Hi, my 855 '95 T5 (manual) has one problem, which occurs sometimes. The issue is that while driving (no matter what rpm, while driving or while standing and idling) engine just stops. It looks like it "dies" for a moment. Ignition, everything is ok. Feels like you have fuel-cut few times and it just stops working. As said, ignition ok, everything is working except engine. Starter is working, but engine does not turn on.
My ECM is chipped and it was remapped about 5 times, probably each time resoldering microscheme. I aslo had DTC 1-1-2 (ECM fault) some time ago.
Yesterday I had another time with this surprise, after a minute engine started and I drove further. This morning engine stopped while driving for a part of a second, I just mentioned turning all dashboard lights and it did not appear no more and I reached my destination successfully. Did diagnostics - no faults in A2...
Do anyone have thoughts about this problem? Might it be related with ECM and some contacts within it which can cause engine death for a while? Or could it be related with engine wires (electricity)?
This cannot be related with fuel pump, because I have lpg installed and it occurs no matterI am driving with lpg or gasoline.

 

It does sound like your problem is within the ECU. I can't think of anything that would cause a shut-down (besides a fuel issue that you have ruled out) that wouldn't also cause a DTC.

Just based on the symptoms, a cam position sensor could cause that (none or intermittent signal would cause no spark), but it should also throw a trouble code.

 

Well, Did not open ECM yet, but I think I will do this.
Worst thing is that no DTC codes detected after that... Previous time I had this surprise I had also DTC about rear knock sensor fault, lamba icon lighted untill codes were deleted. This time - no DTC, no any light, nothing. Car died, after a while was like nothing happened.
Also I mentioned that after that issue happens, it feels the same while driving/idling like after DTC codes erasion: after starting rpm fluctuates a little bit, for some time idle rpms are about 600 (seems like car is calibrating). Everything like after DTC erasion, the same. Maybe something could be related to electricity to ECM and its interruption? But maybe it should cause a DTC.

 

I should have thought of this before - I had a bad battery terminal that caused similar symptoms, and there would be no DTC. Check your terminals, grounds, and main power cables especially.

 

Well after one of this issue I had DTC about toolow/high battery voltage. I'll try to check. For a while this "thing" did not occur, but I'll check it anyway.

 

Well, today it stroke again. Engine died for few minutes, then it after few attempts started. BUT, VENTILATOR STARTED AND DID NOT TURNED!!! I drove about 10 km for about 20 minutes and it was working. Then i turned engine off for few times, but it kept working when engine was turned on. When engine died it was cold. But ventilator was working and did not pay attention to engine's temperature.
Ten I did diagnosis (A2), after first click it showed 1-3-2 (Batery voltage), after second 1-1-2 (Fault in ECM), after third and every next it showed 1-1-1 - no faults...
So it might be related to voltage and it might cause some mess in ECM.
But why ventilator? what could happen to it?

 

Ventilator = Electric radiator cooling fan???

I think that's what you're talking about - yeah if the ECU is getting low voltage (for whatever reason, whether an internal fault or external issue) it can cause all sorts of problems. I accidentally killed my battery one time, and when I tried to start it the cooling fan came on and discharged what little juice was left.

Have you verified that the battery and alternator are working properly?

 

Yes, a cooling fan
Took off ECM for a night, nothing changed, cooling fan starts with engine. But I am coming to issue with engine death. Measured battery, when idling, voltage is 16.5 volts (!!!). It might cause too much electricity to ECM and all the problems. Problem probably will be with generator, it should be repaired/replaced with new one.
Too much voltage might also caused issue with cooling fan. DTC does not show any code regarding engine temperature sensor or any related with cooling fan. It may be issue with cooling fan relay. No problems with dashboard temperature indicator, no problems with engine temperature. But cooling fan is working everytime.

 

Well, voltage regulator changed, now it shows 14V @2000rpm and idle with all electricity turned on. Thought, that cooling fan relay was burned due to high voltage. No. After repalcing voltage regulator coolig fan work good.
Now the thing with ECM will be followed. I do hope it should not accur any more due to normal voltage.

