ECM upgrade (1227730) for stock 2.8 (Page 91/107) mattwa AUG 15, 02:56 PM Hey, I'm doing this swap with a 3.4 and DIS. Question, where is the A/C pressure sensor?? I can't find it for the life of me. Can Someone show me a picture? mtownfiero AUG 16, 01:56 AM Its on one of the hard lines that attaches to the compressor i believe. I think it might be easiest to cut and have the sensor re weleded into the stock lines. Darth Fiero AUG 17, 03:02 PM Here's the deal on the A/C pressure sensor (only applies to those of you using the DIS; distributor cars don't need one with this ECM conversion). The code mask ($A1) used in the 1227730 / 1227727 ECM that works with DIS is configured to read a pressure reading directly from the hi-side of the A/C system using a 3-wire sensor (other systems use a 2-wire switch). On the donor car (you get the 7730/7727 ECM from), the A/C pressure sensor can be found screwed into the hi-side line somewhere between the A/C compressor and the orifice tube (expansion valve) which is before the evaporator core. 1993 - earlier GM cars used R12 refrigerant like the Fiero. If you get an A/C pressure sensor from one of these cars you can install it directly onto the stock Fiero's hi-side pressure test port (front compartment). But there's a catch... The Fiero's test port does not have a groove machined in it to accept the sealing o-ring this sensor uses. So what you will need to do is use 2 o-ring seals (for the A/C pressure sensor) and install them both onto the Fiero fitting first then screw on the A/C pressure sensor. The 2nd O-ring (the one that goes on first) helps keep the one you install last in place during installation that will actually do the sealing. I recommend only installing the hi-side sensor by hand. If you want to tighten it up using a wrench, you can; but take great care in doing so. The threads this sensor attaches to are very thin and will break easily if the sensor is over tightened. Check for leaks (after system is charged) using soapy water around the sensor/fitting. If you get bubbles (indicating a leak), remove the sensor, check the o-rings, and try reinstalling again. Proper fitment of the o-ring into the sensor is tricky but I have gotten it to work in every case I have tried it. Now, if you want you can have a hi-side test port for the A/C pressure sensor installed into the A/C lines back by the compressor. This will require some welding and some A/C shops should be able to help with this. If you are going to use R-134a refrigerant in your car, you might as well have an R-134a fitting installed so you can use the A/C pressure sensor from a 1994-newer car; which are easier to find. If you have any questions, please feel free to ask. -ryan Routs AUG 18, 02:00 AM This is pretty cool stuff, man. Great option to those not planning a swap away from the 2.8L. Very impressed. mtownfiero AUG 18, 11:55 PM Darth i have a couple questions, My a/c right now is completely unconnected since the lines are disconnected where they attach at the drivers side firewall. So would it be easiest to try and install the sensor upfront like you first mentioned or take my compressor off and have the sensor weleded in? Do you have and pictures of the front compartment mounting method by any chance? Thanks. Darth Fiero AUG 19, 12:12 AM quote Originally posted by mtownfiero: Darth i have a couple questions, My a/c right now is completely unconnected since the lines are disconnected where they attach at the drivers side firewall. So would it be easiest to try and install the sensor upfront like you first mentioned or take my compressor off and have the sensor weleded in? Do you have and pictures of the front compartment mounting method by any chance? Thanks. Better to have a sensor fitting welded into the rear A/C lines that attach to the back of the compressor. That way you can use a fitting that is designed for an o-ring seal and connection for a A/C pressure sensor. Darth Fiero AUG 19, 12:23 AM I actually snapped the stock R12 hi-side test port fitting off my stock Fiero line by accident. So I welded one on from an R134-A car that had the groove in it for the sensor o-ring. mtownfiero AUG 20, 12:07 AM So the older style would be a 3 wire setup or we could have the lines cut and rewelded to use the new r-134a sensor? That doesnt look to be as hard as i assumed. Darth Fiero AUG 20, 01:56 AM quote Originally posted by mtownfiero: So the older style would be a 3 wire setup or we could have the lines cut and rewelded to use the new r-134a sensor? That doesnt look to be as hard as i assumed. GM made the 3-wire sensor in both R12 and R134a versions (different threads and size). You can have a fitting welded into your lines that connect to the back of the A/C compressor. Or you can see about getting an R12 sensor to seal up to your Fiero's hi-side test port using the method I mentioned earlier. mtownfiero AUG 28, 12:14 AM I got my a/c sensor today and as i was checking out how it went on and i can visualize the two o ring idea now i was wondering would using teflon tape on the threads help seal it up even better? I dont know if it will work right or not but im assuming it would.