Flapper afm faulty ?
Discussion
Well I'm going to be stripping all of the flapper system off my car in the next month or so, there is everything from ECU through to plenum and manifold and flapper, most of the wiring too as I will be unpicking the loom. But I'm off on hols till 20th of July so won't be touching it till then.
wildoliver said:
Well I'm going to be stripping all of the flapper system off my car in the next month or so, there is everything from ECU through to plenum and manifold and flapper, most of the wiring too as I will be unpicking the loom. But I'm off on hols till 20th of July so won't be touching it till then.
First dibs on the parts please!!!! Looks like I may be needing various bits.Give me a shout once you're ready. I take it your going to carbs then. Keep us all posted with the conversion please I for one would be interested in the outcome Thanks Ron
Edited by Rockettvr on Tuesday 1st July 13:02
It's not the AFM !!!! Tried a replacement (cheers Smash) but am experiencing exactly the same symptoms as before ie: a massive flat spot at a couple of points on the rev range. Not sure which way to go now :- replace FPR or fuel pump. I'm tending toward doing the FPR first as it's a fault that I've had since buying the car ( over a year now)and would have thought if the pump was on its way out it would have failed totally by now
Any thoughts chaps ?
Thanks ron
Any thoughts chaps ?
Thanks ron
I'm not really sure why the suggestion that the TPS may be causing your symptoms, was rejected. A faulty unit has strange and varied symptoms depending upon whereabouts the track is worn. Likewise very common to see local connector corrosion and stressed/broken wires, thereabouts. A really simple test eliminates the possibilities.
Next in line, as AQ suggested, the FPR may be fluttering the fuel pressure when it's supposed to be more stable. Easy to test and inexpensive to replace.
Moving on, a small split in any of the Air Rail pipes can create intermittent power loss depending upon the state of the manifold vacuum. In the same vein, inlet manifold gasket, rocker cover gaskets and breather system all have to be at 100% integrity.
Going away from the Efi system, the ignition amplifier can show intermittent instability before it croaks, sometimes component failure but not always.
Its stability also relies upon a good thermal sink between its base and the mounting area, failure of the thermal paste can occur after about 60-80 k miles so worth dismounting and thoroughly clean both faces before remounting with the merest smear of new paste. ie - no globs.
The likewise failure mode can be caused by prior maintenance not following correct mounting procedure.
Not so likely but dead easy to test, a substitute known good ECU from any 'mates' car will do.
Next in line, as AQ suggested, the FPR may be fluttering the fuel pressure when it's supposed to be more stable. Easy to test and inexpensive to replace.
Moving on, a small split in any of the Air Rail pipes can create intermittent power loss depending upon the state of the manifold vacuum. In the same vein, inlet manifold gasket, rocker cover gaskets and breather system all have to be at 100% integrity.
Going away from the Efi system, the ignition amplifier can show intermittent instability before it croaks, sometimes component failure but not always.
Its stability also relies upon a good thermal sink between its base and the mounting area, failure of the thermal paste can occur after about 60-80 k miles so worth dismounting and thoroughly clean both faces before remounting with the merest smear of new paste. ie - no globs.
The likewise failure mode can be caused by prior maintenance not following correct mounting procedure.
Not so likely but dead easy to test, a substitute known good ECU from any 'mates' car will do.
Thanks for the input chaps.
Here's a quick summary and an idea of my train of thought :-
As said in the first post it's a problem with fuel mix leaning out at a couple of spots on the rev range so definitely not ignition related.
The fact that it occurs at specific points in the rev range- the rolling road guys ran it 3 times with the same result each time -made me think AFM but as mine tested ok ( bang on the resistances and voltages quoted in honest johns vintagemodelairplane ) and Smashs replacement didn't cure it I'm certain that that's not where the fault lies
Air leaks : all gaskets were replaced over the winter as a water pipe under the inlet manifold went. I also had the rocker covers off so replaced :
valley gasket
Rocker cover gaskets
Plenum to manifold gasket
Top plenum gasket
The fault was present before and after the work
If I had an air leak would I not have a lean mix throughout the rev range and more running issues ( hunting at idle etc) rather than a couple of lean spots at specific points ?
TPS: the rolling road test was carried out at WOT so TPS should not be an issue however I'm changing back to my original AFM later today so I'll do a check while there- I'll report back any issues found
Other than this the only things I can think of are
FPR : fluttering ?
Fuel pump : would have thought if this is failing it would lean out the mix at top end where demand is greatest ?
Ecu: bloody hope not !
Is my reasoning ok or am I a total dimwit and missing something bloody obvious ? Lol
Your comments please gents
Cheers Ron
Here's a quick summary and an idea of my train of thought :-
As said in the first post it's a problem with fuel mix leaning out at a couple of spots on the rev range so definitely not ignition related.
