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1985 4runner 22re with a fresh rebuild. I bought the vehicle with a very tired motor and just had it rebuilt so I'm still learning my way around this 22re as I'm breaking it in.
I'm fighting a very slight lean miss and I found the connector while poking around the IAC. Its a green connector under the intake manifold. Similar posts have said that it may be the connector for the IAC, but my throttle body and IAC seem to be a newer version that doesn't have the connector. If this is the connector to the original 1985 IAC and it isn't sending any single to the ECU, what would be the consequences? Also, right next to the green connector is a broken/stripped wire that is green with a red stripe. Any ideas what that may be? A broken ground? Thank you in advance.
First pic is more for the IAC, but you can see the connector hanging down under the intake manifold just about the frame rails. 2nd and 3rd pics are close ups of the connector.
New engine was just a long block from an engine builder. Not sure of the block differences over the years? They reused my intake and throttle body. So one of the previous owners probably switched to the newer IAC.
The connector has a white wire w/ black stripe and the other wire appears to be solid light blue. The broken wire by itself is green w/ red stripe.
The white-black is a standard engine ground. Connector looks like it should be for a sensor. I took a quick look at the '85 wiring diagram for engine sensors using a blue and white-black wire. None that I could see, but the air valve shows as blue and brown (brown is also engine ground). So that connector may be for the IAC. Toyota changed the IAC on the 1989 model year. The pre '89 are hard to source, so that may be why you have a different unit. I'm unfamiliar with the newer ones. What does it have for a connector (the pre '89 are 2 wire units).
The white-black is a standard engine ground. Connector looks like it should be for a sensor. I took a quick look at the '85 wiring diagram for engine sensors using a blue and white-black wire. None that I could see, but the air valve shows as blue and brown (brown is also engine ground). So that connector may be for the IAC. Toyota changed the IAC on the 1989 model year. The pre '89 are hard to source, so that may be why you have a different unit. I'm unfamiliar with the newer ones. What does it have for a connector (the pre '89 are 2 wire units).
Thank you for looking at the Factory wiring diagram to help me out.
There is no connector to the newer IAC. At least not that I can see anywhere on it. Thats why I am concerned as to what the ECU is doing without that connector reading something. I am chasing a slight lean miss once warm at idle. I tested the IAC port in front of the TB by placing tape over it to see if it had any effect on the rough idle but it didn't so I think the IAC is functioning as it should. Ill probably pull it apart and clean it anyway. So far, the only way I can get the lean miss to go away is by pinching the fuel return line. Once I do that, she idles great. I replaced the fuel pressure regulator and I am about to replace the in tank fuel pump. The only sensor I haven't tested or removed to rule it out was the IAC, so that blank connector was concerning me.
Here is a link to some marginal photos of the wiring diagrams. http://6thgeargarage.net/1985-toyota...iring-diagram/
I'm not sure that the ECU even gets a signal back from it.
Sounds like you have identified it as a fuel supply issue. Have you checked fuel pressure from cold to warm? How about during idle to WOT? From what you describe the lean miss is an issue when warm (not when cold). Doesn't seem like a failing fuel pump would just cause issues when warm at idle.
Here is a link to some marginal photos of the wiring diagrams. http://6thgeargarage.net/1985-toyota...iring-diagram/
I'm not sure that the ECU even gets a signal back from it.
Sounds like you have identified it as a fuel supply issue. Have you checked fuel pressure from cold to warm? How about during idle to WOT? From what you describe the lean miss is an issue when warm (not when cold). Doesn't seem like a failing fuel pump would just cause issues when warm at idle.
Youre probably right. I'm just trying to go through it and eliminate anything that could be a problem. According to those diagrams, the broken Green w/ red wire is part of the emissions control systems and goes from the Emissions control computer to the Thermo S/W No.1 (whatever and wherever that is) to T/M indicator (not sure what that is either). Maybe that is my issue as once the truck warms up, the ECU starts reading the sensors and adjusting the air fuel mixture accordingly. That wire looks like it was pinched and cut by the block or something heavy.
Update: So I went out this morning to put a few miles on the new motor and warm her up. After warm up, it started to do its intermittent miss again. I started messing with the wiring harness that runs from the drivers fender under the ignition coil and down to an engine block ground and alternator and the idle started to clear up. I drove another few miles and it started missing again so moved that harness and ground around again and it cleared up. Either the grounding cable to the block (which has a large exposed kink in it) is not grounding well, or there is another issue inside that harness somewhere. Hopefully fixing the ground or harness will permanently solve the rough idle miss.
