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Discussion Starter #1
i have a 84 fj-60, all stock with all the smog stuff. i replaced all vacuum hoses one at a time and looked thru the emmisions book while i was doing it and they all seem to be where they should. i took it in today and failed high in everything at idle. i have the timming set to stock and tunned the carb to the "lean drop method" which was kinda confusing to me.

now can i adjust the timming and tune the carb different to help me get thru? the truck runs great but sometimes i do smell a rotten oder from the exhaust when my foot is off the gas and the motor is slowing down the truck. the cat and exhaust is pretty new(6 months old) and the plugs are new(set to stock gap). any tricks or experience anybody has would be helpful.

by the way the test is on a dyno at idle for 1 minute then reved to 2500 rpm for a minute and then back to idle. it's only tested at idle though.

thanks for any help

dave <IMG SRC="smilies/beer.gif" border="0">

[ 10-13-2001: Message edited by: davefj40 ]
 

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Will it idle with the idle mixture screw all the way in? Is the choke all the way open? If so, chances are that it is leaking gas into throttle body at idle. Pull the air cleaner and look for gas dripping out of either the main jet nozzles (the rings inthe center of the bore or fromthe vent tubes (brass tubes cut at an angle at the top of the carb). You didn't say what the #s are at idle and you didn't say what they were at higher speed. This info would be useful to know whether it is just a carb problem, an idle circuit problem or something else.
 

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Discussion Starter #3
i never turned the mixture screw all the way in but it does drop rpm, had it down to around 350rpm at one point. the choke works fine when i use it in the morning, the carb was rebuilt right before i got the truck in april so i think that stuff is alright. float level is half sight glass.

the readings at idle were 810ppm HC(220 is the state standard) and 6.06pct CO(1.2 is the state standard) and 8.43 pct CO2(state is 6.0, i did pass this). i don't have readings at 2500rpm, they don't log this.

i'm thinking my timing might of been off because i think i might of been confused with the line and the BB mark.

thanks for the help

dave
 

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With those CO #s, I would go ahead and take the air cleaner off and check for gas dripping at idle. The mixture is too rich at idle. Just because the carb was rebuilt, doesn't mean that it was done right. If you see gas leaking into the carb, then take the top cover of the carb and spray out all of the tiny holes in it, make sure that they are flowing freely and replace the cover. If the timing was way retarded so that combustion was unreliable or incomplete, HC would be through the roof. If a cylinder was missing at idle, HC should be much higher.
 

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Discussion Starter #5
no gas dripping at idle from any of the spots you mentioned. could it be that the idle mixture is just way off? i didn't adjust anything before i took it in to get tested but have since done the "lean drop method". if it helps i have 20" vacuum at idle.

dave
 

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Lean drop is the way to do it. Start with the idle mix 1.5 turns out and set the idle speed to 690. Turn the idle mixture screw out until engine speeds up. Turn idle speed back to 690. Repeat until the engine no longer speeds up when you turn the mixture screw out. Then set idle speed to 650.
Did you check compression? Low compression can contribute to high HC. If the engine misses intermittently at idle this could also give you high HC #s.

[ 10-14-2001: Message edited by: Pin Head ]
 

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Discussion Starter #7
i'll try the mixture again, and check compression. the truck idles great, had it wheeling 2 weeks ago and it's was chugging away at 150-200 rpm at some points.

do you have any experience with the aftermarket ignitions or the non-usa toyota jobs?

dave
 
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