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Help - Chronic Flapper Overfuelling.


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Just as I thought things were going well...

The setup is new (recon) 3.9 with flapper efi. Stock ECU and AFM. The ignition system has dizzy with 2 wires (orange and purple) running to a black plastic box of tricks (amplifier?) next to the Bosch coil. 2 wires from the amplifier to the coil (+ and -). There is an earth on the amplifier that runs with the orange and purple that stops at the 3 way conector by the dizzy (i.e. - goes nowhere). Also connected to the coil is a wire running to a relay with a (IIRC 6.8k ohm) resitor in-line. The relay also has a Black, a white and a black/white that disappear into the loom.

I have new fuel tank with efi pump, tubes and filter.

Spliced into the injector wires is the LPG ECU. I assume this is to control the injector signal to kill them when on LPG (Direct Injection).

The problem is that more often than not when started, it runs really rich and lumpy and this will continue sometimes indefinately and sometimes it will sort itself out and run beautifully. I have tried to diagnose any specific time when it changes its mind and have drawn a blank. The only time I did notice a change to leaner running was when it was running out of fuel.

Once it is happy, it will stay happy when restarted until I leave it say overnight and then it will probably play up again, which lead me to suspect a coolant temp sensor issue.

When it does run smoothly, the revs rise slightly. It sometimes hesitates when the accelerator is pressed. It can also stall and be hard to restart for a few minutes.

I have checked Coolant temp sensor, cold start injector system, connections to the injectors, resistor pack, earths from the efi loom (rear of block), and drawn a blank so far.

Answers on a postcard please :D ...

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So it's over-fuelling, this can be several things;

1) Temperature sensor, if it thinks it's cold it will inject more fuel. There is the coolant temp sensor (NOT the cold start thermotime switch or the temperature gauge sender) on the front top of the inlet manifold, it's the sensor nearer the plenum mouth. There is also the inlet air temp sensor in the airflow meter but you can't change that, only the whole AFM.

2) AFM reading wrong - do they ever read right? :rolleyes:

3) Too much fuel - Fuel pressure too high due to broken regulator, or injectors leaking. Splice a clear inline fuel filter (£1 from the motor factors) on the return line from the regulator, you should see fuel returning through it at a decent flow especially at idle. Leaking injectors are harder to diagnose, you'd have to pull the fuel rail & injectors up so you can see the tips then run the fuel pump (poke the flapper so the pump runs) to see if they leak.

4) Dodgy ECU - if you can borrow a known good unit, try that. Better still, replace it with something not made by Lucas ;)

BTW the relay you mention (black, white, black/white wires) is a lucas bodge, it's connected to the pressure switch near the fuel pressure regulator and switches off the signal from the coil to the ECU on over-run. ECU thinks engine has stopped so stops injecting fuel. Obviously this lash-up was far better than putting a proper fuel map into it in the first place :rolleyes:

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OK, so...

1) Checked resistance and continuity - OK.

2) Pass, but assuming OK, cos when it runs right, it is fine. Could try a spare, but finding one that I know is OK maybe tricky.

3) This is where I am at the moment. Assuming injectors are OK as it will run nice and the chances of all blowing at the same time unlikely.

4) On the lookout, but again finding a known good one is not easy. I will ignore the second part of your suggestion :D.

Likely remaining suspects are fuel pressure, ECU and AFM in that order. Let's wait to hear back from HfH...

Cheers Fridge.

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If the coolant sensor is fine ……………. and the resistance actually checks out against the ambient temperature (that is very important) ……….. then it would seem that you have a very old fault that was once common to the 14CU ECU…………………the output pair of transistors get a bit tired and develop a collector /emitter leak thus causing much more fuel than is asked for to be injected………….. if they are the RCA18483 originals, then change them for a pair of BDX65B transistors.

If it is the ECU, then the other option is that the transistor are fine, but due to the continual expansion and contraction from the heat they produce, causes the soldered joints on the TO3 pins to fracture and become slightly high resistance ……… again this gives similar symptoms and can also cause running on 4 pots

My money is still on having a closer look at the coolant sensor…………. ;)

If you suspect the thermotime switch, then just disconnect the ninth injector, as that is all that it fires.

