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Ford Bigot
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4,101 Posts
Discussion Starter #1
First of all, yes I searched the shit out of the Toyota board. Yes, I also bothered MtnYota about throwing this piece of shit 22R away and swapping to a 3RZ. He told me to quit whining and figure this out so I have a DD again.
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My Toyota ran great, then it sat for a couple weeks after I bought a new truck. I came back and started driving it because it gets reasonable mileage and noticed that it had a weird miss at partial throttle. The miss bad enough to where if I had hot female passengers, it would be worth turning the rearview mirror towards the passenger seat - yes that kind of shaking. It doesn't miss at full throttle and idles OK, but a little high at times, definitely higher than I originally set it.

The engine was rebuilt by the original owner and ran great when I parked it. I thought it was the EGR valve, and when I took the old one off to inspect the passages were full of carbon. I bought a new one and put it on yesterday, and the truck ran fine testing it around my house. It idled at where I had set it previously (~750-800 RPM)

Cliff note version:

History:
-1984 22R
-Replaced the EGR valve (the old one was bypassing)
-Checked all the lines, no visible vacuum leaks with carb cleaner
-Ignition components are new
-does full throttle fine
-Ran fine when I parked it
-Pisses me off, considering shooting it

Symptoms:
-idles higher than what I set it at ~1100 after driving
-misses at light engine loads in all gears
-ran well when I replaced EGR yesterday
-now runs like shit



I'm thinking it's something carburetor related, but I'm not entirely sure with all the acronymed valves in the FSM. I checked most of them and they all seem to function. Any ideas?
 

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I bet it's losing ground to the idle cut solenoid (ICS) on the carb. Find the ICS, check the white wire to make sure it is getting ground at all throttle positions. I'm not sure what causes it, but I'ved had several that did this. It would lose ground at part throttle causing a bad miss. I just grounded it to the fender well and problem solved. Good luck.
 

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Ford Bigot
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4,101 Posts
Discussion Starter #3
So that would cause it to miss at RPM? From my understanding it cuts the fuel to the idle circuit when the throttle is released at freeway speed and then returns the idle circuit when the engine RPM approaches idle RPM.

Am I completely nuts? That would be awesome if the problem was this simple.
 

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i know this sounds way out there but a good mechanic told me that new plugs will foul themselves, if you let it sit for a while because of the fuel etc left in pistons //but i didnt believe it either till i tried everything and when i changed the plugs (new plugs at that )) IT RAN PERFECT SOUNDS LIKE THE SAME SYMPTOMS HOPE THIS HELPS /GOOD LUCK (YA GOTTA SCOUT OUT ALL OPTIONS YA KNOW
 

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Ford Bigot
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4,101 Posts
Discussion Starter #5
The plugs are not fouled, it's running with what feels like an ultra-lean condition, negating the possibility of fouling plugs. I did check them though, they look brand new. I'm fairly certain that my Toy is not suffering from fouled plugs since it has power in low vacuum circumstances. Thanks for your input.

Keep the ideas coming, I'm still trying to narrow this issue down.
 

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So that would cause it to miss at RPM? From my understanding it cuts the fuel to the idle circuit when the throttle is released at freeway speed and then returns the idle circuit when the engine RPM approaches idle RPM.

Am I completely nuts? That would be awesome if the problem was this simple.
Yes it will cause a miss at part throttle,(not sure why) I've fixed this same problem on a few trucks.

I don't know what causes it , but the ones I saw the gound would "pulse" at throttle but not at idle. Check yours with a test light. At part throttle it is running mostly off of the idle jet and barely off the primary, when it loses ground it shuts fuel off to the idle jet causing the motor to stumble. It is only noticeable at part throttle when it's still running mostly off the idle jet. At higher throttle it's getting enough fuel from the primary that you won't noticed the stumble in the idle jet.

I fought with this problem for a long time before I found the culprit. There again, I'm still not sure why it's losing ground at throttle, I just grounded it to the fender well and it ran perfect.

good luck.
 

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Once my egr vm was clogged with carbon so it wouldn't control the egr valve and caused a miss at partial throttle. I would just try cleaning that out to see if it helps.
 

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my 85 would miss at about 3500 rpm or when under a load, but ran great otherwise. changed the plugs and the problem was solved...food for thought
 

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have you checked your timeing?
i had a simular problem to this with a RE and it turned out tha the timing had changed some now.
 

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Ford Bigot
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4,101 Posts
Discussion Starter #10
Update -

I rebuilt the carb and went through all the various acronymed valves in the emissions system and they were all fine. Scratching my head, I finally started pulling the individual plug wires at idle to see if it affected how it was running. Pulled the #3 and it had no affect. I looked at the plug wires in better lighting and discovered they were all cracked.

Bought a new $10 wire set and the Toyota is off and running again.

So to recap the solution to this problem:

-New EGR valve
-Rebuilt carb
-Replaced plug wires


The humiliation of having to admit to my dad that the plug wires were the likely culprit (or at least large contributor) to my engine missing and stumbling was demeaning enough to make me replace the wires first on any new project. This was the 2nd of 3 bets I lost to him this week.
 
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