Help me fix my 3fe equipped 1991s crappy idle! (Please) (1 Viewer)

[d3310n]

What effect does the speed sensor have on the fuel injection system on the 3fe equipped 91-92s? Interesting that alldata says it plays a part in fuel injection.

I'm trying to track down a funky idle/misfire and recently I have done the following:

Smoke tested intake found and fixed vacuum leak at oil cap gasket

Fuel pulsation damper replaced

Found that the desmog guide I used has you delete the vsv for the fuel pressure regulator control, for now I have ran the fpr to vacuum 100% of the time as I threw the vsv away. But this is better than no vacuum 100% of the time

Replaced plugs rotor cap wires

Tested fuel pressure TPS water temp sensor afm all tested good

Pcv valve and grommet replaced along with most rubber parts of intake I found issue with. Boots are all new to gasket new

Throttle body cleaned

Carbon can replaced, this fixed my hissing gas cap

O2 sensors I replaced last year with denso

Just adjusted valves last week again.

2 years ago I replaced all the fuel injector connectors because they were brittle and nasty when I had the engine out. Injectors rebuilt at this time.

My idle still sucks. I do have a code 42 though, when I found this on alldata it had me thinking maybe this could play a part.

Gonna smoke test it again soon because I'm going crazy. Also my harness at the oil pressure sensor is mangled, but I don't think that would affect drivability.

 

[jonheld]

Rough idle is almost always caused by unmetered air entering the system.

General Tech - 3FE Tune Up Info

3FE Tune Up Info

forum.ih8mud.com

 

[leonard_nemoy]

Lots of vacum hoses on the 3fe. Double check your air intake tube for cracks. You could also try the old brake cleaner or starting fluid trick to search for vacum leaks.

 

[d3310n]

Intake has been smoked tested already and intake hoses are new. I'm going to smoke test it again though just to be sure, I'll report here once I do

 

[d3310n]

Lots of vacum hoses on the 3fe. Double check your air intake tube for cracks. You could also try the old brake cleaner or starting fluid trick to search for vacum leaks.

This I've already tried to no avail. I much prefer the smoke method. I'm building a new smoke tester out of an ecig, hopefully it will be more effective than my old soldering iron mineral oil tester

 

[Marco Lau]

Can you elaborate on the funky idle? at what rpm, etc.....

 

[d3310n]

Can you elaborate on the funky idle? at what rpm, etc.....

It is a random misfire at idle, sometimes it runs smooth but it randomly stumbles. At part throttle low rpm it'll do it too, but the lower the rpms the more it acts up. If you floor it and let the engine rev out, it runs strong on all cylinders all the way to redline. Engine temp has no effect.

Overall it's minor and does not ever stall or anything, just a little bit of annoying stumbling.

 

[Marco Lau]

It is a random misfire at idle, sometimes it runs smooth but it randomly stumbles. At part throttle low rpm it'll do it too, but the lower the rpms the more it acts up. If you floor it and let the engine rev out, it runs strong on all cylinders all the way to redline. Engine temp has no effect.

Overall it's minor and does not ever stall or anything, just a little bit of annoying stumbling.

You mentioned adjusting your valves again recently in your original post. Was it because you felt like the valves were not properly adjusted prior? How did you adjust your valves? Did you follow the FSM and use the timing window to set to BTDC? Or did you adjust with the engine running?

 

[d3310n]

You mentioned adjusting your valves again recently in your original post. Was it because you felt like the valves were not properly adjusted prior? How did you adjust your valves? Did you follow the FSM and use the timing window to set to BTDC? Or did you adjust with the engine running?

I adjusted them because it's been 10k miles since I did it last, but I felt I should do it early just to rule out a bad adjustment. They were a bit loud and it quieted the engine down, but ultimately it ran the same before and after. I did it with the engine running without the cover, then once up to temp shut it down and make my adjustments with the engine at the right orientation

 

[Marco Lau]

I adjusted them because it's been 10k miles since I did it last, but I felt I should do it early just to rule out a bad adjustment. They were a bit loud and it quieted the engine down, but ultimately it ran the same before and after. I did it with the engine running without the cover, then once up to temp shut it down and make my adjustments with the engine at the right orientation

Have you adjusted your timing at all by rotating the distributor? The reason i asked is because i also have adjusted the valves with the engine running prior, and seems to me this method can really quiet down the valves vs adjusting per the FSM, however, with adjusting the valves with the engine running, you will not be able to set the engine @ BTDC. I would recommend adjust the valves with the timing window set to BTDC, adjust per FSM, then rotate 360 and adjust the rest, set your timing correctlly and see if that fixes your problem.
Here is a pic of BTDC with the BB lining up the window

 

[d3310n]

Have you adjusted your timing at all by rotating the distributor? The reason i asked is because i also have adjusted the valves with the engine running prior, and seems to me this method can really quiet down the valves vs adjusting per the FSM, however, with adjusting the valves with the engine running, you will not be able to set the engine @ BTDC. I would recommend adjust the valves with the timing window set to BTDC, adjust per FSM, then rotate 360 and adjust the rest, set your timing correctlly and see if that fixes your problem.
Here is a pic of BTDC with the BB lining up the window
View attachment 2801189

Sorry not sure what you mean exactly by adjusting with it running? I shut the engine down, set to btdc, adjust, rotate 360 adjust, done. How would you literally be able to adjust the rockers while they're moving up and down? I though the point of this was to have the engine as hot as possible and to best hear any tapping before finishing up.

