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... impedance (or, since these are DC, wouldn't it just be resistance? I always see it listed as impedance...), ...
It's technically impedance because it's being driven by a pulse train. The injector is a coil, so it has inductance, which when driven with a pulse has reactance. (Reactance plus resistance is impedance.) Even though the varying voltage doesn't change sign, it's still AC.
Originally Posted by XJNKY
... Will start with #1 injector unplugged, but not with it plugged in....
I think that just manipulating the wiring is causing your problem; the unplugging and plugging is just being masked by a broken lead somewhere in the harness.
Some basics. Yes, all four injectors (6 on the 3VZE) open at the same time. Yeah, "sequential" makes more sense, but in computer years 1988 was a loooong time ago. As pointed out, you can switch the connectors between injectors and it will work fine. So I suggest you do that. If you get the same "runs unplugged" with the #2 wire connected to the #1 injector, it suggests a problem with the injector (But what? I suppose you could have a "slow" injector that isn't closing fast enough when warm, so it floods the engine. But that's just a WAG.)
But as I said, I fear that you're chasing a wild goose, because it's really a wiring problem, that changes each time you touch it. So try to eliminate that if you can.
But as I said, I fear that you're chasing a wild goose, because it's really a wiring problem, that changes each time you touch it. So try to eliminate that if you can.
...I think that just manipulating the wiring is causing your problem; the unplugging and plugging is just being masked by a broken lead somewhere in the harness....
I guess I'm going to bolt it down to something... But should I assume that's my issue? It isn't in the fuel harness specifically, just sort of runs into the main harness. And I'm not seeing a ground symbol on the fuel circuit diagrams. But, it does look like it has 2-4 wires going to it
This is your primary ground for the ECU/engine harness. It's a pretty big deal. If it was truly just flopping around in there and not in one of the bolts (typically the brace that supports the lower intake) ALL your testing to this point is sort of moot.
This is your primary ground for the ECU/engine harness. It's a pretty big deal. If it was truly just flopping around in there and not in one of the bolts (typically the brace that supports the lower intake) ALL your testing to this point is sort of moot.
i believe the factory connection is on one of the studs used to connect the upper and lower plenum, but it has been a while since i've dismantled my intake system.
This is your primary ground for the ECU/engine harness. It's a pretty big deal. If it was truly just flopping around in there and not in one of the bolts (typically the brace that supports the lower intake) ALL your testing to this point is sort of moot.
I didn't mean to underplay it. I always assume a ground is important... But if this is the ground for the whole harness... how was this thing running? Accidental contact? Making passive contact to the backside of the upper plenum? *rhetorical questions*
Also... there's a brace that supports the lower intake? I don't think mine had one...
I didn't mean to underplay it. I always assume a ground is important... But if this is the ground for the whole harness... how was this thing running? Accidental contact? Making passive contact to the backside of the upper plenum? *rhetorical questions*
Also... there's a brace that supports the lower intake? I don't think mine had one...
Alternate paths to ground. I think the ECU case is "esd shielded", that's one path but it wouldn't carry very much current just a small wire to dissipate static.
A quick look at the schematic shows a path thru the air valve to the fuel pump then to ground.
(Sorry crappy phone drawing)
Excellent question. I don't know. I also don't know if it has been plumbed correctly. Vacuum hoses are a guess here.
I'm thinking about doing an EGR delete to just ditch all that stuff while I have it back apart.
there's a simple test for the EGR system; it's right in the FSM and it doesn't take much effort to run the tests. there are also a few threads where the vacuum hose diagrams are posted, in the underhood emissions sticker. use that for your hose-routing reference if need be.
there's a simple test for the EGR system; it's right in the FSM and it doesn't take much effort to run the tests. there are also a few threads where the vacuum hose diagrams are posted, in the underhood emissions sticker. use that for your hose-routing reference if need be.
I, at one point, had 3 different vacuum diagrams printed out for this thing. Plus the one under the hood. Those suck more than wiring diagrams. I find them incredibly hard to read. And also, where this engine was put together with pieces of others, I doubt everything I have is still factory.
Actually, I think the EGR diaphragm in the back painted red wasn't even hooked up to anything. I noticed that when I pulled the intake. IDK if I missed it originally, or I accidentally pulled it off at some point.
But I've got 3 VSV's on the valve cover, and one of them wasn't hooked to anything when I got the truck. I've got red, blue, and black. And the black was literally plugged in, but just laid back behind the valve cover not connected to any lines. I tried to run it per 1 of the 3 optional diagrams, but... the one under the hood doesn't even show it. (I think).
