Engine management light came on while 60 miles away from home on the M6. Didn't really notice anypower loss as we we're in heavy traffic on a flat part of the M6 doing around 55 mph. 10 minutes later the traffic started to clear and motor way gently sloped up. Put my foot down and nothing! as we hit the slope our speed dropped to 40mph, just making it over the top? Maxiumum revs 3000 to 3200 whether or not the car was in gear. NO POWER AT ALL?? I love the torque of our Stilo but nothing, not a sausage.

After searching the forum I had a suspect, the Overboost Valve. :idea:

So I tried connecting the vacum pipes direct bypassing the Overboost Valve, the actuator for what I think is the Waste Gate then moved. So I jumped to a conclusion and purchased a new Overboost valve, WRONG :bang:

The Overboost Valve still not working, so I guess what ever controls the Overboost Valve is now my new suspect? Could it be the Map Sensor?

Any help would be greatly appreciated.. :worship:

Are you getting any black smoke or hissing when the turbo spins up?

bozzy said:

Are you getting any black smoke or hissing when the turbo spins up?

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No black smoke that I've noticed or hissing but the engine does sound different, reminds me of a large hole in the exhaust but I checked there isn't. Think that might be the Waste Gate being fully open..

You might have a split intercooler hose.

bozzy said:

You might have a split intercooler hose.

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I just checked the intercooler hose, it's fine. But the Engine Management Light when off, the engine stopped making the "Baaaaaaar" hole in the exhaust sound and everything was fine again. I took it for a drive around the block, hit a rather large pot hole and the Engine Management Light came back on, almost instantly loosing power and the return of the "Baaaaaaar" hole in the exhaust sound. I limped home and fiddled with the Map Sensor and Wiring Loom and the Engine Management Light went off again restoring full power and removing the "Baaaaaaar" sound.
Is it possible the connector of the Map Sensor is the problem as when I lift the wiring loom and push the connector onto the Map Sensor everything is as it should be, no Engine Management Light and power is restored?

Sounds like you are close; if fiddling with the loom makes a difference I would have a good look in daylight and cable tie things up a bit. Doesn't sound as drastic then as an intercooler hose (many of us have had this problem in the past).

God, I wish I still had my Stilo despite these issues.

Is there anything else connected close by to the same part of the loom that could be causing the problem?
I trebble checked the Map Sensor connector it seems fine but still a serious fault appears even now I've cable tied it into position?

Stu Davies said:

Is there anything else connected close by to the same part of the loom that could be causing the problem?
I trebble checked the Map Sensor connector it seems fine but still a serious fault appears even now I've cable tied it into position?

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Now you are into the realms of "Deckchair" for assistance; this is out of my skill-set. He no doubt will come across this thread and offer some salient advice. Hang in there; he'll be along sooner or later. Argo's another chap with a deeper appreciation than I have so expect a response from these guys.

Thanks bozzy, think I'm getting closer...

While wer'e all waiting have a look at this beauty which I used to own. Old & new.

The last time our car had a shine like that was the day we brought it ...

Our Stilo does a lot of miles, 15 to 20 thousand a year. We kept everything tip top untill the missus started Uni and I had to give up my job to look after our 2 boys. We've not been as generous with the servicing as we should be... She finishes uni in 2 years and we plan to buy another then but for now we have to keep it running the best we can. I plan to keep it for myself when ther new one arrives. Its been a great car till recently...

Stu Davies said:

Engine management light came on while 60 miles away from home on the M6. Didn't really notice anypower loss as we we're in heavy traffic on a flat part of the M6 doing around 55 mph. 10 minutes later the traffic started to clear and motor way gently sloped up. Put my foot down and nothing! as we hit the slope our speed dropped to 40mph, just making it over the top? Maxiumum revs 3000 to 3200 whether or not the car was in gear. NO POWER AT ALL??

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These are the EXACT symptoms of defective VGT valve or splits in the tubing connected to it.

From your description of the problem going when moving the loom then I'd suspect there's an intermittent connection to the VGT valve (or just possibly a split in the pipe which seals when the loom is moved :chin. Since you've fitted a new valve then I can't see that it could be a poor contact on the connector (might be worth a look though)

The easiest way to discount the MAF is to disconnect it. The car should run much the same and if the problem is VGT related then the car will still show the same issues. Also, I don't know of anyway the MAF sensor can generate a boost error

Argonought! It seems your the man I need to talk to about this problem...

I have disconnected the MAF SENSOR and the problem remained.
I have replaced the VGT valve(overboost valve) and checked the pipes, no splits or leaks.
I by-passed the VGT valve and the actuator worked perfectly.
After reading the forum for an hour I suspected the MAP SENSOR(the one on the intact manifold) so I fiddled with its connections and everything returned to normal.

So it seems VGT related.

So am I right to suspect the MAP SENSOR?

Stu Davies said:

I have disconnected the MAF SENSOR and the problem remained.

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That pretty much proves the MAF is OK.

It certainly sound like a dodgy contact problem but can't say I've come across anything similar. Also not certain if any VGR connections are shared with the loom to the MAF sensor (pretty sure it's only airflow data & temperature on the plug to the MAF).

All you can really do is visually check what cables/pipes move when you move that loom and remember a bad earth is going to be a likely suspect.

EDIT: The MAP sensor (on inlet manifold) directly affects the VGT valve so might be worth checking although it's a long way from the MAF sensor wiring :chin:

Argonought said:

EDIT: The MAP sensor (on inlet manifold) directly affects the VGT valve so might be worth checking although it's a long way from the MAF sensor wiring :chin:

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Hello again Argonought, I think we may have our wires crossed?

I have always thought the problem to be the VGT vavle or something that directly affects it, not the MAF SENSOR or it's wiring.

So back to my original question:
"Is it possible the connector of the MAP SENSOR is the problem as when I lift the wiring loom and push the connector onto the Map Sensor everything is as it should be, no Engine Management Light and power is restored"?

So the MAP SENSOR directly affects the VGT VALVE.
Could it be a faulty MAP SENSOR that some how fixes itself when I apply a little pressure while pushing on the connector? If this is the case replacing the MAP SENSOR should fix things?:idea:
If not faulty wiring?

Oh and thanks for your help, been scratching my head all week end over this... lol

Stu,
can you describe, or even better post a photo of where the map sensor is?
Thanks

Sorry, my bad (didn't read your post properly )

Yes; you're very close to sorting it

Wiring to MAP sensor is highly likely to be suspect (and as you say also the sensor itself)


EDIT: I'd simply clean the plug with Electrical contact spray (NOT WD40) and if it's still a problem then change the sensor

minimad99 said:

Stu,
can you describe, or even better post a photo of where the map sensor is?
Thanks

Click to expand...

It's item 4 in this diagram, fits on the back of the inlet manifold.

Dave.

minimad99 said:

Stu,
can you describe, or even better post a photo of where the map sensor is?
Thanks

Click to expand...

In my Gallery (engine bay) it's slightly in front and to the left of the EGR valve.

I've uploaded a photo of what I'm sure is the MAP SENSOR and connector. This is the area I'm having a problem with.

I have now cleaned the connector and I still have the same intermittent problem.

So I have purchased a new MAP SENSOR and will fit it tomorrow.

I'll let you all know how everthing goes tomorrow evening.

This forum rocks... :slayer:

EDIT:
I got hold of some Castrol Magnatec Diesel, is it ok for use with our Stilo, it being turbo'd?