Air Bypass Valve delete on S4 TII?
 

Ok... I have a 1988 Convertible with the TII S4 swap... I have been having an issue with the Air Bypass Valve.. The opening for the hose that goes into the Intake Manifold keeps cracking and breaking.. I have replaced this part three times thinking I have just gotten a few that were already cracked(even though I fully inspected each one I bought, and they were used.:( )...

I was just wondering is there a way to bypass this valve and take it off the car completely? Everytime it breaks of course the massive leak makes the car shut off... Has anyone heard of doing this? Any hints or tips would be great!

Sure, unplug it, take it off, and cap the inlet/outlet openings on the manifold. A cleaner route would be to use a J-spec UIM, which never had that valve to begin with. It's only there as part of the 3k RPM warm-up system anyhow.

Word!!! Thanks man... I was going to do just what you sad and just plug both ends and pull it off... It doesn't work anyway, but I just wanted to make sure... Another question... After pulling it off/deleting it, will I have an erratic idle/warm up?

Start-up idle will be virtually unchanged if you still have a BAC valve. Idle speed will still jump up to around 3k RPM due to BAC air. It will probably just be a few hundred RPM less than it was with the bypass valve. I removed it on my NA engine and noticed basically no change at all.

Another thing the ASV is used for is during power steering load. But you probably won't notice much of a difference anyway. The ASV is one of those few factory components that I really do consider "unneeded". Mazda had so many damn overlapping systems to control engine speed on these cars...When all they really needed was a BAC (if the ECU didn't suck).

I *think* we're talking about the Air Bypass Solenoid (sometimes called AWS solenoid), which is the one that sits on top of the UIM & connects to the intercooler. If not that one, I'd agree that the Air Supply Valve (ASV) that Aaron mentions (back side of UIM) is also redundant. I don't have either one on my car, but that's partly due to the fact that the ASV would have no plug on my NA harness. Some things are better simplified anyway.

I am talking about the Air Bypass Solenoid(AWS, and it is reffered to in the Haynes manual as both) that sits on top of the UIM and connects to the intercooler... I really appreceate the info... It sucks everytime this thing break I will come to a stop and it dies.. So, I have to slow down real early at stoplights and keep it running or it will cough,spit then die....