Been out "Code Hunting" Its sunny and 72 degrees so the top goes down and I have an excuse to cruse. Cant get it to fail once the engine gets warm.

The codes this morning were emission related. yesterday, after it started and failed, with the reader on, the fuel pressures were normal on both rails.

 

I was reading you can do your own load test by measuring voltage drop when starting

 

I have been driving all afternoon. Not even a stumble. Cant buy a code.


Guess I will check the battery in the morning.


Did I mention this happened on Friday the 13th.

 

Battery at 12.5 volts. Isn't 12.5 a little on the low side? It was 12.9 after driving all day. I need to get it tested but I don't trust the autozones and such around town.

 

Ok Did not start the car....The car is back to P0191 P2505 and P2504 codes just by turning on the ignition. Checked the battery 12.4v

 

Did a load test and it looks ok dropped to 10.4 volts 3 times during a 15 second start. Overall the battery went to 12 volt and recovered to 12.54 volt in 15 minutes so although I cant rule that out....doubtable.

Something new though. The fuel pressure is not fixed at 75 lbs and the PCM senses when I disconnect the fuel pressure module. The pressure is variable to the primary side but > 20 psi higher than the secondary side. Then I disconnect the module the fuel pressure goes fixed at 75 lbs and I get a new code P0193. When the module is connected and the car engine is turned off, with the ignition on, the OBD reader sees a steady drop in fuel pressure from both modules.

Do you know which side the primary PCM is on?

 

Rotating the FPM not too hard but somewhat a pain in the ***. I dont have a 1/4" ratcheting wrench so its one tooth at a time on a tiny 16 tooth box end for the rear and then a squirt of fuel in the eye.

Since I swapped these already the likely hood of both sensors being bad while only on that circuit is fairly low. I guess I need to unplug the good sensor and see if it goes to 75 lbs but I am a little afraid to do this with the engine running.

I need to get to the PCM. That A/C job probably meant the removal of the cowl plug to the PCM so perhaps there is some connection problem.

Getting ready to rain and blow though and I only have a carport. I will see if I can squeeze this PCM inspection later.


Thanks Again!!!

 

Will do

 

ok I went in...There are only 125 screws holding the fender liner in. How do you get the PCM plug unplugged?

 

Ok 2.3 MOhm on the control wire I am not sure regarding the power wire. They are not the same color on the PCM connector

 

Wow This is a real mess. I have huge impedance on these wires. The wires are different colors going into the PCM t from the Pressure sensor. The wire on the 21 pin is blue and red.

The ground wire also has resistance issues

Does this circuit go through any other switch/control or is it a straight wire from the pressure module to the PCM



I also dislodged my washer tank sensor and the rubber gasket plug needs replacing so it leaks now. Easy fix though

It's raining getting cold I have no clue whats going on....I am defeated

Its

 

I don't have any help or advice for you, but I applaud your tenacity. Hang in there.

Jeff

 

I am measuring from the harness plug end of the PCM to the harness plug end of the pressure module. High impedance on all wires with no change in the readings from pins 1-3 on the FPM after disconnect from the PCM

There is some confusion regarding the plug end and the numbering of the wires but I tried multiple spots just to get anything under 1 Ohms. Not even close. The wire was blue and red but the wire in the other spot (mirror image) was the proper color from the FPM. I imagine that is correct

http://www.ebay.com/itm/Engine-Wirin...RYWslO&vxp=mtr

Above is a link to the harness. As you can see on the injector circuit the fuel pressure control circuit ( the one with three wires) looks to be a home run to the PCM through that plastic conduit.

Looking at my harness I can see all of it, save where it goes into that plastic. It all appears in excellent shape with no defects. There doesn't appear to be any connectors unless they are in the plastic conduit which I doubt

I am Vexed

 

Ok After thinking about it and Re reading your post Matt, I was reading the wrong plug. I was reading the cowl plug pin 21 fuel pump monitor....

No wonder the funny readings!

 

Yes that is good news. After spending 3 hours yesterday working in the rain in the cold with my accomplishment being to falsely diagnose a bad wiring harness, and breaking my windshield washer bottle, I was discouraged.

I have been trying my best to do not harm in this process and not to throw parts at the problem and have been fairly successful but I have not found the problem.

I am more and more convinced this is a PCM problem. There are two many indicators that this is a power activated component related problem.

More to come.....



I am not sure why the car runs like it does when it gets warmed up....I am going to put the charger on the battery and see if I can get iy running again