Hi, I have a 1996 d16y5 cvt vtec-e civic vti which is giving odd pre-cat o2 readings. Now looks like at some stage before I bought the car the mani (& head?) has been swapped with y8 parts It only has a 1-wire o2 sensor pre-cat - haven't crawled underneath yet but expect it'll be the same (y5's have pre- & post- + the cat all at the mani from what I've read)
The 1-wire is reading ~ 3.7v at start-up, then after ~ 4mins drops within the normal range of 0.1v to 0.9v, but jumps all over the place (me thinks it is had it) but to confuse that diagnosis I've also noticed several wires at the ecu are missing, one of which is IACV Control. IACV Position readings are all over the place, incl when driving (not more than 20% from memory). Also the STFT (Short Term Fuel Trim) is constantly adjusting, to over -20%

On checking under the hood, the IACV only has a 2-wire connector, not the 3 the y5 is meant to have so more weight to the 'swapped' theory above - and looking like the harness was swapped too.
Which is very disappointing as it was bought as stock-standard - I can't afford putting the sort of money needed to get it all back to d16y5, but is it possible to replace the o2 sensors with 4-wire ones (or at least the pre-cat) understanding the need to run extra wires to the ecu (obd2a) ? Will the 4-wire ones have same thread size etc or are they different ?
Will the IACV Control issue mean it's a lost cause (it has only 2 wires and might be causing the STFT changes) ?
Curiously if I unplug the 1-wire pre-cat sensor it's readings stay at 3.6v, the STFT only switches between -2.2% & -6.2% which would be better fuel-wise, and doesn't trigger any codes/MILs - is it safe to drive in this mode ?

Many thanks for any help ! : )

 

Hi, I have a 1996 d16y5 cvt vtec-e civic vti which is giving odd pre-cat o2 readings. Now looks like at some stage before I bought the car the mani (& head?) had been swapped with y8 parts It only has a 1-wire o2 sensor pre-cat - haven't crawled underneath yet but expect post- will be the same (y5's have pre- & post- + the cat all at the mani from what I've read)
The 1-wire is reading ~ 3.7v at start-up, then after ~ 4mins drops within the normal range of 0.1v to 0.9v, but jumps all over the place (me thinks it is had it) but to confuse that diagnosis I've also noticed several wires at the ecu (P2M-Q61) are missing, one of which is IACV Control. IACV Position readings are all over the place, incl when driving (not more than 18/% from memory). Also the STFT (Short Term Fuel Trim) is constantly adjusting, to over -20%

On checking under the hood, the IACV only has a 2-wire connector, not the 3 the y5 is meant to have so more weight to the 'swapped' theory above - and looking like the harness was swapped too (only 1-wire to vtec solenoid also).
Which is very disappointing as it was bought as stock-standard (1st civic for me) - I can't afford putting the sort of money needed to get it all back to d16y5, but is it possible to replace the o2 sensors with 4-wire ones (or at least the pre-cat) understanding the need to run extra wires to the ecu (obd2a) ? Will the 4-wire ones have same thread size etc or are they different ?
Will the IACV Control issue mean it's a lost cause (it has only 2 wires and might be causing the STFT changes) ?
Curiously if I unplug the 1-wire pre-cat sensor it's readings stay at 3.6v, the STFT only switches between either -2.2% or -6.2% which would be better fuel-wise, and doesn't trigger any codes/MILs - is it safe to drive in this mode ?

Many thanks for any help ! : )
Mike 61 is online now Report Post

 

I have a question hopefully someone can help I’m installing a D16y5 vtec e motor and I need a ecu but was told I could use one from a d16y8 is that correct

 

NO, that is not correct. The Y5 engine is quite different from a Y8... and is reigned in by a wide band O2 sensor. The Y8 ECU utilizes a narrow band O2 sensor. The Y8 programming is mapped for a 127HP engine and the Y5 only produces 102HP.

 

so basically I need to find this unicorn part
D16y5 AT Vtec-E ECU SPACIFICALLY FOR IT TO RUN RIGHT OR ? Stock ecu better off for upgrade also it’s for a 1997 Ex model not Hx

 

Bump ?