Odd running and fuelling issue
Discussion
The Griffs (430) been playing up recently - stalls a lot, runs at 1500-2000 when stopped (but comes down to 1000 after about 10-15 seconds) and more recently the power just drops off like you've lifted off the gas and it kicks loads of fuel out the back, as Mrs FFG found out when she was following me. Also runs very rough and there feels like no power at all. This has happened twice now - the first time on the way back from Goodwood on the M40, pulled over and switched off, checked everything and it seemed fine so started up and went home (no issues on the way home). Took the fuel cap off when got home and there was a big whoosh and I mean bigger than normal. The second time was last week. Went down a dip in the road, as if I'd took my foot off the gas, the power just went, running rough and a very bad fuel smell out the back (sorry Mrs FFG who was frantickly flashing). Stopped again and took the fuel cap off (big whoosh again) and changed the 2 metal relays (as I carry spares). All seemed fine again so carried on no problems. If it was fuel starvation it would stall and not restart but it does restart, as if nothing has happened. I'm guessing some electrical wire is loose and making an intermittent contact but where the hell do I start? Anyone else had this?
FFG
FFG
Mr MoJo said:
As you know Paul, I'm not the most technically minded but it sounds like there's a vacuum forming inside the tank, which is the released when you take the cap off. Does your fuel tank give the odd 'bonging' noise every now and then. Like its sucking it's sides in ?
Simon, couldn't hear it above the exhaust if it did! I don't believe it's this although strange it has just started happening. Still think it is electrical as it seemed to happen at the same time I hit the dip in the road. Fuel cap is now off and relays changed so see if it makes a difference. After it happens the power drops right off, it runs as though on about 4 cylinders and Andrea said it stinks really bad of fuel when following, which I only found out the 2nd time - no evidence of fuel smell in the car.FFG
hmmm. .... The fact that it seems to be going very rich when it happens would suggest that either the injection system is suddenly over-fuelling it (could be many things but airflow meter, throttle potentiometer or water temperature sensor would seem likely culprits) or you are suddenly losing spark (could be ignition module on the distributor, cap, rotor arm, loose wire, dodgy coil, to name a few), I would have to guess it is not a vacuum because as you point out it would likely starve of fuel rather than over fuel. It could be as simple as a fuel pressure regulator that is sticking, causing a sudden rise in fuel pressure. The fact that it intermittent makes it a tough one but I would get someone to check it over and maybe try swapping out some components if nothing shows up on inspection.
FFG - I'll be keeping a keen eye on this thread! I hope you find the answer soon. I've had this problem for years.
I'm pretty sure it's electrical and possibly something to do with the immobiliser. If I rearrange the wiring in the footwell, it can stop this problem occuring. But everytime somebody services it or fiddles about with the wires/ECU/Alarm unit in the passenger footwell, then it can start the problem all over again.
I changed the two metal relays too but to no avail.
I need to get an electrical wizz to have a good look in that spaghetti mess to sort it out as I'm sure this is where the problem originates from.
Oddly, sometimes I can just pull over and restart, or even knock the engine off and bump start it before I come to a stop. Other times, I have to stop, set the alarm/immobiliser, then unset it again before she'll fire up.
f
king annoying.
I'm pretty sure it's electrical and possibly something to do with the immobiliser. If I rearrange the wiring in the footwell, it can stop this problem occuring. But everytime somebody services it or fiddles about with the wires/ECU/Alarm unit in the passenger footwell, then it can start the problem all over again.
I changed the two metal relays too but to no avail.
I need to get an electrical wizz to have a good look in that spaghetti mess to sort it out as I'm sure this is where the problem originates from.
Oddly, sometimes I can just pull over and restart, or even knock the engine off and bump start it before I come to a stop. Other times, I have to stop, set the alarm/immobiliser, then unset it again before she'll fire up.
f
king annoying.I need to sort it as it's undriveable when it happens and I can't live with it. I've had the electrics tidied but still keep getting problem after problem. Spoke to Carl Baker about a complete re-wire but for obvious reasons thats expensive.
