RV8 start-up behaviour
Discussion
I attach a pic of the 'bumpy bits'
I had remembered the efi systems were different, just reminiscing and realising the Vitesse went in 1996!
The plug wetting also corresponds to larger inlet valves, maybe the gas speed over the seat has a negative effect until the engine is warm. Being all ally it does tend to quench heat very rapidly and tends to reach dew point rapidly overnight too.
Peter
I had remembered the efi systems were different, just reminiscing and realising the Vitesse went in 1996!
The plug wetting also corresponds to larger inlet valves, maybe the gas speed over the seat has a negative effect until the engine is warm. Being all ally it does tend to quench heat very rapidly and tends to reach dew point rapidly overnight too.
Peter
Edited by PeterBurgess on Tuesday 1st December 14:08
100SRV said:
Interesting that the Tomcat chap has had similar problems on various vehicles.
The ability of the average homo semisapiens to make correct inferences and deductions from available data is woefully lacking. There may well be some common link between the ignition or fuel systems on these vehicles which causes issues but starting the engine on a regular basis or having to get it to a certain temperature every time is a band aid not the cure for the cause of the problem.
Pumaracing said:
The ability of the average homo semisapiens to make correct inferences and deductions from available data is woefully lacking. There may well be some common link between the ignition or fuel systems on these vehicles which causes issues but starting the engine on a regular basis or having to get it to a certain temperature every time is a band aid not the cure for the cause of the problem.
I agree.I need to do more investigating.
Talking to a mate who picked some V8 heads up this morning. There does seem to be a correlation between plug type and wetting. TVR fitted (for some reason?) non projected B7ECS plugs. My mate reckons once when they foul that is curtains for the plug. We have always used projected plugs with hotter running characteristics with V8s, I think we would not go beyond projected 7s even in full race engines. 6 is far more common.
We have always used NGK plugs but our neighbours with the Cossies get better results from Champion saying the NGKs once they foul die a death whereas the Champions clean up and run again under the high pressure rich mix environment.
As Dave says, make sure your leads are in tip top condition. The fact your Drew special sits around so long cannot help the situation as the water does seem to settle out on the V8 engines.
Peter
We have always used NGK plugs but our neighbours with the Cossies get better results from Champion saying the NGKs once they foul die a death whereas the Champions clean up and run again under the high pressure rich mix environment.
As Dave says, make sure your leads are in tip top condition. The fact your Drew special sits around so long cannot help the situation as the water does seem to settle out on the V8 engines.
Peter
Hi Pete Burgess,
thank you for the reply!
HT leads were new in 2013 and the engine had little use in 2014 as the car was under major refit, is that new enough?
The HT leads look in good condition with no cracks, are routed correctly avoiding contact with metal bits and secured using the plastic combs.
The sparking plugs are NGK BPR6ES, perhaps it is time to try Champions and a new set of leads?
What make / supplier of HT leads would you recommend?
Ignition is by Lumenition with a standard ballasted coil and distributor. I did consider moving to EDIS but am not sure it would be cost effective (open to persuasion).
thank you for the reply!
HT leads were new in 2013 and the engine had little use in 2014 as the car was under major refit, is that new enough?
The HT leads look in good condition with no cracks, are routed correctly avoiding contact with metal bits and secured using the plastic combs.
The sparking plugs are NGK BPR6ES, perhaps it is time to try Champions and a new set of leads?
What make / supplier of HT leads would you recommend?
Ignition is by Lumenition with a standard ballasted coil and distributor. I did consider moving to EDIS but am not sure it would be cost effective (open to persuasion).
Hiya
Gap the plugs at 32 thou", check the engine running in the dark and see if the leads light up like a Christmas tree, if they do change the leads. Programmable ignition is always nice to squeeze the best from the engine in terms of spark quality and power. I am not sure what to say about Champion plugs, why not give them a whirl?
Peter
Gap the plugs at 32 thou", check the engine running in the dark and see if the leads light up like a Christmas tree, if they do change the leads. Programmable ignition is always nice to squeeze the best from the engine in terms of spark quality and power. I am not sure what to say about Champion plugs, why not give them a whirl?
Peter
I forgot to post! We have seen good results with Fastlane lead sets even over seemingly ok leads.
http://www.performanceleads.co.uk/
I don't stock 'em or get paid by 'em, just think they wporked well back to back on a fair few cars.
