Car starts and idles fine, car drives ok, if given highish revs the car seem to stall MCSF and EML come on for about 3-5secs engine revs drop and once they do engine returns to normal and continues to drive ok but this can happen often during the journey...
Whilst on the drive with AlfaDiag connected i can replicate the fault by reving the car above 3500rpm MCSF and EML on and AlfaDiag loses connection with the ECU when reconnecting there are NO fault codes...
My suspicions are a loose or poor conection or ground, crappy TDC sensor or a relay in front of battery... What do you guys think?
Thought as it only seems to occur over 3500 rpm that i might be timing related i tried just unplugging the variator solinoid and didnt solve the issue... its an odd one this...
i would disconnect battery as in ecu reset touch pos and neg together disconnect maf go for drive,see if problem still there
is symton regardless of foot position on pedal
I have a similar issue with my 147, cruising on the motorway at around 3500-4000rpm and the MCSF beeps and the engine light comes on but there is no change in performance like you describe. The engine light will go out after 4-5 restarts.
When it was serviced they read the ECU but there were no faults recorded. Last time the engine light came on I had a read on here and got myself a copy of fiatecuscan and it turns out the codes relate to misfiring in cyclinders 2 and 3.
Going to check my plugs/leads this weekend and perhaps get some replacements.
Check that the brown earth wire next to the ECU is secure and making a good connection, as well as the main earths on the n/s of the inlet manifold.
Also make sure that the ECU casing is properly earthed (ie check that its' mounting nuts are tight).
From your description of the fault and the video, it seems that the ECU is momentarily losing power (or its earth connection). If you have a bad connection, the fault will occur at specific engine revs due to vibrations (resonance).
I will check the earths on the ECU i have already checked the other earths all are good, my thinking is that it only occurs over 3000rpm and that it can occur at anytime after 3000rpm.
I'm still leading to the CAM sensor but will cover all bases before spending money on sensors... It does seem odd that it look like the ECU's power is dropping out...
Whilst on the drive with AlfaDiag connected i can replicate the fault by reving the car above 3500rpm MCSF and EML on and AlfaDiag loses connection with the ECU when reconnecting there are NO fault codes...
I still havnt done anything with this yet but its only happening when the car is really warm or up to temp... I'm almost 100% sure that its the CAM sensor but due to lack of funds and the fact that to change the sensor i'll need to at minimum change the belt i'll be sorting this out at the end of the month, i know the cam belt was done less than 12 or 15k miles ago and the variator has started rattling so i might as well do the lot...
Update: soldered connector behind the ECU (10pin) and fault is no better if not worse, its started to occur at much lower rev's now. The plan is still to change the CAM Sensor but i'm not so confident now. Will update again once i've found time to do sensor.
Ok need some advice if i had hair i'd be pulling it out now, i just cant convince myself that its the CAM sensor... I've had fiatECUscan on it this morning and its a 7.3.1 ecu for sure, is there meant to be a difference in values on the two throttle pot tracks?
I'm considering another theory in the throttle connector on the bulk head behind the lefthand side of the inlet manifold...ideas please if i have to solder it it going to be a pain in the ***
Anyway to finish this tail i fixed it with some fine guidance (cheers)...
After i had pulled the CAM belt off changed the variator (it need doing anyway) and inspected the CAM Sensor it was pysically ok no signs of damage, so i but it back togther and test drove. Great its fixed, Nope went out later and still not right but this time i noticed that not only was the REV counter droping but also the TEMP Gauge too, this had to be wiring, so i started the car and began to wiggle wires low and behold the fault occured at idle with me wiggling wires. The ground on the back of the head was loose, i had checked it was tight before and the nut was but the crimp underneath was loose...
I feel this was a distrbance fault from when i changed the Rocker cover gasket after the pipe split... Thanks for the input guys...
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