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I need a kind, generous JTD 20v owner...

5K views 76 replies 13 participants last post by  Smaky 
#1 ·
Somewhere in the south-Newbury-Salisbury-Southampton-Basingstoke kind of area, who would let me 'borrow' their ecu for 10 minutes...is this you?
Basically my car has the experts stumped-it won't start, drops into limp mode under load, and cuts out under acceleration. The 'fault' shown is fuel pressure, but the pump and injectors have been overhauled, and the regulator and pressure sensor substituted, many, many tests and experiments carried out....
So, I just wondered if there was anyone willing to let me try their ecu on my car-it's only a 10 minute job to swap it over, if it doesn't fix it, then it has saved me the time and expense of sending it away for testing. Will only cost me the price of the beer I will of course buy the kind generous person who helps me out.....:)
 
#4 ·
It's been with S&S Diesels for the last few weeks.
The high pressure pump was overhauled and if the pressure regulator is disconnected (and a second connected to the loom so the ecu 'sees' it) then unregulated fuel pressure is more (too much in fact) than sufficient.
Either something is telling the ecu to reduce or shut off fuel, or it's doing it itself :confused:
 
#10 ·
with the incorrect airflow reading then it may think thecorrect fuel pressure is a fault. Fickle things these 20V engines, I'm actully dealing with one now with the same symptoms as yours, just found that the crank/cam are 1 tooth out on the belt, hoping that correcting this will cure the problem.


The theory is that because the timing is out, the inlets are open slightly and pressurizing the inlet (the MAP is reading this) and this is then dropping the pressure in the cylinder meaning the fuel pressure (which is correct (tested flow and pressure) is too high, this high manifold px is also preventing the turbo from spinning up thus hesitation and lack of power.
 
#13 ·
alternatively when was the last time the fuel filter was changed? also have you taken some real time readings of the fuel pressure???
 
#17 ·
curiouser and curiouser...

filter is as correct as possible-same as the one I'd put on at a previous service.
Pump was removed, overhauled, refitted, removed and checked when symptoms still the same, refitted, removed and checked again...at which point I said enough. I think I also said earlier in this thread that testing the pump 'unregulated' there is more than adequate pressure.
Anyway, onto todays puzzling development.
As suggested by Smaky I have just removed and cleaned the EGR valve, which was a bit sooty but all free and functioning, so fairly sure that is not an issue. So, disconnected the MAF to see if that made a difference. Needed easystart to begin combustion, but after that, as before, would rev to the redline while sitting still, so went for a quick blast. Well, gave it some beans out the end of my road-fine. Down onto the ring road-loads of beans, fine, cruise control light stayed on (my indication that it hasn't dropped into limp mode) and plenty of power. Next roundabout (about a mile) as I accelerated around it-cruise light out, limp mode, floored accelerator, cut out. Tried a few more times on the way back (about 1 minute!) cutting out again.
So....how did disconnecting the MAF fix it for one minute??????
 
#18 ·
filter is as correct as possible-same as the one I'd put on at a previous service.
Pump was removed, overhauled, refitted, removed and checked when symptoms still the same, refitted, removed and checked again...at which point I said enough. I think I also said earlier in this thread that testing the pump 'unregulated' there is more than adequate pressure.
Anyway, onto todays puzzling development.
As suggested by Smaky I have just removed and cleaned the EGR valve, which was a bit sooty but all free and functioning, so fairly sure that is not an issue. So, disconnected the MAF to see if that made a difference. Needed easystart to begin combustion, but after that, as before, would rev to the redline while sitting still, so went for a quick blast. Well, gave it some beans out the end of my road-fine. Down onto the ring road-loads of beans, fine, cruise control light stayed on (my indication that it hasn't dropped into limp mode) and plenty of power. Next roundabout (about a mile) as I accelerated around it-cruise light out, limp mode, floored accelerator, cut out. Tried a few more times on the way back (about 1 minute!) cutting out again.
So....how did disconnecting the MAF fix it for one minute??????
so you did this all from cold with maf disconnected and once warm it played up?
 
#22 ·
I changed the coolant temp sensor as part of the 'attempting to fix' process-which made the temp gauge more sensible-running at 90-100 as opposed to 50-70, but made naff-all difference to the starting problem.
The limp mode/cutting out problem is a more recent development-did it a few times before it went in to S&S diesels, but is now doing it constantly...
 
#24 ·
My suggestion now would be to get it booked in with Adie at AHMotorsports for everything Alfa ... you seem to have changed most things and not got to the bottom of it ... best bet would be to get the best to have a look at it ... :thumbs:
 
#40 ·
:lol: I copy 'n' pasted your name ... but for some reason it included "realslimshady's avatar" :lol:
 
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