Peter
http://www.performanceleads.co.uk/
I don't stock 'em or get paid by 'em, just think they wporked well back to back on a fair few cars.
Peter
Steve_D said:
The earlier Ford coil packs have very well sealed lead connections so are regarded as very suitable if you are going wading with the Bowler.
Steve
Steve
Never known a 1st generation coil pack (with the barbed towers) to fail over a very long period in the motor trade unlike the 2nd generation ones although easier to mount TVR V8 cars use an NGK with a 7 heat range and with on average CR of around 9.1 regardless of what TVR or LR state no way do they need a 7 heat range IMO 6's can cope easily, I have a long career on the tools and wouldnt use a Champion plug to break a friggin window s
te quality and reliabilty to suite just compare an NGK with a Bosch or Champion plug electrodes and get back to me 
no contest Edited by Sardonicus on Wednesday 2nd December 21:06
Taking lots of steps backwards- this set up fires the injectors for a set period for a few seconds on cranking before it starts to read the AFM value and trim the fuel to suit the amount of air being drawn in. Leaving knobbly bits to one side, fouling the plugs is not a design issue, but will either be a wrong sensor value so the ECU is mis interpreting the required fuel (AFM is a prime candidate for this), or fuel pressure is too high. The latter can happen if the fuel return rail gets blocked or pinched for any reason. The AFM can be easily be checked with a test meter, as a common failure is the output becomes too high for any given airflow, so the ECU over fuels horribly.
This is a basic DC test on the AFM:
Peel back the rubber boot on the airflow meter connector and leave it plugged in to the airflow meter. Set up the digital multimeter to read voltage. Insert the negative probe into the Red/Black wire (sensor ground), and the positive into the Blue/Green wire (Airflow signal).Turn on the ignition, but do not start the engine. The meter should immediately indicate a reading of approximately 0.3-0.34 Volts after the initial "warm up" spike. Most defective airflow meters will overshoot to 0.8 Volts or higher, and take at least 2 seconds to come down to the correct voltage. Now start the engine, and the reading should rise to 1.6 Volts (3.5 Litre engine) to 1.75 Volts (5.0 Litre engine).
The TPS is not a big player in setting the overall fuelling- its only there for idle control and fuel enrichment at rapid throttle opening, but if you have RoverGauge, then just do a sweep test on it with the ignition on- you dont need to run the engine- Instructions here:
https://www.dropbox.com/sh/hj9wcuza88hur88/AACZATi...
Also check the temp sensor readings are in range. On a cold engine the fuel rail temp and engine temp should be the same.
Failed HT leads wont cause the plugs to foul with carbon- this only happens if you have lambda sensors as the get the readings wrong for unburnt fuel and mistakenly the ECU puts in more fuel to try and correct it. Its odd to have a problem on one bank- as the injector pulse width is the same for both sides without lambda probes, and air supply and fuel pressure is common to both banks, so Id check all 8 again.
This is a basic DC test on the AFM:
Peel back the rubber boot on the airflow meter connector and leave it plugged in to the airflow meter. Set up the digital multimeter to read voltage. Insert the negative probe into the Red/Black wire (sensor ground), and the positive into the Blue/Green wire (Airflow signal).Turn on the ignition, but do not start the engine. The meter should immediately indicate a reading of approximately 0.3-0.34 Volts after the initial "warm up" spike. Most defective airflow meters will overshoot to 0.8 Volts or higher, and take at least 2 seconds to come down to the correct voltage. Now start the engine, and the reading should rise to 1.6 Volts (3.5 Litre engine) to 1.75 Volts (5.0 Litre engine).
The TPS is not a big player in setting the overall fuelling- its only there for idle control and fuel enrichment at rapid throttle opening, but if you have RoverGauge, then just do a sweep test on it with the ignition on- you dont need to run the engine- Instructions here:
https://www.dropbox.com/sh/hj9wcuza88hur88/AACZATi...
Also check the temp sensor readings are in range. On a cold engine the fuel rail temp and engine temp should be the same.
Failed HT leads wont cause the plugs to foul with carbon- this only happens if you have lambda sensors as the get the readings wrong for unburnt fuel and mistakenly the ECU puts in more fuel to try and correct it. Its odd to have a problem on one bank- as the injector pulse width is the same for both sides without lambda probes, and air supply and fuel pressure is common to both banks, so Id check all 8 again.
