I start my car up, no CEL, it warms up, rpms drop, after awhile CEL comes on. shut off and restart motor, no CEL, let it idle for awhile, comes back on, so i tested it with the motor running and this is what i got...also my redline seems to be at 7500rpm no matter if the CEL is on or off, what could be causing that?? 94 b18c1 with (as far as I know) stock p72 in a 95 cx hatch. Anyone know whats going on? I understand the code 8, but I dont know what code 41 means...any help would be nice! Thanks
8 TDC - top dead centre sensor
41 Primary oxygen sensor heater

 

any vacuum leaks?

 

im pretty sure no

 

Could be a bad distributor, wiring issue or ECU.

 

I got my money on the distributor, because you can not go passed a certain rpm point.

 

now that i think about it...sometimes it hesitates if i give it just a little gas....maybe its time for a tune up...what do you think: new plugs, distributor (cap), maybe wires? anything else?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bull_head360 &raquo;</TD></TR><TR><TD CLASS="quote">94 b18c1 with (as far as I know) stock p72 in a 95 cx hatch.</TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bull_head360 &raquo;</TD></TR><TR><TD CLASS="quote">I understand the code 8, but I dont know what code 41 means...</TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bull_head360 &raquo;</TD></TR><TR><TD CLASS="quote">41 Primary oxygen sensor heater</TD></TR></TABLE>

What code 41 would mean to the stock CX motor/ECU is the O2 sensor or it's connection for the heater element is bad. What this means to a P72 ECU is the same thing yet one factor that could've been overlooked is the fact that the CX uses a 1 wire O2 and the P72 needs a standard 4 wire O2. If the wiring was never converted to a 4 wire O2 setup then there's your problem.

 

Yea that will pose a problem, but the cars was running right with out a check engine light for awhile correct? Also if the O2 was not wired right from the get go the check engine light would immediately be set off right after engine start.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MethodMotorWorks &raquo;</TD></TR><TR><TD CLASS="quote">Also if the O2 was not wired right from the get go the check engine light would immediately be set off right after engine start.</TD></TR></TABLE>

Not for the O2 heater circuit. You can usually drive about 5-10 miles after warm up before it will trip a CEL.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by VTECVillain &raquo;</TD></TR><TR><TD CLASS="quote">

Not for the O2 heater circuit. You can usually drive about 5-10 miles after warm up before it will trip a CEL.</TD></TR></TABLE>

Good point.

 

the motor has been in the car for atleast a year...i know the O2 sensor on the exhaust is a 4 wire, if that helps...but this just started happening last 2-3 weeks, motor still runs fine though. today no CEL at all after driving around town for atleast an hour