Discussion
ok so having a few issues, the wedge will only start when cold and even that is only 30% of the time, it'll tick over at around 900rpm very rough and in a state of shall i or shall i not run, lots of black soot for exhaust and if you go anywhere near the throttle it'll stall!!! come to the conclusion its over fuelling.
so i started doing a few basic diagnostics and general checking, first thought was temp sensor but this is new! so checked the continuity of wiring and earth, all is good also checked all earths on ecu and i also have 2 ecu's! neither runs any better than the other.
still convinced it's getting to much fuel i decided to check fuel pressure and for leaks, i had fitted a power boost valve previously and so connected a pressure gauge just in front of this, stuck fingers inside airmeter and pushed flap and pressure went up to around 40-50psi and backed off quickly to 35psi pushing excess out of fuel return (pulled pipe off) the pressure then dropped to 10-15psi after around 20min but not through fuel return!
my conclusion is leaking injectors or am i missing something more obvious? if i have got to replace the injectors what are my options and cost?
it did run better once and i have removed and refitted alot from the car some new bits added some refurbed so its not unlikely that i've fudged something up somewhere.
so i started doing a few basic diagnostics and general checking, first thought was temp sensor but this is new! so checked the continuity of wiring and earth, all is good also checked all earths on ecu and i also have 2 ecu's! neither runs any better than the other.
still convinced it's getting to much fuel i decided to check fuel pressure and for leaks, i had fitted a power boost valve previously and so connected a pressure gauge just in front of this, stuck fingers inside airmeter and pushed flap and pressure went up to around 40-50psi and backed off quickly to 35psi pushing excess out of fuel return (pulled pipe off) the pressure then dropped to 10-15psi after around 20min but not through fuel return!
my conclusion is leaking injectors or am i missing something more obvious? if i have got to replace the injectors what are my options and cost?
it did run better once and i have removed and refitted alot from the car some new bits added some refurbed so its not unlikely that i've fudged something up somewhere.
On standard injectors on my 350i, over 3.1 bar (45psi ?) will cause injectors to weep. Normal for rover v8s the fuel pressure is 2.5 bar and Steve Heath writes 2.7 is optimum. Based on this it could be you need to reduce the fuel pressure if the engine is sort of standard.
Coolant temperature sensor could still be not ok, even out of the box when new...
Myself would try to run the engine with the lead to the sensor shorted out and see if it would run better as a test.
And not yet worry about the injectors even if the fuel pressure is dropping as you described.
Rob
Coolant temperature sensor could still be not ok, even out of the box when new...
Myself would try to run the engine with the lead to the sensor shorted out and see if it would run better as a test.
And not yet worry about the injectors even if the fuel pressure is dropping as you described.
Rob
Similar symptoms to Ian's car - where after deciding to rip out the EFi system posted up "and I tapped the ECU and it seemed to run again"... Maybe the history with that car led everyone on a wild goose chase...
After checking and double-checking the coolant temp sensor sometimes it turns out that the fault is with the ECU itself. I and a few others have experienced this, and it's usually not a component fault but a bad joint, cured by reflowing both PCB's in the ECU - by this I means go over the whole lot with a soldering iron and some fresh solder. It takes about an hour to do so not a bad job.
After checking and double-checking the coolant temp sensor sometimes it turns out that the fault is with the ECU itself. I and a few others have experienced this, and it's usually not a component fault but a bad joint, cured by reflowing both PCB's in the ECU - by this I means go over the whole lot with a soldering iron and some fresh solder. It takes about an hour to do so not a bad job.
adam quantrill said:
Similar symptoms to Ian's car - where after deciding to rip out the EFi system posted up "and I tapped the ECU and it seemed to run again"... Maybe the history with that car led everyone on a wild goose chase...
After checking and double-checking the coolant temp sensor sometimes it turns out that the fault is with the ECU itself. I and a few others have experienced this, and it's usually not a component fault but a bad joint, cured by reflowing both PCB's in the ECU - by this I means go over the whole lot with a soldering iron and some fresh solder. It takes about an hour to do so not a bad job.
HiAfter checking and double-checking the coolant temp sensor sometimes it turns out that the fault is with the ECU itself. I and a few others have experienced this, and it's usually not a component fault but a bad joint, cured by reflowing both PCB's in the ECU - by this I means go over the whole lot with a soldering iron and some fresh solder. It takes about an hour to do so not a bad job.
