Flapper afm faulty ?
Discussion
Yes this old chestnut again....
At the fest yesterday I put the old girl in the RR and got a reasonable result (185Bhp). It also showed up a problem with the air/fuel ratio being all over he place through the rev range going lean in a few places- the top line in this graph
Thought possibly fuel starvation ( blocked filters, failing pump or faulty fuel pressure regulator ) but would have thought that would have given me a lean mix throughout the rev range or got progressively worse toward the top end as demand for fuel gets greatest - not at specific rpm(they did the run 3 times - same result ) This leads me to think that the AFM may be at fault.
Can it be tested to see if a fault exists ?
If there is a fault can it be repaired or do I just replace with another ?
Any other possible causes ?
Thanks In advance chaps
Ron
At the fest yesterday I put the old girl in the RR and got a reasonable result (185Bhp). It also showed up a problem with the air/fuel ratio being all over he place through the rev range going lean in a few places- the top line in this graph
Thought possibly fuel starvation ( blocked filters, failing pump or faulty fuel pressure regulator ) but would have thought that would have given me a lean mix throughout the rev range or got progressively worse toward the top end as demand for fuel gets greatest - not at specific rpm(they did the run 3 times - same result ) This leads me to think that the AFM may be at fault.
Can it be tested to see if a fault exists ?
If there is a fault can it be repaired or do I just replace with another ?
Any other possible causes ?
Thanks In advance chaps
Ron
Edited by Rockettvr on Sunday 8th June 12:24
Edited by Rockettvr on Sunday 8th June 12:26
smash said:
Ron - I've got my own spare and Stu's spare here at the mo. if you need
Cheers Smash. Gonna try a few tests on it during the week to see if anything obvious. I'll Let you know how I get on and if I need to borrow one to eliminate it as the cause I'll let you know. Thanks Ron
Ok- got round to testing the AFM and ........ all voltages and resistances are bang on the money ( used honest johns info on vintagemodelairplane ). It's clearly a fuel delivery problem and the fact that it occurs at specific rpm I would have put money on it being the afm. So where do I go from here ? Fuel pressure regulator? Fuel pump? Injectors ? Your Advice please 
Jack Valiant said:
Ron, I would be tempted to do some simple swap outs to find this type of fault, if you have done the flapper swap with a test drive under load then put your original back on and try another known good stock 4CX ECU and re-test. In my opinion cold voltage tests are all good but a drive with a known good item is far better and helps to localise the problem rather than the scatter gun effect! Given that the power looks good for a stock 350i and the AFR is all over the place I would go to the AFM and ECU as my first stop. I assume you have made sure that there is no air leaks any where first?
Chris
Hi Chris good to hear from youChris
Not swapped out the afm just did the static voltage and resistance tests as per honest johns website (vintagemodelairplane) as said all ok - in fact absolutely bang on the money. The voltage drop during opening the flap was smooth no peaks or troughs.
To be honest the fault is a little bit erratic - definitely worse sometimes than others, usually when cold it's at it's worse - other times it seems to disappear almost altogether.
May try to borrow the spare one smash has - at least that way I can rule the afm out as the cause for certain.
Gonna try to get down for the meet on Sunday - the run down to the bush would be a good opportunity to try it out
mrzigazaga said:
Ron...My fuel pump played up for weeks before it eventually failed...I was getting some really lean running..(White spark plug tips)...There were times when it would misfire or stall and start again whilst driving and then times it was fine...After a while it started to pop and bang on hard acceleration..Then it just failed....Ziga
Hi zigThink I'll try the afm swap first. It's an easy job and it'll eliminate it from the equation. If that fails I'll look at the pump and FPR next. As Chris said I think I need to be systematic in trouble shooting - don't want to be changing too many things at once it can just cloud things if a cure isn't forthcoming.
Cheers Ron
adam quantrill said:
My money is on the FPR. As the revs build up you will get different pressure in the plenum, it will be dropping slightly as the engine pulls air through the open throttle, the air filter and along the tube. As you get the dips at similar places in the rev range it could well be the FPR not sensing the drop in pressure and allowing the rail to build up too high a pressure.
Besides I though you had already tested the AFM and it was working?
Only static voltage and resistance tests Adam. my gut feeling is that its ok but thought if i swap it out with a known good AFM and the symptoms persist it rules out a faulty AFM 100%.Besides I though you had already tested the AFM and it was working?