:)

Ian

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…………………the output pair of transistors get a bit tired and develop a collector /emitter leak thus causing much more fuel than is asked for to be injected………….. if they are the RCA18483 originals, then change them for a pair of BDX65B transistors.

If it is the ECU, then the other option is that the transistor are fine, but due to the continual expansion and contraction from the heat they produce, causes the soldered joints on the TO3 pins to fracture and become slightly high resistance ……… again this gives similar symptoms and can also cause running on 4 pots

Maybe I'll have another look at the coolant sensor then :blink::lol:.

I did check its resistance prior to firing up and it was in the correct range, so how could it then overfuel?

Definately not thermotime or 9th injector as I have done every check known to man on these (and disconnected it!).

PM also sent.

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Disconnect 9th Injector

CHANGE the CTS sensor, they do play up and I have had one where it seems ok on Multimeter, but problem disappeared on changing it :(

42 PSI IS FAR TO HIGH, why is it that high, and how are you meausring it (power on engine not running or engine tickover etc), it wants to be 35psi +/- a couple of PSI ...engine running ion tickover)

Then advise :

What are the spaerk plugs make type age and gap setting

Same for Dizzy is it genuine plus genuine rotor arm

What is the fuel pump type and is the PRV std in which case why is it 42PSI ?

Post up we can then move on a bit

I can honesty say I do not think a Ris Rate PRV is going to help (other than lowering the PSI)

Are you running Resisitor pack, and other than mass overfuelling does the engine fire on all cylinders ?...

Have you also a copy of the flapper EFI disgnostic manual I posted up on the forum ?

nige

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Tested CTS again today back to ECU, was OK. As you say, for the sake of a couple of quid I may just replace it anyway rather than mucking around with a pan of water!!

Not running 42psi at the moment. As per other post, it is a recognised fix (bodge) to increase fuel through injectors (i.e volume up 3.5 - 3.9, so fuel pressure up in same ratio). Waiting to hear back from the 2 people who have offered fuel regulators. (Were you insulted by my offer? :ph34r: )

I do have a diagnostic booklet, but please post the link to yours (never too many manuals).

About to go off and plunder a 110 someone is breaking in the village, so will check and answer other Q's either later or tomorrow am.

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Tested CTS again today back to ECU, was OK. As you say, for the sake of a couple of quid I may just replace it anyway rather than mucking around with a pan of water!!

Not running 42psi at the moment. As per other post, it is a recognised fix (bodge) to increase fuel through injectors (i.e volume up 3.5 - 3.9, so fuel pressure up in same ratio). Waiting to hear back from the 2 people who have offered fuel regulators. (Were you insulted by my offer? :ph34r: )

I do have a diagnostic booklet, but please post the link to yours (never too many manuals).

About to go off and plunder a 110 someone is breaking in the village, so will check and answer other Q's either later or tomorrow am.

http://forums.lr4x4.com/index.php?showtopic=16466

Here you go, thought I had aready done this obvious not, so have done now !

Not so much insulted as I do not think you need it, the 3.9 will be fine with 3.5 injectors without going to 42 PSI, at this pressure they can dribble when they are supposed to be closed and then you have all sorts of problems.

Can you clarify my prev Qs re dizzy leads plugs resistor packs etc etc ?

Nige

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I have to say I'm with Fridge on the Megasquirt suggestion, having spent many frustrating hours playing hunt the fault on my old Range Rovers hotwire system - eventually I got hacked off enough to hook up the Megasquirt that was already running the ignition and it's been no trouble since (plus I could see straight away where the intermittent problem was, by driving round with a laptop displaying the sensor readouts).

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Not running 42psi at the moment. As per other post, it is a recognised fix (bodge) to increase fuel through injectors (i.e volume up 3.5 - 3.9, so fuel pressure up in same ratio). Waiting to hear back from the 2 people who have offered fuel regulators. (Were you insulted by my offer? :ph34r: )

I'll say this loud: You do not need to up the fuel pressure to run 3.5 EFi on a 3.9

It is a Mass-airflow system and hence will inject fuel in the correct proportion to the amount of air your engine ingests. I ran 3.5 EFi on my 3.9 for years with no problem whatsoever.

