Where to buy a charcoal purge valve

[rcfanatic]

I looked around on bavauto, pelicanparts, and realoem. I know it should at least be at realoem, but I can't find the right diagram. Anyway, does someone know where to get these without going through the dealership?

I haven't gotten a chance to test it per the bentley manual, but my engine falls flat on its face when returning to idle (drops to 250rpm or stalls completely). When I disconnect the valve from the throttle body the idle is a little shaky, around 700rpm, but aside from that no other issue. Problem appears to be consistent whether the engine is warm or cold. Maybe the canister is bad as well.

Any thoughts on this or where to buy them appreciated. Thanks

[jlevie]

I suspect that your problem isn't the valve. A simple diagnostic is to plug the hose that runs from the valve to the charcoal cannister. It that doesn't help, you have other problems.

My guess is that you have intake leaks and possibly a problem with the ICV. The only sure way of finding intake leaks it to have a smoke test run on the intake. Also check to see that the TPS is correctly adjusted and that the idle switch closes (test electrically) when the throttle stop is 0.020-0.06" off the idle stop screw. And remove the ICV and clean it with carb cleaner until the vane moves freely. The ICV should buzz when the ignition is switched on. If you don't feel the ICV vibrating with the TPS operating as it is supposed to, either the ICV is bad or it isn't being driven. On an M20B25 or SuperETA engine the ICV is controlled by the DME, but on an M20B27 engine there is a separate Idle Control Module.

[rcfanatic]

Thanks for the fast reply. A little more background - back in July I replaced the TPS and adjusted it per Bentley, and cleaned out the ICV and AFM and tested them per Bentley but all was well. None of this solved the problem I was having at the time with the idle dropping upon initially opening the throttle. It did turn out that the old TPS wasn't sensing WOT, so it wasn't a total loss.

This new issue started last week after I replaced my oil pan, and in the process of raising the engine the purge valve became disconnected. My throttle lag problem disappeared (?) but the idle now bounced around 700rpm. When I reconnected the purge valve the idle was steady, but laged when throttle opens and falls very low (250rpm) when returning to idle. This makes me think that the TPS could have been rotated out of adjustment when raising the engine (resulting in the idle bottoming out), and the purge valve may be bad (resulting in the throttle lag).

It's just odd that with the purge disconnected, the idle doesn't bottom out when the throttle is open or closed. If it was a TPS, why would this have anything to do with the purge valve?

All of that said, using brake cleaner I did find a vacuum leak where the vacuum lines from the brake booster insert into the throttle body. I'm working on a way to make this seal tighter (teflon tape?), but have my suspicions that it would be causing all this trouble, esp. considering the dramatic changes I found when connecting the purge valve.


Edit: Final note my engine is a B27 converted to b25 electronics with b25 throttle body and intake

[SpecM]

maybe its idleing too rich, causing it to bog, and the little vac leak you creaked may have artifically leaned the mixure out a tad...

[rcfanatic]

Good point. I guess my next moves are the smoke test, check the fuel system, coolant temp and O2 sensor.

[jlevie]

All of that said, using brake cleaner I did find a vacuum leak where the vacuum lines from the brake booster insert into the throttle body. I'm working on a way to make this seal tighter (teflon tape?), but have my suspicions that it would be causing all this trouble, esp. considering the dramatic changes I found when connecting the purge valve.

I'll bet a smoke test will find other leaks that you can't locate with carb cleaner.

The best fix for a loose elbow on the throttle body is to throughly clean the bore in the throttle body and the elbow with acetone or lacquer thinner. Then fix the elbow in place with JB weld. Be sure to allow the epoxy to harden overnight (or longer in cold weather) before stressing the joint in any way (like starting the engine).

[87-325ic]

i JB welded my TB push in elbows years ago and they are still holding fine. it definitely fixed a few of my vacuum leaks!

[rcfanatic]

Just for the sake of answering the title to the thread, does anyone know where to buy a purge valve other than the dealership?

[hotballs]

Any reason you want to keep the charcoal canister? Just plug it up at throttle body and at the hard line the hose from the canister went to. Car will run much better without it.

BTW I have another one of those valves in my FS thread if you wanna try that one, but the car should run fine if you plug it up at the TB. Asking $8 shipped.

[rcfanatic]

Well the purge valve is working fine, I was able to listen to it while turning the ignition on, and it clicked per the Bentley manual. I noticed that I didn't have the notch on the socket mated up with the ridge on the side of the valve, so that could have introduced another leak.

I adjusted the throttle stop screw, TPS, and used JB weld on the elbows that go to the brake booster and the ICV. I ended up hooking the purge valve up with the notch aligned correctly, because I didn't have a good way to plug the nipple on the bottom of the throttle body.

The idle is much better now. Sits steady at 800rpm, and when I let my foot off the throttle it makes smooth transition back to 800. However, I still have an issue with the rpm dropping suddenly when I first open the throttle.

I checked the coolant temp sensor with the engine cold (70 F) and it read 1600ohm, and when it was warm it read 240. The Bentley states that it should be 2200-2700 when cold and above 300 (forget the exact range) when warm. Is Bentley correct, or does 1600 and 240 seem reasonable for cold and hot?