In my S4 NA Swapped B2200 I am not getting the 1500RPM startup when warm like I hear they are supposed to. When my engine is warm, it starts, and does not go above 1000RPM. The BAC is working correctly, and my warm idle is steady at 800RPM. Would a misadjusted TPS cause this? I have been noticing just off idle when in gear, the engine sounds like it is "missing" at the exact same throttle position. By accident I know the 1500RPM startup works, because when I first started the motor, it was running rich and had a high rpm due to me having the start wire going to the ecm hooked up to the ignition (making the computer run in engine cranking mode). I am also running the B2200 rad, which has no location for the rad temp switch thing, so I have that grounded out, which is what the sensor does above 70f.

 

The high rpm warm up is for a cold engine. Once the car has been run and is warm the start up will not be very high relative to a cold start.

 

I thought it was supposed to shoot up to 1500 RPM for a second, then drop to 750 when warm?

 

I`d be sceptical about shorting themwires out on the ~rad temp thing~
put the sensor back on and hang it somewhere.

 

I would, however the sensor came out in more than one piece when I unplugged it. I am planning on putting the RX7 rad back in the truck, as the B2200 rad is not quite up to the cooling of the motor in spirited driving lol.

I am going to try adjusting the TPS sensor, and swap it for my spare sensor. I will adjust it by using the light method. Let the ECU tell me when it is satisfied.

 

Cranking mode opens the the BAC 100%, so that's probably where your rpm bump came from.
The 1500->750 rpm transition is due to the mechanical movement of the thermowax. If it idles at 800, the thermowax isn't engaging when cold. FYI, mine does the same thing and haven't noticed any adverse affects. It's probably more helpful in colder climates.

 

Having the two wires connected to each other just tells the ECU that the coolant temp is above 62 degrees F. If the engine were cold it would initially start up by reving up to 3000 rpm for 17 seconds before dropping to 1500 rpm and then slowly dropping to 750 rpm. Again, this would be for a cold engine start.

 

Im gonna screw with the tb settings, as i played with them trying to figure out my high idle (which was ignition power to start wire on ecm above). I think my thermowax is set too low, i only get about 1300rpm on cold start, and i was playing with it. My tb is from another motor too and it was modified. My motor when installed in the RX7 did startup like it should, so im sure its an adjustment.

 

I dinked around with the throttle body settings, and they were kind of messed up. I started off by removing the dashpot so I could get to the thermowax adjustment screw. I initially adjusted that to 1500RPM when cold, but that turned into it holding the throttle open when warm and a 1200RPM idle, so I adjusted that so it fully released when warm, and then I had a bouncing 500-800RPM idle and unable to get it higher with the idle screw. Which made me adjust the lower throttle body stop screw under the tb. I then re-adjusted the thermowax screw to not hold the throttle plates open when warm (measured with tps voltage, made sure it does not move). Started it up, no fluctuating rpm, and 750-800RPM was attainable by adjusting the idle screw on top of the throttle body. Replaced my TPS with my spare one, and adjusted it to 1.002V at idle measured at the ecm. Now I seem to get a consistent idle RPM, and startup goes up to 1200-1500 for a second then back down to 800RPM like it should, and I get no wierd fluttering like it is missing just off idle (must have been bad tps). I notice now that when I play with the idle mixture screw, the motor stumbles a little with it full rich and full lean, before it made no difference, so I must have everything sort of kosher.