I guess its a loose wire making an intermittent contact but finding it is going to be a nightmare. I'll start swapping the usual suspects to see the impact but could take some time. Its with Jamie Rogers at the minute having a new dissy - maybe this is the culprit? It happened on the way over to Jamies this time which is why Mrs FFG was following me.
Have you had any other symptoms when it happens, such as the erratic tickover, and random stalling?
FFG
I guess its a loose wire making an intermittent contact but finding it is going to be a nightmare. I'll start swapping the usual suspects to see the impact but could take some time. Its with Jamie Rogers at the minute having a new dissy - maybe this is the culprit? It happened on the way over to Jamies this time which is why Mrs FFG was following me.
Have you had any other symptoms when it happens, such as the erratic tickover, and random stalling?
FFG
FlipFlopGriff said:
Have you had any other symptoms when it happens, such as the erratic tickover, and random stalling?
FFG
Yes, both of these. (Stepper motor cleaned but not the culprit here) What you have described in your OP is identical.FFG
After 'rearranging' where things lay in the footwell a few years back, I managed to get rid of the problem for a whole year
. Then I had a service done and the wires were disturbed and so the problem came back. 
Maybe the way forward is to perhaps change all the relays down there one at a time (or all at once?) to try to locate the issue.
FFG,
I would look at the connections to the air flow meter. Try unplugging the connector and reconnecting and dozen times or so. This should clean the contacts and may clear the fault for a while.
I had similar simptoms and found the air flow meter connections were the problem. I replaced the connector with a new set of crimps, plug body and boot and has been fine since.
Out of interest when it runs rough at part throttle try flooring it and see if it runs better.
This was also a simptom when the air flow meter connections were faulty. The car would kangaroo at part
throttle but went like stink when floored. It also had the smelly over fueling smell and poor idle when the fault occured.
Paul.
I would look at the connections to the air flow meter. Try unplugging the connector and reconnecting and dozen times or so. This should clean the contacts and may clear the fault for a while.
I had similar simptoms and found the air flow meter connections were the problem. I replaced the connector with a new set of crimps, plug body and boot and has been fine since.
Out of interest when it runs rough at part throttle try flooring it and see if it runs better.
This was also a simptom when the air flow meter connections were faulty. The car would kangaroo at part
throttle but went like stink when floored. It also had the smelly over fueling smell and poor idle when the fault occured.
Paul.
If you have been disturbing the rats nest there is another possibility.
The wires in the large multiway plug connected to the ECU can be quite stressed if the cable is moved, there is very little slack.
Worth unplugging the ECU, removing the plug cover and inspecting the connections. Also check that the pins are not corroded. If the footwell suffers with damp at all, corrosion can set in. Not TVRs finest hour!
The wires in the large multiway plug connected to the ECU can be quite stressed if the cable is moved, there is very little slack.
Worth unplugging the ECU, removing the plug cover and inspecting the connections. Also check that the pins are not corroded. If the footwell suffers with damp at all, corrosion can set in. Not TVRs finest hour!
check the afm wiring
if the fault is intermittent.
unplug the afm that puts the the ECU to a default setting try driving the car the car will run like a dog overfuelling etc if it gives you the same symptons you experiencing then buzz out all cabling and check Connections at AFM and ECU.
measure and note down all resistances etc.
if the fault is intermittent.
unplug the afm that puts the the ECU to a default setting try driving the car the car will run like a dog overfuelling etc if it gives you the same symptons you experiencing then buzz out all cabling and check Connections at AFM and ECU.
measure and note down all resistances etc.
What was the fuel tank level when these problems occured ?.... approaching empty both times or at varying levels ? recent running issues on mine seem to be related to tank vacumn and an overtight leven fuel cap,just another thought as you mentioned a larger than normal vac level when removing yours.
rigga said:
What was the fuel tank level when these problems occured ?.... approaching empty both times or at varying levels ? recent running issues on mine seem to be related to tank vacumn and an overtight leven fuel cap,just another thought as you mentioned a larger than normal vac level when removing yours.