The fact that it occurs at specific points in the rev range- the rolling road guys ran it 3 times with the same result each time -made me think AFM but as mine tested ok ( bang on the resistances and voltages quoted in honest johns vintagemodelairplane ) and Smashs replacement didn't cure it I'm certain that that's not where the fault lies
Air leaks : all gaskets were replaced over the winter as a water pipe under the inlet manifold went. I also had the rocker covers off so replaced :
valley gasket
Rocker cover gaskets
Plenum to manifold gasket
Top plenum gasket
The fault was present before and after the work
If I had an air leak would I not have a lean mix throughout the rev range and more running issues ( hunting at idle etc) rather than a couple of lean spots at specific points ?
TPS: the rolling road test was carried out at WOT so TPS should not be an issue however I'm changing back to my original AFM later today so I'll do a check while there- I'll report back any issues found
Other than this the only things I can think of are
FPR : fluttering ?
Fuel pump : would have thought if this is failing it would lean out the mix at top end where demand is greatest ?
Ecu: bloody hope not !
Is my reasoning ok or am I a total dimwit and missing something bloody obvious ? Lol
Your comments please gents
Cheers Ron
honestjohntoo said:
I'm not really sure why the suggestion that the TPS may be causing your symptoms, was rejected.
Simple - because on the rolling road you stamp on the accelerator and hold it at full deflection. Usually the TPS fails in the middle of the track (where you're cruising with 1/3 throttle) and the end stops are still OK.adam quantrill said:
Simple - because on the rolling road you stamp on the accelerator and hold it at full deflection. Usually the TPS fails in the middle of the track (where you're cruising with 1/3 throttle) and the end stops are still OK.
Eeeeerrrrrrmmm - not in my case Adam. Tested my TPS - 0.325v at rest then smoothly rises in voltage until you get to 4/5 throttle 3.8v then the voltage collapses quite quickly down to about 0.8v at full throttle. I'm not 100% convinced this is the cause of my erratic fuelling as I still get the symptoms on part throttle but it's obviously not helpingmrzigazaga said:
How old is the fuel pump?...Mine was playing up for a couple of months before it packed up altogether and i use my Wedge as my main car..I was always under the impression that they either worked or fail...Obviously not the case...Ziga
Came with the car Zig and I've been running it for about 16 months - maybe 1500 milesThe fault was present when I bought the car - it's not got any worse in my time with it either
Bobby Shaftoe said:
Rockettvr said:
Eeeeerrrrrrmmm - 0.325v at rest then smoothly rises in voltage until you get to 4/5 throttle 3.8v then the voltage collapses quite quickly down to about 0.8v at full throttle. I'm not 100% convinced this is the cause of my erratic fuelling as I still get the symptoms on part throttle but it's obviously not helping
Err, that could be quite probably your entire problem. The ecu uses the throttle pot voltage for 2 things, when it detects a rate of change over a certain figure it triggers transient throttle enrichment, and more importantly it uses the full throttle voltage as a pulse width multiplier for high to wide open throttle. The air flap at full deflection on it's own won't give you enough fuel without the correct throttle pot voltage. It'd be bloody daft to write it off as not the source of your issues!
Rockettvr said:
Tested my TPS - 0.325v at rest then smoothly rises in voltage until you get to 4/5 throttle 3.8v then the voltage collapses quite quickly down to about 0.8v at full throttle. I'm not 100% convinced this is the cause of my erratic fuelling as I still get the symptoms on part throttle but it's obviously not helping
'obviously not helping' - Surprised that was overlooked?If the TPS (or its local wiring) is not faulty then my koks a kipper.
Having said that, the source of the 4.3v voltage is the ECU, so if I am to be kippered then the ECU is now in play if the source is collapsing.
Just goes to show - persistence pays eh?
If the test was done with the engine not running (as per usual) it would be unusual for the feed voltage to collapse as the ECU is fairly idle. Best to measure the not-ground wire to the TPS to double-check there is still 4.3V feeding in at all times when the pot is twiddled.
This one is looking like the red herrings are being kippered too ;^)
If the test was done with the engine not running (as per usual) it would be unusual for the feed voltage to collapse as the ECU is fairly idle. Best to measure the not-ground wire to the TPS to double-check there is still 4.3V feeding in at all times when the pot is twiddled.
This one is looking like the red herrings are being kippered too ;^)
Edited by adam quantrill on Monday 14th July 13:41
Morning chaps
May be talking at cross purposes here ?
The test I did was the one outlined in vintagemodelairplane ie:
Test between green and red wires on TPS I'm assuming this is the signal voltage that is sent to the ecu?
