3A90 Intake valves stuck open, carbonized, full of gunk and car won't start

[gone.a]

Gotta bump this out of curiosity if the OP was able to gain updated info?

[foama]

Gotta bump this out of curiosity if the OP was able to gain updated info?

Nope! Nothing new.

A) Contrary to his promise, the dealer has not mailed me any pix of the stuck valves.

B) I am on assignment far away, and the car is still sitting in the garage after repair.

[91cavgt]

Might i suggest a different possibility?

Is it not possible that this shop has a wrong diagnosis? I have seen shops give a wrong diagnosis only to get paid more, then do the actual work required to get the car running again thus making more money.

[HitShane]

"Coming home after a 300km drive on the autobahn, driving at 100 - 130kmh"

I wouldn't consider 60-80MPH Autobahn speeds... That's normal highway speeds for me here in NA... If that happened to my brand new car I would be pissed! Sounds like someone messed with your fuel...

[foama]

UPDATE, March 12 2016

1) The dealer briefly showed me a picture of badly fouled exhaust valves, but did not let me take either the photo with me or to photograph or copy it. He said:"The picture (supposedly of my car's valves) is Mitsubishi property and may not be disclosed, copied or given away!"

2) Since the repair, I have noticed higher fuel consumption and lower top speed. Driving to work the bult-in display showed around 4.3 to 4.5 L/100km before repair, and now afterward always more than 5L/100km, usually about 5.2L/100km.

The top speed on a flat autobahn with no wind was displayed at around 172-175kmh according to the car's speedo. Now it reaches around 160kmh under the same conditions.

After visiting the dealer about this, I was told new software was flashed into the ECU.

I hope to find out more, or get the situation resolved.
I will post updates.

[inuvik]

UPDATE, March 12 2016

1) The dealer briefly showed me a picture of badly fouled exhaust valves, but did not let me take either the photo with me or to photograph or copy it. He said:"The picture (supposedly of my car's valves) is Mitsubishi property and may not be disclosed, copied or given away!"
2) Since the repair, I have noticed higher fuel consumption and lower top speed. Driving to work the bult-in display showed around 4.3 to 4.5 L/100km before repair, and now afterward always more than 5L/100km, usually about 5.2L/100km.
After visiting the dealer about this, I was told new software was flashed into the ECU.

I hope to find out more, or get the situation resolved.
I will post updates.

I'm pretty suspicious of the shop still. If this was a problem in the 3A92 or 3A90 for that matter we would be seeing this issue pop up all over the place with many members accumulating substantial number of miles/kilometers on their Mirages/Space Star. We have hyper milers who never rev past 2500 rpm and people who rev to 6000 all the time and there hasn't been an issue. The fact that the shop won't let you have a picture sends up a lot of red flags. Although I understand you don't believe it's from bad fuel I think "Occam's Razor" applies here. The simplest explanation is the most likely.

[foama]

UPDATE, March 12 2016

1) The dealer briefly showed me a picture of badly fouled exhaust valves, but did not let me take either the photo with me or to photograph or copy it. He said:"The picture (supposedly of my car's valves) is Mitsubishi property and may not be disclosed, copied or given away!"

2) Since the repair, I have noticed higher fuel consumption and lower top speed. Driving to work the bult-in display showed around 4.3 to 4.5 L/100km before repair, and now afterward always more than 5L/100km, usually about 5.2L/100km.

The top speed on a flat autobahn with no wind was displayed at around 172-175kmh according to the car's speedo. Now it reaches around 160kmh under the same conditions.

After visiting the dealer about this, I was told new software was flashed into the ECU.

I hope to find out more, or get the situation resolved.
I will post updates.

UPDATE May 5, 2016

I revisited the dealer because of the raised fuel consumption issue since repair of my 1.0L model with the stuck-open intake valves.
The dealer had no explaination for the elevated consumption, but stated there had been NO ECU software upgrade to this car. Previously I was told there had been.
His only work other than diagnosis had been removing the head and taking out the intake valves, cleaning, and reassembly with the original parts. The exhaust valves had been OK and untouched.
The only part actually replaced being the head gasket, plus the use of some sealant.

In the mean time, a few thousand km later, and after another long ride at higher speeds, the elevated consumption suddenly dropped and normalized from one day to the next!

I have no explaination. The car has always had practically no detectable oil consumption. After 12000km and shortly before yearly servicing, the oil is of honey colour and transparent. No extra additives in fuel or oil ever added, only dealer-servicing, normal use for only long distances, no racing, no abuse...

The local firm with half a dozen 3A90 (1.0L model) running customer-to-customer within the same town, their cars never really getting warmed up, has suffered the same problem at least once in each vehicle. The are only running short distances and filling up locally.
I am running only long distances and filling up at brand name stations wherever I may be, usually far away from home and seldom at the same place.

Btw: The 3A92 Manual states nothing at all about EGR. Otherwise it seems to mention just about everything.

Anyone have a link to a 3A90 Manual? Would really appreciate that.

[MetroMPG]

Very mysterious. Glad your fuel consumption went back to normal. Top speed the same?

Thanks for the update.

[foama]

Haven't checked top speed yet, but I assume the car performs normally again.

[Dgd]

I just read in the MAP or MAF thread one member noted that EGR may introduce gunk in the engine at cruising speeds when it operates. So it may be that...kicking in At the wrong moment...