My feeling is that its a supply pressure issue - so as Zig says weak/failing pump or as you say an iffy FPR but its the fact that it occurs at certain rpm which nags at me to think it maybe the AFM.
Efi is not a strong point of mine, and i'm just wondering if the TPS could be an issue if mal-adjusted or faulty? what symptoms would it cause?
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
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
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
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
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
mrzigazaga said:
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
No still running on my existing leads - they were cleaned and given a wipe with a bit if wd40. Will be changing though as they're past they're best. Cleaned the mushroom too - it was clear but as you say the foam was crumbling so I have put a bit of washing up sponge in as a temp.
Need to get a few more miles in to make sure all ok then I may try to get it back on a RR to see where my fueling is at.
Afternoon all
Resurrecting this thread as my old problem with erratic fueling (which never really went away) is back and worsening
Zig was kind enough the lend me his spare TPS which certainly helped but never quite cured the problem. I was never quite convinced that the TPS was the culprit in the first place, I felt it was a contributing factor but not the root cause.
In the past the car ran pretty well most of the time only on occasions holding back on acceleration particularly when cold and the effect lessening as the engine warmed. This is happening on a more and more regular basis.
I have rechecked most of the efi components as per honest johns website and all is pretty spot on leading me to feel it's a mechanical rather than electrical fault
My current train of thought is that the fuel pressure regulator is slowly failing and not holding pressure in the fuel rail?
So does anyone have a recommendation for a Fuel Pressure Regulator ? ( Or a good unused one laying around for beer tokens?)
I've done the usual *bay and google searches but there's a huge range out there from £20 to £150 so was looking for someone to point me in the right direction
It's for an 1987 flapper
Thanks peeps
Ron
Resurrecting this thread as my old problem with erratic fueling (which never really went away) is back and worsening
Zig was kind enough the lend me his spare TPS which certainly helped but never quite cured the problem. I was never quite convinced that the TPS was the culprit in the first place, I felt it was a contributing factor but not the root cause. In the past the car ran pretty well most of the time only on occasions holding back on acceleration particularly when cold and the effect lessening as the engine warmed. This is happening on a more and more regular basis.
I have rechecked most of the efi components as per honest johns website and all is pretty spot on leading me to feel it's a mechanical rather than electrical fault
My current train of thought is that the fuel pressure regulator is slowly failing and not holding pressure in the fuel rail?
So does anyone have a recommendation for a Fuel Pressure Regulator ? ( Or a good unused one laying around for beer tokens?)
I've done the usual *bay and google searches but there's a huge range out there from £20 to £150 so was looking for someone to point me in the right direction
It's for an 1987 flapper
Thanks peeps
Ron
Afternoon gents.
My running issues are solved. Found an FSE "powerboost" fuel pressure regulator up for sale locally - fitted it this afternoon. Upon start up there was an obvious improvement in the idle - super smooth where before it was like I had a very slight misfire. On the road it's transformed the running. There's no more "holding back" during acceleration and the pick up when putting my foot down is instantaneous - before it would sort of cough before accelerating. Happy days
There is one fly in the ointment in that it keeps cutting out when braking to a halt - I'm putting it down to the fact that the regulator is "as fitted" ie I'm not sure I'm running the correct pressure as it didn't come with a gauge - once I've been able to set it correctly I'm hoping it'll sort that little issue - there's no "fuelly" smell at the exhaust so I recon it's running lean rather than rich. also need to make a bracket and resite the valve at the moment it's held (very firmly) in with a couple of cable ties. It's safe but not a long term solution.
Cheers all for your inputs
Ron
My running issues are solved. Found an FSE "powerboost" fuel pressure regulator up for sale locally - fitted it this afternoon. Upon start up there was an obvious improvement in the idle - super smooth where before it was like I had a very slight misfire. On the road it's transformed the running. There's no more "holding back" during acceleration and the pick up when putting my foot down is instantaneous - before it would sort of cough before accelerating. Happy days
There is one fly in the ointment in that it keeps cutting out when braking to a halt - I'm putting it down to the fact that the regulator is "as fitted" ie I'm not sure I'm running the correct pressure as it didn't come with a gauge - once I've been able to set it correctly I'm hoping it'll sort that little issue - there's no "fuelly" smell at the exhaust so I recon it's running lean rather than rich. also need to make a bracket and resite the valve at the moment it's held (very firmly) in with a couple of cable ties. It's safe but not a long term solution.
Cheers all for your inputs
Ron
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