Kilgorq

I recently pickup up a 2000 Silverado 5.3L 4L60E Mechanics special. It needed a transmission. I put a used one in and it just does not seem right. A Quick rundown of What I am seeing.

I was getting the P1870 error on the used trans I put in, so I replaced the valve body. The P1870 went away and the transmission is working much better but not quite right.

It does not shift right during moderately heavy acceleration. When it goes to shift down it feels more like it goes into Neutral for a second then shifts down. and it shifts down late. Light acceleration feels normal with an occasional late shift.

Also I keep getting error codes and they are not making sense to me.

I get P0420 and P0430 (Catalytic Convertor not working), However when I monitor the O2 sensors the readings are anything but normal. Sometimes Bank 1 Sensor one looks good but sensor 2 is all over the place, Then it will start doing the same thing on bank 2. Sometimes bank 1 sensor 1 reads like the output you would expect to see from sensor 2 and sensor 2 reads nothing or reads a steady voltage. There is no consistency to the readings on any of the O2 sensors. They are all over the place, It will run like this for 20 or 30 minutes. Then I will shut the truck off and restart it. Everything will look as expected when I restart it for a few minutes then it all goes south again.

The Knocks sensor P0325 error is very consistent and probably needs replaced, I have a new set with harnesses that will go in this weekend. I believe the code for the know sensor also had P0330.

Questions???

Can a bad knock sensor make the O2 Sensors go nuts.
Can a bad knock sensor make the transmission shift poorly.

Can faulty O2 sensors call out bad cats without calling out the sensors.

I also looked at MAF and TPS signals and they both look good. The signals are clean and smooth. They follow my driving spot on with no spikes or dips.

FFDP

iTrader: (2)

Bank 1 sensor 2 and bank 2 sensor 1 should always been switching lean or rich of stoich, ( aka 450mv) so it's completely normal if they are all over the place. But one of the sensor (1)'s should not just be flat lining or staying a constant voltage as that would make it either a bad sensor or wiring problems.

Both bank's sensor 2's should be around that 500-700mv range once fully warmed up and the exhaust is hot. Those readings would show the cat converters are doing there job. If they start to swing all over the place like the front sensors, then the cats are likely not doing anything anymore and thus the cat codes you see.

Kilgorq

I Follow... Normally I would see a rise and fall on the front sensors. Almost like a switch running up and down on an oscilloscope, Ranging from about .45 to 1.25 v and fairly consistent. The output should be fairly flat with a similar pattern but very flattened out. Obviously there will be some minor variation in this but the overall you average fall in this range. Sometimes I get exactly what I would expect from good cats and O2 Sensors. Others it all just goes haywire and the readings go all over the place. The part the has me puzzled is that all 4 of them go haywire at the same time. I am tempted to replace the O2 sensors to see what happens, but honestly I do not think it will fix the issue. I think there is something else going on. Bad ground maybe. I checked all of my engine compartment grounds with a DMM and did not find any that looked even questionable.


The other thing that has me scratching my head is the error codes. What I am seeing from the O2 sensors should trigger an O2 sensor code. And it is not. The picture below is normal.

I have tried to capture mine but am not getting the capture to work. If I do get it to work I will post it.




The other question I still am not sure how to answer is what effect that has on the transmission issues.

Wolftrk99

iTrader: (5)

The knock sensors could be pulling spark on shifts, which would make the shifts feel weird

Kilgorq

I think I found my shifting issues. Today I replaced the catalytic converters and looked at the O2 output and they were perfect afterwards. The engine idled a lot better, not that it seamed all the bad before. Took it for a test drive and wow what a difference. Transmission did not miss a beat. Downshifts were spot on. Up shifts were smoother and Moderate to heavy acceleration did not act like it wanted to slip before shifting down.

I tried replacing the knock sensors and the new ones I got were either defective or wrong. It started failing for both of them afterwards. The replacements are going to be here next week so they will have to wait.

Been fighting a transfer case rear seal leak. Turned out to be the Freeze plug in the yoke.

Now time for tracking down oil leaks. I have done the Top end. valve Covers and valley cover. But it is still wet by the oil filter. I think it is the Oil cooler adapter plate or the oil Pan Gasket. I checked the rear main when I had the transmission out and it is good.

When I replace the knock sensors again I will also replace the Oil sending unit and anything else under the intake that has an o-ring or gasket.