1990 Honda Civic DX need help from a master tech


Old 07-03-04, 10:56 PM
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Angry 1990 Honda Civic DX need help from a master tech

I own a 1990 Honda Civic DX 4 door sedan with DPFI and last year it failed the emmisions test on the NOx. My first guess that it was the EGR valve. I looked under the hood and couldn't find it. I purchased a Haynes book and compared the illustrations with my car and still couldn't find it. The picture clearly showed and EGR bolted on the intake manifold, but my intake doesn't have a place for an EGR. So I thought maybe my car uses a diapragm egr for carbureted models and still couldn't find it. Could it be that my car just doesn't have an EGR? I took it up to about 3 different garages and it looked like the mechanics didn't know what where it was either. Dear God, there has to be someone that knows.
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Old 07-04-04, 06:20 PM
Join Date: Feb 2004
Location: So Cal
Posts: 248
Most cars have a Vehicle Emissions Control Information (VECI) label under the hood that tells you what emission controls your vehicle has. Your car may not have an EGR valve.

That said, what were the readings from the emissions test? I'd be happy to evaluate them for you.

Keep in mind that NOx is affected by engine temperature, timing and lean fuel conditions. Is your vehicle operating temperature normal? Is the timing set correctly? You should also have the oxygen (O2) sensor checked for proper operation. If you don't want to spend the money to have it checked, you can buy a Bosch sensor at AZ for about $40. Another casue of lean fuel conditions is a dirty or plugged fuel filter.

Get back to us with the readings and some additional info, such as mileage, and we may be able to help.

Old 07-04-04, 07:23 PM
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Thanks for the info, here's the results from the emissions test:

Stan Curr Result Stan Curr Result
HC 197 86 PASS 203 102 PASS
CO 1.27 0.50 PASS 1.15 0.50 PASS
CO2 14.2 14.1
NOx 1440 2317FAIL 1577 2773 FAIL
DIL >6.0 14.7 PASS >6.0 14.6 PASS

I suspected the fuel filter, but haven't replaced it and will check on the O2 sensor when I get paid.
Old 07-04-04, 08:51 PM
Join Date: Feb 2004
Location: So Cal
Posts: 248
Forgot to ask how many miles on the odometer, but if no EGR, I would check and/or replace O2 and fuel filter for sure. After that, check the timing.

When my 86 Accord failed for NOx, I replaced the O2 and it dropped significantly (about 900-1000PPM) and passed.

Good Luck,


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