Edited by blitzracing on Thursday 3rd December 16:47
Edited by blitzracing on Thursday 3rd December 16:48
I believe the plug wetting issue if not allowed to run also affected the 4.0 V8 in the Jaguar.
I did some work a few years ago for a customer with one of these.(Not on the Jag!) He moved the Jag 4 or 5 times whilst I was there on a start, move a few yards, switch off. Went to move it again & it wouldn't start although it did try to fire.
He called the RAC who turned up. Wouldn't start for them either. Removed & dried 4 plugs which did make the attempt to start sound a bit more optimistic but the other bank apparently needed a lot of work to remove bits to access the plugs & not a roadside/driveway option. RAC chap said that this was an issue with this engine & they saw quite a few. Multiple cold starts put too much fuel into the engine. Eventually recovered to the local main dealer.
I can't verify whether it was a known issue, but it did sound plausible.
I did some work a few years ago for a customer with one of these.(Not on the Jag!) He moved the Jag 4 or 5 times whilst I was there on a start, move a few yards, switch off. Went to move it again & it wouldn't start although it did try to fire.
He called the RAC who turned up. Wouldn't start for them either. Removed & dried 4 plugs which did make the attempt to start sound a bit more optimistic but the other bank apparently needed a lot of work to remove bits to access the plugs & not a roadside/driveway option. RAC chap said that this was an issue with this engine & they saw quite a few. Multiple cold starts put too much fuel into the engine. Eventually recovered to the local main dealer.
I can't verify whether it was a known issue, but it did sound plausible.
The stock Range Rover fuel map does over fuel horribly on cold start- its one of the tweaks done on aftermarket chips to reduce this by about 25%. Its worse on cars without lambda sensors as the ECU keeps throwing in fuel based purely on the ECU programming and sensor values, where at least with lambdas the ECU will pick the mixture up as being too rich, and wind the fuelling back until the probes start to switch at lambda 1. If you dont want to get into reprogramming the ECU, then you can simply put a variable resistor across the engine temperature sensor, and using RoverGauge tweak it so lets say the ambient is 10'c you can make the ECU think its say 40'c so it reduces the cold start fuelling accordingly. Luckily this approach has little affect at the higher engine temps as the sensor has a massive resistance when cold, but a very low value when hot, so putting a parallel resistor has little affect against a low resistance sensor reading.
Just another thought- if the vacuum pipe from the fuel regulator to the plenum is disconnected it will cause the fuel pressure to become too high, as the regulator holds the pressure to 2.5 bar above the plenum pressure, that is normally lower that atmospheric, so at a guess you might see 28 psi at idle, where as with the vacuum missing it will be 37.5 psi. That adds a load more fuel when you dont need it.
Just another thought- if the vacuum pipe from the fuel regulator to the plenum is disconnected it will cause the fuel pressure to become too high, as the regulator holds the pressure to 2.5 bar above the plenum pressure, that is normally lower that atmospheric, so at a guess you might see 28 psi at idle, where as with the vacuum missing it will be 37.5 psi. That adds a load more fuel when you dont need it.
Good stuff Dr Blitz!
It appears you were correct about the AFM. I made the mistake of dicking about with it and a multimeter before going for MoT.
The AFM fitted was showing a high voltage at key-on and at start-up way beyond what you prescribed. I started and let it idle to check the voltages when running and the sodding thing fouled all eight plugs (photos to follow) 30 minutes before MoT. Out with the old plugs and in with a new set (NGK again) as there was no time to clean the dirty ones, I also swapped the AFM with my spare.
Time to lock up and set off...luckily nice clean start and no plug fouling.
I got to the test station with a minute to spare (pass).
I'll do some more testing over the weekend.
It appears you were correct about the AFM. I made the mistake of dicking about with it and a multimeter before going for MoT.
The AFM fitted was showing a high voltage at key-on and at start-up way beyond what you prescribed. I started and let it idle to check the voltages when running and the sodding thing fouled all eight plugs (photos to follow) 30 minutes before MoT. Out with the old plugs and in with a new set (NGK again) as there was no time to clean the dirty ones, I also swapped the AFM with my spare.
Time to lock up and set off...luckily nice clean start and no plug fouling.
I got to the test station with a minute to spare (pass).
I'll do some more testing over the weekend.
100SRV said:
Good stuff Dr Blitz!
It appears you were correct about the AFM. I made the mistake of dicking about with it and a multimeter before going for MoT.
