I took my car over to Maranello Motors today just to get another clean bill of health - everything looks great all around. However, my car has a Forza control for the bypass valve. We hooked a T into the vacuum line and were able to see that the control module works to open and close the valve. When I start off in 1st the valve opens properly at a low RPM. However, in 2nd and above, it doesn't seem to want to open until later - 5-6k or so - even with my foot to the floor. Any ideas what could be causing that? Thanks!
I think that is expected- p1448 means the bypass thermocouple is experiencing heat when it thinks the valve should be closed, or not experiencing heat when it thinks the valve should be open. I also believe the bypass behavior sounds normal- it opens around 4500 rpm for me in all gears except 2nd where it opens at closer to 6500. There’s a post somewhere here where someone actually read the LUT from the ecu and noted what it was.
So do you think having the Forza controller in full open caused it? I reset the code and I'm hoping it doesn't come back. I have to go through emissions testing soon to register the car so I'm hoping it stay off.
Here are the official values for the 2.7 car. Image Unavailable, Please Login Is the 5.2 different? The main function (or perhaps even the only function) of the bypass valve thermocouple is to detect when the valve is open or closed when it is not supposed to be. Since the Motronics ECU is basing its own "valve open" command on engine rpms, throttle position, etc, I can't see how the Forza system can fool the Motronics ECU into thinking that the rpm, throttle, etc, have the appropriate values for the valve to be "just open" for your drive home. Does the Forza system have any documentation on this?
It does not have this function, it simply bypasses the oem trigger and keeps it open. Hence the check engine light.
So why would anyone really want this then? I hate check engine lights so I'm not sure why I would really use this that much.
The 2.7 cars do not have a thermocouple at the bypass junction so you can use this controller with no ill effect. I personally don't like the controller as it is designed that way for a reason and feels more responsive with the system working as intended.
Reverse the install instructions. I had it on my 355. I also had a bluetooth BlueDriver OBD2 scanner for clearing the inevitable CEL on the go via my cell phone...but sometimes I just wanted it straight open for some spirited driving.
Simply remove the thermocoupler, cap the hole and the code will not come back. The probes sole purpose is to taddle to the ECU when the valve is open to long. I have the capristo valve controller in mine
Affirmative, it provides no fuel trim no spark advance nothing related to the engine. It just simply is there to sense if the valve gets stuck open. Leave it connected, but just zip tie it away and cap the bung
If you get no stored message or CEL, with your configuration, then that would seem to prove it. We've had so many (reputable) experts saying otherwise, it's hard to know who to believe. Seems like a bad design if that's how it works.
They're many post with claims either way from people who have speculated but have never actually tried it. The few Ive found with actual experience have all posted no bypas related cel with the sensor removed. heres one from Goth in post #7 by a user in post #14 https://www.ferrarichat.com/forum/threads/hyperflow-capristo-installation-and-question.165071/#post-137020196 also here in post #3 https://www.ferrarichat.com/forum/threads/bypass-valve-removed-slowdown-light.243098/#post-138648061
Convinced. Thanks. I'm trying to remember the codes I got for having the Right cat SDECU and Exhaust Bypass SDECU plugs swapped over. There was at least one code for the main cat. The main cat temperatures are probably compared and see one cat cold (at least with the bypass valve closed). This is with new cats installed and a Goth Bypass valve fitted. But, as you say, cold bypass thermocouples are not flagged.
I had a few threads bookmarked regarding this and I quickly posted an example here, I guess i referenced the wrong post on that thread. Later there is mentioned of someone else with success.
But the moral of the story is I can leave the forza controller and just not hit the "B" button that leaves the bypass valve open all the time and then avoid the check engine light, correct?
Considering it's completely free to try. Why not? Go to Home Depot and buy a 1/4-in or 3/8-in NPT brass cap (can't remember the exact size but it's one of those) zip tie the sensor away so it's not dangling. Reset the code, see if the 1448 comes back
That chart varies slightly for the 355 5.2 cars. The bypass valve operation is not only gear and RPM specific, but also monitors throttle position. I have that data at home somewhere and will dig it up when I can. The bypass theromcouple is looking for heat when the bypass is supposed to be open and no heat when it is supposed to be closed. If you remove the thermocouple from the exhaust stream, you will still get a CEL and 1448 code. If you wire the bypass valve open you will also get the 1448 code. If you open the bypass valve when the ECU thinks it should be closed you wil get a 1448 code. As far as I know, people that run with open bypass valves just pull the CEL bulb. There is a theory (real or perceived is up to you) about exhaust back flow and damaged headers running with an always open bypass valve. In response to your slow opening valve, check the solenoid supplying the vacuum from the air pump in the back. If that leaks it doesn't engage correctly and does not supply proper vacuum to open the bypass valve.