Just below 1/2 both occasions. Not sure that is conclusive though. I didn't take the cap off the first time and drove home (another 30 miles) with no issues. Only took the cap when I got home as it wouldn't start - lights all on but wouldn't turnover. Cap off and started - again not sure if coincidental or I just hadn't disarmed the immobiliser properly. I'll start with the AFM, ECU and footwell areas, and I'll cut a chunk out of the rubber on the leven fuel cap so it can breathe.I've asked Jamie to change the distributor (as he said it was on its way out) and asked him to set the car up as normal, so i'll have a good starting point. I love the car but it is grinding me down as I just can't trust it which takes the fun out of the driving experience.
FFG
FlipFlopGriff said:
Dissy changed (which apparently has made it incredibly quick - Jamies words not mine) but it has gone wierd on Jamie. He's highlighted it to one bank (the odds) so the investigation continues. He's going to try another ECU to start with.
FFG
Oh far too much guess work here.....Check for ECU fault codes, as these will flag up if the ECU cant maintain the correct mixture (assuming its a catalyst car). The idle will be very unstable or non existant is the mixture is wrong, and if the mixture is over rich (look for black sooty plugs) then the AFM is a good place to start as they can go over voltage at low airflows, but it does not always throw a fault code. Severe misfires can also make the car overfuel as the ECU cant tell if the mixture is over lean or unburnt, so it cranks up the fuel. To see if the ECU is trying to control the mixture, put a test meter across the lambda extention wire connector behind the fuel rail on each side. You should see a 0 to 1.2 volt DC switching signal across the black and white wires at idle on a warm engine. If its stuck at 1.2 its very rich, or 0 volts its lean or the lamda probe has failed and you will get a fault code. (It may take a while to show up, the ecu is not trigger happy with fault codes).FFG
Just my bit:http://www.g33.co.uk/fuel_injection.htm
Just read the profile, that changes everything, as fault codes are little use. You are really down to reading plug colours and testing the AFM output at idle then (This is around 1.6 volts, but is dependent on engine size and idle speed) . Has the CO trim been set up to the recommended voltages on the side of the AFM, or possibly the CO trim connection wire has failed? Other things like open circuit or faulty temp sensors, or possibly fuel pressure (blocked return line from the regulator / faulty regulator or missing vaccume connection) can cause overfueling. A misfire wont cause overfuelling as the ECU cant detect the error without lamda probes.
Edited by blitzracing on Wednesday 6th July 13:08
FlipFlopGriff said:
No fault codes before or after the problem.
Its a pre cat so not a lambda issue. Was going to start with AFM but Jamie's just took the stepper out to check and it fell apart into 2 pieces!!!!
Hopefully a good starting point but i'll update later.
FFG
Yes, i've found this had happened to a 4.5 Chimaera. There also appeared to be some green corrosion where it had broken.Its a pre cat so not a lambda issue. Was going to start with AFM but Jamie's just took the stepper out to check and it fell apart into 2 pieces!!!!
Hopefully a good starting point but i'll update later.
FFG
blitzracing said:
Just read the profile, that changes everything, as fault codes are little use. You are really down to reading plug colours and testing the AFM output at idle then (This is around 1.6 volts, but is dependent on engine size and idle speed) . Has the CO trim been set up to the recommended voltages on the side of the AFM, or possibly the CO trim connection wire has failed? Other things like open circuit or faulty temp sensors, or possibly fuel pressure (blocked return line from the regulator / faulty regulator or missing vaccume connection) can cause overfueling. A misfire wont cause overfuelling as the ECU cant detect the error without lamda probes.
Jamie is well known and knows his onions so hopefully get to the bottom of the issue soon. I'm sure it won't be as straight forward as the stepper motor and await the next problem to arise.Edited by blitzracing on Wednesday 6th July 13:08
Thanks for all the help.
FFG
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