Chrysler Repair: 1999 intrepid multiple cylinder misfire, coolant temperature sensor, camshaft sensor

Question
Hey Roland, so 3 months ago i started noticing small jerks in my car while driving or accelerating.  Even rough idle at start and once i pressed on the gas a bit, the roughness smoothed out.  Each month it started happening more and more till 1 month ago it was happening continuously while driving, jerking a lot.  Then 2 weeks ago i finally got a check engine light and my car was stalling now at red lights and being worse then ever.  So i gave it to my friend and he put the scanner to it.  Said there was a multiple cylinder misfire on 4 cylinders.  So he replaced the coil packs, plugs, fuel filter and still nothing.   Now it is so bad that it does not even start.  He also bought a new camshaft sensor and still nothing.  the only way my car starts is by unplugging the camshaft sensor so it runs on limp mode.  But even then it takes quite a few tries for it to start and once it does it sounds different then before.  Also he said probably the PCM, so i had that changed by the dealership and still.  I just brought the car back home on limp mode and its parked.  I did the key thing and I got the codes

P1684   (unplugged battery before)
P0340  ( cause camshaft is unplugged)
P0118  (I dont know why i got this one, never got it before)

I did not even get a misfire code which i find weird.

PLEASE HELP!!! I spent so much money already and I cant afford any more waste.

thanks!

Answer
Hi Justin,
On the 0118, that is saying that the circuit for the engine coolant temperature sensor doesn't make sense. That sensor is located immediately adjacent to the thermostat housing and has a 2-wire connector, tan/black and black/light blue. It may be the sensor is not plugged together with the 2-wire plug, or the sensor is off value, or the wires from the plug to the pcm are either shorted to the battery voltage wire of some sort, or the ground wire is 'open', etc.
So make sure it has its plug connected to it.
If you have an ohmmeter then remove the plug and measure the resistance across its two connector pins which should be in the range of 10,000 to 14,000 ohms when it is cold. After you have drive the car far enough to get it to operating temperature you should find the resistance has dropeed to around 1,000 ohms.
Check that the tan/black wire is continuous to pin 26 at the pcm (0 ohms resistance between the ends of the wire) and that it is not showing 12v when you measure it at the plug end, with the plug removed and the ignition is 'on'. Rather it should show about 5v.
Check that the black light blue is continuous to pin 49 of the pcm.
As for the general problem you described, may I suggest that you check the egr valve as possibly being stuck slightly ajar. That will lean out the mixture and make for missing, hard starting, poor running, etc. It is not monitored very well for that sort of an issue. Because there are 3 possible engines for the '99 I can't tell you the details. So let me know and I will either describe the valve and checking it out or send you copies of the pages from the manual via postal mail.
It is surprising that you don't have the multiple misfire code now, but maybe it will show up shortly. The problem with that code is it can be caused by a miriad things, including the egr, so it is hard to know where to start on it, though the friend did several of the possiblitilies.
So, lets start with the egr and of course the coolant temp sensor code.
Roland