I have used this forum many times in the past to figure out problems with my Neons, this is the first time I have had to ask a question.

I have a 2003 SXT 5 spd that is throwing a P0352 code at me. When I pull the #2 or #3 plug wire, the rpms don't drop, however, I can here the spark jumping to the plug tube. To me, that tells me the pcm is providing a negative pulse to the coil. I did pull the coil off my running 1998 Neon, no difference. Replaced the existing coil anyway, no difference. When the Wife wasn't looking, I snuck the plugs out of her 2001 ES and installed them in the SXT, no difference. (Yes, I got the plugs back in her car before she figured out what I was up to.....) The car has new plug wires also.

I have done a comp test, was 175, 165, 165, 175. I have tested the resistance of the fuel injectors, all around 16 ohms. I can hear all 4 injectors clicking when the car is running. When I pull #2 and #3 plugs after the car has ran a little, they are wet with fuel.

The car starts very easily, and on the initial rev up, the car appears to be running on all 4 cylinders, although it is kind of hard to tell. As the revs start dropping toward idle, the CEL comes on, and the car drops the 2 cylinders..

I have not done any wire continuity test from the coil connector to the PCM, but with the plug wires sparking to the plug tubes it seems to rule out a short or open to the coil pack....

Any help you can give me on this will be greatly appreciated.

Thank you,
Mike

 

2 and 3 are companion cylinders, remember that as well. Being off timing any way can effect them together.

 

When you say timing, are you referring to the cam belt timing?
Thank you for your response....

 

Yes. There should be some data in PCM named "Cam/Crank Difference"

 

The only code tossed is the P0352 one. If the cam belt timing was off, wouldn't it effect both sides of the coil? What is really throwing me for a loop is the car seemingly running on all 4 cylinders when the car is first started, and then the CEL light coming on when the initial rev up is coming down. That is when the 2 holes drop out.

I'm sorry if I am sounding a little dense here, back in my day all you had to do was set the point gap, set the initial timing.....and you were good to go. This computer crap kicks my butt every time it seems.....

 

A quick update.....I checked for ground signaling for both sides of the coil pack, and the injectors, all are present. I kind of confirmed that the car runs on all 4 cylinders when first started by pulling the injector harness off of 2 and 3 cylinders (the ones dropping out...) and then starting the car. You can definitely tell the car is running on only 2 cylinders when doing this, as opposed to how it runs on first startup with all 4 injectors functional.

While I had the car running I checked for vacuum leaks by spraying carb cleaner around the intake manifold and I think there is a leak where the #3 runner bolts to the head.....

I have a bluetooth OBDII scanner running Torque Pro on my phone, which works great with my 98 Neon, however, doesn't work worth a crap on my Wife's 2001, or the 2003.

Sooooo.....I guess I will be headed into town today to get a gasket and maybe a plug in code reader, we will see what happens.....wish me luck!

Mike

 

Ok, another quick update....even though I seem to be talking to myself.....I got an OBDII reader, and looking at the live data, I noticed that the first o2 senor was reading 0 volts, and the second was reading .17-.19 volts.

I'm not sure....but even in an open loop situation the sensors should be producing a voltage, no? I haven't checked for Vcc to see if the heater is working....it's getting a little too cold around here to be doing much to a car in the driveway.......

 

Can anyone here please tell me at what frequency (hertz) the PCM sends out the grounding signal to the coils at idle?

 

So, to continue talking to myself, here is the latest.....

Waveform at coil B, 12.8 Hz.......



Waveform at coil A, 13.1 Hz....



Code reader showing live data.....o2 sensor 1 @ 0 volts, sensor 2 @ 0.075 volts......



To recap:
Code P0352
Car running on 2 cylinders, when pulling plug wires 2 and 3, there is no drop in rpm, can hear very strong arcing from plug wire to plug tubes in head.
Have exchanged coil from running Neon, no difference. Has brand new coil currently.
New plug wires, have exchanged plugs from running Neon, no difference.
Had a slight vacuum leak on intake runner 3, replaced intake gaskets, now no noticeable leak
All injectors have signaling ground, however, when listening to the injectors with a stethoscope, injector 2 and 3 have a softer sounding "click" to them
Have done massive cussing and idiot dancing around car, no difference

Surely someone here has an idea as to which direction I should be looking to...at this point I'm stumped. I am going to pull the upstream o2 sensor and test it, other than that I am back to idiot dancing.....

Thanks,
Mike

{UPDATE} I just checked my Wife's 2001 Neon, when in open loop both o2 sensors were at about .470 volts. It took maybe 45 to 60 seconds before it went closed loop. At that point, the upstream o2 was fluctuating between .2 to .8 volts, while the downstream sensor was hovering around .650 volts.

What can cause both sensors to be so far off....even in open loop? It is my understanding that when in open loop, the PCM has a built in program that runs the car on the rich side.....but the car will run none the less.

 

Ok...it looks like I'm on my own here.....so, to continue:

I disconnected the upstream o2 sensor harness, now the scanner shows both upstream and downstream o2 sensors at 1.25 volts. Is it possible that the upstream sensor is messing with the PCM? I have a new sensor, however I am hesitant to open it's packaging....once I do that I own it. I don't want to drop $80 on a sensor I don't need.......


{UPDATE} Ok.....I pulled the trigger on putting in the new o2 sensor.....and as I feared.....I just tossed $80 down the drain.....made no difference.....