Questions about rough idle, and ODB2 system.

[zerodevil]

I have the 4.6L v8 engine. 106,000 miles
ODB2 question.

ok so over this last year i have managed to shoot 3 spark plugs...and have had all instances repaired...but the last time i shot a spark plug my ODB2 system didnt thorw a single code(i checked using two devices)..i am currently having some small issues with my truck(mainly a rough idle) and im having a hard time getting it ironed out...if i had a code to go by things would go easier...is there anyway for the ODB2 system to fail? Could a fuse have blown? Is the system not as effective as i thought?

Rough idle question.

as i have already stated, My engine is having a rough idle in N and gear...it will be doing fine and all of a sudden the RPM drops and and the truck shutters...then the engien idles ok for about 10 seconds, and then repeats the cycle. When in Nutral the engine apears to idle rough from idle all the way to 2200 rpm. I have checked for kinked air hoses and found none. The first two of my spark plug blow outs were repaired via helica coil...the latest was done with this kit that uses a longer heavy duty plug(that isnt gaped like my others, bosch 4 pin platinum) and also had to replace the High voltage piece between the coil and the plug(my other 7 have a braded wire, the one in question uses the standard Spring like piece)..so i have 7 bosch 4 pin platinum plugs with 60,000 volt coils...and 1 extra long heavy duty plug that is missing the high voltage connector that the other 7 are...I also have not replaced my IAC as i have yet to get an ODB2 code, nore have i cleaned my MAF...i run a fuel system cleaner twice a year...

any one else have any thing like this?

 

[tackleberry]

4.6L is notorious for ejecting sparkplugs. IMO, if you ejected 3 already, id be replacing heads period.

also, as for your idle surge, lets go with a possible vac leak

and use autolite plats single tipped in 4.6L. bosch plugs are for ricer cars and not very well reactive in larger displacement motors. i remember in a crown vic forum people would in CAPS say NO Bosch.

 

[crash594]

Here is what I would do and if it dont work it will only help with MPG.
1) Clean the intake around the butterfly with carb cleaner. Do it a couple of times after driving around the block.

2) They have a cleaner for the MAF sensor. Get it and clean the sensor.

3) Pull the EGR valve and make sure the tube is not pluged. (if you have the $$$ replace the valve it will help with MPG)

4) Im not sure about your model but if it has a idle valve clean or replace it. (I would start with cleaning and lubing first unless you just want to get it done.

5) Replace fuel filter. The ethonal is really plugging these.

These are all comon issues that can cause your issue without a code. The money spent will not be wasted. If it dont fix it, it will help it run better in the long run. Some of these I do every oil change or once a year.

 

[crash594]

4.6L is notorious for ejecting sparkplugs. IMO, if you ejected 3 already, id be replacing heads period.

also, as for your idle surge, lets go with a possible vac leak

and use autolite plats single tipped in 4.6L. bosch plugs are for ricer cars and not very well reactive in larger displacement motors. i remember in a crown vic forum people would in CAPS say NO Bosch.

Sorry but for 4.6 I would not use anything but Motorcraft plugs. The 4.0 is not picky but the V8's only like OEM

 

[zerodevil]

thanks for the tips guys, stupid question, what the hell is the butter fly?

 

[crash594]

Goto this site
http://www.mustangworld.com/ourpics/fcar/mwtb.htm

Go to the 2 pics next to item 2. The round disk in the center that opens and closes is the butterfly

 

[zerodevil]

the throttle body...lol gotcha, I just put in a new throttle body...bbk 75mm...about 4 months ago...its clean and in working order(was under my hood a week ago to check on what was causing this idle...other than some oil coming from the breather lines on the heads...nothing was dirty(i wiped that up on both sides of the throttle body).

 

[crash594]

Is this when your idel issue started. Maby something is loose.

 

[zerodevil]

no, rough idle started about 2-2.5 weeks ago...before that i was running a bbk 70mm throttle body...nothing is lose as far as i could tell. thats what i was checking for last week.

 

[zerodevil]

so today it went up and just died in my drive way...so i figured it was a safe bet that it was either a clogged fuel system...or a bad IAC...so i repaced the IAC valve(was over 100 bucks...we alaskans get robbed on prices..), and the fuel filter...i also cleaned the MAF Sensor...its no longer surging, but it still has a little bit of a roughness to it...im thinking new heads will fix that...so thats my next project. Thanks for the help guys.