Fuel Not Burning
 

So I took my SVX to my local service station for its annual inspection/emissions test. It pasted the inspection just fine, but not the emissions test. Apparently although the emissions are fine while it is driving, when it is idling it isn't burning up all the fuel and there is some detectable amount left. The mechanic suggested I raise the idle to like 1000 rpms to try and get that fuel to burn and he would reinspect it. So now I guess I need to know how to adjust the idle. He didn't know and also added a comment about not being allowed to or something. Does anyone know how to temporally raise the idle to burn off extra fuel or have another solution?

Re: Fuel Not Burning
 

you can raise the idle by adjusting the idle stop, it's a small screw on the passenger side of the throttle body, you can also adjust your tps to raise the idle. i would recommend actually fixing the car because if it is running too rich then that extra fuel is going to destroy your converters. if you just want to make it pass then try creating a small vacuum leak to lean it out, just unplug a small vacuum line, you can also put e85 in and the emissions will be better because it is only 15 percent gas.

Re: Fuel Not Burning
 

I would not alter that screw. It is set to allow the throttle plates to close fully, but not touch the body. If you do alter it to change the idle speed, the ECU will adjust the Idle Air Valve down, to maintain the normal speed.

I agree that you need to fix the problem that is causing the rich mixture.

Harvey.

Re: Fuel Not Burning
 

Where do you get e85 and what do you do with it? Do you put it in with the regular gas to dilute it?

Re: Fuel Not Burning
 

If I were to undo one of the vacuum lines, which one would it be? I mean, don't they need to be connected? And might the inspector just reconnect it?

Re: Fuel Not Burning
 

i don't know about where you live but around here you can buy e85 at almost any gas station. you really don't want to run it all the time unless you modify your car to do so but for emissions reasons you can run your car until almost empty put in a couple gallons and get it tested. if you can't buy it locally add some "Heat" gas dryer, it's alcohol and will increase the amount in your gas (which reduces emissions). as far as the vacuum line if you are going to try that route then try to find one that is not in an obvious place and either barely disconnect it or put a small hole in it depending how hard the emissions tech will look. keep in mind that these are not the ideal thing to do but are really cheap ways to cheat the test.

Re: Fuel Not Burning
 

I got that Heet stuff and put it in. Unfortuantely when I went to get it inspected the guy was out sick. So I'm going to try tomorrow.

I was just thinking, what would be better? High octane gas or low octane gas for this situation. It seems that whatever burnt the best would be the way to go. Does high octane burn better? I know it produces more power, but not whether it actually lights better.

Re: Fuel Not Burning
 

in theory a lower octane gas would burn better because the octane is the rating of how much it takes to make it self ignite with higher numbers being more difficult. however in your high compression engine it will retard the timing if it begins to see any pre ignition on the knock sensor which will in turn reduce the amount of efficiency you can get. i would recommend a high octane gas from a reputable gas station.

Re: Fuel Not Burning
 

You probably should run 91 octane for the emissions test, but not because it burns more thoroughly or produces more power. It doesn't.

Can you just take the car to another testing station and get a "second opinion?"

dcb

Re: Fuel Not Burning
 

Yes, I can go to another station, but it was so close to passing I thought I might as well just try this station again as the retest is free there. If it fails again I will definitely go somewhere else.

Why put 91 in it if it doesn't burn better or produce more power? Why not 93?

And I had 91 in it the first time.

Re: Fuel Not Burning
 

A higher octane rating means the AF mixture burns more SLOWLY, which allows more timing advance and more power, as the burning mixture is acting on the piston for a slightly longer duration.