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Technical 1.2 8V - engine idle randomly stops/alternator load

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Technical 1.2 8V - engine idle randomly stops/alternator load

Diwiak

Diwiak

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Hi,

so new horse at home, and it definitely stand its name - new day-new problem :D,

now I cant solve cut outs at idle, happens random or when there is a electrical load - lights on, fan on, etc..,

running nice, holding 110 - 140kmh on motorway easily, has power in uphills, no overheating, good mpg, idle is holding steady 750rpm (engine sounds slow to me), and then suddenly stops after throttle release/changing to neutral/turning on lights, fan../randomly stops from idle.

Done so far/changed:
Oil + filters
Sparks plugs+leads
Alternator belt (due to regular service)
Before cat O2 sensor (Bosch) (sensor dead/engine light)
Cranskhaft sealing ring (oil leak)
Crankshaft sensor
TB insides cleaned, Idle stepper valve removed/cleaned, MAP sensor removed/cleaned
Battery/gearbox/body earth cleaned
ECU/sensors connectors cleaned (contact spray)
Battery charged/alternator measured
Using petrol injectors cleaner

Timing belt re set/tensioned properly, done Self-adaptation zero reset + phonic wheel reset.

Diagnosis shows no faults, I was measuring live data while driving and cant see any anomalies.


Ideas?? Thanks!
 
Last edited:
My first thought was the idle valve, but you appear to have addressed that one.

Next thought, is alternator seizing. Getting it off to have a good inspection is itself a challenge. If the problem can be replicated, does the problem occur if the alternator belt is removed? That'd help point at alternator or idle valve.

When electrical loads increase, the ECU should operate the idle valve to manage engine revs. You've ensured the valve is clean, can you check it actually moves when required?
 
Diwiak said:
Hi,

so new horse at home, and it definitely stand its name - new day-new problem :D,

now I cant solve cut outs at idle, happens random or when there is a electrical load - lights on, fan on, etc..,

running nice, holding 110 - 140kmh on motorway easily, has power in uphills, no overheating, good mpg, idle is holding steady 750rpm (engine sounds slow to me), and then suddenly stops after throttle release/changing to neutral/turning on lights, fan../randomly stops from idle.

Done so far/changed:
Oil + filters
Sparks plugs+leads
Alternator belt (due to regular service)
Before cat O2 sensor (Bosch) (sensor dead/engine light)
Cranskhaft sealing ring (oil leak)
Crankshaft sensor
TB insides cleaned, Idle stepper valve removed/cleaned, MAP sensor removed/cleaned
Battery/gearbox/body earth cleaned
ECU/sensors connectors cleaned (contact spray)
Battery charged/alternator measured
Using petrol injectors cleaner

Timing belt re set/tensioned properly, done Self-adaptation zero reset + phonic wheel reset.

Diagnosis shows no faults, I was measuring live data while driving and cant see any anomalies.


Ideas?? Thanks!
Click to expand...

I have the 16V. Mine idles at 900. I am assuming that is computer controlled because if you turn on the AC the engine revs increase before the AC pump clutch engages.

If you can give your ECU number it is possible a member can give you the 8V idle speed for the ECU
 
Thanks for replies,

so with alternator belt removed engine seems working..

Done:
Alternator remove, cleaned with brake cleaner inside-out, cleaned brushes/rotor, brushed and cleaned terminals and cables, loosen belt tension when mounted back.

It seems to be fine (not cutting out when turning lights on) for now, need more drive-testing, will let you know (now Iam using other car).

From eLearn proper idle speed need to be 750 +/- 50 rpm
 
Last edited:
Re: 1.2 8V - engine randomly stops/braking

So back again :(:( -

done so far
-cleaned TB earth
-disassembled/cleaned/greased Stepper motor
-new ignition switch (old one was making strange things sometimes)
-fuel pump cleaning, testing
-re-done timing belt tension, phonic wheel reassembled, zero-reset and phonic wheel learn

It is much much better now, but still randomly ocasionaly instantly stops when shifted to neutral - It will keep running 20 minutes in heavy traffic with instant brake/clutch with no problems holding steady idle rpm, than leaving motorway shifting to neutral from 2-3k rpm and it instantly die without warning.

Also and when hot and pressing brake hardly 2-3 times it stops almost everytime.

Attached diagnosis graph, videos. Graph is from Start-1/4 throttle-Pressing brake frequently-Engine dies-Start again... See strange stepper motor spike.

Any ideas??

Thanks




Brake servo test
https://streamable.com/xtvv0s

Fuel pump test
https://streamable.com/g6cd0h
 
Last edited:
Diwiak said:
No one..?? :(
One more question - Where could I find Throttle body and all the sensors within EPER catalogue?? Thanks
Click to expand...

hello,
Found the TB according to the tree path from attach (the link is so big..)

Few suggestions regarding a possible electrical issue:
- the other end of the ecu earth (on the TB) is in the starter motor area. So the earth link connection is: TB - starter motor - engine - gearbox - chassis (near battery) - the minus of battery. I provided a new earth directly from negative to the ECU bolt, just to be sure. The cable should be a serious one, like the main earth to gearbox, for example.

- if any serious load can reproduce the issue, the fuse boxe in the engine bay should be analysed. It contains the fuses and relees for engine injection, but also for the lights, the AC, the fans (passenger and radiator). If you don't find the diagrams, please let me know.

- i would investigate and repair any electric malfunction in the car, since the italian spaghetti are the best. The punto diagrams looks the same...

Good luck!
 

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Last edited:
It sounds like a heavy electrical load. A voltmeter would be a cheap way to watch what is going on and much easier to fit than an ammeter. A sudden load will creat a volt drop that you should see on the meter. If it's stopping with no effect on the system volts then it has a another cause.

A failing engine crank position sensor can randomly stop the engine - and it won't raise any OBD fault codes. Is it worse when the engine is hot?
 
Hi,

thank you all for your response and tips,

finally I got to new diagnostics, and its finally pointing somewhere??

U1600 - Unknown fault code (immo-electronic key not feasible)
U1602 - Unknown fault code (Can line error)
U1700 - Can network (NCM-NBC) - Intermittent (Engine ECU - Body ECU)

Power steering:
C1011 - Service battery
- Intermittent

Any ideas where to move next?? Body computer dying?? :(:(

So far:

-changed TB (incl. idle valve and throttle sensor-got cheap from scrapyard)
-additional earth cables-alternator side of engine, TB earthed to body
-connect another battery through jump leads - no change
-disconnected both front/rear lights
-tried to "wiggle" all cables/connectors in engine area when running
-charging keeps 13.7-14V, no drops (using multimeter), battery when stationary is keeping over 12V
-stalls MOSTLY when hot
(crankshaft sensor already changed (brand new DELPHI)

 
Last edited:
Check the body computer for damp.
Under the windscreen is a chamber that can fill with rain if the drains are blocked with dead leaves. It then overflows to the car interior, and has been known to flood over the body computer. Worth a look.
 
Thanks for response,

body computer looks brand-new, no signs of moisture/damage,

done till now:
-new battery (44Ah, 420A BOSCH)
-new breather hose
-new coil units
-new thermostat
-changed alternator (working, from scrap)
-measured RPM sensor - ECU connection (no resistance)
-reduced RPM sensor gap - sanding plastic sensor surface area some 0.5mm..

For now it seems to be definitely gone - driven daily last two weeks approx. 400miles city/regional road without single cut out, thanks for ideas, will let you know (y)
 
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