 

Do you know anyone that may let you swap out your ECM for a test? Where do you live?

 

You know, it happened once a month, so I can live with that. Now I will wait for another strike if it will happen, then will try to do something. I'm from Lithuania, in case it would be necessary I would find someone. Maybe, because 2.3's are rare enough at the moment. Country became a diesel country, not a petrol turbo country

 

About swapping ECM, it would be difficult to find, maybe I could buy another one, not new. I will think about it.
Today it stroke again. On a cold engine, after few minutes idling it shaked, then it worked for a while, then lambada occured, it shaked again (like having some interruption in its work and aslo lambda light accuring). Then it died. After few minutes I could start it, but it died again after skaking. Then after few minutes it started, everything is fine except lambda light. Haven't time to do diagnostics, after work will do this.
Maybe it could be related with O2 sensor, but maybe then DTC should appear...

 

Seems, that I have the same problem, thread was marked as SOLVED, but no solution in anty post...
http://www.matthewsvolvosite.com/for...hp?f=1&t=20950
Commonly everyone is writing about fuel relay, but I had engine stalling also when driving on LPG, so this could not be related with fuel...

 

Good idea for a problem, will try to check this: http://www.justanswer.com/volvo/4dvo...ies-speed.html
or maybe like in this case...
http://volvospeed.com/vs_forum/topic...m/page__st__40

 

Today this issue stroke again, engine stalled two times for a part of second while driving at hot engine driving on LPG, lambda light occured as in previous times. Last time it was on cold engine while idling on a petrol (because it was not warm enough for lpg). So version of a fuel relay of fuel pump is not a case. Did diagnostics, it showed code 1-4-3 and 4-3-3. Both about knock sensors... A day before driving I felt like car is responding very hard on a accelerator when I am putting my leg off, but when accelerating it felt like a slight jerking (not fluent) acceleration. And today after it occurd it felt like accelerator is a bit lagging, after I put my leg off it responded with a part of a second later. I thought it will be related with rpm sensor, but no, rear and front knock sensors DTC appeared...


The best description of a problem I found in this page, but no solution... 850 2.5L 1996 intermittent stalling

 

Today I tried to enter test mode 2: with ignition on briefly push 2 times and the led should blank and codes from throttle position sensor should appear. But the led blanked for 1 minute and no codes would appear. Entered this test 2 mode with engine runnig - it showed codes from CMP and RPM sensor. Maybe there is a clue??? sensor did not responded, but no dtc about it appeared.

 

Today car died again, and could not drive. So tried to do diagnostics, but it did not worked. While ingnition on it was heard a noise in idle air control valve, like relay was broken. And the sound like air going out (the same noise when DTC codes are deleted the same air going out noise occurs). So perhaps this will be the problem with idle air control valve.
But after research in other forums I've discovered ytah buzzing sound in IAC valve is normal. So it should be good. I have to mention, that yesterday I had lambda on, DTC showed 2-3-1 long term fuel trim part load and nothing else. After engine stalling there was no possibility to do DTC, because it did not showed any code. With ignition on IAC valve buzzed, cooling fan tried to start, sound of going out air appeared countinuously, efter taking ECM off and putting it back no lambda, engine felt like after DTC clearing. But after few minutes it stalled. It starts, but stall. No possibility to drive...

 

This is just a long shot, but perhaps your ignition switch is at fault. This problem manifests itself in different forms.

 

Changed camshaft position sensor and will be looking how it will effect car.

 

I had the same problem once and it took some time to find out it was the positive terminal at the battery. I had pulled the battery to charge it and only tightened down one side of the positive.
Seems both sides need to be tight. My guess is one side tightens the battery terminal and the other just tightens the wires on that side. The loose side was the one with the wires coming off it and would allow the vehicle to die while running.
It happened to me once more about a year later (after replacing the battery) but this time I knew what to look for after a moment or two.