wow, i searched and searched and could find no reliable info on this.
Some have said that if you run an OBD1 ECU in a late model prelude, you need to change to an earlier model distributor and rewire in the crank angle sensor in order to have a proper crank angle signal to the ECU.

Is this true? jeeze, i've been running OBD1 ecu's along with conversion harnesses in several preludes so far without trouble.

can someone comment?

thanks

 

ttt
anyone with any comments on this one?

 

the point of the conversion harness is so you don't have to do that.

the only reason you would switch is if now with OBDI you wanted to manually advance timing

 

obd2 preludes do not have the 4 tooth cylinder position sensor. you HAVE to have that sensor in order for the obd1 ecu to work.

the sensor by the oil pump is a crank speed fluctuation sensor, NOT a crank position sensor. the crank position sensor is a 24 tooth sensor that is located in the distributor for both obd1 and obd2. crank speed fluctuation sensor dosnt exist in anything obd1, therefore obd1 ecus will not understand that input.

you have to convert to an obd1 distributor to use an obd1 ecu

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg &raquo;</TD></TR><TR><TD CLASS="quote">obd2 preludes do not have the 4 tooth cylinder position sensor. you HAVE to have that sensor in order for the obd1 ecu to work. </TD></TR></TABLE>

Yes they do. It's mounted in the distributor. Reference: page 11-95 in the 5th Gen Helms manual.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg &raquo;</TD></TR><TR><TD CLASS="quote">the sensor by the oil pump is a crank speed fluctuation sensor </TD></TR></TABLE>

5th Gen Preludes don't have a crank fluctuation sensor. Most other OBD2 Hondas/Acuras do. Reference: page 11-44 in the 5th Gen Helms manual.

The top dead center position sensor and crankshaft position sensor is mounted on the oil pump. Reference: page 11-88 in the 5th Gen Helms manual.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg &raquo;</TD></TR><TR><TD CLASS="quote">you have to convert to an obd1 distributor to use an obd1 ecu</TD></TR></TABLE>

Incorrect. Keep your OBD2 distributor and you'll be fine. Been there, done that.


Again, the 5th Gen Prelude is different that most other Hondas/Acuras in the positioning of the three sensors in question.

 

I agree. I have seen many OBDI ecus on OBDII dist.

Boomslang has it covered. CYP is still in the dist. and has no CKF, which btw you blow codes (54) if you ever run an OBDII P72 on an H22a

 

then they must have changed that **** at some point

we did a 97 prelude with jrsc.. put obd1 ecu on there and it wouldnt run for ****.. took the stuff apart to find what i said above.. wouldnt run on obd1 ecu, but would run on aem ems, aem ems only needs the 24tooth crank position sensor and the 1 tooth cam position sensor to run.

 

Some JDM distros will not work with swaps for some reason. TDC is off and car will never start..

 

boomslang.
thats what i thought.
i haven't had a problem yet with US prelude running US obd1 with conversion harness.

thanks for the clarification.

 

got a question here so what you are saying is if you have an obd2 car and convert the ecu to obd1 with the conversion harness you have to change the distributer obd1.. i have a 96 accord that i have boosted and i hooked up the conversion harness and the obd1 po6 computer and was gonna attempt to tune on chrome but got the cel #9 code cylinder postion sensor and couldent do anything cause of that..

 

Run the wires from the crank sensor on the oil pump,to the crank sensor in the OBDI dizzy.

Should take care of it.