Admittedly only two weeks of that was on flapper before I MegaSquirted it though :P

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Plundering over - until Saturday :D

Really appreciate this help guys. Hopefully all answered below:

1) I dented the current pressure valve getting it off, so I DO need another known good 'un. Happy if it runs at standard pressure. The aftermarket adjustables you guys were selling just looked more substantially built.

2) The following were all new under 1k miles ago when engine installed in previous RR. Plugs are Champion N12YC (gap 0.75mm). Leads are 7mm double silicone RFI suppressed ISO 3808 Class F. Dizzy cap is blue, not sure if OE (the contacts are completely recessed in the moulding, I also have another where the contacts are proud of the moulding). Rotor arm unknown, but have swapped with a spare and makes no difference.

3) Yes, I am running a resistor pack.

4) Is it running on all cylinders? Good question, when running rich it is juddery which would lead me to suggest not, but could this be a side effect of the fuelling? Any clever tests as I don't have proper ignition diagnostic kit. When running normally, smooth as a smooth thing. In both cases the AFM seems to be fine as it responds promptly to accelerator position (albeit a bit hesitant on rich running).

4) MS is an option down the line, but I have done and have enough to do without adding to the list :lol:. I want to get this thing Mot'd.

5) Manuals look great. They are different to the ones I have, so will see if there are some hidden gems.

So far on the shopping list is a coolant temp sensor and fuel regulator.

Cheers.

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1) I dented the current pressure valve getting it off, so I DO need another known good 'un. Happy if it runs at standard pressure. The aftermarket adjustables you guys were selling just looked more substantially built.

Erm "Denting it" won't have helped :) this is the way that the clever tuners get more pressure by squeezing the PRV in a vice, can you / have you measured the pressure on the ful in pipe to the RR with the engine running ?

2) The following were all new under 1k miles ago when engine installed in previous RR. Plugs are Champion N12YC (gap 0.75mm).

They may be new but please absolutely definately throw them away, buy and fit a set of NGK BP6RES or BP6ES, the R is only the resistor bit for radios and teles :lol:

Leads are 7mm double silicone RFI suppressed ISO 3808 Class F.

Sounds impressive, but I would again suggest you go buy a set of genuine leads, they are the right length and are damned good quality, leads can and have plaqued V8s for a long time - new or not....ask me how I know :rolleyes:

Dizzy cap is blue, not sure if OE (the contacts are completely recessed in the moulding, I also have another where the contacts are proud of the moulding). Rotor arm unknown, but have swapped with a spare and makes no difference.

If it isn't genuine it really needs to be, I have a spare Dizzy cap (genuine) plus all the leads and a rotor arm, you are welcome to borrow them

non genuine stuff is often dreadfull, mix with wrong plugs (and champions are one of the worst culprits don't know why but V8s often just do not like them) :blink: and "OK" leads and hey presto..... if not this at kleast we will know the bits are 101%

3) Yes, I am running a resistor pack.

I have a spare you can try

4) Is it running on all cylinders? Good question, when running rich it is juddery which would lead me to suggest not, but could this be a side effect of the fuelling? Any clever tests as I don't have proper ignition diagnostic kit. When running normally, smooth as a smooth thing. In both cases the AFM seems to be fine as it responds promptly to accelerator position (albeit a bit hesitant on rich running).

4) MS is an option down the line, but I have done and have enough to do without adding to the list :lol:. I want to get this thing Mot'd.

5) Manuals look great. They are different to the ones I have, so will see if there are some hidden gems.

So far on the shopping list is a coolant temp sensor and fuel regulator.

CTS absolutely and make sure its genuine, about £12 IRRC, you can borrow the Fuel reg off me SOR

Nige

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In both cases the AFM seems to be fine as it responds promptly to accelerator position (albeit a bit hesitant on rich running).

The AFM doesn't respond to throttle position, that's the job of the throttle position sensor ;) on the side of the plenum, I'd explain about it but it's all in those manuals Nige posted so work through those and see how you get on.

I may have a spare flapper ECU and AFM somewhere, no guarantees but they did function on the RR until I squirted it :D notice a pattern emerging? :P

BTW I see you're in Chichester, if you're really stumped on something I'm not a million miles from you and I have a collection of multimeters and hammers :rolleyes:

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Right, now armed with even more info, offers of bits etc. etc I have no excuse :lol:.