Just to make it a bit clearer, the car would not run with the CTS connected at all, so once plug was removed and a link put in, the car would run even when hot but was very poor and as quote, i did smack the Ecu a few time and it did appear to make a difference, not alot, but it did, so i would agree that a re-solder on the ecu would be a good course of action, but i read you have try another???? good luck mate it drove me mad and i ended up ripping the lot out and am in the process of installing a carb set up, o and by the way i did fit a brand new coolant temp sensor.
Regards
Ralph
anything over 35psi on fuel pressure is sent back to tank, but must admit that the amount seeping past injectors shouldn't effect that much on tick over.
have tried disconnecting and shorting plug which does make it slightly better to start but not that great difference.
will try ecu trick but to be honest i have one that came with car and is very likely to be knackered due to car sitting under trapoling for 10 years but the other ecu i bought has been refurbed so would like to think its in good nick.
what i have noticed is that the new spark plugs have got black and sooty very quickly and the excess fuel is washing the bores and loosing compression so have to clean up plugs and introduce a small amount of oil to bores (common jaguar xk8 problem).
have tried disconnecting and shorting plug which does make it slightly better to start but not that great difference.
will try ecu trick but to be honest i have one that came with car and is very likely to be knackered due to car sitting under trapoling for 10 years but the other ecu i bought has been refurbed so would like to think its in good nick.
what i have noticed is that the new spark plugs have got black and sooty very quickly and the excess fuel is washing the bores and loosing compression so have to clean up plugs and introduce a small amount of oil to bores (common jaguar xk8 problem).
al 350i said:
the pressure then dropped to 10-15psi after around 20min but not through fuel return!
If you mean that you left the car stood for 20 mins and the fuel rail pressure had by then dropped to 10 psi, that's about right, I wouldn't suspect leaky injectors. They either dribble or don't: if they do, the rail goes dowm to zero psi in a minute or so.If you've recently bought the car and it's always been like this, I'd be wondering whether the previous owner had swapped the ECU for some random one off Ebay/ a mate/ an 'expert'. If it's just started then as Adam says, I'd be looking for dry solder joints in the ECU.
Wedg1e said:
If you mean that you left the car stood for 20 mins and the fuel rail pressure had by then dropped to 10 psi, that's about right, I wouldn't suspect leaky injectors. They either dribble or don't: if they do, the rail goes dowm to zero psi in a minute or so.
If you've recently bought the car and it's always been like this, I'd be wondering whether the previous owner had swapped the ECU for some random one off Ebay/ a mate/ an 'expert'. If it's just started then as Adam says, I'd be looking for dry solder joints in the ECU.
yes thats about what the injectors do, so sounds like they are ok. i've decided to start from scratch and take a more methodical approach and start checking all systems using help from http://www.vintagemodelairplane.com/index.html going to check ignition, fuel and air systems and make sure everything is working properly first. i think i've got caught up in try to make the problem more complicate than what it actual is!If you've recently bought the car and it's always been like this, I'd be wondering whether the previous owner had swapped the ECU for some random one off Ebay/ a mate/ an 'expert'. If it's just started then as Adam says, I'd be looking for dry solder joints in the ECU.
sorry should have said i've been restoring the car for the last couple of years and for 10 years before that was parked outside! the previous owner is a friend and only parked it up due to increasing family and not because it broke down. when i first got it i change the fluids plugs and bits and it did fire up and run not too bad although a test drive was not happening, i've then since stripped it and put it back together ............although from the sounds off it not the well!! lol
well checked ignition today, took me a while tracing wires back and finding out where they go and trying to get my head around how it all works, found some bad connections and a broken earth on a 3 pin plug in the back of the rev counter, having had dash binnacle in and out a few times already, i know that the white/yellow wire on plug sends power to coil. also checked continuity of wiring, fitted new amplifier and gave distributor a clean and spray of WD40. Pulled no.1 plug and used it to see what sort of spark i was getting (plug was very black and sooty so gave it a clean), no spark!! connected it to king lead on coil, no spark!! spent an hour checking the coil and what runs to it and came to conclusion that coil was knackered.............but then remembered that i had a brand new spark plug in the garage draws somewhere, think it was for a 2stoke bike but was new so tried that and hey presto got spark ...........so a trip down the local motor factors 8 new plugs, back home pull out and chuck old ones!!! the old plugs weren't that old and have hardly seen much use but engine is running so rich i think it just killed them.
