2004 Ford Escape

[svtlincoln]

So this weekend I got volunteered to help my friend replace the valve cover gaskets on his wife's 2004 Ford Escape(actually it's a mazda tribute according to the grill and badges, but it's all FORD) Anyway he'd already done the front gasket by the time I got there. To do the rear cover you have to pull throttle cables, upper intake, all vaccuum hoses, some wiring etc. Anways, I pulled everything on the rear and let him put it back together and I contested but he INSISTED on spraying the intake hose with WD-40 so it'd "slide on easier" and he did. Then we fired it up and it had a dead miss. hmmmm. So I grab a can of brake cleaner and spray the intake and the revs pick up.... he didn't follow the torque sequence. So I pull the upper intake back off and sure enough there's gas outside the gasket. I clean off the lower intake, wipe off the new gaskets(rubber o-rings) put everything back on and torque it back down IN SEQUENCE and no more intake leak and it ran smoother but there was still a nice vaccuum leak. I hunt that down to the brake booster hose, fix that and it idles fine til it gets warm. Then the miss comes back. Start pulling coils, find that two of the cylinder are practically dead. Swap known good coils and plugs to where the misfiring cylinders are and no change. So then I tested the wiring to those cylinders and it all comes back normal. Let it cool off, fire it up and it's smooth again. Warms up, misses again. He then pulls the connector off the MAF and idle increases and the engine smooths out. To him this "proves" the MAF is the issue. He goes and gets a new one, slaps it on and it idles GREAT! til it gets warm. Still dead, on two cylinders. Any ideas? I know there's spark at those two cylinders and I know there's fuel(plugs were wet when I pulled them) I told him to leave the battery disconnected tonight and maybe the puter is just having problems relearning everything and it'll be fine in the morning but I doubt it. I'm really stumped. Any help is greatly appreciated. Don't want my buddy having to sleep on the couch :thumbsup:

 

[J]

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First of all, a failed MAF sensor won't cause a dead miss on independent cylinders.

Sounds like you're intake manifold is warping when the car heats up causing air to leak by that gasket you had an issue with already.

Try warming it up and spraying ether near the intake by those cylinders.

Basic rules. Misfires are caused by lack of fuel, air, spark, or compression.

Check for spark (you did by swapping coils, unless the wiring is jacked), check for fuel, check for air (ether or brake parts cleaner), lastly check for compression.

 

[svtlincoln]

Yea the MAF was his idea.... not mine... and it failed like I figured. I sprayed the intake with the engine warm and nothing happened after I'd installed it with the correct torque sequence. It is a plastic intake on a DOHC 3.0 liter V6. I think I forgot to mention that. I checked for spark at the two dead cylinders, and there is spark and fuel. The way I was taught is that engines Suck, Squeeze, Bang, Blow. So I know they're getting air and fuel(suck), I know I've got spark(Bang) but I don't know bout the squeeze and blow. I offered to bring him my compression gauge, he thinks it's a waste, I strongly disagree. Thanks though J, you were thinking along the same lines I was. Which just reinforces what I was thinking to begin with which is the old plugs were shot, it idled rough to begin with and now that is has 4 "healthy" cylinders the 2 "sick" cylinders stick out like a sore thumb. I'm thinking it's either having a compression issue at this point or those two injectors are stuck open dumping fuel and fouling out the plugs. Thanks again.

 

[svtlincoln]

UPDATE..... I'm actually ashamed to post this. Ok first like I had said above, he'd already done the front valve cover and put all that back together BEFORE I got there. Anways long story short, he had the connectors for the coils backwards. So instead of 1,2,3 he had it 3,2,1. For some reason I never even thought to check that, I just assumed he'd done it right and marked things before he took them apart. I don't know why the engine was so smooth when it was cold.... but it was. Anways it's running now!! I forgot to apply another method I learned at my first auto shop. The K.I.S.S. method. Keep It Simple Stupid.

 

[driller]

That's easier to do than most think.