As I recall, the coil and ignitor have a known problem with heat. They ohm out correctly cold, but when they get good-n-warm, they drift out of spec. Causes all kinds of troubles. Might be something to look at. The FSM has the ohm readings for cold and warm, IIRC. If you don't want to drive it around to heat things up, you can just use a heat gun, one designed for electronics work. NOT one for stripping paint. Those are way to powerful.
It may well be that when you're driving it, they get hot enough to fail, and then, when you stop and open the hood to play with the wiring they cool down enough to come back into specs. Thus, it SEEMS like a wiring problem, but it's really not related at all.
Whether it's related to the problems you're experiencing or not, you definitely want to repair/replace that ground wire. A kink like that can cause the copper strands inside the insulation to break. NOT good! Personally, I would replace the wire completely. Just ensure you use wire that's as big, or the next size larger, to do it. Make certain that where the o-rings bolt down, it's nice and clean. No dirt, grease, corrosion, nothing but shiney, bare metal. A lot of people ignore grounds, but they are just as critical to the operation of the system as any other connection.
Good luck, and let us know what finally fixes the problem
Pat☺
As I recall, the coil and ignitor have a known problem with heat. They ohm out correctly cold, but when they get good-n-warm, they drift out of spec. Causes all kinds of troubles. Might be something to look at. The FSM has the ohm readings for cold and warm, IIRC. If you don't want to drive it around to heat things up, you can just use a heat gun, one designed for electronics work. NOT one for stripping paint. Those are way to powerful.
It may well be that when you're driving it, they get hot enough to fail, and then, when you stop and open the hood to play with the wiring they cool down enough to come back into specs. Thus, it SEEMS like a wiring problem, but it's really not related at all.
Whether it's related to the problems you're experiencing or not, you definitely want to repair/replace that ground wire. A kink like that can cause the copper strands inside the insulation to break. NOT good! Personally, I would replace the wire completely. Just ensure you use wire that's as big, or the next size larger, to do it. Make certain that where the o-rings bolt down, it's nice and clean. No dirt, grease, corrosion, nothing but shiney, bare metal. A lot of people ignore grounds, but they are just as critical to the operation of the system as any other connection.
Good luck, and let us know what finally fixes the problem
Pat☺
T4. Thank you for the info. I will check out the coil as well. I put a spare coil I had on the truck early on to try to eliminate the coil and the alternate had no effect on the miss but I will test it anyway.
I fixed the ground and it didn't help. I'm now thinking its in the harness that runs to the coil. When I hold the harness a certain way it seems to smooth out. I ohm'd out the coil per the FSM, but the FSM only shows cold parameters, not hot. Maybe I'm missing something.
Edit: Upon closer inspection today, the lower end of that harness runs to the back of the alternator. I had to just about climb head first into the engine with my head against the header to see the smaller wires going into the back of the alternator are beat up pretty bad. One wire is completely skinned and exposed. Maybe that is part of the problem. One of those wires on the back goes to circuit B per the wiring diagram which supplies power to the ECU and the ECC. I will repair that next.
Edit: Upon closer inspection today, the lower end of that harness runs to the back of the alternator. I had to just about climb head first into the engine with my head against the header to see the smaller wires going into the back of the alternator are beat up pretty bad. One wire is completely skinned and exposed. Maybe that is part of the problem.
Definitely sounds like that could be a problem. You might want to try ohming each wire end-to-end, and while you're doing so, move the harness around. If the ohms are anything more than 0.01 ohms or so, maybe even as high as 0.1 ohms, they're OK. If you get higher readings when you wiggle the wires, anything higher than 0.1 ohms end-to-end, the wire is bad, and should be replaced. You may need to get ahold of the harness it's self, or even whatever the harness is attached to at the end inside the distributor. Probably the sensor wires. See below:
The red and white wires off the ignitor to the distributor. Darned if I recall the name of the bloody thing, but if it that thing's harness, I believe hen you get a ne sensor, it comes with the harness attached. You just need to remove the old one, install the new one, and set the air gap correctly.
Just so you know, the FSM give the ohm range for the coil and ignitor, not a hot and cold reading. If it varies outside the specified range when it get's hot, it's bad.
Ok. Finally got this thing home and had a chance to start messing with it. I put in a heated O2 sensor since I'm running a Doug Thorley header with the bung down after the #2 and #3 collector. Also changed plugs, cap/rotor, wires, and coil. All of this really helped the miss, however the miss is still slightly there.
I really need to pull the intake off and check the harness on that side as the more I inspect of the harness, the more damage or exposed wires I find. The green w/ red wire I mentioned above goes to a thermo switch and then to the T/M indicator which then feeds into the emissions control computer for both Fed and CA models. So question is what is the T/M indicator and where is it at?
Last edited by CTDST16; 02-28-2022 at 07:19 AM.
Reason: Addtl info
05-28-2021, 11:56 AM
