High Idle '92

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alkaline747trio

alkaline747trio

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Feb 2, 2005
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264
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4,509
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Albemarle NC
Thumbing through the FSM and kept seeing 650rpms as the idle for the 3FE, never really clicked that I was idling at 800-1100rpms warm w/o AC until today. Is there any way to set the idle on these (could save me some gas with this thing guzzling it like it does)? Should I worry about it? Should I be happy with it?
 
It could be lots of different things. Do searches on the 60 series tech forum of this site and on the 3FE archieve of birfield.com, and you will find hours worth of reading on the subject. In the meantime, some things to think about would be a sticking throttle cable, vacuum leak(s), an out of adjustment throttle position sensor, bad O2 sensor(s), and a few other things that are not occurring to me at the moment.
 
idle

alkaline747trio said:
Thumbing through the FSM and kept seeing 650rpms as the idle for the 3FE, never really clicked that I was idling at 800-1100rpms warm w/o AC until today. Is there any way to set the idle on these (could save me some gas with this thing guzzling it like it does)? Should I worry about it? Should I be happy with it?
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Yeah under the hood there is a idle speed adjuster. the screw is right on the top of the throttle body?? and faces towards the front. I have a small exhast leak at the cats (catless) so mine is low and I have mine pretty much all the way up cause it is idling at 600rpms and shutters from time to time while waiting in traffic. hope that helps on the gas, usually does on mine but with the high altitude I hafta keep mine high anyway.
 
I'll give the "Golden Screw" a few turns (counter clockwise to lower, right?). My cats are in question, I have a leak around the left side O2 sensor, and I'm sure my vac hoses could be replaced. I wish I had the time right now to get my exhaust re-done, I have the feeling it may be the cause of this. Would a leaky exhaust (leaks around O2 sensor) cause high, but rough, idle?
 
Not sure about the high idle, possibly, but I have a leak in about the same spot as you and like I said mine is idling low and a tad rough, prolly cause the idle speed is so low when it warms up. I can mos. def. hear and feel my leak. Kinda making a clicking sound from the air pushing through around a clamp.
 
Two other things that will affect the idle.

Timing: make sure you're at 7º BTDC
TPS: make sure your ohms out correctly.

I suffered for 2 years (when I got to it) at 1100 rpms until I adjusted all three.
 
Ok, so get my exhaust fixed, adjust golden screw, check timing (would advancing it speed up or slow down the idle?), check resistance on TPS.

Just for the run down, symptoms are:
High idle at startup even when warm (above 900rpms) in N or P
Rough, but still high when in D and stopped (800-1000)

Anything else to add? I need to change my plugs, I think they are around 60k, I have done a full tune-up, really should re-check my hoses, have done SeaFoam through PCV hose and in the tank (a bottle each), and just had the oil changed (sticking with dino, been that way it's whole life, don't wanna mess up what works at 1 qt for 5k miles).
 
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I would say change the O2 sensors if they are the original. I think that is a servicable item at 100k. I greatly improved engine idle on my 88 3fe after changing it that I am going to change the sensors on all my vehicles over 100k.
 
Since the 02 sensors are about $130 a piece, I'll save those for last in hopes that the cheaper stuff might solve it knowing that they are already broken, if it ain't broke, don't fix it, ya know?

If the problem is still there after replacing all hoses, re-doing exhaust, TPS checking out/replaced, golden screw adjusted, adjusting the timing, then I will replace those damn sensors. I really wish those had never been created, seem to be more of a hassle then they are worth; heck, I don't really care what little emmisions that our world's autos put out are gonna do in 500 years, do you?
 
sensors

alkaline747trio said:
Since the 02 sensors are about $130 a piece, I'll save those for last in hopes that the cheaper stuff might solve it knowing that they are already broken, if it ain't broke, don't fix it, ya know?

