gave the stepper motor a real good clean and then took the car out yesterday. The problem did not come back, though the drive was only short as bedding in new brakes (black diamond discs and pads - the car barely stops at the moment!).
It's amazing how much difference a clean stepper motor can make - idle was perfect and the engine was so smooth. I'm gonna take it out for another gentle run today to bed in the brakes and see if the problem occurs again.
I think i'll try to get a new water temp sensor just in case (Lucas SNB802) though am hoping it was just an airblock in the fuel lines.
Fuel pump relay.
Look in the passenger footwell, 2 metallic relays. Unplug them both, give em a clean, and re-attach. I'm not sure if they're identical, so do one at once so you don't get em mixed up.
I know because exactly the same thing happened to me tonight, driving normally then it stalled, fired itup and then died. Ian at Middlewich MOT centre diagnosed it over the phone! Its also been cutting out randomly over the last few days, on the motorway, chugging along and then a momentary loss of power before coming back online.
Look in the passenger footwell, 2 metallic relays. Unplug them both, give em a clean, and re-attach. I'm not sure if they're identical, so do one at once so you don't get em mixed up.
I know because exactly the same thing happened to me tonight, driving normally then it stalled, fired itup and then died. Ian at Middlewich MOT centre diagnosed it over the phone! Its also been cutting out randomly over the last few days, on the motorway, chugging along and then a momentary loss of power before coming back online.
You can check the realys by just turning the ignition on and seeing if they click. Hold them in your hand or close to your ear. The fuel pump relay should click once, then again a few seconds later.
You dont have to turn the engine over, just a couple of turns. Its easier if you get someone else to do the ignition whilst you check the relays. If I remember rightly they are both the same, so you can switch them over to do a thorough check.
You dont have to turn the engine over, just a couple of turns. Its easier if you get someone else to do the ignition whilst you check the relays. If I remember rightly they are both the same, so you can switch them over to do a thorough check.
Fitted Magnecor KV85 leads, Champion Eon plugs, Flamethrower coil, new distributor cap and rotor arm today. Had these on order prior to my cutting-out problems.
Throttle response is greatly improved and a quick test on my data logger shows low down torque (>2600rpm) is increased dramatically. Was really enjoying driving the car again...
...and then just as i got home, the engine died. I started it up, reversed onto the drive and it died again. went to restart, but it wouldn't. The water temp was 90 (maybe just under) when the engine died - as it was the other two times when the engine died.
I'm now pretty certain it is the coolant temperature sensor for the ecu (Lucas SNB802). I know how hard these are to get hold of but will phone a few lucas distributors tomorrow to see if one can be ordered.
Once the car had had a few minutes to cool down, it started up again with no problems.
Throttle response is greatly improved and a quick test on my data logger shows low down torque (>2600rpm) is increased dramatically. Was really enjoying driving the car again...
...and then just as i got home, the engine died. I started it up, reversed onto the drive and it died again. went to restart, but it wouldn't. The water temp was 90 (maybe just under) when the engine died - as it was the other two times when the engine died.
I'm now pretty certain it is the coolant temperature sensor for the ecu (Lucas SNB802). I know how hard these are to get hold of but will phone a few lucas distributors tomorrow to see if one can be ordered.
Once the car had had a few minutes to cool down, it started up again with no problems.
I had a similar problem which turned out to be the connector on the fuel pump. The relays passed the test suggested.
I had a couple of breakdowns which mysteriously cured themselves until it stopped and would not restart
Does your fuel pump always whirr. My did sometimes but when the car fired the connection failed and the car would not start.
No further problems since sorting the connector
Good luck
Chris
>> Edited by tvr+bubblecar on Sunday 21st August 22:24
I had a couple of breakdowns which mysteriously cured themselves until it stopped and would not restart
Does your fuel pump always whirr. My did sometimes but when the car fired the connection failed and the car would not start.
No further problems since sorting the connector
Good luck
Chris
>> Edited by tvr+bubblecar on Sunday 21st August 22:24
If you suspect the coolant temp sender then wait for the problem to uccur and then measure the resistance across the sender. The best way to do this is at the ECU multiplug because this also picks up any wiring fault.
From memory, the coolant temp sender is between pins 7/25, at a coolant temp of 90 deg you should get a resistance of about 200 Ohms.
From memory, the coolant temp sender is between pins 7/25, at a coolant temp of 90 deg you should get a resistance of about 200 Ohms.
Replaced the coolant sensor with the Intermotor part. Once again, the car cut out when the temperature got to about 90'c.
I'm clueless as to what the problem may be. Faulty ECU perhaps?
This is really getting on my nerves now as i'm just throwing money away - as i have been over the 21 months i've owned it. Seriously considering getting rid of it.
I'm clueless as to what the problem may be. Faulty ECU perhaps?
This is really getting on my nerves now as i'm just throwing money away - as i have been over the 21 months i've owned it. Seriously considering getting rid of it.
It sounds like the amp for the coil to me, if the coil isnt fired then the ECU doesnt know the engine is running and stops fuel, spark will obviously stop too due to the amp failure. These things are notorious for problems when they are hot, so what does TVR do with them! Stick them on top of the engine as it will be nice and warm up there. Anyhow, they are cheap as chips, loads and loads of cars use them, Metro's I think even use the same thing, go down your local Auto shop and get a new one, £20 Max!!
Phil
Phil
Thanks phil, but have actually just fitted new coil, leads, plugs, dizzy cap and rotor. Once the engine has died, it won't restart until the temperature has gone down a little - fuel pump whirs and the engine turns over but the ECU doesn't want to let it spark.
After 5 minutes or so, the engine will fire back into life with no problems.
It's so frustrating because it is so intermitent - it'd only cut out about 8 times in 200 miles or so.
Have a service booked for the 7th Sept, so maybe they'll spot what's wrong then.
After 5 minutes or so, the engine will fire back into life with no problems.
It's so frustrating because it is so intermitent - it'd only cut out about 8 times in 200 miles or so.
Have a service booked for the 7th Sept, so maybe they'll spot what's wrong then.
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