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| factory preset idle speed set screw; news for those that moved theirs | |
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| Topic Started: Dec 8 2009, 05:49 PM (691 Views) | |
| geonewbie | Dec 8 2009, 05:49 PM Post #1 |
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Advanced Member
  ![]](http://209.85.62.24/static/1/pip_r.png)
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i've read many threads both here and on TS where people have commented about adjusting the factory setting on the throttle stop for various reasons and many responses about how that should never be done, the manual says the same. i did the same thing in utter frustration while having idle and vac. issues, and having the nagging question of just what IS the factory setting i went junkyarding to find as many TB's as i could and try to find out. what i found was that 5 out of 5 TB's that i could suspect of being untampered had the very same setting. measuring directly beside the set screw from the bottom of the casting the screw goes thru down to the arm on the throttle bell crank was exactly 1/8" in each case. SO........... if you moved yours before you knew better or suspect that yours may have been tampered with you now have a pretty good idea of where to reset it. don't forget to readjust your TPS afterward, then recheck your idle and timing. steve |
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| Bad Bent | Dec 8 2009, 06:08 PM Post #2 |
Facetious Educated Donkey
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I guess I am bad.  I had to adjust mine because the PO thought he was a great mechanic. The pedal was sticking when you applied gas. Turns out the Throttle Stop was adjusted all the way out so the rpm would idle down to around 1000 rpm. The butterfly was choking the engine and sticking. I kept the Allen and open end wrenches handy and adjusted it 1/8 turn each stop to where it stopped sticking. Had to, no choice. Adjusted the TPS, yeda, yada, yada and I get 52 mpg in the summer.   I'll check that 1/8", thanks. |
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| Woodie | Dec 9 2009, 06:08 AM Post #3 |
 
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I think that is the adjustment, Bad Bent. As closed as possible without sticking in the bore. |
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| rmcelwee | Dec 9 2009, 08:09 AM Post #4 |
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I never understood what the problem with adjusting it is. If your idle is good but your throttle stop isn't at the factory setting what is the big deal? |
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| Bad Bent | Dec 9 2009, 02:05 PM Post #5 |
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Facetious Educated Donkey
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 Trick question?How much some Dealer and Grease Monkey get paid to adjust it when you are not looking? My logic was, if it's open more, then you have a higher rpm which would affect your Idle Adj. Screw/TPS/ISC/PCM/ECM, yeda, yada, yada.  You are right, rmcelwee, it's a cable adjustment. 
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| geonewbie | Dec 9 2009, 04:08 PM Post #6 |
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Advanced Member
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Bad Bent, so did you check yours, how close was it ? when i was messing with mine i had taken it all the way back till the screw wasn't touching, then out till i felt contact and just enough more to raise the idle by the meerest audible amount. it wasn't sticking any place. when i made a little 1/8" rod as a feeler it was pretty darn close. i think it could be more important than it may first seem. if the factory had a specific set point for it i'd have to believe that the rest of the system (as you mention) is factored to expect that as the starting point. maybe not ? steve |
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| geonewbie | Mar 11 2010, 08:31 PM Post #7 |
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Advanced Member
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this topic thread is kind of old but i just did another tuning sequence that i'm pretty happy with. i've had things in a steady state all winter and averaged 48-49mpg which i thought was OK, but i had some minor drive-ability issues. slight hesitation at tip in from a stop and an odd chuffing throttle response at sudden large throttle angle openings. this evening after work i closed the idle speed adjuster screw in the TB and set the base timing to 10* BTDC( formerly 8*BTDC) at 700rpm using just the throttle stop screw with the jumper in. then i took out the jumper and moved the idle up to 800rpm with the idle speed screw, and reset the TS/ TPS. i had formerly had the throttle stop adjusted to the 1/8" mark mentioned earlier in this thread and the idle screw turned out enough to get the 700 rpm then set the timing to 8*BTDC over the top of that idle. this new setting gave me an even, sure tip in from idle and instant response and acceleration at all rpms and throttle angles. this may still not be the technically correct way to approach this but it seems to be working very well for me. steve Edited by geonewbie, Mar 11 2010, 08:35 PM.
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| bogs | Mar 12 2010, 07:34 AM Post #8 |
Duct tape heals all wounds
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Very interesting to know, any pics to help illustrate? |
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| geonewbie | Mar 12 2010, 01:12 PM Post #9 |
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Advanced Member
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no pics, this is the only site of this type that i frequent that doesnt' have a pic uploader on board. the location of all the mentioned pieces and the adjustments is pretty common knowledge around here. i didn't do anything revolutionary or new, just a slightly diff. process of getting it done. i'm not a fan of the wobbly, shakey idle of these 3's esp. at 5*BTDC and 700rpm !! in my case it worked out better to set the timing at 5*BTDC and 700rpm with just the throttle stop, THEN, push the timing up to 10*BTDC (EDIT) AND backed the set screw out just enough to return to 700rpm, THEN, remove the DIAG. jumper, THEN, push the idle on up to 800rpm using the idle ajustment screw, THEN, reset the TS /TPS. i could have left the timing at 8*BTDC but i've been there all winter and wanted to try to squeeze just alittle more in there if i could. i'll be checking for ping and signs of material migration at the plugs REAL close. steve Edited by geonewbie, Mar 12 2010, 03:33 PM.
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| bogs | Mar 12 2010, 05:57 PM Post #10 |
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Duct tape heals all wounds
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True there is no uploader for pictures, however, posting them is a fairly easy process, even if you don't want to start an account at any of the free places. there are other free places that don't even require that. Just keep in mind, whats common knowledge to one (or even many) isn't to everyone, myself for one. Pretty sure I'm not alone. |
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| Jittney | Mar 12 2010, 07:13 PM Post #11 |
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Anchorage, AK 93 & 94
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 pictures are helpful to the newbies: especially since there is no car diagram on this site yet, and people sometimes have different names for the same car part. That said, my compliments to geonewbie for his good narrative, which does a fine job of explaining what he did.
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| KY Metro | Mar 12 2010, 07:38 PM Post #12 |
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" pictures are helpful to the newbies: especially since there is no car diagram on this site yet....." Yes! We need some diagrams and a FAQ/"Best Of" page. |
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| BryanTheGhostRider | Mar 12 2010, 08:14 PM Post #13 |
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the last owner set mine so low that it dies if the AC is on when i stop >.< Im going to be slowly tightening it till im happy with the results. |
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| geonewbie | Mar 12 2010, 09:16 PM Post #14 |
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Advanced Member
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Bryan, you may have already correctly established that your base timing or idle rpm or both are lower than recommended but, your car should have another device known as an Idle Air Controller, this item is SUPPOSED to bypass some air under the throttle plate and raise the idle rpm when there are additional loads present. THAT could be part of your problem. as to the pics, perhaps i'll look into a place to upload from. my apologies to everyone that felt left out by my reply. sorry bogs, i've gleaned helpful info from your many posts and i've found lots of pics of the items i've mentioned in other threads here on the site. i also have a history of needing to be able to trouble shoot and repair anything i own ( should have paid attention back in school ) so the very first thing i buy is a manual, i have 2 for the XFI because the first one i bought is full of errors. but they all have lots of pics and descriptions. steve |
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| Bad Bent | Mar 12 2010, 11:58 PM Post #15 |
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Facetious Educated Donkey
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My apologies, geonewbie, for forgetting to measure the depth of the threads on the set screw we are NOT supposed to touch. It's about 1/8" as you had set it at. Again, just enough to keep the butterfly valve from sticking.
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5:15 PM Jul 30
