RE: Montero Misfire Cylinder 6 (Full Version)

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RE: Montero Misfire Cylinder 6

  

dcvee -> RE: Montero Misfire Cylinder 6 (4/4/2007 9:55:10 PM)

Well I've got good news and bad news.  Good news is it IS the valves.  Matter of fact ALL but one cylinder is leaking past the intake valves.  The amount of carbon gunk in the heads is terrible.  It's an obvious sign of my wife's short driving.  She only drives 2 miles a day, TOTAL and that is killing this engine I believe.  Seriously the intake manifold, passages leading to the valves and the back of the valves are COATED with stuff that looks like undercoating spray!!
Bad news is I could have detected this WEEKS ago but my leakdown tester is faulty.  With the intake manifold on I couldn't hear the valves leaking.  With the intake off I could.  So I knew something was wrong with the tester.  The orifice inside had turned sideways and was letting more air get through then it should.  Hence the precentages were within tolerance.  My bud came over tonight with his tester and we had 20-30% leakage on every cylinder but 1....which had 12%.  With the intake off you didn't even need a stethescope...you could hear the air escaping from the intakes.

So, I've got the timing belt off and I'm ready to pull both heads tomorrow night and get them to my bud.  Hopefully I can start to assemble Saturday morning.  'll be glad to get this buttoned up and some pixs posted.  It was a REAL PITA to work on.  Seems like every bolt is a challenge once you get lower than the heads.  I can't believe how much of this engine you have to remove to change the timing belt!!  Took me 2 hours to find the block drain bolt.[:'(]  I'll stick to my Chevy's and BMW's from on....next time this Mitz breaks it's off do the dealer!!!

Don


  
tj90 -> RE: Montero Misfire Cylinder 6 (4/5/2007 2:32:44 PM)

Glad that you found the culprit. Your post worries me, since my wife is short haul specialist. Good to take the thing out for Italian tune up once in a while... How is your buddy going to clean the heads? Is it a DIY job or does it require machine shop? +1 on the timing belt - I struggled with that one as well..... I look forward to the pics - did you happen to get any during the leakdown test? Im curious on the procedure. Ive seen leakdown testers at Harbor freight, but did not buy cause I dont know the procedure to do this. I assume since you have to rotate the crankshaft, maybe its a complicated process to test leakage on each cylinder.....

dcvee -> RE: Montero Misfire Cylinder 6 (4/10/2007 12:06:44 PM)

gas, Gas, GAS!  That's what my machinest says.  He said don't run the low grade...run the top.  On long trips you can sneak a tank or two in but if you are doing city driving and short trips stick to 92 octane.  He thinks that is the main factor for this failure...coupled with fact that the vehicle never gets completely heated before it shuts off.  Twice a day(wifes short commute).  Heads will be finished Thursday evening and I'll start installing everything Friday night.

tj.  We checked for warped head, replaced valve guides(intakes were ok, some of the exhaust were not)reground seats, reground valves.  He'll reassemble using new valve stem seals.  Heads were hot tanked(chemically cleaned).  It does require a machine shop...but only to do the valve grinding.  You can remove and press new valve guides in yourself.  Total cost is $180 for the pair of heads.

Leakdown tester is a simple device when you really know what it's doing.  I built mine.  It's a regulator with a gauge feeding a "T" with a gauge.  The only tricky thing is the orifice which resides between the first gauge and the second gauge.  It's a slug with a .040" hole drilled in it.  What it does is compensates for the air that leaks past your rings.  So, you'd screw the hose from the second gauge into the sparkplug hole.  Rotate the crankshaft until that cylinder is TDC(all valves on that cylinder are closed and crank "throw" is centered in the bore).  You can feel this by placing a piece of wooden dowel into the bore first.  Rotate the crank until the dowel sticks up at it's maximum.  Eye-ball a mark on the balancer.  Then continue to turn the crank watching the dowel.  When it starts to go down stop again.  Eye-ball the balancer and compare the first mark to the second mark.  Move the crank backwards and split the difference.  MAKE SURE YOU HAVE ALL THE PLUGS OUT!  Otherwise do NOT rotate the crank backwards...just come around TWICE and split the difference.  Rotating the crank backwards with plugs in will mess up your timing belt(possibly). 