I priced those O2 sensors from Toyota and they were $160! Someone on here had a site sparkplugs.com it had NGK OE O2 sensors. They looked to be a safe bet... an easy plug in and close to the OE. only $39 a piece! Let me know if you get them and notice a diff!
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alkaline747trio said:
I don't really care what little emmisions that our world's autos put out are gonna do in 500 years, do you?
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Well, yeah, actually I do.

However, that's not even the point. O2 sensors are as much about controlling engine performance as controlling emissions.

Curtis
 
I would do a search on replacing O2 sensors and you will see that most people have had favorable responses on engine performance by changing them. I replaced mine at the time for about 70 bucks each. This will save you alot on fuel expenses eventually.
 
jklubens said:
While your ohming out the TPS, I would clean the throttle body also. WD40 and 20 minutes of cleaning. Not hard at all.
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How long will it take me to get the throttle body off? I hate that I never have time to work on my junk anymore, damn school and sports. Maybe one day I'll find a nice garage hidden in all the mess in the space at the end of the house to work on it at night.

cjf said:
Well, yeah, actually I do.

However, that's not even the point. O2 sensors are as much about controlling engine performance as controlling emissions.

Curtis
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You're right, I thought about it a few seconds after the post and I really do care, but I was just under the assumption that these were an essential part of the emmisions system and when they don't work right, the engine runs bad, but if they were completely removed, then engine preformance would be pretty consistant and not deminish due to something that really doesn't need to be there in the first place.

archie said:
I would do a search on replacing O2 sensors and you will see that most people have had favorable responses on engine performance by changing them. I replaced mine at the time for about 70 bucks each. This will save you alot on fuel expenses eventually.
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jason andrews said:
I priced those O2 sensors from Toyota and they were $160! Someone on here had a site sparkplugs.com it had NGK OE O2 sensors. They looked to be a safe bet... an easy plug in and close to the OE. only $39 a piece! Let me know if you get them and notice a diff!
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Archie, where did you find the $70 O2 sensors, I'm assuming A/M, good quality?

Jason, you say "close to OE," if they are inferior, then I think I might would go with actual OE just for piece in mind, unless these will hold up like the OEM sensors are suposed to.
 
I found the O2 sensors at www.oxygensensors.com but I think that they have raised the prices a bit since I changed them 3 yrs ago(fast svc and free shipping). Go for the ones that plugs right in to the existing connector. Of course, try the least expensive fixes first before thinking that this is the problem.

the vacuum hose ends that slip over without a clamp are to be suspect because they do crack there( more often than in the middle) because they are being stretched.
 
alkaline747trio said:
You're right, I thought about it a few seconds after the post and I really do care, but I was just under the assumption that these were an essential part of the emmisions system and when they don't work right, the engine runs bad, but if they were completely removed, then engine preformance would be pretty consistant and not deminish due to something that really doesn't need to be there in the first place.
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I'm pretty sure that if they're actually removed (or disconnected), the engine will consistently run like crap, as the ECU figures something's seriously wrong and goes into an extra-rich, no feedback "limp home" mode.

Cheers,

Curtis
 
CJF said:
I'm pretty sure that if they're actually removed (or disconnected), the engine will consistently run like crap, as the ECU figures something's seriously wrong and goes into an extra-rich, no feedback "limp home" mode.

Cheers,

Curtis
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By completely remove, I meant them and all the soft/hardware they are required for be changed. Essentially a system w/o O2 sensors ever being a part of.
 
alkaline747trio said:
By completely remove, I meant them and all the soft/hardware they are required for be changed. Essentially a system w/o O2 sensors ever being a part of.
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Exactly. You're talking about turning a computer controlled 3FE (electronically fuel injected) into a carburated 3F. It can be done if you really want to, but it's not as simple as keeping the EFI but taking the sensors out of the loop.

Curtis
 
CJF said:
Exactly. You're talking about turning a computer controlled 3FE (electronically fuel injected) into a carburated 3F. It can be done if you really want to, but it's not as simple as keeping the EFI but taking the sensors out of the loop.

Curtis
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Oh, I'm not talking abotu doing it. I'm saying that it should have been fuel injected w/o O2 sensors from the start.
 
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