Interpret these results please

IF you rule out the simple stuff.....iac....maf....and still have problems..
then you might go thru the egr system and how the charcoal canister purges itself....

On live data on mine....98 2.4.....I can watch egr valve switching under load....
and can watch the purge valve clicking on and off...

and when that egr is open....you should be able to see that in the fuel trim responses.....

 

I have tested purge valve and it does not work. It is either stuck open or closed. It is getting power and it ohms within spec. I am about to change maf and i will see if things look better.

 

Just got a new maf sensor installed and it still has rough idle, but the values look better on live data. The maf is now at .44 not .67 and the o2 sensor is hovering around -4 to 0, instead of -40. Here are a few pics and a video of live data

 

Wont let me load video, so the pics will have to do. My next fix will be purge valve and o2 sensor, thanks for all the help, but i will be needing more advice to get this 5 lugger purring like a kitten.

 

That's much better, your in fuel control now.
When you say rough idle you mean like a misfire or the engine runs poorly?

 

Engine runs great at 1000 rpm or higher, but 750 to 700 rpm it has a pretty good shake. It was very bad before new manifold, injectors, iac valve, fixed vacuum leak, cleaned throttle body, new plugs and now new maf. I know purge valve is stuck closed or open, i dont know which. Some times the idle will fall to 500 rpm and die.

 

I'd recheck for vac leak.....do you have a gauge??

look at weird stuff .....like charcoal can lines....or maybe brake booster....pcv valve...

 

I would like to get a smoke machine and check it good, but i hear they are very expensive. Pvc valve changed, replaced all charcoal canister lines, tested purge valve and it doesnt work, looking to replace it next and possibly o2 sensor. I am going to adjust the idle up a little in hopes to get past the stumbling phase , maybe 850 to 900 rpm

 

Even tho there is no idle adjustment.....I can up my idle a tiny bit by adjusting the throttle cable nut a little bit...
a little is all it takes.....
some have a little too much slack in that cable causing low rpm pedal dysfunction there... a hick up...

AS far as a smoke machine ....for my first one I took an old glass sun ice tea jar...
stuck an old solder iron in there....two hoses ....one to pump air in(aquariam pump) and a hose out...
and some baby oil......


Now I've gone uptown....a good investment for these old trucks...


https://www.ebay.com/itm/314503194311

 

....

 

Plenty of good inexpensive smoke machines out there like auto line for about 100$

 

Check for throttle body wear… wiggle the bellcrank assembly and push it in and out. It doesn take much for the idle to vary with a worn assembly.

 

It does have some end play, bu movements are smooth. I have no doubt a new throttle body would probably help alot, or maybe fit it altogether. It just is not in the budget right now.

 

I played with the idle adjustment screw and when warm, it is holding around 850 rpm. It sounds alot better, smoother and dont have the throttle lag like it did before. And so far, no misfire code.

 

So there are 2 boxes attached to intake tube one is a preheater and i dont know what they do for sure. Can i buy a rubber tube that goes frm airbox to throttle body pipe and do away withe these 2 boxes.

 

Pic

 

one is a resonator, the other is a water catch.....

IF you get rid of those you'll have a throater sound like the cold air intakes do....



.
.
.
.



However if you do.....make sure your filter box has a small drain in it....
for the unthinkable......

As far as pre heating....thats a no.....however by getting all that stuff out of there it increases the cooling on the most heat problematic side of the engine.....instead of trapping the radiant heat....

should make the engine/heads/headers last longer.....

....this is where the head gasket leaks predominately pop up...around cyl 2 and 3......on that side.








Cold air intake systems start at $70/$80......and typically top in the $400 to $500 range......
the plastic tube is cheap.....those silicone adapter rings are not......

 

I have a 2001 V6 3.4 (California specs, no 4x4) that I bought as a project truck. It had a few major issues, but I’ve managed to sort most of them out. However, I’m still dealing with two recurring CEL codes: P0420 (Catalyst System Efficiency Below Threshold - Bank 1) and P0505 (Idle Air Control System Malfunction).

As I was reading through this forum, I realized I might have a bigger problem than I initially thought. Here’s what I’ve noticed so far:

1. Aftermarket Sensors:
   
   • While replacing the rear heated oxygen sensor, I noticed it wasn’t an OEM part.
   • I checked the A/F sensor, and it’s also aftermarket.
   • The throttle position sensor and a sensor on the charcoal canister (not sure which one yet) are aftermarket too.
2. Live Data:
   
   • I reviewed the live data, and the readings don’t look good at all.
3. Other Issues:
   
   • I suspect a possible bad timing or crankshaft position sensor.
   • The truck struggles to start or stumbles after the engine is warmed up.

I’m looking for advice on how to approach these issues. Could the aftermarket sensors be the main cause of the codes? Or could the timing and crankshaft position sensor be contributing to these problems? Any help or insights would be greatly appreciated!

 

Providing there are no exhaust leaks a P0420 is nearly always a failed catyletic converter but need to graph upstream AFR and downstream O2 sensors to see how things are working.

P0505 sets when the actual idle speed is not within about 200 RPM of target idle speed, many things can cause that such as:

A worn, dirty, or mis-adjusted throttle body that is allowing too much or not enough air to bypass with the throttle plate closed
vacuum leak
stuck or failed idle air control valve
open or short in the idle air control valve circuit
engine is running very poorly
in rare cases a failed idle air control driver in the ECM

 

Sorry the pics were giving trouble to upload. This is what I am getting on data stream. The mass air flow reading is 4 times displacement. And the engine load looks off. I just recently replaced the mass air flow sensor to a denso sensor. As far as i can tell the vehicle is stock

This is at idle after engine warms up