That was hiding around here somewhere... If I find the link I will post it.

What I recall is that it's actually based on the CPS. Really, the engine isn't a smooth running machine, you have a burst of energy each time a cylinder fires. The CPS is monitoring the motion of the flywheel for a "push" every time a cylinder is supposed to go. If that cylinder's turn comes up and the computer doesn't see enough of a "push" at that point it will log it. I believe it's something like X "bad" fires in a given period of time will throw a code.

 

Right, Salad, comes from the CPS. I believe the magic number for our Jeeps is 200 misfires out of 600 fires gives a code.

 

I love my Renix......

 

I'm beginning to love it too.

I've been asking about how the PCM figures out a misfire too.
I fully understand how you would get a P020X (x for cylinder #). It's an electrical pulse the PCM can look for. Easily repeatable by just disconnecting an injector.
But it seems that the P030X code is purely mechanical and that has me wondering how the electronic PCM can show it without a physical sensor. And if there is a physical sensor, which is it?

Something else I've learned is that when the PCM detects a misfire it shuts off the pulse to the cylinder's injector. So as long as you have a P020X or P030X code on your system the injector will not fire until it's been cleared.

Anyways I have a partial update for you all.
I took apart the wiring harness. What a mess. Right where the lead for injectors 5 & 6 are taped off, the wires must have gotten pretty warm as the insulation was all stuck together. I peeled apart all the wires and found a broken one that I'm sure I cut while I was undoing the tape. I reconnected it with a shrink wrapped splice. I left the wires out of the black plastic holder for the time being. So far for the last few days my idle has been higher where it's supposed to be and no CEL.
But I just know I'm tempting fate. Murphy is my constant companion.
I've placed an order for valve springs. I can get 4 for $12 so I'll replace them all. Next trip to Port Huron and Harbor Freight to get a valve spring compressor.

To be continued.......................

 

IIRC P020x are caused by a lack of impedance drop on the injectors when ground is applied.

CPS dude, scroll up lol

No Princess Auto nearby? Not sure which is better but they carry a few

 

I like the drive too.

 

The plug on the injector? Yes that would be quite a change in impedance - infinite one could say.

Fair enough. These should help:

http://www.obdii.com/articles/OBDII_...s_Testing.html
http://www.autotap.com/techlibrary/o...emystified.asp
http://www.underhoodservice.com/issu...ontentid=71962


That's quite a price difference for what it essentially the same store! Drive works for me

 

Now we're talking Thanks!!
Got called into work so I couldn't play on the computer.


And another follow up.
I haven't seen the CEL on the dash but my copy of Torque Pro tells me I have a pending fault P0306 AND another one for the abnormal voltage at the TPS
oh Joy!

 

thanks got mine figured out bad 784 injector

 

Wish my was that easy. Looks like its going to be new valve springs.
Will keep you all updated.

 

For all those who hate a thread without a conclusion , here you go.
I've battled this for some time now. I didn't post a resolution after I changed the valve springs , well because it didn't work.
I had purchased a compression tester but has anyone else noticed that the plug threads on our heads are very far down the hole? First one didn't work so I ended up buying another. Finally did a test one day and found the first 5 cylinders at an even 175 PSI. The sixth however....... how about 30 PSI.
Could only be one thing. A burnt exhaust valve.
I had lost my job and was just getting back into home renovations so money was tight. I had another good 99 engine sitting around but I was really trying to get a new 0331 casting from clear water or somebody. After I got my 4:11 rear end installed I found I was getting around 11 miles to the gallon.
So I made the decision to rebuild the spare 99 head and go with it.
I'll have it on this afternoon. will give you all the results after that.
Here are some pics of my 0331 head

 

After running to the auto parts place to get a proper intake manifold gasket I got everything buttoned up nice. DON'T buy the head gasket set from Amazon. See the reviews for the reason.
Been driving it for 2 weeks now and what a difference. No more shaking engine. Idle is perfect. All my sensors are showing completed on my Torque Pro app.
Finally working right. I did notice a bit less power in the butt dyno. Probably from the THICK head gasket. I'll bet it lowered my compression ratio.
Anyways it's now time to start my Stoker build.

 

MAN! That is a pretty motor! Sorry for jacking this thread but, I couldn't help myself!

 

A lot of good information here. Glad you got it fixed and I would love to do a stroker one day. Keep us posted on the build cause I would like to follow the build and learn a few tips and tricks.