I had this condidtion about a week ago as well as P0304 (cyl 4 misfire) and was told to clear the code and unplug/clean the sensor connector and check plugs, wire, ect. I cleaned connector and cleaned inside of wire boots and all was good. I cleaned intake/throttle body and sensors and got idiot light. Figured it was emissions code, so i took neg off again and let it sit for about 30min. Started and ran in driveway for a while with no check engine, then drove 5 min to get it scanned and got a P0606 internal memory error. I cleaned ECM connector. Even peeled back harness loom and visually checked for breaks or damage with nothing found. Hooked everything up and truck ran good with no check engine light. So never the less i drove to/for work with it (mobile gen tech). I get to work and my sub blows... ok, thats fine. gona go bigger anyway Then when i start the truck to leave i get idiot light. got it scanned P0316 and P0304 again. bought/changed plugs on spot. No difference, but drove anyway because i had to do my service calls. Bought/installed a set of Bosh wires as soon as i got off. No difference. it only has a slight misfire that you can bearly notice. I only hear/feel it because there is no more sub
truck was sunk and had bad lifter tap that i mannaged to get to go away after it warms up. is it possible that i bent a valve and am getting blow by or inadequate pressure in the head causing a misfire? Im going to change sensor ASAP of course, i just have a feeling that the head has something wrong with it internally.
I would really like some opinions...

 

First thing I would do is run a compression test. Find the lowest cyl then add about a cap's worth of oil in the cyl then redo the test if the compression comes up a lot its the rings not the valves. Let me know what you find!

 

316 can also come from misfire on start up. Chase 304.

 

thank you. i will try that.

I also get a misfire on start up (or atleast it comes up on the scanner). in the last two days the misfire has gotten worse. Im having a hard time getting a new crank sensor due to my schedual at work lately. It now misfires from 900-2500rpm ever so slightly like one cylinder isnt all there.

 

Since you've replaced the plugs and wires that leaves the coil pack, crankshaft sensor, fuel injector or compression related issue. If you don't want to simply through parts at it, I'd recommend a doing a few diagnostic tests first. I'd start with a simple vacuum test and or a compression test since you did say "truck was sunk and had bad lifter tap" just to rule out hard part damage, You can also test the fuel injector to determine if its firing by doing a fuel pressure drop test,

 

thanks for the good advice. What would i use to test fule pressure. I work with NG and LP systems at work so im at a loss here

 

A fuel pressure gauge like this one

 

Gotcha. Any clue where i can find a timing pin?

 

Finaly got around to my truck after ordering a timing kit and crank sensor. Replaced sensor and truck runs alot better. also performed compression test and cylinders 1,2,3 got 155psi. #4 has 100psi. it also idles higher now (900-1000). I drove the truck yesterday to see if it would fault and it did. P0316 and P0304 again... is it poss that i got a bad sensor out of the box? its supposedly a one time deal and Im kinda irate about the situation. had to wait 2 weeks to get this done and ive gotten no where

 

Cylinder #4 is out of spec. Did you conduct a wet test on it? If not, I'd recommend re-testing by putting a tablespoon of oil down the plug hole, cranking it a few times to distribute the oil and re-testing its compression. Read through this thread for more info Ranger Forums

 

they have v6's tho? and no one mentioned the crank sensor? I had a feeling initially that the head was damaged like a valve,seat,spring,ect. but where dose that leave me as far as the sensor goes? should i test wire continuity? hanes isnt that indepth. You have givin me hope but also alot more questions. will do wet test tomorrow morning at work. what exactly will that test, seats? turck has 178k

 

I'd hold off on the sensor for now and concentrate on the cylinder issue.

The wet test will help determine wither the problem lies with the piston rings or valves. If the compression comes up from 100psi with the oil in the cylinder you may have a broken ring. If the pressure stays the same, then its more likely in the valves, pushrods, or lifter.

 

cyl 4 with oil only 80 psi. i didn't expect that much of a drop. what dose this mean? and im guessing this motor is a lego so i cant just r&r the head. im feeling like i should drive it till it blows up and then put a crate motor in it. my ball joints are squeaking and the pass tie rod end is binding. I spray white grease periodically in it through out the day.this morning when i got in it the headliner had a good portin hanging off, out of no where. Im probably gona get another truck.

 

i found a 95 stx 4x4 ex-cab 4.0 for 3500 only 90k on it. gona check it out tomorrow