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XF EFI (sort of) intermittent engine fault n erratic dash

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Hi all , have an intermittent fault 

 XF EFI 4 speed sort of late ECU etc, but does it on XF system too.

Is doing my head in, car runs fine then goes to hell no throttle take up misses etc which also causes the XF Fairmont digital cluster speedo and taco to jump all over the place.

running out of things to try  anyone encountered this ?

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Hi all , have an intermittent fault 
 XF EFI 4 speed sort of late ECU etc, but does it on XF system too.
Is doing my head in, car runs fine then goes to hell no throttle take up misses etc which also causes the XF Fairmont digital cluster speedo and taco to jump all over the place.
running out of things to try  anyone encountered this ?
Have you tried testing or replacing the TFI module on the side of the dizzy?
It may even be the heatsink paste is old and buggered and just needs old stuff scrapped off and new coating put on.

Just be careful with the module, it doesn't pull off, after you undo the 2 screws, slide it downwards to disengage the connectors, if you pull it straight from the side you will break the connectors internally.
Heatsink paste is Dow Corning 340

Try that, sounds like it's ok until it heats up.

Sent from my S21 using Tapatalk

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1 minute ago, Outback Jack said:

Have you tried testing or replacing the TFI module on the side of the dizzy?
It may even be the heatsink paste is old and buggered and just needs old stuff scrapped off and new coating put on.

Just be careful with the module, it doesn't pull off, after you undo the 2 screws, slide it downwards to disengage the connectors, if you pull it straight from the side you will break the connectors internally.
Heatsink paste is Dow Corning 340

Try that, sounds like it's ok until it heats up.

Sent from my S21 using Tapatalk
 

Would that cause the dash to jump all over the place ?

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gone over the earths even tinned the 6 wires that were going to one above rh headlight n soldered to the one larger connector didn't fix  fault, but passenger power window goes up n down at speed now lol.

found my paste now just got to get tfi off new ea dizzy haven't got around to striped a screw its always something. 

 

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1 hour ago, STARK said:

Would that cause the dash to jump all over the place ?

 

those clusters can get a jumpy fault due to bad connections inside, i've fixed a few back 15yrs ago. 

they can get a tarnish/oxidizing on the pins joining the boards and dry/cracked joints.. this may be unrelated to the running of the engine. 

 

i'd have said earths or connections  first also.. seems you have it sussed.. the dash earths are common to have bad connections(where the ECU lives and i think the drivers side has one also? ) 

engine to body earth is very important. 

other than that, 
air flow meters could be troublesome 20yrs ago, 

TFi, Coil, worn bushes in the dissy, worn timing chain.. all factors on EFI crossflows, even air leaks such as dipsticks etc are issues (IAC idle air controller valves could be gunked up)

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2 minutes ago, deankdx said:

 

those clusters can get a jumpy fault due to bad connections inside, i've fixed a few back 15yrs ago. 

they can get a tarnish/oxidizing on the pins joining the boards and dry/cracked joints.. this may be unrelated to the running of the engine. 

 

i'd have said earths or connections  first also.. seems you have it sussed.. the dash earths are common to have bad connections(where the ECU lives and i think the drivers side has one also? ) 

engine to body earth is very important. 

other than that, 
air flow meters could be troublesome 20yrs ago, 

TFi, Coil, worn bushes in the dissy, worn timing chain.. all factors on EFI crossflows, even air leaks such as dipsticks etc are issues (IAC idle air controller valves could be gunked up)

just swapped out tfi might try cluster swap next ran extra earths got EA setup on atm but same fault XF system ,so no airflow meter on atm new timing chain new EA coil inkectors etc do have IAC disconnected ATM till work out what works in reverse from XF to EA means lol 

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5 minutes ago, STARK said:

do have IAC disconnected ATM till work out what works in reverse from XF to EA means lol 

@Panko explained it's(XF IAC) normally open(or closed, can't remember) and in an E series it's normally closed(or open, opposite/reverse) 

so he made a bracket and ran the hoses a different way. 

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1 minute ago, deankdx said:

@Panko explained it's(XF IAC) normally open(or closed, can't remember) and in an E series it's normally closed(or open, opposite/reverse) 

so he made a bracket and ran the hoses a different way. 

cool miss Xfalcon assume normally opened/ closed would be electric side  of things ? have a late throttle body with IAC mounted to it just haven't got there yet lol.

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5 hours ago, STARK said:

cool miss Xfalcon assume normally opened/ closed would be electric side  of things ? have a late throttle body with IAC mounted to it just haven't got there yet lol.

What car are You putting this late model TB in? 
 

i looked at doing this, but on a crossflow in an X series, the bonnet will not shut. 

