Engine runs rough at idle. Changed injection unit, cap, pulgs and wires and rotor button. Fuel pump and fuel filter has alson been changed. I am still getting codes 0326 and p01406. I know p1406 is the egr valve. I took it out and cleaned the egr valve and the pin now move free. Or is the valve just bad and causing the other problem. please help.

 

It is possible for some detonation due to a malfunctioning EGR valve, but which code are you experiencing? P0325 or P0326? I can post the diagnostic sheets for P0325, but my typical references do not cover P0326...

 

The biggest problem is code 0325. I know it is knock sensor 1 or 1 bank. I want to know what causes the rougn running. I smells like it is running rich or flooding. I have replaced all the fuel parts. Need help on what else it might be.

 

Here is the code listing:
P0325 - Knock Sensor 1 Circuit Bank 1

 

The code is right. engine does run rough mostly at idle. I watched the pids with my mack scanner and the only one that dosen't hardly react is LTFTRM%. Is stays at -16.4% at idle after warmup. It seems to flood. Strong smell of gas. At 2000 rpm it smooths out and the % moves up to -18.0%. I have replace alot of parts on what could control fuel and spark. Scanner says no missfires. I know that ftrm stands for fuel trim. but what does st and lt in front mean.

 

ST == Short Term
LT == Long Term

The LT & ST trims combine to form the deviation from the standard fuel map. The PCM monitors trends in the ST and stores this in the LT. LT is a kind of moving average of the ST corrections. As such, the LTFT should not change anywhere near as rapidly as STFT.

But having such a high negative trim means that the PCM is really leaning out the mixture.

 

I might have found the problem. In looking at the o2 sensor readings. I only have 2. 1 in front of the cat and 1 behinde the cat. I think the cat is stopped up and frceing exhaust gas back un=p in to the engine and making it 2 rich and running rough. Almost like a misfire but no misfires show up. It is the only the left. I even replace the egr and now it starts better but there was a load of chuncks of carbon in the egr valve. I put in a new egr gasket that was made with a built in screen. So tomorrow I am going to take the cat down and see if it is stopped up. Wish me luck.

 

Pop out the pre-cat O2 sensor and drive it like that. If it runs better (it will be louder), then the problem is the cat.

And I would have run the engine a bit with the EGR valve off and the intake port plugged. This would have blown any loose chunks of carbon out of the EGR supply tube. Another good thing to do is get a long brass pipe brush and work it in the EGR supply port just prior to starting the engine with the EGR valve off.

 

cleaned out and replaced egr valve. Still smells rich and high negative fuel trim. Checked cat and it is burned out from running rich, cat is hollow. What else could mke it run rich besides a fuel leak in intake. Check operation of map sensor and it operates fine.