dugr
Just got it firing!
To spare you my agony, here's the cutting to the chase question… What is the best method to establish the TPS position without using the 150mv method on a 15M system.
Forewarned... Below is an overview of what I've been going through historically in regards TPS, settings, some theories and just how tormented I am...
I have read and reread everything I could find regarding setting up the 15M Marelli fuel injection for my 2000 Bassa and still, it’s up for debate.
Some subscribe to the idea that with the TB completely closed with the idle/degree stop backed off as to not interfere with the TB, the voltage should read 150mv. This gives you an absolute reference point for setting the TPS. Then, set the voltage for idle/degree stop somewhere between 470-520mv which gives you 3.6 degrees +/-. Measuring with GuzziDiag or, other software, the TB should be around 3.6 degrees. Sync the right TB idle/degree stop using vacuum gauges using the left as the master. With the vacuum gauges still attached, take it up to 4-5K rpms to balance the TB linkage. Recheck the TPS voltage and the vacuum at idle then you’re set.
Makes sense, or does it? Not in my case. I can’t get the idle down below 1350 rpm's unless the air bleeds are closed and I back the idle/degree stop down to 3.03 degrees / 470mv. Currently, at full throttle it reads, 87.86 degrees and 4.939V.
Others take a more “maybe” approach and disregard the 150mv reference point completely and use 3.6 degrees as the Holy Grail as a reference point which, should have your TPS voltage @ 470-520mv.
Maybe I missing something but, I see a flaw in this theory is, since the TPS is what tells the computer what degree the TB is at. How can that be accurate measurement of degrees since the TPS setting is part of the variable too?
The only way I know the degree method would work is to have an absolute reference point with a degree wheel attached to the TB shaft to set the stop at 3.6 degrees, then take measurements to adjust the voltage on the TPS to 470-520mv. That seems to be a difficult task unless you remove the TB from the engine and make those measurements on a bench.
Tell me if I’m going the wrong direction with this “maybe” next thought. Taking readings from GuzziDiag, when I open the throttle to 3.58 degrees the voltage is at 529mv. Using the current TB setting (whatever degree it is at) since the idle is decent, then using a voltmeter, adjusting the TPS to 529mv would give me 3.6 degrees as a new “maybe” baseline.
When I got this Bassa it had a sensitive off-idle throttle response, a lean stumble cruising and a random cough. I cleaned the TB’s recalibrated the TPS to 150mv, replaced the spark plugs, plug caps (one was bad), and plug wires. It was an improvement but, still not right. I ran GuzziDiag and changed the CO trim from -43 to -10 (I just grabbed a random number as a starting point), it cleared up the cough, throttle sensitivity is now gone and it cruises with less vibration. It’s not bad now but, in the process of the changes, there has been loss in power as though the timing is retarded which leads me back to the TPS settings. It's a vicious circle.
“Maybe”, may just be the Italian way… Maybe...
Forewarned... Below is an overview of what I've been going through historically in regards TPS, settings, some theories and just how tormented I am...
I have read and reread everything I could find regarding setting up the 15M Marelli fuel injection for my 2000 Bassa and still, it’s up for debate.
Some subscribe to the idea that with the TB completely closed with the idle/degree stop backed off as to not interfere with the TB, the voltage should read 150mv. This gives you an absolute reference point for setting the TPS. Then, set the voltage for idle/degree stop somewhere between 470-520mv which gives you 3.6 degrees +/-. Measuring with GuzziDiag or, other software, the TB should be around 3.6 degrees. Sync the right TB idle/degree stop using vacuum gauges using the left as the master. With the vacuum gauges still attached, take it up to 4-5K rpms to balance the TB linkage. Recheck the TPS voltage and the vacuum at idle then you’re set.
Makes sense, or does it? Not in my case. I can’t get the idle down below 1350 rpm's unless the air bleeds are closed and I back the idle/degree stop down to 3.03 degrees / 470mv. Currently, at full throttle it reads, 87.86 degrees and 4.939V.
Others take a more “maybe” approach and disregard the 150mv reference point completely and use 3.6 degrees as the Holy Grail as a reference point which, should have your TPS voltage @ 470-520mv.
Maybe I missing something but, I see a flaw in this theory is, since the TPS is what tells the computer what degree the TB is at. How can that be accurate measurement of degrees since the TPS setting is part of the variable too?
The only way I know the degree method would work is to have an absolute reference point with a degree wheel attached to the TB shaft to set the stop at 3.6 degrees, then take measurements to adjust the voltage on the TPS to 470-520mv. That seems to be a difficult task unless you remove the TB from the engine and make those measurements on a bench.
Tell me if I’m going the wrong direction with this “maybe” next thought. Taking readings from GuzziDiag, when I open the throttle to 3.58 degrees the voltage is at 529mv. Using the current TB setting (whatever degree it is at) since the idle is decent, then using a voltmeter, adjusting the TPS to 529mv would give me 3.6 degrees as a new “maybe” baseline.
When I got this Bassa it had a sensitive off-idle throttle response, a lean stumble cruising and a random cough. I cleaned the TB’s recalibrated the TPS to 150mv, replaced the spark plugs, plug caps (one was bad), and plug wires. It was an improvement but, still not right. I ran GuzziDiag and changed the CO trim from -43 to -10 (I just grabbed a random number as a starting point), it cleared up the cough, throttle sensitivity is now gone and it cruises with less vibration. It’s not bad now but, in the process of the changes, there has been loss in power as though the timing is retarded which leads me back to the TPS settings. It's a vicious circle.
“Maybe”, may just be the Italian way… Maybe...