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10 hours ago, STARK said:

Hi all , have an intermittent fault 

 XF EFI 4 speed sort of late ECU etc, but does it on XF system too.

Is doing my head in, car runs fine then goes to hell no throttle take up misses etc which also causes the XF Fairmont digital cluster speedo and taco to jump all over the place.

running out of things to try  anyone encountered this ?

 

9 hours ago, Outback Jack said:

It would cause the tacho to be erratic.
Not sure about the speedo.
Bad earths usually cause instruments jumping around.

 

The only two things which can realistically cause issues like that, is either AC Ripple interference from bad diodes in the alternator rectifier,

(both the Speedometer (transducer) and Tacho (distributor PIP hall sensor) are AC reluctance sensors - ie, they generate a small AC voltage)

 

or a high resistance connection -

a positive or earth connection, common to both the speedometer, tachometer/distributor/coil.

ie, you're losing supply for minuscule amounts of time.

 

Main power relays near the brake booster can fail as they warm up.

 

Don't play swaptronics, look for commonalities between the affected components -

Speedometer/Transducer, Tachometer/Distributor/Coil

 

Is there any pattern to the problem occurrences?

ie, after x amount of run-time, or only in hot/cold weather, etc.

 

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21 hours ago, Panko said:

What car are You putting this late model TB in? 
 

i looked at doing this, but on a crossflow in an X series, the bonnet will not shut. 

picked one up was a scrap pile at at wreckers 94da manifold no idea what model its out of $15 plugs r different  but looks smaller than ea one still thinking about custom bonnet scoop/airbox. 

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19 hours ago, SPArKy_Dave said:

 

 

The only two things which can realistically cause issues like that, is either AC Ripple interference from bad diodes in the alternator rectifier,

(both the Speedometer (transducer) and Tacho (distributor PIP hall sensor) are AC reluctance sensors - ie, they generate a small AC voltage)

 

or a high resistance connection -

a positive or earth connection, common to both the speedometer, tachometer/distributor/coil.

ie, you're losing supply for minuscule amounts of time.

 

Main power relays near the brake booster can fail as they warm up.

 

Don't play swaptronics, look for commonalities between the affected components -

Speedometer/Transducer, Tachometer/Distributor/Coil

 

Is there any pattern to the problem occurrences?

ie, after x amount of run-time, or only in hot/cold weather, etc.

 

 

19 hours ago, SPArKy_Dave said:

 

 

The only two things which can realistically cause issues like that, is either AC Ripple interference from bad diodes in the alternator rectifier,

(both the Speedometer (transducer) and Tacho (distributor PIP hall sensor) are AC reluctance sensors - ie, they generate a small AC voltage)

 

or a high resistance connection -

a positive or earth connection, common to both the speedometer, tachometer/distributor/coil.

ie, you're losing supply for minuscule amounts of time.

 

Main power relays near the brake booster can fail as they warm up.

 

Don't play swaptronics, look for commonalities between the affected components -

Speedometer/Transducer, Tachometer/Distributor/Coil

 

Is there any pattern to the problem occurrences?

ie, after x amount of run-time, or only in hot/cold weather, etc.

 

 

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update still haven't changed tfi one from new dizzy wouldn't star.t  went to car club  meeting played up on way in to town late arvo but coming home cold nite ran perfect

 

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2 hours ago, Outback Jack said:

And everyone thinks I'm a dumb arse.
Glad you got it sorted mate.

 

Nobody thinks that mate! 😮

The info in your rebuild thread, is invaluable to anyone who reads it. 👍

 

In other thoughts,

I wonder how a dodgy TFI module, could affect the Speedometer reading too?

 

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Nobody thinks that mate!
The info in your rebuild thread, is invaluable to anyone who reads it.
 
In other thoughts,
I wonder how a dodgy TFI module, could affect the Speedometer reading too?
 
Haha. Cheers Sparky.
I think it maybe affecting the ground circuit in the instrument cluster, they must share a common earth.
I think the TFI module shorting or lifting it's earth, as the tacho signal has no Earth in its circuit until the cluster.
Don't quote me on this though it's just a theory at the moment.

Sent from my S21 using Tapatalk

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24 minutes ago, Outback Jack said:

I think it maybe affecting the ground circuit in the instrument cluster, they must share a common earth.
I think the TFI module shorting or lifting it's earth, as the tacho signal has no Earth in its circuit until the cluster.
 

 

Could quite likely be right.

The Tacho reads the pulses, generated by the coil negative/ground wire.

In other words, it's duty-cycle controlled?

 

I guess one would have to draw up a wiring diagram just for the two affected gauges,

and try to map things out?

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