rough idle but goes away when driving??

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vikingdiesel

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The other last problem is the car idles rough, shakes a little, the idles isnt that bad but you can definetly feel it. As soon as you start moving the roughness goes away and everything is normak. CHECK ENGINE is on. Plugs, wires, coil all changed. What else could it be? Cats, MAF, o2?
 
the first place to start is to get the check engine light code pulled. go to autozone.
 
BlueLS said:
Most likely that is a cat or o2 sensor problem. (some of the symptoms are rough idle when cold, and decreased gas mileage)

The most common are p0420 and p0430...
http://www.obd-codes.com/p0420
http://www.obd-codes.com/p0430

Go to auto zone and have them pull the code(s), they do it for free.
Click to expand...

the code I got was p0174, lean code seems MAF sensor or dirty fuel filter. Highly doubt tha car has a vacum leak and is running lean
 
well I checked all the plugs and coil, plugs are brand new as well as the coils, and when i took it all off, everything is nice and clean and dry. I was suspecting maybe oil on the plugs but NOTHIN. I took it to the lincoln dealer just for a quick peek and they said there seems to be NO vacum leak which pretty much most likely can be the MAF or fuel filter, well the fuel wouldnt cause a check engine, the MAF would. What do you guys think, MAF sensor it is? I had a BMW 750 before this and a similiar issue and it was the MAF, cleaning really didnt help any. When I bought a new one, it fixed the problem. Also, anyone have the steps to replace the fuel filter?
 
my only other thing is fuel injectors need to get cleaned out, but that wouldnt throw a code tho
 
Well accroding to http://www.obd-codes.com/p0174

- The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
- There could be a vacuum leak downstream of the MAF sensor.

Since you have eliminated a vacuum leak as the problem, the MAF is the next logical step. I would try cleaning it first, but most likely you will need to replace it.
 
BlueLS said:
Well accroding to http://www.obd-codes.com/p0174

- The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
- There could be a vacuum leak downstream of the MAF sensor.

Since you have eliminated a vacuum leak as the problem, the MAF is the next logical step. I would try cleaning it first, but most likely you will need to replace it.
Click to expand...

whats the best way of cleaning the mef sensor? Can I just spray brake cleaner or should I get a Q-Tip and get alcohol and rub the sensor with the q-tip and then clean out the sensor with Simple Green
 
its a 2000 V8, UPDATE: Here are the codes the came up:

p0302=Cylinder #2 Misfire Detected
p0304=Cylinder #4 Misfire Detected
p0172=System Too Rich (Bank 1)
po174System Too Lean (Bank 2)


OK, As of right now. Plugs and coils have all been checked and are all brand new. MAF Sensor and Fuel Filter changed and still NO DIFFERENCE. Rough idle that goes away as soon as you start driving. The Ford/Lincoln tech took a quick peek yesterday and said it does NOT sound like a vacum leak. This has got to be something small and stupid I think, either a plug or sensor not connected or that leaves me with about 3 more things. INJECTORS need cleaning, o2 Sensors or CATS. PLEASE HELP:frown:
 
p0172 and p0174 are probably being caused by the two misfires.

Did you replace/have replaced the valve cover gaskets when the coils were replaced (all of them, outer and inner O rings)?

The VCGs are also a common problem. Pull the coil covers and coils off and look for oil in the wells (even a small amount can cause a short). If you see ANY oil in the wells then you need to replace your VCGs and the 2 coils for the misfiring cylinders.

I had a similar problem and finally got tired of it and replaced all of the gaskets, coils, plugs and wiring. I haven't has any problems since, it's been a little over a year now.
 
Bad connection to an ignition coil? Maybe a bad coil harness?
 
BlueLS said:
p0172 and p0174 are probably being caused by the two misfires.

Did you replace/have replaced the valve cover gaskets when the coils were replaced (all of them, outer and inner O rings)?

The VCGs are also a common problem. Pull the coil covers and coils off and look for oil in the wells (even a small amount can cause a short). If you see ANY oil in the wells then you need to replace your VCGs and the 2 coils for the misfiring cylinders.

I had a similar problem and finally got tired of it and replaced all of the gaskets, coils, plugs and wiring. I haven't has any problems since, it's been a little over a year now.
Click to expand...

I checked all the coils for spark and they all have spark. NO OIL on anything, all dry
 
Could easily be a vacuum leak. If it is downstream from the o2 sensor then unmetered air is getting into the system causing lean situation. Then the computer overreacts and adds gas causing rich. This can cause a rough/surging idle. I had this exact problem on my M5 (even my peak codes showed misfires). The way we found it was to spray carb cleaner onto the various vacuum hoses as the car was idling. Sure enuough the revs jumped when the carb clean got sucked in and burned. I hope it is as simple as this for youl
 
ok UPDATE from the dealer: So far the following has been checked by the dealer:

Colis, Plugs, Fuel Filter, MAF (all new btw) Injectors, and o2 sensors. Everything is fine but one o2 sensor is bad however, this really doesnt do much for my problem. They pretty much no clue what it is and the only thing left that they think it would be is BAD TIMING and bad tensioner which at one point they think it skipped timing and now the timing is all off which = $1500 job since the whole front end needs to come apart but still they arent even 100% sure about that either, thats just the only thing they can think of. C'mon guys I need help big time, Who has experience with this problem.
 
I had the same prob & it was #6 misfiring, & I pulled the coil off & it had coolant in the plug well, is this a head gasket guys?
 
BEATZZ said:
I had the same prob & it was #6 misfiring, & I pulled the coil off & it had coolant in the plug well, is this a head gasket guys?
Click to expand...

i still think that its the injectors, for the cylinder #2 and #4 which the plugs and coils itselves are new. The scanners can show the injector but not how much flow is actually going through them, I personally think the dealer is giving me bull. I can put some injector cleaner in my tank and see what happens, the feeling feels like the cylinders arent running on all 8 which they arent when idling b/c not enough fuel is spraying through #2 and #4 but as soon as I give it gas, it shoots more obviously and then all cylinders work fine, opinions?
 
Also, if it had anything to do with timing being off such as tensioners and timing chain issues, OBD-II would read a different code such as "cam retard timing" or somthing along those lines, not cylinder # 2 and #4 misfire and too rich and too lean, im almost positive the o2 sensor will fix the rich and lean part and 2 new injectors will fix cylinder #2 and #4, thoughts?
 
All I really wanna know if this is a serious issue like the dealer says(which I highly doubt) or is it most likely just dirty injectors and something overall small
 
have the coils been bench tested or are you just assumung their good because their new?
 
I just read this damn thing to realize it's from 2008. Anyways orrgroup are asking cause you are having similar problems?
 
vikingdiesel said:
Also, if it had anything to do with timing being off such as tensioners and timing chain issues, OBD-II would read a different code such as "cam retard timing" or somthing along those lines, not cylinder # 2 and #4 misfire and too rich and too lean, im almost positive the o2 sensor will fix the rich and lean part and 2 new injectors will fix cylinder #2 and #4, thoughts?
Click to expand...

WRONG!!! It could very well be that the chain has enough slack in it to be off at idle but be fine while driving. Best thing to check now is to pull off the valve cover gaskets and check to make sure the flats of the cams are perfectly lined up. If you can put a straight edge across them without any gap, then your car is in time. Listen to the warning and check those things now before something breaks and then you have to repair a head like I did.
 
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