Will do some more homework, try out some new bits one at a time, start at chapter 1 and work through it.

Did someone mention that there was an alternative efi control system :hysterical:

Hopefully report back in the next few days.

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Ok, having got some replacement bits from a v. kind Mr. Hybrid, I have this morning completed the following.

1) Replaced (rubbish plastic snapped in half when tried to undo it) CTS with a nice all metal Bosch CTS.

2) Replaced Fuel regulator with used Lucas part.

3) Checked TDC and realigned dizzy so No. 1 is at 4 o'clock.

4) Replaced rotor arm, dizzy cap and leads with Lucas/LR genuine.

Pushed the go button and she fired up beautifully and ran well until... she warmed up (about the time the thermostat opened / EAV valve closed), suddenly the idle speed dropped to almost dead and started running rich and smoky (although nothing like as bad as before) and a bit lumpy.

So, tried to adjust idle speed using the plenum hex screw. Undid about an extra threequarters of a turn which improved idle speed slightly.

The similar hex adjuster on the AFM was out 8 or 9 turns (!), so reset this to provisional 2.5 turns (made little difference).

Checked voltage and resistance tests on AFM which all read OK (pretty much bang on). Throttle potentiometer slightly low, so adjusted to correct.

My thoughts are that she is probably running slightly rich during warm up, but not visibly so, then when the EAV shuts, it cuts of enough air to rich the mixture too much, so next steps:

1) Coil - will try replacement to get a bit more bang to burn (less drastic first step).

2) AFM adjustment. This is now my prime suspect. Someone has had the top off this and god knows what they have done (I have my suspicions :blink: ), so will try my spare and see what happens and/or adjust it's spring (having marked where I started from!) to see if it makes a difference.

3) Fuel pressure (will check). But unlikely as OK until warms up.

4) Timing maybe slightly out, but again shouldn't make too much difference.

Any other bright ideas? I think the key is the fact that, certainly this time, it is fine until warm.

Hopefully I can duplicate this tomorrow and at least I then have a constant to work to. Need to take kids to the beach this pm :) .

So, a step in the right direction me thinks.

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You're going to love this...

Went out this morning and having leaned (clockwise) the AFM spring 3 notches, started her up. Running rich and lumpy from the start, so I disconnected the ECU for a couple of minutes (thinking this may reset it?), started again and it improved slightly.

Once warmed up (about the same as yesteday ie. thermostat just opening), suddenly sprung into normal life (the opposite to yesterday) - idle revs rose and smoke disappeared, but every now and again, the revs drop to almost stall and then pick up again after a blip or two on the throttle.

The fault does seem both temperature related and erratic, so I assume adding the ECU as a serious contender now could be justified (as per BBC above).

Nige, forgot to mention yesterday, I did change the plugs to the NGK's in the first set of mods. Don't think timing is far enough out to cause this amount of fluctuation. [EDIT] Just played around - it does make quite a lot of difference to the smoke ;), so will check timing and sort out the vacuum unit before anything more drastic [END EDIT]

Vehicle has no MOT at the moment, so any sensible 'blast' not really on the cards.

Shopping list (or loaners - pretty please :D ):

AFM

ECU

Distributor vacuum unit.

Timing Light

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Alistair,

Been thinking :huh: .............

Couple of More thoughts.

1 - Have you got the adjustable Throttle Pos Sensor (Think you will have), if so check the settings for .325, AND get someone to then sqeeze the throttle gently to full travel and back again (Enhine off :) ), and note if the readings SMOOTHLY go up and then back down. Big jumps = knackered TPS, if not at .325 all sorts of issues.

2. Butterfly in Plenum, should have 19 thou extra at the top vs the bottom

3. Once you have No 2 right then set the tickover, loosen the throttle cable and use the screw or allen bolt to the back of the plemum air entry, there may be a blanking plug in this is so remove with screwdriver :), then set tickover

4. Go and Buy a bottle of FORTE Injector cleaner add to about half a tank, if your tank is full add 2, if 1/3 thats good for a bottle !

5. Check PRV and Vacumn hoses for clean ends without splits (ie air leaks), similarly the rest of the air hoses whizzing around the plenum area.

