does anyone know why the 7m likes to stall when the rpms drop fast they drop all the way and the car stalls? I've read bout this on another thread somewhere before and mine does it but no one on the thread knew why it did that anyone on here know?
stalling when rpms drop fast
- Thread starter BryanDyer
- Start date
In theory, if your TPS is set properly, a vented BOV should do absolutely nothing in regards to stalling. In theory, this is what would happen...
Boosting, half throttle or so, TPS IDL contacts are open. Engine speed has to be above 2000 RPM IIRC
Let off throttle, TPS IDL contacts close, since engine speed is over 2000 RPM, ECU cuts fuel.
Engine drops below 2000 RPM, ECU resumes fueling. All of the air should be vented from the BOV and it should be closed by now.
The problem occurs if your blow off valve opens around or under 2000 rpm. THEN you run into a rich scenario, as the ECU will NOT cut fuel.
Ever notice how if you engine brake above 2000 rpm it doesn't afterfire? Thats because the ECU cut fuel..
Boosting, half throttle or so, TPS IDL contacts are open. Engine speed has to be above 2000 RPM IIRC
Let off throttle, TPS IDL contacts close, since engine speed is over 2000 RPM, ECU cuts fuel.
Engine drops below 2000 RPM, ECU resumes fueling. All of the air should be vented from the BOV and it should be closed by now.
The problem occurs if your blow off valve opens around or under 2000 rpm. THEN you run into a rich scenario, as the ECU will NOT cut fuel.
Ever notice how if you engine brake above 2000 rpm it doesn't afterfire? Thats because the ECU cut fuel..
Have you checked for codes?
http://www.cygnusx1.net/Supra/TechTips/engine_error_codes.aspx
There is a very good flow chart located here for for things to check in the event of stalling.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=14
Also a malfunctioning dashpot will not cause a properly running engine to stall out. The only purpose that the dashpot serves on the 7M is to allow any fuel remaining in the intake to be properly burned off deceleration reducing HC and Co emissions. It is an emissions control device.
http://www.cygnusx1.net/Supra/TechTips/engine_error_codes.aspx
There is a very good flow chart located here for for things to check in the event of stalling.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=14
Also a malfunctioning dashpot will not cause a properly running engine to stall out. The only purpose that the dashpot serves on the 7M is to allow any fuel remaining in the intake to be properly burned off deceleration reducing HC and Co emissions. It is an emissions control device.
I has This problem also the bov was not recirculated. My tps was off. And the p/o messed with the dash pot screw
Check ur codes first
Check ur codes first
I don't have any codes a boost leak and my tps is set correctly
last time I took the throttle body off I checked the dashpot and it seemed to be ok and functioning correctly and this was a little over a month ago which it did this before that also
it doesn't do it when it cold only once it's warmed up
last time I took the throttle body off I checked the dashpot and it seemed to be ok and functioning correctly and this was a little over a month ago which it did this before that also
it doesn't do it when it cold only once it's warmed up
Are you still running the Lex/550 combos like your profile states? What do you have your fuel pressure set to?
I've read on another thread on a different forum that a lot of 7ms have this problem but no one seemed to know on there either and they checked everything they could think of all vaccum lines etc
so idk
but I don't think it's anything that's going to cause a problem it just gets annoying
also is it possible to have an o2 sensor that is getting faulty readings
not making the car have a loss of power or anything but making it run excessively rich and becuase it's running rich the gas washes down the cylinder walls and makes me burn oil?
so idk
but I don't think it's anything that's going to cause a problem it just gets annoying
also is it possible to have an o2 sensor that is getting faulty readings
not making the car have a loss of power or anything but making it run excessively rich and becuase it's running rich the gas washes down the cylinder walls and makes me burn oil?
That fuel pressure is a little high. Was that number determine necessary through tuning, and monitoring your AFR's. Normally you start at 33-40psi at idle with the vacuum hose off and plugged. Then when you attach the vacuum hose it should pull it down to 23-30psi. So you are going to be running pretty rich, even enough to cause the stumbling after decell. You might even check your spark plugs for fouling. Unless you know you need the fuel pressure turned up that high to keep the AFR's safe on WOT pulls I would turn it down.
TSRM states what it should be and the TCCS makes fuel calculations with these baselines in mind. The only need to deviate is if at some point the AFR's get to rich or lean and you have no other way to correct the fuel trim, as adjusting the fuel pressure makes across the board, general changes.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=73
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=73