My sister has an 04 Escape 3.0 with around 162k on it. She brought the car to me with a bad misfire. It was reading random multiple misfire, cylinder 4, cylinder 6 misfire, and bank 2 lean codes.
I started out with plugs, then that didn't work so I changed 4 and 6 coils. The front exhaust manifold was leaking, so I tore into that to fix what I thought was a leaky exhaust manifold gasket. To my surprise, the manifold was broke around the cylinder 5 port, and both manifold studs were broke off in the block at cylinder 4. My guess is that someone attempted to fix the car before she got it and broke 2 studs, so they quit.
Well after having to remove basically the whole front end of the vehicle so that I could get room for my drill I drilled out the two studs and used an easy out to pull the broken studs out and replaced all the studs with grade 10.6 bolts. I had the exhaust manifold welded back together. Put it all back together and low and behold it was still missing. Well the fact that it was misfiring and still reading lean (I previously thought the lean reading was from the leaking manifold) it was still showing the same codes.
Next up was to change the cylinder 4 and 6 injectors. That meant removing the intake manifold once again. I changed both the #4 and #6 injectors. Put it all back together once again to only find that it's still missing. I also decided to give the MAF sensor a cleaning with some mass air flow sensor cleaner I keep on hand. It ran better for about the first 5 minutes of idling and then started again. But the codes changed. One code in particular. It now shows Oxygen sensor signal biased/stuck lean instead of showing the bank 2 system lean code.

Here are the current OBDII codes.
P2197 Oxygen sensor signal biased/stuck lean
P0316 misfire detected on start up
P0300 random multiple misfire
P0304 cylinder 4 misfire detected
P0306 cylinder 6 misfire detected

The only other thing I know to do is to check compression. Does anyone else have any ideas on what else to check? I'm at a loss here. I've spent a lot of money on trying to get this fixed for her and I'm not wanting to put much more into it. She can't afford to have the car fixed or to take it to a garage to have it fixed because she is in a tougher spot financially than I am. She's my sister so I'm trying to do whatever I can to help her out. Please give me some new ideas.

 

With two cylinders misfiring on bank 2, the bank 2 upstream O2 sensor is getting swamped with unburned fuel. Pretty soon, it will be the bank 2 catalyst that gets swamped if the misfire isn't corrected soon enough.

Dry/wet compression tests appear to be in order.

 

Remember that the O2 sensors just measure the quantity of 'free' Oxygen molecules in the gas flow. If you do not burn the fuel(misfire) the oxygen it would have consumed is still in the gas flowing by the sensor. Thus, the sensor finds oxygens... and assumes there was not enough fuel to eat up the O2s, so it is lean. Not so fast, buster. You have to make sure you do not have misfire occurring to avoid the mis-diagnosis of a 'lean' condition.
With all that in mind, did you check that there is not a crack in the intake manifold that is bleeding in excess air, causing misfire? The engine is noted for having a slight tendency to backfire and pop the intake manifold. It could have done that, and made a somewhat minor leak, which might be found using a carb-cleaner spray or brake 'kleen' spray to provide something else to burn with all that air. Spritz around near the intake and listen for a change in engine running.
If you listen to the exhaust does it go mmmmmPoommmmmPooMmmmmmmmPooMM with little burps in the midst of a 'common' sound? Those would be misfires if so. Does the engine rock back and forth or does it sit smoothly in the engine bay? An engine that misses will usually shake a bit more as it misfires.
And last but not least, a compression test or better yet, a leakdown test would help a whole lot in diagnosing. In general, a mechanical problem affecting the engine will be more pronounced at low rpm, and hidden amidst the higher frequency firing of high rpm. So, if you have a bad valve or two, it may be hidden at high rpm, and show as a miss at low rpm.
tom

 

Thanks for all the info guys. I've not had much time to work on the car the past few days due to work. I did get a chance to check for leaks with carb spray. No leaks were found. Did find a collapsing vacuum hose on the backside of the engine. I replaced it and it didn't help any. I've done some reading and read that after the engine misfires bad that the computer could go bad. Does anyone think that may be the issue? The engine does shake pretty hard from the miss and you can hear the miss from the exhaust.

 

Did you replace the lower intake manifold gaskets?

 

I suggest that you closely examine the epoxy tops of ALL of the coil-on-plug units. They can develop hairline cracks, barely visible, which allows moisture in (misfire will be worse on rainy days). The resulting misfire allows raw fuel to pass into the manifold cat(s) at which time it ignites and in the worst case completely melts the cat's ceramic honeycomb. Been there... Fix is to replace bad (or all) coils and "catifold", with Parts from Rock Auto (my choice-ymmv). And yes, R/R on exhaust manifold is miserable. Good luck!

 

Just to add more questionable parts, if an O2 sensor dies, it will quit producing any voltage at all. Thus it will be stuck on 'lean'. The 2197 might indicate an O2 that has died, or a failure of the wires connecting to the computer, power, or ground. Visual inspection may help, as would reading the O2 sensor output using a scan tool.
tom

 

Before the vehicle came to you was there any other work performed? Did someone else service the fuel injectors or the spark plugs?
I had a vehicle (from another manufacture) come to me with the same concern. Long story short and to the point. The coil pac connectors for 2 of the cylinders were swapped.
I had to look at the wiring harness to figure out where the connectors went.
On your 2004 Escape the #4 coil pac the wire colors are WHT/PPL - 12v and WHT/PINK. The #6 coil pac has WHT/PPL - 12v and LT GRN/YELLOW. I would look to see if these 2 connectors are swapped.

 

I forgot the wire colors for the injectors,
#4 has a RED - 12v and BRN/LT BLU
#6 has a RED - 12v and LT GRN/ORG.


Hope this helps...

 

Well I am not trying to say that it will fix this, because you have apparently gone through alot of stuff so far. HERE is what I can say. I worked on a 2004 Mazda MPV with a 3.0 V6 and it gave the same thing. Mine was the two Coil packs, and then I had to take the intake manifold off to change one on the back of the engine since it was front wheel drive, anyways, I ordered a whole set off of ebay, and they worked for me, I would never ever ever spray anything into a MAF sensor. I dont care what anyone else says.... it cost way too much money to replace those things in my opinion. But even with the O2 sensor going out it never made a misfire code pop up on my fords... just CEL. I would check again for vacuum leaks, and plug placement like Mustard suggested. I dont have a diagram for it with me.

 

A thought I just had was where does the EGR gas get fed into the intake? On the Windstar v6, the ports in the bottom of the manifold would get plugged, or restricted, and the one port left open would end up getting all the EGR gas flow. That caused a misfire in that cylinder. If the 3.0 has ports that can get plugged, it could be EGR causing misfire.
Have you replaced the lower intake manifold O-rings? Or fed fuel in vapor form to richen up a lean misfire? Wanding a hose around the intake(near where the sections meet or where the lower attaches to the cylinder head) with the engine running and misfiring, you can sometimes detect an air leak that otherwise cannot be seen nor heard.
tom

 

Can also check to see if the front O2 sensor connectors are swapped or are the correct parts. The upper and post catalyst sensors are different.

 

I understand your financial bind but a Ford dealer or a mechanic that travels may be your cheapest route. Throwing parts at it gets expensive and it could be anything at this point.

 

The OP hasn't visited this site in 6 weeks and has likely moved on.

Let the thread die...

 

I get your point but you never know.