help with rough condition

[bmxr152]

Alright so my ex started running like crap a few days ago, It runs at an idle almost if it has a cam or something. really rough no matter cold or hot, and rough at throttle until at WOT around 3800 it clears up and runs perfect then when i let off and press the gas again it runs like crap, till i repeat the wot pull. i scanned it and got code 42r with indicates system is lean. So i changed the o2 sensor, cleaned the maf, IAC. Also the coil, plugs, wires only have 4k miles on them. Anything else i should look at or check? vacuum leak maybie or fuel pressure related? I just dont know why i would get full power and smooth running at around 4k rpm and it be rough and slow like a miss under that rpm? Please help

 

[MrShorty]

Did replacing all those things clear up the KOER 42 or does the code still come back?

I would almost certainly test fuel pressure: I could see these symptoms caused by a leaky FPR (if there's gas in the vacuum line to the FPR, replace FPR) or fuel pressure too high.

 

[aldive]

Take a look at this thread.

http://www.explorerforum.com/forums/showthread.php?t=169335&highlight=quest

 

[bmxr152]

I checked the fpr and no gas in the vacuum line. And still same code and still runs the same, i even thought it was the injectors and took the intake manifold off and replaced the injectors with a spare set and still nothing. Oh and just checked fuel filter and its fine to. You think it might be the fuel pump. I just dont understand why when i rev it out, it hits 4k rpm and its like a night and day difference. almost like a 2 stroke hittin powerband.

 

[bmxr152]

here is what i got from the fuel pressure test
27 psi key on engine off
34 psi engine on
40 psi vacuum line off engine on

 

[MrShorty]

Can you tell if it's really running rich as indicated (black smoke from the exhaust, condition of spark plugs, ???)? It might help diagnosis if we knew if the code was simply reporting the engine's status or if the computer was seeing the wrong condition.

Do you have a voltmeter and a wiring diagram so you can check the output of the MAF, TPS, O2 sensor?

 

[bmxr152]

I have a digital multimeter, but no wiring diagram. No black smoke and ill pull the plugs and take some pics so you can see. first pic is 123 cyls, second is 456 facing the block.

 

[bmxr152]

Why does cyl 5 spark plug have a brown coating on the ceramic part?

 

[MrShorty]

Did the check engine light come on and/or was it idling rough during your fuel pressure test? Just recently, someone else came on with a problem. Initial fuel pressure test looked normal, but after letting the engine run a little bit with the gauge hooked up, the pressure jumped to 90 or so. It seems that sometimes the FPR runs ok for a bit before it gets stuck closed.

Deposits on #5 usually point to an intake manifold gasket leak on these engines. The bolts for the intake manifold have a nasty habit of coming loose, and it seems to focus a lot on cylinder #5. Usually tightening the bolts back down is enough to fix it.

Other than that, the spark plugs look ok (I've always hated point and shoot cameras and their annoying habit of focusing on something other than what I want to see, don't you?)

Just to make sure, I assumed from your initial post that you are getting a KOER 42, is that correct, or is it a CM 42, or both? Any other codes (including KOEO 11 pass)?

 

[bmxr152]

IM getting KOER 41 and then it will pop up 11 after about 10 mins. Still with the rough idle and rough running. as far as the intake leak, i just had the intake off the look at the injectors and replaced the lower and upper plenum gaskets. Still ran rough after that. Could it be the lower one maybie? Also the check engine light doesnt come on until its been driven for a little while. and yeah sorry for the pics camera phone sucks.

 

[bmxr152]

Just to clarify it runs rough no matter hot or cold, right on start up. This is really confusing me and eating gas. about 5 miles a gallon. Changed plugs, wires, coil, maf, and o2 sensor. Cleaned IAC, throttle body, and put new lower and upper plenum gaskets in. i guess i could try swaping in my other tps and see if it helps. Im stumped. I cant explain why it would have full power and run smooth after it hits 3800prm and beyond. and when it shifts into 4th and go's below 3k rpm its rough again. oh and something i found interesting, once i unplugged the maf it didn't effect the idle or anything just threw a CEL as soon as it was unplugged.

 

[bmxr152]

just swapped and EDIS and the TPS and still nothing. re checked all vacuum lines to and nothing. could the lower intake manifold gasket be leaking? or #5 cyl injector be stuck open or something?
and re checked fuel pressure. here it is

40 psi engine off key on
32 psi engine on
40 psi engine on vacuum line off.

 

[MrShorty]

This one is getting challenging.

1st thing: Post #1 says you were getting a KOER 42. Post #10 says a KOER 41 (at least until the engine runs for a while). Is one of these a typo or are you really getting both codes? If you are getting both codes, when do you get the 42 and when do you get the 41? I still would like to know what you are getting from the KOEO/CM portions as well.

Fuel pressure looks normal. How long did you leave the gauge on with it running? I still want to make sure the pressure isn't spiking after running a little bit.

As common as that lower intake manifold gasket problem is, I guess I got lazy and didn't specify in post #9 that I was referring to the lower intake manifold gasket.

Injector #5 could be sticking open: does the fuel system hold pressure when the pump is shut off? However, as common as the lower intake gasket issue is, I'd check that first.

Did you ever thoroughly check for a vacuum leak?

I might start poking around at some of the sensors (TPS, MAF, ECT, and so on) to see if their output looks reasonable. It's not unheard of for some of these sensors to be out of bounds enough to cause problems, but not so far out of range that it triggers a trouble code/CEL.

 

[bmxr152]

OK today i spent all day on it. swaped #5 injector around and still the same rich condition on the plug in cyl 5. As far as maf goes i swaped it and the tps out to spare good ones i had laying around. And the code im gettin is KOER 41 on the ethos scanner it says EGO not opening lean on bank one. fuel pressure holds no leak down at least for 15 mins. 40 psi engine off 32 engine on, 40 psi engine on vacuum off. I did a block tester on it to to see if it was a bad head gasket and came up negative. Also ive checked every vacuum line i can find and no leaks there. Could the lower manifold gasket be leaking oil into cyl. 5 and fouling out the plug maybe? i dont know ive almost given up on this. i think the culprit is #5 cyl but i cannot explain why it runs good after i hit a certain rpm and smoothes out?

***also i saw that the IAC was at 40% while idling (but its been replaced)
well last try for success is going to be replacing lower manifold gasket and see if it helps. if not i dont know what to do.

 

[MrShorty]

Fuel pressure is normal, no vacuum leaks. How much do you trust that new O2 sensor? I haven't bought one bad out of the box, but I have had them go bad very soon after installation. Have you verified the wiring between the O2 sensor and the PCM (More than one person have reported those wires get pinched between the bellhousing and the block or melted through by the exhaust).

 

[bmxr152]

yeah i trust it, the wires were all clear no pinching or burning. It didnt make one bit of difference when i put the new one in so i pretty much bought it for nothing. lol i guess im going to try the lower manifold gasket and see if that helps, maybie thats where the vacuum leak is and could be leaking some oil into cyl 5 and fouling the plug out.

 

[bmxr152]

found the problem, check this out...

Luckily i got a whole other longblock...

 

[bmxr152]

issue was resolved. It was the broken valve spring. replaced it and intake gaskets and all is good now. Well thanks for all the help guys. Just wondering why it would just break on a fairly new motor?