ECU type

Post Sat Jun 12, 2021 3:06 pm

Good afternoon
Can any one advise whether a 0261 200 172 ECU will work correctly when fitted with a ECU Upgrade EPROM Chip from Speed touch , its for 1989 2.5 m20 . which normally uses a 0261 200 380
Cheers

Post Sat Jun 12, 2021 5:05 pm

Hello.

0261 200 380 ECU is used on M20B25 engine and it is compatible with 0261 200 173, so 0261 200 381 is compatible with 0261 200 172,used on M20B20. Biggest difference between M20B20 and M20B25 ECUs are in EPROM (different fuel maps, timings, etc...), It is quite sure that 172/381 will work in M20B25 with 173/380 EPROM and vice versa. This upgrade EPROM will work in 172 for sure, but its fuel maps are for M20B25 and you may experience somewhat rich running, maybe higher fuel consumption and so on....

Post Mon Jun 14, 2021 4:39 pm

petdej wrote: ↑
Sat Jun 12, 2021 5:05 pm
Hello.

0261 200 380 ECU is used on M20B25 engine and it is compatible with 0261 200 173, so 0261 200 381 is compatible with 0261 200 172,used on M20B20. Biggest difference between M20B20 and M20B25 ECUs are in EPROM (different fuel maps, timings, etc...), It is quite sure that 172/381 will work in M20B25 with 173/380 EPROM and vice versa. This upgrade EPROM will work in 172 for sure, but its fuel maps are for M20B25 and you may experience somewhat rich running, maybe higher fuel consumption and so on....

Hi Many thanks for taking the time to respond, I think I understand , the car was originally a 320 which was changed many years ago to a 2.5 but the 0261 200 173 ECU was left but with a EPROM upgrade. She does run rich and 20 ish mpg around town So i was thinking of finally sorting her out and fit the correct unit. and try it with a standard chip