hi im new to the forum and at wits in im not sure if im a plenum case or not.my 98 1500, 5.2 keeps throwing cyl 8 misfire I have replaced plugs wires coil o2 sensors #8 injector and it doesnt fix anything truck reecks of raw gas help

 

Welcome to DF.

First, before anything else, please read this:
https://dodgeforum.com/forum/dodge-ra...s-section.html

I will move this to the 2nd gen section for ya.

 

#8 misfire usually indicates the plenum is blown and the cat is clogging.

 

Cat is empty but either way plenum time I guess

 

Before you start pulling things apart I would do a comp test on the motor and see just what kind of shape it's in. Comp test for sure on cyld 8.

 

Hmm, "reeks of raw gas". Where can you smell it most strongly? In the cab, under the hood, at the exhaust? Among other things, a cat (which you don't have) removes unburned hydrocarbons from the exhaust. If you smell it at the tailpipe, maybe that's why. if you smell it in the cab, does your exhaust have any bad leaks?

Are you getting a good, strong spark at all the plugs? (And do you own a screwdriver?) Is #8 getting a spark? Maybe the injector is firing, but the fuel isn't getting burned. (Plug fouled already? Wire loose, or routed wrong?)

Lastly, +1 on a compression test. When you say "rich exhaust", is it blue, like oil, or black, like unburned fuel? Low compression will make the fuel charge burn poorly or not at all.

 

Cyl 8 was tested it has plenty of compression the smell is the exhaust at the tail pipe no leaks

 

Sorry but.

Warning: Using a screwdriver to test for spark is so old school it just bad to even suggest it, there a lots of cheap spark testers on the market. If the person does the test wrong with a screwdriver they will get a shock and if that person has a pacemaker or a heart condition well it won’t be pretty.

Please use the right tool for the job.

 

I'm guessing the exhaust looks black, like unburned fuel - correct?

Are you getting a good, strong. consistent spark at the ends of all the wires? I'd try each one with the engine running.

Is the truck idling smoothly, or kinda rough? (Especially at idle).

***

"Sorry but.

Warning: Using a screwdriver to test for spark is so old school it just bad to even suggest it, there a lots of cheap spark testers on the market. If the person does the test wrong with a screwdriver they will get a shock and if that person has a pacemaker or a heart condition well it won’t be pretty.

Please use the right tool for the job".

Gotta completely disagree with most of that. (Yes, if you have a pacemaker or a bad ticker, please don't do this).


I own, and used, an inline spark tester to try to diagnose my recent ignition problem (bad CKPS). The inline tester gave very ambiguous results, since it is relatively easy to fire and didn't do a very good job of separating the weak sparks from the strong sparks. With a screwdriver, you can slowly increase the distance between spark and ground to get a much better idea of just how strong it really is. If there's an inline tester out there with an adjustable gap, I'll get one and put the screwdriver away. In the meantime, it works great for me. For best results, use one (clean) hand, a very clean (non-oily/greasy) insulated screwdriver, and rubbers gloves wouldn't hurt.

 

Ok put your screwdriver away and never suggest that test again.

http://www.ebasicpower.com/c/OB-MERT...iner+Outboards


Quantity in Basket: none Spark Gap Tester, Adjustable


511-9766 Spark Tester
Spark tester can be used to test from 1 to 8 cylinders. Sealed design reduces the possibility of fire.
NOTE: If extension wires are needed, order P/N: 511-9903 (set of 4 wires).
Tech Sheet (pdf)