Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I've been battling this vehicle for a while. I randomly get a misfire code. And I'm always getting po172 po175. I also intermittently get a PO420 code. I'm back to thinking now it may be the catalytic converters. The vehicle has 152,000 miles on it. I just noticed while viewing my overlay between O2 sensors 1 and 2 from bank one and Bank two that the sensors are pretty much mimicking each other on the graph. And since I am very often getting a 420 code is it safe to assume the catalytic converters are bad? I did do a pyrometer test on the catalytic converters. And they are hotter leaving than they are entering by about a hundred degrees. Any help would be appreciated. Thanks
Both O2 signals are rich, suggesting a true rich condition. What are the O2 signals for bank 1? . Make sure you like the video if you have not already done so.
It's identical on Bank One. Basically the downstream O2 sensor is mimicking the Upstream O2 sensor. I wish I could attach the video but it's too large. But basically both bank one and Bank two downstream O2 sensors are pretty much mimicking the Upstream and from my understanding they should be more of a straight line at the catalytic converters working correctly but I honestly don't know how it works. I will say that every time I get a check engine light and I go to the Freeze Frame it is always at low RPMs or idle so it's always whenever I'm sitting still or coasting from accelerating to a stop. I was monitoring the fuel trims while driving and under normal driving the fuel trims are acting correct within the 10%. But as soon as you let off the gas or stop the fuel trims go crazy. Hopefully this helps you help me
The mimicking of the rear O2s with the front O2s is due to the fact that the vehicle is running rich. The p0420 code can be resulted from the rear o2 stuck rich. Try fixing the rich condition first before attacking the p0420.
Unfortunately a lot of parts have been thrown in this vehicle from a bunch of different mechanics. All the spark plugs and coil packs have been changed. The fuel injectors have been replaced with OEM injectors, the 4 02 sensors were changed to ntk. The camshaft and crankshaft sensors were changed. New map sensor new air intake sensor also. I did a smoke test with not such a great smoke machine the other day and I did have smoke coming out from under the air intake resonator and some smoke coming from between the air and take resonator where it attaches to the throttle body. Now the smoker I was using was adding pressure to the system because it was being ran off of a compressor so I don't know if that's what was causing me smoke to come out. But I'm at a loss to find what is causing this rich condition
Also from my understanding after those camshaft sensors were changed there should have been a relearn done to the system I'm stopping by a mechanic shop today so they can do a relearn on it just to mark that off the list my ODB won't do that
So after taking it to the mechanic today they attempted to do a relearn on the camshaft systems and it wouldn't take ,they drive three different times and it was unsuccessful
If you induce a lean condition by pulling a vacuum hose off or repeatedly pumping the brake pedal, do all the O2s go lean?
Do the rich (idle)fuel trims get better under higher rpm?
So when you pump the brakes all the voltages go down to .015 there in about. And idle if you hold the RPMs at 2000 the long-term fuel trim goes right to -32
It is kind of hard for me to figure out rich running condition since I haven't dealt with one yet.
ECT, IAT, too high fuel pressure, fuel pressure regulator, purge valve, clogged cat, stuck open thermostat and others can cause rich condition.
The intake air temperature sensor has been replaced and so has the map sensor. And they seem to be working correctly. The fuel pressure was checked and it is correct. The purge valve is working correctly and is not stuck open. I have not replaced the engine coolant temperature sensor but it appears to be working properly well I will say it displays properly. You had me going LOL, when you had me test those things and that's exactly what it was doing I thought you knew what it was LMAO I was excited. But I understand I will take any help I can get or suggestions.
So to add to all my other issues I brought the van to a mechanic shop today because I don't have a scanner that will do a camshaft relearn and I was told that since the camshaft sensors are changed that it would be required. I took it to the mechanic shop they tried to do a relearn and it failed three times. I drove home and didn't really notice anything but traffic was heavy so I didn't go very fast. For this evening I took it for a ride now the van is stuck in limp mode with every code you can think of for camshaft sensor and timing
Keep looking through the PIDs to see if you can find something out of the ordinary. The vehicle runs rich in both banks at any RPM. Look for things that will affect both banks like MAF if so equipped and every other things that can cause a rich condition. I hope someone else will chime in.
For this evening I took it for a ride now the van is stuck in limp mode with every code you can think of for camshaft sensor and timing
What are the codes it is setting now?
I can see there has been a lot of work done to try to correct this issue. Was there any engine repair work done before this issue? Anything that would have had the timing chain or camshafts removed?
So previous to this incident the van seemed to run fine but was running rich and throwing the po172 and po175 codes. I went to start it one day and it seemed to have some run on when it went to start. That's the best I can explain it. So a mechanic friend said he thought it was the camshaft sensors so I bought a set of camshaft and crankshaft sensors and had him replaced them. That was probably 3 months ago. The van ran okay after that that was still getting the codes po172 po175 but the run-on was gone. I had read online that these Vans required a relearn anytime the sensors were changed. So I thought it would be a good idea to go ahead and have that done. So I contact the local mechanic shop which said they could do the relearn and after they tried three times and it failed I took the van home. It was that afternoon when I learned it was in limp mode. It is throwing about five different slow to respond sensor codes and one crankshaft camshaft out of sync code as best I can remember. None of these codes were there previously to the relearn
Going to need to know what those codes are.
There's no point trying to diagnose a rich fuel mixture if the base mechanical systems are not sound.
That's why I was wondering if there was any major engine repair done that could have resulted in the chains being misaligned or the magnetic reluctors on the camshafts damaged or possibly installed in the wrong position.
I understand, and thanks for the help. I will get you those codes as soon as I'm back to the van. There was nothing done at all prior to the limp mode. And the van was running okay just getting the same 172,175 codes. Be changing of the camshaft and crankshaft sensors is done months ago. And I never got any codes after that about them until this relearn was performed. One of the other mechanics I had the van thought they may have been an issue with the timing and inspected the timing chain and timing and said everything there was good. I'll get you those codes