So now you are TDC on the compression stroke and your ready.  The hose from the second gauge side is screwed into the sparkplug hole.  Apply shop air to the other side and using the regulator put 100psi in.  If the first gauge is set to100psi the second gauge will be reading the "leakdown" amount.  IE, if the second gauge says 80psi the % leakdown is 20...or 20%.  A 5-8% reading is what you are looking for.  10% is "ok".    Anything over 10 is a problem.  What's cool about a leakdown test is you can diagnosis on the fly.  If the cylinder has a 11% or more reading you can hear where the problem is by following the air trail.  If it's coming from the exhaust pipe, you've got some bad exhaust valves.  If it's leaking from the intake runners(like mine)you can hear it in the intake plenum/ports.  You can use a stethescope or a large rubber hose to find the leaks.  If it's pouring from the block, good chance it's rings.  Here, read this and do a search on leakdown testers.  They really are a GREAT tool.
http://www.xs11.com/tips/misc/misc3.shtml

Don

tj90 -> RE: Montero Misfire Cylinder 6 (4/10/2007 1:22:26 PM)

Thanks - I will take a look at the link you sent. If possible a pic of the homebrew tester would be helpful.

I did my own timing advance and octane test with the monty 2 years ago. I found that running 87 octane retarded timing (due to knock sensors) and reduced fuel economy by ~10%. It was a careful experiment that took a month driving around with a laptop in the OBD port but I really believe the numbers. The conclusion? The money you are saving at the pump with 87, is really hurting MPG by the same amount. If premium is 10% cost adder, its a wash - might as well run 91 or 93 so that you get the full timing advance intended by Mitsu!

dcvee -> RE: Montero Misfire Cylinder 6 (4/11/2007 6:55:49 PM)

You're spot-on TJ with the octane deal.  She's getting nothing but the good stuff after this.  I have a ton of pics and I'll include one of my leakdown tester.  Trickiest part is the .040 orifice which I initially made using a disc of aluminum and drilled a .040 hole through it.  But that turned sideways and gave me the error[:@].  So now I have to make a "plug" of sorts and drill the orifice in it.  I'll post pictures.

We found 4 light indentations from the fire rings of the gasket in the heads.  So they're taking a light cut in the morning and I'll pick them up in the afternoon.  Shop said it would prolly be ok but for 30 bucks more they could take a skim cut on both heads and promise me a perfect sealing surface.  I'm cleaning my lash adjusters/valve train and getting ready for assembly!!

Can't wait to get this puppy going...it's holding up my other projects.

Don

tj90 -> RE: Montero Misfire Cylinder 6 (4/12/2007 10:58:06 AM)

Cool! Please post any pics of the motor and leakdown when you get a chance. Let us know how she runs!

dcvee -> RE: Montero Misfire Cylinder 6 (4/19/2007 8:02:28 PM)

Well, she didn't run too good.  Matter of fact, I never even lit it off!!  I had some time and put the heads on.  Attached the water tubes and such.  Intake.  Injectors.  Injector harness.  And then I thought, Hmmm.  I really SHOULD do a leakdown test on these heads before I go much further.  Guess what?  20-30% leakage on all intakes.  Machinist messed up the seats.  He came to my house tonight and picked them up.  Said he'll have them ready for tomorrow.  I told him I'll be in Carlisle tomorrow(friday) so I won't be able to pick them up.  He said he'll deliver them with all new top gaskets too.

Man what a PITA this simple job has been.  Wrong water pump.  Wrong timing belt.  Bad valve job.  At least I'm catching the mistakes[;)]

I pushed her back out on the driveway tonight.  Took the M3 off the lift and I'm going to play with that for a couple days.....release some frustration[:D]

I'm going to upload some photos....I'll post the url when ready.

Don

tj90 -> RE: Montero Misfire Cylinder 6 (4/20/2007 12:49:35 PM)

M3?! - Ya baby! Give your sore, cut-up hands a break. Enjoy!

Winshawn -> RE: Montero Misfire Cylinder 6 (5/1/2007 6:48:33 PM)

Why wouldn't this have been covered under the 7year 100k powertrain warrenty?

dcvee -> RE: Montero Misfire Cylinder 6 (6/5/2007 4:40:26 AM)

Warranty?  What warranty?  I'm not the original owner if that matters and the vehicle was not bought CPO either.  I'll call my mitz dealer and ask but I'm pretty sure there is no warranty.  I'm the 3rd owner and I bought it privately.  If you know something please pass it along.  Thanks.

Anyway, a quick update.  Finally got the heads done correctly and installed on Saturday.  It was a breeze and the vehicle runs fantastic, BUT it still has the misfire cylinder 6 code and rough idle.  At this point, about the only other thing it can be is ecu related.  I've tested/changed everthing else.  Going to talk to mitz dealer today and see if there is some test or swap they can do.  It's kinda bittersweet at the moment but the valves did fail the leakdown test and they were gunked up like none I've ever seen so it was a worthwhile $420(heads, gaskets, timing belt, water pump, plugs, wires etc)spent so far.  Nothing I've replaced was "good".  Even the timing belt showed a light wear on the outer edge(@66k mileage).

So, we still have a rough running Monty and at this point my focus is on ecu/injection timing.

I'll keep this thread rolling until I find an answer.  Now that the M3 is finished and I've completed my first HPDE at Summit Point, I can get back on this Monty after parking it for a month.

Don


  

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