WOT O2 Question
07-07-2009, 01:27 PM
#62
Yes, using the scanner to disable closed loop and then also using it to reset the fuel trims will indeed be just like flashing it with a tune that has closed loop disabled.
A-Dub, you're correct, on the window with the cylinder balance test, it will display the results, and as Texas WS6 said, you can't be actively scanning, just click connect, then take over the IAC and begin the test. I think it might require that you wait for the engine to be at operating temperature before beginning the test, but if it doesn't, I would wait anyways.
A-Dub, you're correct, on the window with the cylinder balance test, it will display the results, and as Texas WS6 said, you can't be actively scanning, just click connect, then take over the IAC and begin the test. I think it might require that you wait for the engine to be at operating temperature before beginning the test, but if it doesn't, I would wait anyways.
07-10-2009, 04:25 PM
#63
UPDATE
So I pulled all the plugs, plug wires, rockers, and pushrods to inspect for issues. Found nothing and put the car back together. Did a balance test and lowest was #1 cyl at 92% and highest was #8 at 96%.
Idle, off idle, and part throttle are all operating great, no issue whatsoever. WOT prob is now worse than ever. I forced the car into OL and reset trims and tried to scan a WOT run, but it was misfiring hard, so I got out of it quick.
I don't think its leaning out. Its not a constant lean popping sort of problem. The car is misfiring hard, but only under WOT regardless of rpm.
Any tips on checking for clogged CAT? Car still has the post CAT O2s installed and reading.
So I pulled all the plugs, plug wires, rockers, and pushrods to inspect for issues. Found nothing and put the car back together. Did a balance test and lowest was #1 cyl at 92% and highest was #8 at 96%.
Idle, off idle, and part throttle are all operating great, no issue whatsoever. WOT prob is now worse than ever. I forced the car into OL and reset trims and tried to scan a WOT run, but it was misfiring hard, so I got out of it quick.
I don't think its leaning out. Its not a constant lean popping sort of problem. The car is misfiring hard, but only under WOT regardless of rpm.
Any tips on checking for clogged CAT? Car still has the post CAT O2s installed and reading.
Last edited by A-Dub; 07-10-2009 at 04:40 PM.
07-10-2009, 09:36 PM
#64
Maybe a week coil. Does anyone know how to test the coils? What they should ohm to? I guess you could swap the coil packs and see if it follows. If the valve train is good and the cylinders are good, then it has to be something external like a coil, wiring to the coil, injector, injector wiring. You know the tune is not the problem, and you say it is not leaning out as if from a bad MAF sensor, so it has to be in the ignition system or fuel system, but only on one cylinder.
Last edited by Texas_WS6; 07-10-2009 at 09:43 PM.
07-10-2009, 10:16 PM
#65
The correct method for checking WOT fueling on the plugs would be to make a WOT run and shut the car off immediately after you close the throttle. Then pull the plugs (keeping track of which cylinder is which) and cut the threads off and compare the fuel rings on all the plugs. Driving it around and letting it idle (where fueling is fine) will hide the problem as far as the plug is concerned.
07-11-2009, 07:36 AM
#66
The more I thought about it, the more I think its an injector. There isn't anything about the coil that changes with WOT. If it only did it at high RPMs, I might think it was the coil, but its not RPM dependent, only WOT. I'm going to pull and inspect the injectors
07-11-2009, 10:15 PM
#69
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if any one cat was clogged or no longer efficient enough, you would get a related code. but you can get an idea of how efficient the cat is by comparing activity between the front and rear o2s, the more efficient a cat is the less activity rear 02 will show. personally i think if it was in fact a faulty/intermittent coil you would not go lean, due to the fact that during the cycle that the coil fails there is no combustion and so excess fuel makes it to the 02s. i have gone real rich at wot [10 -9 afr] and the car will just bog and sputter.
07-12-2009, 09:27 AM
#71
Well I still can't understand why a bad coil pack only shows itself at WOT, but thats the problem. Swapped coil pack rails from bank to bank and as you can see in the scan, the problem has moved to bank 2. Now I just have to find out which coil pack is bad.
07-12-2009, 09:44 AM
#72
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that makes sense then, at lower loads the spark is strong enough but not at higher loads. evidenced by the swap. thank you for correcting me. it's unusual he didn't get a misfire code.