Starts at 0.325v at rest, slowly open throttle and voltage rises until 4/5 full throttle where I read 3.8v then as throttle opened further voltage drops away quite quickly until at WOT the meter reads about 0.8v.
Obviously this makes the ecu think I'm only on light throttle so buggering up the fuel/air mix.
However I'm not convinced this is the root cause of my problem as the symptoms of a big flat spot in the rev range occurs even when on part throttle ( when the pot is giving the correct signal voltage to the ecu )
The workings of the rover efi is a mystery to me so I bow to your greater knowledge of the effects of a faulty TPS but would have thought at part throttle I would not be having the problem ?
Anyhow will replace as it's fubared anyway and see what happens before looking elsewhere for the source of my issue
Thanks fellas
Ron
May be talking at cross purposes here ?
The test I did was the one outlined in vintagemodelairplane ie:
Test between green and red wires on TPS I'm assuming this is the signal voltage that is sent to the ecu?
Starts at 0.325v at rest, slowly open throttle and voltage rises until 4/5 full throttle where I read 3.8v then as throttle opened further voltage drops away quite quickly until at WOT the meter reads about 0.8v.
Obviously this makes the ecu think I'm only on light throttle so buggering up the fuel/air mix.
However I'm not convinced this is the root cause of my problem as the symptoms of a big flat spot in the rev range occurs even when on part throttle ( when the pot is giving the correct signal voltage to the ecu )
The workings of the rover efi is a mystery to me so I bow to your greater knowledge of the effects of a faulty TPS but would have thought at part throttle I would not be having the problem ?
Anyhow will replace as it's fubared anyway and see what happens before looking elsewhere for the source of my issue
Thanks fellas
Ron
Rockettvr said:
The workings of the rover efi is a mystery to me
With it's simplification and clarity aimed at the average RV8 Efi enthusiast plus your obvious enthusiasm and current knowledge you'll be amazed at how fast you will become your own expert!
Evening chaps
Well it looks like it was the TPS.
Nipped down to the diner on Sunday and borrowed Zigs spare. From there went down to TVR Service station Kent division (Chris's house) and we had a bit of a prod and poke. Anyway returned home and armed with honest johns guide to the efi system and some excellent advice from Chris and Zig set to and cleaned and checked connections, outputs and sprayed wd40 on all electrical bits ( AFM Ecu Power resistor, coolant temp sensor etc etc) tightened every clip on the intake and other air and fuel hoses, cleaned and adjusted the overrun valve, checked that the afm bypass was correctly set, cleaned the flame trap on the rocker cover (it was truly gunged up) and fitted and set up Zigs TPS.
Then the heavens opened and it pi55ed down.
Finally got a chance to have a run out earlier and it looks like (touch wood) that my hesitant acceleration is cured. The car pulled like a train nice and smoothly all the way through the rev range.
it also idles a lot better and where as before when I stamped on the loud pedal it would sometimes do a little cough before responding it seems that has gone too.
I am at the moment a happy bunny
Thanks to all for the help and suggestions particularly Chris (jack valliant) Zig and Smash for the loan of spare parts for elimination purposes.
Cheers all
Ron
Well it looks like it was the TPS.
Nipped down to the diner on Sunday and borrowed Zigs spare. From there went down to TVR Service station Kent division (Chris's house) and we had a bit of a prod and poke. Anyway returned home and armed with honest johns guide to the efi system and some excellent advice from Chris and Zig set to and cleaned and checked connections, outputs and sprayed wd40 on all electrical bits ( AFM Ecu Power resistor, coolant temp sensor etc etc) tightened every clip on the intake and other air and fuel hoses, cleaned and adjusted the overrun valve, checked that the afm bypass was correctly set, cleaned the flame trap on the rocker cover (it was truly gunged up) and fitted and set up Zigs TPS.
Then the heavens opened and it pi55ed down.
Finally got a chance to have a run out earlier and it looks like (touch wood) that my hesitant acceleration is cured. The car pulled like a train nice and smoothly all the way through the rev range.
it also idles a lot better and where as before when I stamped on the loud pedal it would sometimes do a little cough before responding it seems that has gone too. I am at the moment a happy bunny
Thanks to all for the help and suggestions particularly Chris (jack valliant) Zig and Smash for the loan of spare parts for elimination purposes.
Cheers all
Ron
Hi Ron...Glad to of helped mate...Out of interest did you changed the king lead?...If you did could you put the other one back on to see if that was the problem, Its always good when things get fixed but its nice to understand what actually was at fault...Far too often a load of bits get changed at once and the culprit is never found, It just helps to diagnose issues for others...Did you also clean out the mushroom breather on the N\S rocker cover...I sent you some filter foam so you can replace the crumbled remnants that was there..Cheers..Ziga
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