I have a 2005 WK Laredo 4.7L V8 with 115k miles on it. It smells that it is burning rich from the engine. It has a P0443 Evap Purge control error.

I replaced the EVAP Purge control solenoid but that is not the problem. You clear the code and in a few cycles the P0443 comes back.

I am unable to license the jeep until it passes emission, and it's definitely not going to pass. What's the next thing to try?

It definately smells of burning oil or something like that like it's running rich. Any advise is appreciated as I try to fix this on a very limited budget. The engine does not smoke and there are no leaks from underneath.

TIA.

HJ

you have used a scanner and p0443 is the only code?

P0443-EVAP PURGE SOLENOID CIRCUIT key word is CIRCUIT.

EVAP PURGE SOL CONTROL CIRCUIT OPEN
EVAP PURGE SOL CONTROL CIRCUIT SHORTED TO GROUND
EVAP PURGE SOL SIGNAL CIRCUIT OPEN
EVAP PURGE SOL SIGNAL CIRCUIT SHORTED TO GROUND

Attached Files

File Type: pdf

2005_purge.pdf (93.0 KB, 6 views)

Yes that is the only code. Any idea what the voltage should be at the plug? Also would this make it run rich?

As for richness I see no reason other than you sense of smell - the sensors would code if there are issues with fuel mixture that is why I suggested you use a scanner to be sure to see all codes.

you would use scanner to command purge - and check operation, a test light inserted across the purge valve connector should pulse thus confirming circuit. You could check the wires from purge to PCM - open, grounded.

Welcome to the forum and sorry to hear about your problems. As said above, it's important that you put a good scanner on the vehicle and check for other stored or historical codes. When you fill it up, do you "top it off" or shut the pump off as soon as it stops? There are also other components with the purge system and everything should be checked. With a good scanner, also check all engine management modules. Pay close attention to long and short term fuel trims. Also, when is the last time the engine has been tuned up, specifically the spark plugs? What type (copper core, platinum, iridium or other "gee whiz" ones) of plugs are in the vehicle?

Also, once you get everything in proper order, be aware that all emissions readiness items MUST be showing completed satisfactorily BEFORE you take to have the emissions test done again. If any of them are not showing ready, you'll fail again.

Good luck and keep us posted on your findings.

Thanks, I do have a good Autel scanner. As far as the oil smell i think it may be a bad PCV valve the hose that comes from the air box and splits into a T fitting
On top of the passenger side valve cover is saturated with oil at the fitting, and i think this hose goes to the other side to the valve. Will check tomorrow.

Focus on the problem - P0443. Check the wiring to the purge valve - power and ground and control. The problem could be as simple as a dirty connector or a non working connector.

Did you just purchase this Jeep? Was there a check engine light on when you made the purchase?

Yes just checked then circuit to the main valve, key on engine off 12v, at the plug, engine on, 15-16v at the plug with fluctuations. This tells me the circuit to the valve is good. Checked the ground to the negative battery post with engine off and i get continuity with some small resistance as would be expected. With engine on ground on plug to ground on battery the ohms fluctuate between 40 and 60 ohms. Also i checked the ohms on both old and new valves and they were the same.

Thoughts

Let me check the service manual...give me a few...

PM me your email and I will send you the diagnostic steps for P0443.

see attachment

Attached Files

File Type: pdf

P0443.pdf (53.1 KB, 5 views)

Ok thanks to Robert for sending the test procedure. I am going to past the steps here and post the results so you can confirm my thinking.

2. EVAP PURGE SOLENOID OPERATION
Turn the ignition off.
Disconnect the EVAP Purge Solenoid harness connector.
Ignition on, engine not running.
Using a 12-volt test light, jump across the (K52) Evap Purge Solenoid
Control circuit and (K70) Evap Purge Solenoid Signal circuit in the
EVAP Purge Solenoid harness connector.
With a scan tool, actuate the EVAP Purge Solenoid.
Does the test light flash on and off?
Yes >> Replace the EVAP Purge Solenoid.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
No >> Go To 3

My Results - I don't have a test light but between with engine running voltage at the valve harness was around 15 volts that fluctuated a little.

3. (K52) EVAP PURGE SOLENOID CONTROL CIRCUIT OPEN
Turn the ignition off.
Disconnect the C3 PCM harness connector.
CAUTION: Do not probe the PCM harness connectors. Probing
the PCM harness connectors will damage the PCM terminals
resulting in poor terminal to pin connection. Install Miller Special
Tool #8815 to perform diagnosis.
Measure the resistance of the (K52) Evap Purge Solenoid Control circuit from the Evap Purge Solenoid harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes >> Go To 4
No >> Repair the open in the (K52) EVAP Purge Solenoid Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

I did this test and the resistance was below 5 ohms. .3 to be exact moved to step 4


4. (K52) EVAP PURGE SOLENOID CONTROL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (K52) Evap Purge
Solenoid Control circuit in the Evap Purge Solenoid harness connector.
Is the resistance below 100 ohms?
Yes >> Repair the short to ground in the (K52) EVAP Purge Solenoid Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
No >> Go To 5

I did this test I got an open. No connection

5. (K70) EVAP PURGE SOLENOID SIGNAL CIRCUIT OPEN
CAUTION: Do not probe the PCM harness connectors. Probing
the PCM harness connectors will damage the PCM terminals
resulting in poor terminal to pin connection. Install Miller Special
Tool #8815 to perform diagnosis.
Measure the resistance of the (K70) Evap Purge Solenoid Signal circuit from the EVAP Purge Solenoid harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes >> Go To 6
No >> Repair the open in the (K70) Evap Purge Solenoid Signal
circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

resistance was .3ohm

6. (K70) EVAP PURGE SOLENOID SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (K70) Evap Purge
Solenoid Signal circuit in the Evap Purge Solenoid harness connector.
Is the resistance below 100 ohms?
Yes >> Repair the short to ground in the (K70) Evap Purge Solenoid Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
No >> Go To 7

Open, no reading

So correct me if i am wrong, I believe this is telling the wiring between the valve and PCM checks out with no shorts. Agree?

test #2 will really show if the PCM is controlling the circuit, try the test with your DVOM into each cavity of purge valve connector it should show voltage as the PCM commands PURGE.



The old purge valve - did you keep, check operation, not stuck closed, any thing stuck in valve keeping it open or closed ie charcoal bits,

I did that on step 2 see above, my voltage readings are there with the dvom

I am not a mechanic but have done diagnostics on my own 4.7L V8 Jeep engine and have changed engine heads, valve springs, lash adjusters, and many other things.

Can you perform test #2? Does your scan tool control the purge valve? Can you purchase an inexpensive test light at the local auto store?

It would seem based on your limited testing so far that there may be an issue with the control wire or the PCM.

Was there a check engine light "on" before you purchased the vehicle? Reason I ask is that a pcm is very expensive to replace and reprogram and could be a reason to motivate a previous owner to sell.

this is a bit confusing to me - yeah it likely me but I cant understand it.

"My Results - I don't have a test light but between with engine running voltage at the valve harness was around 15 volts that fluctuated a little."

Ok you connected DVOM between connectors -
voltage was?
you commanded purge and voltage what then?

Why what am I looking for -

During closed loop operation, the PCM energizes and de-energizes the solenoid 5 or 10 times per second, depending upon operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. The PCM adjusts solenoid pulse width based on engine operating condition.

Would the fast cycle time be clear with DVOM I am not sure. ANd Sunday is Church day
and family time - can't wrap my head around this now.