Won't Pass Emissions
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 27
From: FORT WORTH, TEXAS,USA
The catalytic converter must be in half way good shape.
The ACV MUST be working right. In other words the two vacuum signals to it MUST be correct.
The airpump MUST be working.
The TPS should be outputting approx 1 volt dc to the ECU when the engine is HOT and at an idle of approx 750 rpm. The TPS output determines the vacuum input to the ACV.
There is a seciton in the FSM that deals with the above. Pictures also. Free online FSM available. Haynes manual abailable at the auto store.
The 02 sensor is not in the loop at idle. If they put the car on rollers and drive it on the rollers, then the 02 is a player.
IF you have a series four, adjust the variable resistor to the lean position but not so lean that the engine dies on you.
Scan your emissions test and post it on this thread so we can see it.
And believe it or not, your choice, if the atmospheric pressure sensor is unplugged on a series four, the engine will run a bit richer over the full range. I accidently got my emissions done on my 86 n/a with that plug off and still passed well within range. A good catalytic converter does wonders.
IF your at sea level or below, then that does not apply because the ECU defaults to sea level if the plug is off (some assuming in that statement).
I'd bet your problem is a combination of bad catalyic converter and acv not working right.
The ACV MUST be working right. In other words the two vacuum signals to it MUST be correct.
The airpump MUST be working.
The TPS should be outputting approx 1 volt dc to the ECU when the engine is HOT and at an idle of approx 750 rpm. The TPS output determines the vacuum input to the ACV.
There is a seciton in the FSM that deals with the above. Pictures also. Free online FSM available. Haynes manual abailable at the auto store.
The 02 sensor is not in the loop at idle. If they put the car on rollers and drive it on the rollers, then the 02 is a player.
IF you have a series four, adjust the variable resistor to the lean position but not so lean that the engine dies on you.
Scan your emissions test and post it on this thread so we can see it.
And believe it or not, your choice, if the atmospheric pressure sensor is unplugged on a series four, the engine will run a bit richer over the full range. I accidently got my emissions done on my 86 n/a with that plug off and still passed well within range. A good catalytic converter does wonders.
IF your at sea level or below, then that does not apply because the ECU defaults to sea level if the plug is off (some assuming in that statement).
I'd bet your problem is a combination of bad catalyic converter and acv not working right.
Air control valve. It's on the LIM.
It controls when the airpump sends air to the cat.
If you don't normally have a cat then you can gut the acv so it sends air to the cat 24/7.
I passed within 10 seconds on the dyno doing this method.
I had fake vac hoses plugged into lines/BB's in vac lines to make the ACV look like it did something but the internal diaphragm was removed so it just pumped all air to the cat.
The minimum you need is Cat,ACV,and airpump.
If you have a cat on the car at all times then do not do this since it could damage the cat over time.
It controls when the airpump sends air to the cat.
If you don't normally have a cat then you can gut the acv so it sends air to the cat 24/7.
I passed within 10 seconds on the dyno doing this method.
I had fake vac hoses plugged into lines/BB's in vac lines to make the ACV look like it did something but the internal diaphragm was removed so it just pumped all air to the cat.
The minimum you need is Cat,ACV,and airpump.
If you have a cat on the car at all times then do not do this since it could damage the cat over time.
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