I'm right there with you vacuum diagrams are confusing as heck! It helped me a lot just by looking at photos of other engine bays to find out where the lines run. Even if the lines are completely missing, a roll of vacuum line is pretty cheap at your nearest parts store. I changed all of mine out once I did my rebuild. GTC- what I call Google that crap. literally every line probably has a pic on google images and what they connect to.
Hello my name is Brett. I'm new to the party and already digging this forum. Very similar symptoms as OP, starts and runs good but will not start warm until it cools off for 30 minutes or so.
I bought this truck back in May and lets just say it ran. I then started reading and did some diagnostics, o2 sensor was hanging in the open air so the poor thing was dumping so much fuel I can't believe it even ran. Bung hole was welded over so I drilled that out and installed the sensor. TPS was bad and replaced and calibrated, AFM was bad and replaced, EFI thermal switches tested bad but my test could be flawed. Hard to find items so they were put on back burner. It was throwing codes through all of this of course.
I finally have gotten it running pretty darn good, I had it purring along at 65mph this morning, and it doesn't do too bad getting there either. It has not thrown any codes for 150 miles or so now. But, this warm start issue has been there all along and will not go away. It's not a daily so lately it has just been started up and ran an hour or so every few weeks. I have not gone into the wiring very in depth like the OP and other members have, but I thought this little video might get you folks scratching your heads. I've read a good bit about these little engines but not heard of anything like my situation being able to start it by pulling the AFM connector. I have to get it plugged back in quickly or it will die. Luckily I have long arms.
When I was having hot start issues it ended up being my valves out of adjustment??? I'm no mechanic so I don't know if you guys are having the same issue.
Hello my name is Brett.
...
but I thought this little video might get you folks scratching your heads. I've read a good bit about these little engines but not heard of anything like my situation being able to start it by pulling the AFM connector. I have to get it plugged back in quickly or it will die. Luckily I have long arms. Warm start issue 1988 4Runner DLX auto
That is a good one, my first guess is something with the two coils to the cor. More likely something with the five volt reference. Highly unlikely but a heat soaked temp sensor in the vafm.
You will have to unpin the circuits one at a time from that connector, or hook up a scope, most likely to figure it out and still have a head scratcher..
That is a good one, my first guess is something with the two coils to the cor. More likely something with the five volt reference. Highly unlikely but a heat soaked temp sensor in the vafm.
You will have to unpin the circuits one at a time from that connector, or hook up a scope, most likely to figure it out and still have a head scratcher..
What's the FP to B+ jumper effect?
Thanks for the help! I am not sure what your reference to COR is (circuit open relay?). But, I do know that the fuel tank and pump are new per the PO. The tank is shiny and the pump starts right up and stays on when FP to B+ are jumped so I'm inclined to believe him. I just in the last hour had it out exercising the 4x4 in some sand and then made this video of how well it's running. Still not setting off any CELs what so ever (25 miles just now), but still will not start at running temp. Tried the FP to B+ with no results but it does start with the AFM unplugged, and then reconnected before it dies like the previous video. I would also like to say that my current tires and rims are 5th gen take offs for the street. I know it won't run 70+ mph with the big 33s that came with it, but none the less I never thought I'd see 75 mph. Seems to be running pretty well!!
C.O.R. should be working fine if you're able to start and stay running.
Originally Posted by Co_94_PU
... Highly unlikely but a heat soaked temp sensor in the vafm....
Originally Posted by MI-FL1+5
... it does start with the AFM unplugged, and then reconnected before it dies...
Looks like something to do with THA (Air temp) sensing... I suggest you check that circuit between AFM and ECU. That may also be related to our rough warm restarts, although yours is a worse case.
Work-around / practical way to verify? Put normally-CLOSED, momentary-open switch in series with THA wire and monitor it.
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Last edited by RAD4Runner; 02-02-2018 at 03:59 PM.
C.O.R. should be working fine if you're able to start and stay running.
Looks like something to do with THA (Air temp) sensing... I suggest you check that circuit between AFM and ECU. That may also be related to our rough warm restarts, although yours is a worse case.
Work-around / practical way to verify? Put normally-CLOSED, momentary-open switch in series with THA wire and monitor it.
just want to clarify that this pic is from an 86 Fsm. I posted it and radrunner drew on it in another thread. The circled area might be the same on all years (not sure), but the 1988 22re at the top is not completely accurate. You can tell it's not an 88 22re because of the one wire O2 sensor.
Thank you Gentlemen! I have a copy of the 88' FSM, checking to see if similar schematics. I wondered about a certain amount of heat resistance built up in a wire from AFM to the ECU. Once the engine bay cools the resistance changes and the ECU allows it to start. SMH I still have a lot to learn about this thing. I do enjoy the puzzle though.
01-30-2018, 05:25 PM
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