jmoore16:
Thanks for the detailed disassembly instructions. That will help a lot!
mo_dingo:
I’m replacing my EVR because I got a code 33 – “EGR valve opening not detected”. This code could be caused by three possible components: the EGR valve itself (if the diaphragm leaks), the EVP (EGR valve position sensor, if its resistance was not correct) that screws onto the top of the EGR valve and sends a position signal to the computer, or the EVR (EGR valve vacuum regulator).
I tested all three parts according to the procedures in my Chilton’s manual. The EGR valve and EVP both tested good. The EVR tested bad.
The computer uses the EVR to control how much the EGR valve opens by controlling the amount of vacuum that is applied to the EGR valve diaphragm. The EGR valve should be closed at idle and at WOT, so no vacuum should be applied by the EVR. Starting at just off idle, the EVR should increase the vacuum to the EGR valve in direct proportion to throttle opening up to about 5 or 6 inches of vacuum at about 50% to 75% throttle opening.
I tested mine without having to remove it first like Chilton’s said! I built a little vacuum line adapter to do it with. I did it by adding a 1.5 inch piece of vacuum hose to the end of the EGR valve vacuum connector, putting a “T” fitting in it, and hooking up an 8-foot piece of vacuum hose to that. I then ran the hose across the top of the engine and under the far left corner of the hood so I could shut the hood without pinching off the vacuum hose. Then I connected a vacuum gauge to the end of that hose and dropped the hose and gauge through the driver’s side window into the car.
Then I went for a drive and watched the vacuum gauge for proper readings at idle, part throttle, and WOT. Mine was not reading right, it never got past 2 inches vacuum and dropped off to zero just shortly after getting off idle. Definitely not correct! The EVR was probably leaking air and was definitely bad.
BTW, an EGR system that is not functioning correctly is a definite candidate for causing PINGING problems!
When exhaust gases are re-circulated into the combustion chambers, they SLOW the burn rate since they are inert gases. This means that the computer has to INCREASE spark timing so that the fuel/air/EGR gas mixture completes burning at the proper time for optimum power. According to industry articles that I’ve read the computer will advance the timing about 2 degrees for each 1% of EGR flow, up to a total of 20 degrees of additional advance at 10% EGR flow! So, if your system is NOT re-circulating the correct amount of EGR gases and the computer still advances the timing… you’re gonna ping for sure!
Same thing will happen if your EGR system is sucking in outside air from anywhere that it shouldn’t, e.g. a leaking EGR valve to intake manifold gasket or a leak in the exhaust header to EGR valve transfer tube. Air burns! EGR gasses don’t. The extra air is gonna cause pinging if the computer thinks that it’s all EGR gases and advances the timing.
Just something else to check out if you are having pinging problems.