Hey guys so i picked up this 95 ex coupe as a dd. It is automagic and it sucks up gas. I get about 21mpg granny driving it and yesterday i brought it to the inspection place and it failed for NOx i think accepteable was 800 and mine was 2700+. What i've done to the car so far, brand new 02 sensor, new plugs, new wires, new air filter. The motor is completely stock. What should i be looking for? btw this is the 1.6 vtec motor Thanks

also there are no check engine light or codes


Modified by bhom920 at 5:37 AM 5/15/2008

 

Could be a bad cat. How many miles are on this motor? Check for vacuum leaks.

 

150k on the motor, i will check for vaccum leaks later today. BTW do you know how much vaccum i should be pulling? i have a old boost guage laying around that i can use to test it

 

bad cat won't cause terrible gas mileage, but a pre-cat exhaust leak definitely will. I'd definitely check the vac leak idea.... Check the dist. coil/rotor. Check the PCV valve too.

Maybe run a can of seafoam through it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bhom920 &raquo;</TD></TR><TR><TD CLASS="quote">150k on the motor, i will check for vaccum leaks later today. BTW do you know how much vaccum i should be pulling? i have a old boost guage laying around that i can use to test it</TD></TR></TABLE>Healthy engines will pull somewhere around 17-21Hg (inches of mercury?)

 

god damn.... 2700ppm nox is insane.. nox is created with heat, over heating, running very lean.. do you have the rest of the co co2 o2 and hc readings?
and if its a 95 i dont know what state your in but in pa they dont test for nox in a obd1 car..

 

Once NOx get started they blow up. I've had runaway NOx problems. For me it's always been the ignition timing.

Set your base ignition timing. Run 91 Octane. You may also try Seafoam to clear out carbon build up which can cause hot spots.

 

The car maybe running too rich.

Also, how's the cooling system on the car? Is everything running ok?

 

02 sensor

 

Here's the deal, i saved this from a very ghetto rigged owner. I first found out that the check engine bulb was pulled, so i put a new one in and found out i was throwing a bad o2 sensor code. So i put a brand new denso in and all codes were gone. What i am thinking is that the previous owner was too cheap to buy a o2 sensor and just increased the timing to sort of balance things out. That is my guess to this NOx problem which i will retime the car when i get home tonight. But even that doesn't solve my gas mileage problems, so i will check that out tonight also. I also found out that the owner had jumped the temp sensor so that the fan would be on all the time. That i haven't gotten a chance to replace but i was talking to my honda friend who said he shouldn't effect anything except the fan will always be on.

so tonight or tomorrow night i will try to retime the car as well as check for vaccum leaks and possibly seafoam the car. i will report back with my results.

 

btw what should the ignition timing be set at? 15?

 

here's my update, i filled up with gas today and it got 29mpg.. not shabby i guess. i also seafoamed the car and checked for leaks, no leaks. my analysis on the timing was right. it was pinned on the most advanced

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bhom920 &raquo;</TD></TR><TR><TD CLASS="quote">btw what should the ignition timing be set at? 15?</TD></TR></TABLE>

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