skewed sensor readings

[tiff]

hi i am running microsquirt 2.888 in tuner studio i have a few issues. the vehicle is a 79 hd spoortster with a hand fabbed intake and fuel system. it has a suzuki sport bike fuel pump 45psi internally regulated ,ford windstar 3.8 injectors a turbo chev sprint throttle body now the questions 1 .my map sensor reads 125-126 kpa key on engine off should be 99-101 ? 2. my coolant temp appears to read ok but when unplugged it reads 170f should be -40 ? 3 .my tps is 1994 toyota corrola when calibrating low adc is around 925 hi is 950 guage is jumpy and i suspect low resolution. 4. i tried all of the map options in tunerstudio no luck at any with 3 different gm map sensors . the part numbers for the map sensors are not gm ? i have had the bike idling adjusted the ve map slightly to smooth it a bit and went on a few short test rides next i plan to put the laptop in the saddle bag and data log a test drive. thanks for any help. also i had a hard time accessing the site as i cant remember my previous user/pass .

[grippo]

If you post your msq that will help. If you suck on the map line does the reading go down ?

The coolant temp reads 170 deg when unplugged because that is the default - if the sensor fails in the car while driving you don't want it to use -40 deg to determine your fueling.

The resolution on your tps is way too poor. I don't know if it is broken, miswired, or just not compatible with what microsquirt expects.

[tiff]

thanks for the info . as a automotive tech im used to -40 being the default. the map sensor reading changes fine with my vacuum pump and also gets the bike running but should it not read 100kpa not running also i am good with engines but computers not so much how would i go about posting my msq. the tps is brand new maybe just the wrong type, i will see if i can get a gm sensor to fit the throttle body. i used alldata to get the wiring diagram for the sensor but i will check it again. thanks again.

[grippo]

To get your msq file you turn on MS, open MT and do a File save or save as. (If you do a 'save as' you can put it in a dirtectory you know.)

[tiff]

sorry i didnt get my msq yet my bike and tuning computer are at a different location in the country ( no highspeed internet ). i was there this week end but forgot my usb stick. i adjusted my tps and got the closed adc count to 80 open 980 so now i have plenty of range and resolution and my guage is steady. the problem is at 1/4 throttle the guage reads 90% then slowly increases to 100% by full throttle is there any way to adjust that . thanks again

[tiff]

hi i got my msq i also noticed that my idle pw is high 12-13 ms any tips greatly appreciated my map is a denso 079800-5410 ps-4a if anybody knows what to set my map values to.none of the values in tuner studio gave me a koeo reading of 100kpa can you backprobe the sensor and put in the value at 2 different voltages/kpas using a vacuum pump? sorry about the lack of computer/typing skills.

[grippo]

In looking at your msq I see that two vraiables, map0 and mapmax, are both set to 0. These are the scale factors for map that are used to convert the sensor reading to a real map value. map0 is the value when the sensor reads 0 volts and mapmax is the value when the sensor reads 5 volts. They can't both be 0 - I don't see how you are getting any reading.

The equation used for this in the code is:

map = map0 + (mapmax -map0) x sensor volts / 5 V

I suspect that when you went though the calibration something got hosed. You basically want to measure the sensor voltage in open air (engine off) and then pull as much vacuum as you can and record that voltage. From that data and the above eq you can get the values of map0 and mapmax that will make map correct everywhere, assuming the sensor is linear, which I believe most are.

[tiff]

I viewed the last post, my sensor reading key on engine off is 2.806 v. With my vacuum pump at 28 inhg is .29 v I can't draw anymore vacuum to get it to 0 v and I don't know what Kpa that represents between -90 kpa & -100 kpa. Also I don't know the exact kpa at 5 v. The only place that I can find to put in sensor values is under tools/calibrate sensor and this doesn't show map 0 and map max it shows value at 5 volts and value at 0 v.

See attatchments

[grippo]

With key on/ engine off your sensor should read about 100 kPa unless you are on a high mountain. So this corresponds to 2.806 V. 28 in hg corresponds to about 5 kPa at .29V. So plot these two points on a piece of graph paper with 0.3 V, 2.8 V and 5V on the horizontal axis and 5, 100 and 200 kPa on the vertical axis. Connect the 2 measured points with a straight line and run the line out to 5 V. Read the vertical axis and you will get something a little less than 200 kPa. Enter this number for the value at 5 V (=mapmax) and then project the line back to 0 V, read the vertical axis (will be a little less than 5 kPa) and enter that number for the value at 0 V (=map0). Then follow the calibration instructions and that should give you decent readings from your sensor. If you wanted to be a bit more accurate, you could get the exact weather barometric pressure at your elevation and use that number instead of 100 kPa.

[tiff]

thanks again i got my map issues fixed i think i got the idle tuned pretty well also but i have a new problem my tach signal is coming out of a crane hi-4 ignition system and it doesnt seem very stable sometimes when the engine is running the rpm guage in tunerstudio drops out to 0 then comes back causing a lean miss? i believe it should be able to get the tach signal from the coil negative terminal since it doesnt seem to have an ignition miss. i am also not sure if the tach signal the ignition puts out is consistent enough. the engine is an odd fir v twin running waste spark so if i go to the coil for rpm my tach will read double and dependent on where the engine shuts off my injector timing delay may be way off.can i runoff the coil and set my cylinders to 4 to fix my rpm? any help greatly appreciated.