 

[ColoradoBoy]

Sorry not sure what you mean exactly by adjusting with it running? I shut the engine down, set to btdc, adjust, rotate 360 adjust, done. How would you literally be able to adjust the rockers while they're moving up and down? I though the point of this was to have the engine as hot as possible and to best hear any tapping before finishing up.

Toyota 3FE Valve Adjustment (with engine running) From Summit Cruisers

After you get the valve cover removed,

Plug the two vacuum ports that go to the valve cover.

Put your intake hose back on.

Put a level on your head and do your best to get it level front to back. This helps to keep the oil from running off the back.

If your truck is lifted, you may want to lower it down on blocks after you remove all 4 tires.

Break loose and slightly tighten all adjustment nuts.

Start truck, keep the AC off, and get the idle down to 650 rpms or less.

Do your adjustments.

You will notice when the valve is too tight you will hear a slight miss or thud sound in the engine. When it is too loose you will hear a tap. The difference in the two is about 1/4 of a turn of the adjustment screw. I then set mine in the middle of the two and slightly on the loose side. Once you figure this out, I usually just loosen the adjustment to hear the tap then tighten it back down until is a little past the quiet point.

Once you are done with the adjustments, you can recheck your clearances with a feeler gauge if you want to and torque down the nuts. I would recommend not using the feeler gauges while the engine is running (no ties, pony tails or loose clothing either).

It's amazing how quiet and smooth your engine will run when you make your adjustments this way.

 

[d3310n]

Toyota 3FE Valve Adjustment (with engine running) From Summit Cruisers

After you get the valve cover removed,

Plug the two vacuum ports that go to the valve cover.

Put your intake hose back on.

Put a level on your head and do your best to get it level front to back. This helps to keep the oil from running off the back.

If your truck is lifted, you may want to lower it down on blocks after you remove all 4 tires.

Break loose and slightly tighten all adjustment nuts.

Start truck, keep the AC off, and get the idle down to 650 rpms or less.

Do your adjustments.

You will notice when the valve is too tight you will hear a slight miss or thud sound in the engine. When it is too loose you will hear a tap. The difference in the two is about 1/4 of a turn of the adjustment screw. I then set mine in the middle of the two and slightly on the loose side. Once you figure this out, I usually just loosen the adjustment to hear the tap then tighten it back down until is a little past the quiet point.

Once you are done with the adjustments, you can recheck your clearances with a feeler gauge if you want to and torque down the nuts. I would recommend not using the feeler gauges while the engine is running (no ties, pony tails or loose clothing either).

It's amazing how quiet and smooth your engine will run when you make your adjustments this way.

Huh, I figured it'd be impossible to spin the adjustment screw while the rocker is moving, maybe I'm overthinking it. I think I I it pretty good as the engine is fairly quiet but I'll have to try this next time.

 

[d3310n]

UPDATE: Well we can pretty much consider this solved. Long story short I underestimated the need for strong air pressure behind an intake smoke test. My coworker is a Saint and let me borrow his snap on uv dye smoke tester. Naturally, as it's a $1600 state of the art tool vs my previous homade garbage, I found the actual offending vacuum leak withing 30 seconds. Uv dye dripping from it and all, I found the cylinder #2 fuel injector making a poor connection with the intake manifold.

The funny thing is I pulled the fuel rail off to look for a vacuum leak at the injectors about a year ago, but I screwed up on the installation/ overlooked the problem clearly.

Oh well. I'm just happy this will finally be a closed case. I've been battling driving performance issues since I bought this cruiser 2 years ago, and I can finally say with confidence this is the last peice of the puzzle, I think the amount of smoke seen in the video makes that pretty obvious. It's a bad leak.

Any way here's a video of it if you're curious.

 

[d3310n]

I owe this thread an update. The approve mentioned leak was fixed, but this was NOT the end of it. I borrowed my buddies machine again to look for more leaks, and I found 2 more. 1 was coming from the pushrod cover gasket, the other from the idle speed control valve oring. I removed the isc valve and cleaned it, and used an o ring from the parts store that is way too thick, but better than what I had. It still leaks from there but not as much as before, I think there is a crack in the plastic body of the valve, I will have to try and find the "right" o ring and keep testing to confirm. But the pushrod cover is definitley an issue, I beleive it is not flat enough to make a good seal with the gasket.

Picture of uv dye seeping from the pushrod cover below.

 

[jonheld]

1 was coming from the pushrod cover gasket,

Part# 11253-61010. $12 from your local dealer.
It is a thick cork gasket, not unlike the cork gasket for the oil pan.

 

[d3310n]

Part# 11253-61010. $12 from your local dealer.
It is a thick cork gasket, not unlike the cork gasket for the oil pan.

Thanks, the tough one to find for me is the oring for the idle control valve, any idea where I could get a part number for that bad boy?

 

[jonheld]

Thanks, the tough one to find for me is the oring for the idle control valve, any idea where I could get a part number for that bad boy?

I don't see an O ring for the ISC valve in the parts diagram. It has a gasket between the ISC and throttle body 22278-61010.

 

[d3310n]

For some reason toyota doesn't break it down in their diagram, but its the oring you will have exposed if you remove the 3 small Philips/jis head screws

 

[jonheld]

For some reason toyota doesn't break it down in their diagram, but its the oring you will have exposed if you remove the 3 small Philips/jis head screws

Have a look at this thread from the old 80sCOOL list. It is for the 1FZ-FE ISC valve, but might just be the same for the 3FE ISC valve.

http://www.lcool.org/technical/80_series/fast_idle/fast_idle.html