1997 mercury mountaineer p0174

[saywheresarny]

1997 mercury mountaineer, awd 5.0 auto.
This thing is driving me crazy! It idles ruff, runs like crap and the only code i have is p0174.
i have changed the plugs and wires, fuel pump and filter, mass air sensor pcv valve, and I have checked up and down for some kind of vacuum leak. ran 3 cans of seafoam in the tank. I also tried stp and lucas injector cleaners. compression was all tested and they seem fine all within 10 psi of each other. but i do want to check this again with a better tester.

I have read the live data on my code reader and it is indeed running lean on bank 2. and the percentages move as they should so I dont think its an o2 sensor, but i havent ruled it out.

So i have narrowed it down to either a bad injector ,burnt valve or a bad intake gasket (though im not losing water or over heating). im just looking for any fresh ideas before i tear into it. Or if anybody has had similar problems with a 5.0 explorer.

thanks in advance.

 

[Turdle]

Have you checked the pcv valve grommet? Also, you might try looking at the brake booster-one way valve.

You might also "double check" the firing order of the spark plug wires.

If these check out, try pulling spark plug wires one by one while the engine is running. if you pull one off with no change in idle, it will help narrow down which cylinders are misfiring. If you do have a bad injector this might help find which one it is, however, I would think this would trigger a misfire code.

Do you have access to a vacuum gauge?

 

[saywheresarny]

I haven't checked the pcv grommet. I can't actually see it, the intake is in the way. I never thought of the check valve.

I don't have a vacuum gauge of any kind.

I have checked the wires several times but they are all where they are supposed to be.

My first thought was th cat was clogged. Because I was pulling my trailer when it started and I could smell matches. But I don't think its the issue because both o2 sensores seem to be working and I'm not getting any other code than the p0174. I did have a missfire code on cyl 5 but its gone now.

It does seem to be worse on start up and until the engine warms up. And I can hear the lean pop coming from the air cleaner when I rev it up.

Thanks for the reply

 

[jremington59]

It's probably not the MAF sensor or you'd be throwing the 0171 code with it. Turdle had a good suggestion regarding vacuum. You might also check your fuel pressure. If it's low a partially clogged injector might cause a problem.

 

[saywheresarny]

I did change the fuel pump and filter. Before the change I was running about 27 lbs now I'm right at 30 with jump to 40 with a blimp of the throttle. It very possibly could be an injector. I know thy all are working cus I used a piece of brake line to listen to them all. But it is getting worse so I'm thinking its a gasket or a valve.

I do thank you for your input, its exactly what I was looking for.

 

[jremington59]

If it were me I'd do what Turdle suggested and check the grommet and vacuum lines before changing injectors. Also, did you change the plugs before or after the three cans of seafoam? I'd also check the fuel pressure at the rail again.

 

[saywheresarny]

I ran the seafoam after I changed the plugs. I've had the plugs all out since and they still look new. They are all firing as well.

I have checked the fuel pressure several times and its running right at 30lbs.

Any suggestions on checking the grommet? In order to change the pcv valve I had to reach in behind and pull it out. Was no way I could see down in there. It fits down in between two lines and I can't reach it to pull it out short of removing the upper intake at wich point I might as well change the injectors or atleast remove them.

Has any body ever had an intake gasket go bad on a v8? I've had about 10 5.0 mustangs over the years and when a lower gasket went it leaked water. Never had an upper intake go bad but these intakes are a little different.

If I wasn't getting the p0174 code I would have guessed it was out of time. I did check the cam sensor. it had lots of dirt on it and I blew it out but it looked like it was ok.

Thanks again for the reply.

 

[jremington59]

I'd do what Turdle suggested and pull the wires on the drivers side one at a time and if one has no change it narrows it to that cylinder. If it doesn't then you can go back to looking for a vac problem. Around here you can get a smoke test done for 50 bucks. That will show you where a vac leak is.

 

[saywheresarny]

it turned out all but number 8 cylinder injectors on bank 2 were clogged. took them out cleaned them up and it runs better than the day i bought it.

thanks for all the replies.