FAILED EMISSIONS! Have a few questions...

Give this a shot. Go to advance auto, or autozone, one of those places. Look for a box of fuel additive called guarenteed to pass. I used it last year and got through emissions with 2 cats blown slam out. Considering you are only off a point or 2, it will work wonders for your car. If you cant find it, try putting some regular gas in it, adjust your timing to keep you from spark knocking if needed, and try it that way .

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.dalidesign.com/hbook/eectest.html for more descriptive help
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $33.

not positive but i think not having your EGR hooked up and functioning properly would cause you to run rich.

The EGR not being hooked up could be causing some problems, but I think the fuel pressure is probably a little high. Is there a fine for not passing the second time through, or do they just tell you to come back later? If the latter, then try backing off the pressure, if only for the duration of the test. If you may be fined or suffer other repercutions then back off the fuel and try the fuel additive. It should work.

EGR does not get constant vacuum so you had the wrong line on it. I *think* egr only works at idle and part throttle.

jmattix1

I had the same problem in WA. I ended up putting on two new cats that take the place of the OEM four on the car. My EGR valve was also not working so it was replaced. The O/2 sensors were also bad. The inspection station told me that after the work was completed this is the cleanest mustang they have ever tested. Not cheap but it will be good for a long time now.

I'd retard the timing to the stock 10* just for the test and also do the fuel additive.

New cat's can really make the difference. the old h-pipe technology seems to be lacking.

Don't forget to change your oil before you go as well.

If you really want to fix the problem, dump the codes. The computer's built in diagnostic software knows what's working & what isn't.

You can guess all you want, throw parts and money at it and never get it fixed. OR you can dump the codes, post them & get answers on how to fix the offending items. It is the best path to success and the easiest on your wallet too.

my guess is the timing, that will greatly effect the emissions. chris

1990LXDropTop said:

You should really read the previous posts before posting.

Click to expand...

Sorry. my apology. I missed your previous post of the codes. Here's some EGR help...

EGR operational theory:
The EGR system has a vacuum source (line from the intake manifold) that goes to the EVR, computer operated electronic vacuum regulator. The EGR valve and the passages in the heads and intake manifold route exhaust gas to the EGR spacer (throttle body spacer). The computer uses RPM, Load. and some other factors to tell the EVR to pass vacuum to open the EGR valve. The EGR sensor tells the computer how far the EGR valve is open. Then computer adjusts the signal sent to the EVR to hold, increase or decrease the vacuum. The computer adds spark advance to compensate for the recirculated gases and the slower rate they burn at.


The EGR shuts off at Wide Open Throttle (WOT), so it has minimal effect on performance. The addition of exhaust gas drops combustion temperature, increases gas mileage and reduces the tendency of the engine to ping. It can also reduce HC emissions by reducing fuel consumption.

Code 34 Or 334 - EGR voltage above closed limit - Failed sensor, carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the flange side of the EGR by mouth. If it leaks, there is carbon stuck on the pintle valve seat, replace the EGR valve ($85-$95).

If the blow by test passes, and you have replaced the sensor, then you have sensor electrical ground problems. Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohm. Next check the resistance between the black/white wire and the negative battery post. It should be less than 1 ohm.

Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.

This will affect idle quality by diluting the intake air charge

Code 87 – fuel pump primary circuit failure. The fuel pump lost power while the engine was running. Check fuel pump relay, check inertia switch, wiring to/from inertia switch, red wire going to inertia switch for +12volts. Check the other side of inertia switch for +12 volts.

To help troubleshoot the 87 code, follow this link for a wiring diagram for 89-93 cars [urlhttp://www.autozone.com/servlet/UiBroker?ForwardPage=az/cds/en_us/0900823d/80/19/59/5a/0900823d8019595a.jsp [/url]

For 79-88 cars use, http://www.autozone.com/servlet/UiB..._us/0900823d/80/16/71/3c/0900823d8016713c.jsp

Code 67 - clutch not depressed (5 speed) or car not in neutral or park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code may prevent you from running the Key On Engine On tests. You can generally ignore this code, since it has no effect on engine performance.

My car failed....I backed the timing down to stock and put some guarenteed to pass in.....it passed

put 87 in the tank with 10 degrees timing should do the trick. i went yesterday here in NJ and passed with flying colors. oh ya, romp on her before you go, get those cats nice and hot.

Just and FYI, I recently passed here in Ca. with everything in the sig. I didn't do any tweaking beforehand but I guess every little bit helps. I'll try to remember to look over my numbers when I get home. Hopefully it was the egr/vacuum causing the problem.