6. Check the earths on the back of the passenger head at the back, remove clean up with emery and refit, also earths from engine to chassis and Battery to chassis, EFIs do NOT like poor earths

Keep us up to date !

Nige

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Now have my shiny new timing lamp. So...

On what it claims to be TDC, which looks about right (regards to rotor arm), the smoke and stench of neat petrol is unbelievable.

It is when I retard the ignition (turn dizzy clockwise), the level of smoke reduces quite considerably, but starts popping.

However, as I turn the dizzy back to TDC from the low smoke (retarded - I am feeling a bit this way :lol:) position, the revs do rise as the smoke returns.

Have also replaced the AFM with another one I have (albeit condition unknown), but makes no difference.

In answer to your thoughts Nige:

1) Throttle Potentiometer - Done this check twice, but happy to change it and try.

2) Throttle Butterfly - Not tested this (what's 19 thou in Euro speak?)

3) Air By pass valve - I have done this but the idle speed varies so considerably, it is hard to pinpoint a setting (so left it at default 4.5 turns out)

4) Forte Snake Oil ;) - This needs more than a bit of injector cleaner. But point taken and will be on the list as soon as some semblance of normality returns.

5) Air/ Vacuum Hoses - Done. Most are new.

6) Earths - Will redo again.

My vote is now completely ECU (everything else is new or changed - apart from dizzy). Let's see if I can get my paws on one.

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ERM

I may be reading this wrong but :o

You don't set the timuing at TDC.

You set it at around (I'll either get corrected or look it up) at 800 rpm and 6 degrees BTC, mark the pulley at 6 degress with some white hammerite / tippex etc, clean it 1st and you will see the marks, then with the timing light on you then want the 6 degree mark to disappear under the timer blade which sticks out across the surface of the pulley ?

Injector cleaner incase you have a sticky injector not closing 100% as it should :(

nige

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Nige - some EFi's are specced to be set at TDC. See the thread about my dad's one when I swapped the dizzy, I have currently set it as close as I can get the dizzy to go - 3deg BTDC - as it was pinking at 6deg and blummin' afwul at 8-9deg.

God knows if it's actually right for the new dizzy :rolleyes: if I could afford it I'd have EDIS'ed it ages ago and have done :angry:

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I also recall that Flapper is set to TDC (will double check). Anyhow it's only retarding it that reduces the smoke (seems wierd - maybe the fuel is just pouring through neat). My timing light allows advance to be set on it (slick eh!) and I did try around the 6ish mark, but made little as no difference. Plus, I can't even get it to idle at one speed - ranges from next to 0 to about 1500 rpm without touching it (The Prince of Darkness at work).

Only other thing, having spent another 4 hours on it, is the LPG system screwing things up (done by Hants Auto gas). Its only link with the main EFI system is splicing into the injector wires. I have checked them all for continuity (just in case some bozo mixed them up) and also done the voltage drop test via the injectors to earth. This test should only show a difference of .5v max from battery voltage, I have about .65v, which I assume is the extra wire length to the LPG ECU. Unfortunately, I can't do the resistance test as the ignition needs to be off and the LPG ECU only seems to complete the circuit when it gets the ignition on signal from the injector wires.

Only other test I thought of to do on the LPG ECU was to test voltage in and voltage out (via earth?). This could be a complete red herring test as my recollection of circuitry from Physics is waning. Anyhow volts in OK but volts out (in series on 'an' earth wire) was around 9.3v. Thinks - does this just mean that there is another circuit earth?

Money still on EFI ECU.

(Still taking the Megasquirt pills - they may kick in soon - hopefully before I find my 'Special Occasion' Hammer :lol: )

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Put new (well the one from previous engine) dizzy on this morning. Started up and ran like a peach... for a while.

I had a voltmeter on the throttle potentiometer (as not changed this) and the timing gun on it (running at both TDC and 6 BTDC). Both of these were rock steady as it started to play up. Not too badly during this first run though.

Just been back this afternoon and running like a dog again. Interesting is that the only thing that could have changed since yesterday is the fact that I disconnected the battery overnight and it has now 'warmed up' and gone faulty again.

150% sure ECU is toast now :angry: ... nothing else left... off to the classifieds board.

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