background: i bought a 88 crx si..had an occasional problem of going up to 3-3500 rpm at idle for no apparent reason. i would cut the car off and restart, no problem. never threw any codes. i took that motor and put it in a 89 civic si last week. first real day of driving the car and i get a code one (O2 sensor) on the way to work. coming home i also threw a code one. i was almost home when the car felt like it was pulling itself at 3000 rpm with no pressure on the throttle at all, and when i pressed on the throttle the car jerked and hesitated really hard. i pushed in the clutch and coasted in my driveway..the idle steady at 3K rpm, and code one flashing. i turned the car off, but when i went to restart it kinda started then died. i pulled the hazard fuse to reset the ecu..but it would just turn over, it would not start. my fuel pressure gauge showed pressure at the filter, not sure if the injecters were squirting. gave the car a few more minutes, it started right up. if anyone can help or offer advice, it would be appreciated. thanks.

 

anyone?

 

did you chang out the o2 sensor yet?

 

update: i took off the heat shield and removed the o2 sensor. i've never noticed this before, but there is something loose inside the o2 rattling around. is this normal? also, i noticed a large crack across the exhaust manifold. while i was at it, i pulled the main relay, which has been having intermittant failing. upon testing with a battery, the main relay was definately failing intermittantly. that was the reason the car wouldn't start after i cut it off. perhaps the idle spike has something to do with the o2 sensor or crack in the exhaust manifold? any input is appreciated.

 

i seem to remember my b16a2 idle'ing high when my alarm took a funny turn and cut the fuel pump(bloody cliffords). it sent the ecu into safe mode(no power, no high revs, high idle) as it had discovered what it percieved as a serious fault and tried to limit any damage caused. Does this sound familiar? (the ecu warning light stayed on on mine, wouldnt flash)resetting the ecu's memory(removing the fuse) cures this. it in itself is nothing to worry about, only the cause is... could be the relay.

 

yes, the bad relay did cause the check engine to stay on. replaced both relays with a known good one, no more problems there. also replaced the o2 sensor with a good one, but haven't driven the car long enough to see if the o2 cel comes on. there is definately a significant crack in the exhaust manifold though..i can feel exhaust gas coming out through the crack.

 

There are 2 things to remember here. First O2 sensors do go bad. You can expect to replace them after anywhere from 50k to 100kmiles. The Main Relay is an ongoing issue with many Honda models. My 96 Civic HB actually needed one and it only had 60k on it; the CRX has 175 and it too needed one.

You mention a cracked exhaust manifold. If you need one-I do have one available. There should be no cracks or other signs of failure-this will upset the flow and the O2 readings may be affected depending on where the crack actually is. Cast Iron is not easily welded BTW. If you need mine, drop me an e-mail.
Last thing-the ECU should clear after you have completed the repairs and give you a single short flash-ONLY when you turn the key to the ON position. You should also check the vacuum lines (the car is 15 years old <G&gt

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jc836 &raquo;</TD></TR><TR><TD CLASS="quote">You mention a cracked exhaust manifold. If you need one-I do have one available. There should be no cracks or other signs of failure-this will upset the flow and the O2 readings may be affected depending on where the crack actually is. Cast Iron is not easily welded BTW. If you need mine, drop me an e-mail. </TD></TR></TABLE>

the crack is about 4 inches long and runs between the 2 and 3 runners of the manifold, definately upstream from the 02, and more than likely effecting readings. i do need another top portion of the manifold, unless it is the same as a 1.5 dual point 4th gen civic, as i have access to those in the local junkyard. shipping would probably be very expensive, as those manifolds are fairly heavy. if the manifold is the same, i will just pick one up from the local yard. thanks for the help!