Sorry...somehow that last message got posted to the wrong thread! User error I'm sure.

 

Ok I've got a major update to this thread. I bought a code reader and after some trouble getting it to work properly (there's another thread on this forum about that...) I was able to use it to get some good information.

I went for a drive to Home Despot today and on the way home the truck started hesitating while I accelerated from about 35-45mph. If I backed off the pedal it settled down but if I kept trying to accelerate the engine bucked and missed and nearly cut out. It kind of felt like what happens when your fuel filter is clogged. Only mine is new!

Well, I got the truck home and ran codes on it as soon as I pulled in the driveway. These are the codes I got:

122 - TPS below minimum voltage
172 - H02S sensor fault/lean - I know this because of the modified exhaust w/out O2 sensor
332 - insufficient EGR flow - I know this because the headers don't have a connection for EGR and right now the valve is still in place without a hose connecting it
553 - Air management circuit 2 failure -- what is this?
558 - EGR so.enlid circuit fault - probably not a surprise given what I said above

So, I pursued the TPS issue and it looks like it needs to be replaced. Perhaps this was the cause of my hesitation and not the PIP sensor. Here's some videos.




So, I'll change the TPS tomorrow and let you know what happens.

The only other thing I don't understand is the air management failure in circuit 2...my coffee can is missing. Could it be something to do with that?

Thanks.

 

Got the new TPS installed but I must have done something wrong. The truck starts and idles in Park but dies sometimes when I slowly press the gas pedal down and rev up the engine.

I reconnected the vacuum lines to the throttle body. I used a new gasket and tested the new TPS. I have 5 volts to it and it ranges from 1 volt with the throttle closed to about 5 with the throttle turned all the way open. Although I can't get it to go all the way to five volts unless I disconnect the throttle cable. My hands might be too weak I guess!

The code 122 is gone now and I get 111 from continuous memory codes. So I think the TPS is fixed. But there seems to be a vacuum leak somewhere.

I still have that 553 code...air management circuit 2 failure. Could that have something to do with it?

 

The stumbling and cutting out when I pressed the pedal has nothing to do with air management or the TPS. After it died a third time while I revved the motor in park I think wouldn't start again.

Cranks good and I can smell the fuel. Started the Haynes diagnostic procedures for ignition coil. Put the test light in the negative side of the coil and cranked the engine...constant dim light, no flashing. Primary and secondary coil resistance are OK. Got 11.9 volts at the coil. Unplugged coil harness and ICM harness. Have about 1.5 ohms from coil negative plug in the harness to pin 2 in the ICM harness so that's within the 5 ohm spec. Next is where the failure is....checked resistance from coil harness negative to ground....open circuit! Manual says it should be 10,000 ohms.

So, looks like my ignition coil isn't grounded? Can't believe this happened right when I changed the TPS. When it rains it pours...

So, I'm off to hunt for where this ground is supposed to be. This ought to keep me busy for a week!

 

At lease a week as the coil is not grounded.

 

You did not say what 332 code you got so I will guess Continuous Memory.

Continuous Memory DTC 332 indicates the EGR valve did not open with the engine stabilized and the EVR solenoid duty cycle present sometime during vehicle operation.

Possible causes:
-- Obstructed or cracked hose to EGR valve.
-- Icing.
-- Damaged EGR valve.
-- Damaged EVR solenoid harness.

OR if it was KOER:
DTC 332 in Key On Engine Running (KOER) indicates the EVP sensor input did not change after the EVR solenoid was instructed by the Powertrain Control Module (PCM) to open the EGR valve.

Possible causes:
-- Vacuum hose leaks.
-- Icing.
-- Obstructed vacuum hose.
-- Obstructed EVR solenoid filter.
-- Damaged EVR solenoid.
-- Damaged EVP sensor.
-- Damaged EGR valve.

KOEO DTC 122 indicates the Throttle Position (TP) sensor signal is less than the Self-Test minimum value.
Possible causes:
-- TP sensor may not be seated properly (tightened down).
-- Damaged TP sensor.
-- Open harness.
-- Grounded harness.
-- Damaged Powertrain Control Module (PCM).

KOEO DTCs 553 indicate that voltage output for Secondary Air Injection solenoid(s) did not change when activated.

Possible causes:
-- AIRB/AIRD circuits shorted to power.
-- AIRB/AIRD circuits open or grounded.
-- AIRB/AIRD resistance out of range.
-- Damaged Powertrain Control Module (PCM).

KOEO DTC 558 indicates a failure in the EGR Vacuum Regulator (EVR) solenoid circuit.

Possible causes:
-- Damaged EVR solenoid.
-- Open harness.
-- Shorted harness.
-- Damaged Powertrain Control Module (PCM).

 

Right, it looks like the coil isn't grounded. Do you know where the major ground points are on this truck? I want to start by making sure those are tight and clean. If they are I'll have to trace that coil negative wire through the harness and try to find a break in it. That's going to suck!

 

The coil NEG wire goes to the ICM & the cluster plug.

/

 

Yes, the engine block from the NEG cable from the battery and then the following.










/

 

Thanks very much! I'll investigate all of these. I guess in the worst case I could just splice into the coil harness negative wire and run my own ground to the battery or chassis.

 

If you do that it will not run and you will have no spark.
More than likely you will also burn up the Ignition coil.

 

How is that possible? The coil needs a path to ground....whether it's through another component or directly to ground shouldn't matter. No?

 

The coils path to ground is through the ICM.
Look at the diagram in post #23 above.
If you ground that wire the ICM would have no control over the ICM and the coil would not build up and work.

 

Ok I think I get it. You're saying the ICM is interrupting the ground connection to cause the magnetic field collapse in the coil?

If I'm understanding you then it sounds like it narrows the scope of the problem. Either the bad ground is in the harness between the coil and ICM or the ICM isn't grounded to the chassis.

This is very helpful. Thanks. Sorry I'm slow on the uptake. Electricity boggles my mind.

 

Yes that is the way it works.
I do not think there is anything wrong in the harness as far as the ground goes.