So I've got 98 RAM 1500 w/ 318 motor. I just did the plenum, NTK plugs, 8mm wires, brass cap & rotor, gaskets, Bosch 4-port injectors, oil pump and timing chain. I had a bad misfire before and it ran rich. I thought it was the blown plenum and a bad upstream O2. So I did all this work and replaced both the O2's with NGK sensors as well (Yes the sensors were bad). Now, I STILL have a misfire and it still runs rich PLUSS it doesn't like to start sometimes and I have to hold down the gas. SOOOO, I replaced the Idle air control and idle air temp sensors and progress was gained in how it ran but it STILL misfires. Had my buddie throw his scanner on it, front O2 is reading fine, the IAC and IAT read fine, MAP sensor was reading a voltage so its probably still good and the idle changed when he switched from open to closed loop. All good things. Fuel sync is also good. Then he looked up misfires, I had 16 on Cyl 1. So he went back to sensors and noticed my crank was reading anywhere from 150-560 (Give or take 30-40) and my cam or ignition coil/plate was reading 30-60 (Give or take 5-10). He doesn't really work on gassers but thought this could be my problem. Since it misfired before and after I think its an underlying issue so my QUESTION is do you think its my new injectors or that I have a sensor or something else bad?

 

is your check engine light on again? also, id pull all plugs again and inspect, are they all dark or some dark and some white or tan in color, also id have your buddy plug the scan tool back in and check fuel trims as well,they should read the same on both banks, you want them both to read around 0, if the readings are high at idle then go away with increased rpm, you got a vaccum leak..

 

I don't know how it could be a vacuum leak. I replaced the hoses and I sit at like 598 on the idle which is about right.

 

Try running a little bit of higher octane fuel through it and see how it acts. It may still run rich but should resist misfiring a little better. Temporary fix for the misfires until you can get more figured out.


Random question: Your name Casey? Truck and description looks identical to a post on a fb group lol

 

Yeah, thats my name. I'll try switching to super unleaded the next time I fill up. Kum and Go now has ethanol free unleaded gas now and I'm kinda thinking about switching to it. Were the 1998 trucks designed for ethanol at that point I know the earlier trucks didn't like it to much.

 

update?

 

Replaced the CAM pickup coil/sensor/whatever the heck and it helped some more. Got tired of replacing **** so for ****s and giggles I put stock injectors back in. I could tell as soon as I started it up that it liked them better.

NEXT PROBLEM... Stupid me decided lets clean it up and run some seafoam through the brake booster line. It'll like that. Yeah.... NOOO. I totally forgot about the fact that I just cut 2" off of the runners and took the center plate out. From what I can gather all my Seafoam went though the vacuum line and into the intake and then sat there on the plenum pan until I went to leave. I put it in drive, gave it some gas and it started bogging down and tapping and I look behind me and the whole neighborhood is white with smoke. Yup, I just burned a whole can of seafoam at once. NOT GOOD, I stopped. Raised up the idle enough till it mostly stopped smoking and then went and ran it down the road. After I was sure that the tapping had mostly gone away I went out to a side road, started out with just dropping it out of overdrive. Then went to running it and dropping it into third, then did more runs and dropped it all the way to first. Got home, pulled the air cleaner and looked down inside. Dry as could be... HOWEVER....

I can still hear a little tap or more of a tick while sitting in park at around 1200. Doesn't do it much under that and can hear over the exhaust and intake after that. I don't know what the Seafoam could have messed up. I have something squeaking now as well which could be either the PS which was already noisy or the ALT which I think the bearings are starting to go out of.

Also I left the crankcase breather hose off on accident. Don't know how that just wasn't I good day for me and I was mad and just forgot to put it on so it got some hard driving with it off. Hope that didn't hurt anything either. So if you could answer why its tapping, what you think is tapping and if you think I hurt anything leaving the breather tube off that would be awesome.

 

Leaving the breather tube off for a short time shouldn't hurt anything.

Can you post a vid (with audio) of the tapping?

 

Can you tell where the tapping sound is coming from? Valve covers, exhaust manifold, etc?

 

Locate your vapor purge solenoid, and give a listen to it with a stethoscope as you bring the engine up to about 1500RPM at no load. It might be the culprit. Mine gets to sounding like a ticking lifter under certain conditions, and often seems to be coming from the opposite side of the engine compartment, too. Made me crazy until I identified the source of the sound.

Running with the breather tube off just meant allowing unfiltered air into the crankcase. Unless it was a severely dusty environment, the bit of dust that got in there was almost certainly almost all captured as it passed through the oil mist that's thrown on the up stroke of the rocker arms. Nuthin' to worry over.