The AFM fitted was showing a high voltage at key-on and at start-up way beyond what you prescribed. I started and let it idle to check the voltages when running and the sodding thing fouled all eight plugs (photos to follow) 30 minutes before MoT. Out with the old plugs and in with a new set (NGK again) as there was no time to clean the dirty ones, I also swapped the AFM with my spare.
Time to lock up and set off...luckily nice clean start and no plug fouling.
I got to the test station with a minute to spare (pass).
I'll do some more testing over the weekend.
Sorted It appears you were correct about the AFM. I made the mistake of dicking about with it and a multimeter before going for MoT.
The AFM fitted was showing a high voltage at key-on and at start-up way beyond what you prescribed. I started and let it idle to check the voltages when running and the sodding thing fouled all eight plugs (photos to follow) 30 minutes before MoT. Out with the old plugs and in with a new set (NGK again) as there was no time to clean the dirty ones, I also swapped the AFM with my spare.
Time to lock up and set off...luckily nice clean start and no plug fouling.
I got to the test station with a minute to spare (pass).
I'll do some more testing over the weekend.
Hi,
do you clever folks have any recommendations for a compentent company to refurbish my airflow meter?
I've seen a page on the internet showing how to diagnose and repair but would rather pay a professional to do it; I rely on the car to work where it is a long walk for help and would rather not have to carry a spare airflow meter with me.
ETA,
when looking for failure/repair details of the AFM I found the Tornado systems chip page, interesting list of changes and improvements - would it be worth me investing in one?
thank you for your advice and assistance!
do you clever folks have any recommendations for a compentent company to refurbish my airflow meter?
I've seen a page on the internet showing how to diagnose and repair but would rather pay a professional to do it; I rely on the car to work where it is a long walk for help and would rather not have to carry a spare airflow meter with me.
ETA,
when looking for failure/repair details of the AFM I found the Tornado systems chip page, interesting list of changes and improvements - would it be worth me investing in one?
thank you for your advice and assistance!
Edited by 100SRV on Monday 7th December 08:56
Difficult one- The electronics inside is pretty basic, so it depends what "referb" actually means- I doubt for one minute you get a new PCB and all the components, its more likely a clean and make sure its working and nothing more, so you might as well source a second hand one and test it when you get it. A new Lucas one would be nice (These where about £200) but I dont know how good the supply is now. Most of the new ones on Ebay are nasty Chinese copies, and my experience in general of Chinese AFM's has not been good- calibration or heat sensitivity wise. As for the Tornado chip- I personally think its very overpriced for what you get, as any improvements are very hard to measure in real terms, and it now costs less to get a proper full remap on a rolling road than a "best guess" Tornado chip. Go and speak to Joolz here:
http://www.kitsandclassics.co.uk/
http://www.kitsandclassics.co.uk/
Hi,
shipped the faulty airflow meter off to a reputable automotive electronics repair. They inspected it and claim that the fault with the airflow meter would cause it to run lean, they asked for details of the ECU to verify compatibility and to see whether they could repair it. I supplied details and was told that they could check the ECU and repair if required. No mention of whether the airflow meter could be repaired...fishy.
100SRV
shipped the faulty airflow meter off to a reputable automotive electronics repair. They inspected it and claim that the fault with the airflow meter would cause it to run lean, they asked for details of the ECU to verify compatibility and to see whether they could repair it. I supplied details and was told that they could check the ECU and repair if required. No mention of whether the airflow meter could be repaired...fishy.
100SRV
Any AFM fault will alter the fuelling be it rich (over voltage) or lean (under voltage) as the AFM is the major component that controls the feeling requirements, so its a bit like saying if I remove a spark plug it will run on 7 cylinders. Nothing guru like here. In terms of ECU compatibility- the voltage output across the whole range of 5AMs is exactly the same- the part numbers only change because of the castings, so any 5AM will work with any 14CUX, Ive also the swapped 5am and the 3AM (the hitachi version from the early 90's) without any compatibility issues. TBH you are better off getting another 14CUX from a breaker, and an AFM (or a new one) than throwing lots of money for doubtful repairs on old hardware. The 14CUX is tough as old boots as long as you dont get it wet, ( check for case and terminal corrosion) so you would be unlucky to get a bad one. AFMs fail in the TVR's as they get cooked by the exhaust manifolds, but less of an issue on the Range Rover.
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