next checked fuel supply and pressure, adjusted pressure to 36psi, checked resistance on temp sensor (2700 at 15 Celsius seemed ok) then stuck fully charged battery on cranked over and started but still over fueling!
so now time to look at air! so put multimeter on air flow meter and did not get very good resistance readings so will read up on checking it throughly, i also checked resistance on potentiometer and found that readings between red and green wires are ok but between yellow and green are 5000ohms not 500ohms so suspect to be faulty.
i pulled off air pipe that connects to back of plenum on what i think is the idle control valve and straight away the revs picked up and there was a distinct improvement, still not great but better.
conclusion so far then is that ignition is ok, fuel supply ok but ecu is receiving bulls
t from air meter and potentiometer so mixture is all out causing over fuelling!! so my question is can i get the afm refurbed, buy new/second hand or fit from another vehicle? its a flapper type lucas 2AM i've noticed these are also fitted to range rovers and jaguars can i use these?
next checked fuel supply and pressure, adjusted pressure to 36psi, checked resistance on temp sensor (2700 at 15 Celsius seemed ok) then stuck fully charged battery on cranked over and started but still over fueling!
so now time to look at air! so put multimeter on air flow meter and did not get very good resistance readings so will read up on checking it throughly, i also checked resistance on potentiometer and found that readings between red and green wires are ok but between yellow and green are 5000ohms not 500ohms so suspect to be faulty.
i pulled off air pipe that connects to back of plenum on what i think is the idle control valve and straight away the revs picked up and there was a distinct improvement, still not great but better.
conclusion so far then is that ignition is ok, fuel supply ok but ecu is receiving bulls
t from air meter and potentiometer so mixture is all out causing over fuelling!! so my question is can i get the afm refurbed, buy new/second hand or fit from another vehicle? its a flapper type lucas 2AM i've noticed these are also fitted to range rovers and jaguars can i use these? 
Dose you car have the 4cxu or the 4cx ecu.
You say the air flow meter is a flapper if so you shoudnt have a idle control valve. the bit at the back of the plenum on a flapper is an extra air valve and only open when the vacum increases on off throtal.
If its a flapper you can tell ny looking inside and seeing a silver flap you can move with your finger. You can open the top cover with a knife and check the carbon tracks, if that is causing a prob proberly due to wrong spring tention or poor contact. The flapper should tunned to the ecu and engine. If the car is over fueling at tick over and sounded better with more air getting in then you could manualy move the flap to see if the engine note changes.
it sounds like you are getting close to the end of the problems, narrowing the faults down is good.
Cambelt
You say the air flow meter is a flapper if so you shoudnt have a idle control valve. the bit at the back of the plenum on a flapper is an extra air valve and only open when the vacum increases on off throtal.
If its a flapper you can tell ny looking inside and seeing a silver flap you can move with your finger. You can open the top cover with a knife and check the carbon tracks, if that is causing a prob proberly due to wrong spring tention or poor contact. The flapper should tunned to the ecu and engine. If the car is over fueling at tick over and sounded better with more air getting in then you could manualy move the flap to see if the engine note changes.
it sounds like you are getting close to the end of the problems, narrowing the faults down is good.
Cambelt
al 350i said:
so now time to look at air! so put multimeter on air flow meter and did not get very good resistance readings so will read up on checking it throughly, i also checked resistance on potentiometer and found that readings between red and green wires are ok but between yellow and green are 5000ohms not 500ohms so suspect to be faulty.
i pulled off air pipe that connects to back of plenum on what i think is the idle control valve and straight away the revs picked up and there was a distinct improvement, still not great but better.
conclusion so far then is that ignition is ok, fuel supply ok but ecu is receiving bullst from air meter and potentiometer so mixture is all out causing over fuelling!! so my question is can i get the afm refurbed, buy new/second hand or fit from another vehicle? its a flapper type lucas 2AM i've noticed these are also fitted to range rovers and jaguars can i use these?
It's not an idle control valve, it's the over-run valve that admits air to the plenum under conditions of high manifold depression. i pulled off air pipe that connects to back of plenum on what i think is the idle control valve and straight away the revs picked up and there was a distinct improvement, still not great but better.
conclusion so far then is that ignition is ok, fuel supply ok but ecu is receiving bulls
t from air meter and potentiometer so mixture is all out causing over fuelling!! so my question is can i get the afm refurbed, buy new/second hand or fit from another vehicle? its a flapper type lucas 2AM i've noticed these are also fitted to range rovers and jaguars can i use these? The AFM used on some Jags is of a larger bore and although you can make it work if you're lucky/competent at setting-up, Mark Adams et al will tell you that it will tend to make the mixture lean. You certainly don't need one to get any more power from a 3.5L (or a 3.9 come to that) as the standard one can flow more than enough air (my 390 makes 256bhp and uses a standard 3.5L AFM).
