slightly rough idle at low rpm range

[Beanmachine7000]

If you already did plugs and wires, check and make sure something didn't get screwed up...

 

[RumpRanger98]

everything looks ok. It only seems to misfire in lower rpms and on cylinder 1. my cousin check the injector electrical pulse to see if they are working and all seemed ok. i put new plugs in when i first got it, maybe 120 miles on them, pulled those all looked brand new. he is about to smoke test the intake to check for leaks. then he is going to run some motorcraft injector cleaner through.

could a bad TPS be causing me to misfire on cylinder 1 in low rpms?

 

[RumpRanger98]

so I got it back, no intake leak was found. checked resistance on plug wires all spec to new, they are new. plugs looked new, are new. The idle is just a little bit smoother after running the cleaner through. But it still seems like the idle is rough. It seems to rev up fine. Any other ideas?

Thanks

 

[RumpRanger98]

ya, he checked, im getting spark all around. i even saw the spark when he was checking. What coilpack did you replace it with? motorcraft? or are parts store parts ok?

not that it would cause the misfire, but Im going to replace the fuel filter because I don't know when it was changed last, and the pcv.

It seems to run fine. I took it out on the freeway a bit and everything seems fine. Sometimes the idle doesnt drop to 1k when I stop tho. Im not sure what the idle should sit at on these rangers. on my maxima the car can idle 500-600rpm and sit smooth. this truck dont want to idle under 900. since he ran that injector cleaner through sometimes the idle will sit at 900. but usually if it falls down it will be at 1k or 1100rpm. intermitently it will just idle at 1400rpm when i stop, sometimes it will drop to 1k sometimes it stays at 1400rpm. Ive heard of a mod for the IAC to help the rpm drop alot faster, by making a gasket type restrictor, click the restrictor reduces some of the air flow sucked into the motor on deceleration. but increases emissions from what I hear. but people like the fact it revs down faster. Basically when I rev the truck the rpm slowly fally to 1400 then sometimes to 1k.

so far the CEL hasn't come on yet.

 

[RumpRanger98]

update. I have found that it only idles at 1400 once its full warmed. When its cold it will idle down to 900-1k rpms. but once its warmed when I come to a stop or if its parked and rev it, the idle will stay at 1400 rpms.

going to go check the ECT again now that its real hot to get a hot reading.

 

[Ranger Rod]

Mine usually sits at 900 rpm warm, 1100 or more cold.

Sounds like you said the missing is ok now so it would seem to me something is sticking and in need of wd40 either at the pedal or the linkage where bolted to the intake?

just a thought

 

[06RangerXLT]

my truck usually idles at 690 on a warm day, first start can go up to 2000rpm. i also have a rough idle, but its not so much starting, but when i get home and put the truck in park, the truck stumbles slightly. if you give it a little bit of gas it revs up fine, but then drops below 500rpm, stumbles for a few seconds and then comes back up to 960. also it will cause the whole truck to shudder slightly at random times. im thinking bad plugs. i got the truck with 38,000 km and its at 40,680 now. ive pulled #5 cylinder plug and it looked worn. diod thing was rounded slightly, and brown marks on the ceramic isolator. let me know if this is common?