Part of the problem with using one from another car is that all AFMs are calibrated slightly differently and were tuned by Lucas to match a given ECU... so although another MAY work better than the one you have, it may also be nowhere near the correct response for your engine.
If you could find a matched AFM and ECU, preferably from an SD1 rather than a RangeRover you might have a fighting chance of hitting the spot.
You really need to be absolutely certain of your resistance readings before you go off on a wild goose chase for AFMs; they tend to be pretty reliable unless monkeyed with (flap spring tension being the usual target).
Wedg1e said:
It's not an idle control valve, it's the over-run valve that admits air to the plenum under conditions of high manifold depression.
The AFM used on some Jags is of a larger bore and although you can make it work if you're lucky/competent at setting-up, Mark Adams et al will tell you that it will tend to make the mixture lean. You certainly don't need one to get any more power from a 3.5L (or a 3.9 come to that) as the standard one can flow more than enough air (my 390 makes 256bhp and uses a standard 3.5L AFM).
Part of the problem with using one from another car is that all AFMs are calibrated slightly differently and were tuned by Lucas to match a given ECU... so although another MAY work better than the one you have, it may also be nowhere near the correct response for your engine.
If you could find a matched AFM and ECU, preferably from an SD1 rather than a RangeRover you might have a fighting chance of hitting the spot.
You really need to be absolutely certain of your resistance readings before you go off on a wild goose chase for AFMs; they tend to be pretty reliable unless monkeyed with (flap spring tension being the usual target).
so more than man enough to run my 400! (must change profile name...350i was my first TVR and sold it a long time ago!!) i think you're right i need to investigate my AFM first, i can see silicone around the plastic cover so fear that said monkey has beaten me to it!! The AFM used on some Jags is of a larger bore and although you can make it work if you're lucky/competent at setting-up, Mark Adams et al will tell you that it will tend to make the mixture lean. You certainly don't need one to get any more power from a 3.5L (or a 3.9 come to that) as the standard one can flow more than enough air (my 390 makes 256bhp and uses a standard 3.5L AFM).
Part of the problem with using one from another car is that all AFMs are calibrated slightly differently and were tuned by Lucas to match a given ECU... so although another MAY work better than the one you have, it may also be nowhere near the correct response for your engine.
If you could find a matched AFM and ECU, preferably from an SD1 rather than a RangeRover you might have a fighting chance of hitting the spot.
You really need to be absolutely certain of your resistance readings before you go off on a wild goose chase for AFMs; they tend to be pretty reliable unless monkeyed with (flap spring tension being the usual target).
al 350i said:
got figures from vintagemodelplane, 5000ohms between red/green and 500ohms between yellow/green!
Best way to measure it is with it removed from the car, as its basic position will have the wiper part-way round the carbon track (may well be 500 Ohms in that case, you normally set it by the voltage it develops, not its resistance).Essentially you should have 5000 Ohms across the ends of the track which won't change irrespective of wiper position (check all three wires just in case the colours are wrong; I have seen it, some 'experts' overlook this). Then with the wiper at rest (it's spring-biased one way) you should see very low Ohms from the third wire to one, and pretty much 5000 Ohms to the other. These two figures then vary as you sweep the wiper through its range until you see more or less the reverse measurements (hope you follow, I'm a do-er, not a teacher). The usually-quoted problem is that the carbon track breaks up causing the wiper to randomly 'miss', thus sending erratic voltages to the ECU. The quickest way to rule out the pot is just to disconnect it: on the 4CU system it's only used to fine-tune the AFM information. The car will run quite well without it. Sometimes the leadout wires break (they're brittle at the best of times) and this'll give the same result.
al 350i said:
so more than man enough to run my 400! (must change profile name...350i was my first TVR and sold it a long time ago!!) i think you're right i need to investigate my AFM first, i can see silicone around the plastic cover so fear that said monkey has beaten me to it!!
What you need are the voltages from the AFM with the engine warm and running at idle. When you can't find the information from :cough: any other web resource, give me a shout and I'll tell you what it should be and how to achieve it.Some people are good at cribbing information from other (copyright) sources and rehashing it as their own but wouldn't know a multimeter from a TV remote
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