huffman102833

I recently purchased a running 1986 4runner as a project truck. Originally I was having random hard starts (and an even more random check engine light during these hard starts). I performed typical maintenance on the truck (i.e. air filter, oil, fuel filter, fuel pump, plugs, rotor, cap, coil). None of this seemed to have much impact on my problem.

I later read on a forum about bad factory wiring spices in ECM wiring bundle below upper plenum. I was able to locate these and repair them. This seemed to help the truck run better but soon after, I had the same starting issue.

At this point I was convinced that the injectors were clogged. I replaced them and still had the same random issue.

One day, while driving home from an FE alignment the truck quit running. I towed it back home and discovered that the injectors were not firing.

Here's where I'm at now:
-CSI (jumped) will run the truck for a few seconds.
-Injector harness (jumped) will run the truck with injectors wide open. This was tested at the splice and at the ECM harness.
-Gapped pickup coil and tested resistance (good).
-Tested ohms across all injection-related wires that I can think of (good).
-Tested ohms across igniter (good) and went ahead and tried a replacement with no luck.
-Tested "known good" ECM with no luck.
-ECM is getting power to the harness.
-Getting codes 7 and 11 on one ECM, and code 11 on the other.

Can someone please tell me what I'm missing here? I have an FSM and can't seem to locate anything else that would disable the injectors.

Thanks,
Dustin

cman1

iTrader: (1)

test your injector wire up from the split all the way up the harness.i had a bad injector wire that was corroded,black inside and actually broke in half when I bent it,it was above the y-splice.

huffman102833

Thank you for the response. I'm considering replacing the harness, but as I mentioned above, I am able to jump the injectors at both the splice and at no10\20 on the ECM connector. I may be wrong, but that tells me that I have good connectivity (ground) all the way from the injectors to the ECM.

Terrys87

iTrader: (1)

The ground on the manifold? I went thru this on my 86 and it wound up being the splices. They will pass a resistance check but still not fire the injectors. I see you repaired that. Here is what I went thru that might help>> https://www.yotatech.com/forums/f199...l#post51897320

huffman102833

I did check all grounds and they are good, and as you mentioned I did replace the bad factory splices. As far as the injectors, they do test fine and the motor did run after the injector swap.

I'm pretty convinced that something isn't triggering the ECM to fire, but everything down to the pickup coil test OK. Is there anything that I'm missing outside of the igniter and pickup coil?

scope103

What do the codes mean? I think they're both TPS related (possibly), but that should not cause the injectors to receive no signal.

Do you have the intake connected? No signal from the VAF will cause the injectors to not fire.

Have you used a "noid" light right on the injector to confirm the lack of signal? Or at the ecu?

huffman102833

Are the "VAF" and AFM the same thing?

If so, someone brought that to my attention earlier and I will test it this evening.

huffman102833

I tested the AFM per service manual and E2-VB is open but should be 200-400ohms. Also, I propped the flapper and tried starting. To my surprise it actually started and idled. Although rough, this is the first time the injectors opened on their own since it broke down.

I will try replacing the air flow meter.

huffman102833

***Correction: I pulled the AFM out of the air box housing and re-tested the terminals. Everything test okay. My ohm meter is junk.

Is it possible that everything test OK and it still be bad? I am still able to make the motor somewhat run by moving the flapper by hand. At WOT there doesnt seem to be enough air coming through the flapper to hold it open.

Any advise is greatly appreciated.

huffman102833

Any other ideas out there? If anyone is in the Houston area and would like to help, I will gladly pay you for your time.

Terrys87

iTrader: (1)

You arent getting any major air leaks are you? You said with the flap propped open it will run. If it is drawing air from other sources other then the air box it will give you the same results. Dont ask how I know

RustBucket

iTrader: (1)

How does the resistance of the injector resistor look?

huffman102833

I don't have any leaks that I'm aware of, but if you tell me that you had a similar problem and found a leak, then I will optimistically rush home to find one.

As far as the resistor, I believe 3 Ohms. This was one of the first things I tested and it was within spec. I also tested in\out voltage here and it was good.

scope103

Either there is a major intake leak (so the VAF is reading "little bit" of air and giving a very short injector duration, which is too lean to fire) or the VAF vane is faulty so that it is not correctly measuring the air flow. At least, that's what the above sounds like to me.

huffman102833

Is it possible that the "extra air" is coming through a stuck EGR? If so, would pinching off the lines be a good test?

Terrys87

iTrader: (1)

Scope103 is a lot better on information about things like you are asking. As far as EGR questions I can help a little below.

On my air leak and this is a little embarrasing for me, but I didnt have the fan shroud on and the fan rubbed a hole into the pipe is how I had the big air leak. I never heard it rubbing but it took awhile for me to find something so simple. If your fan has possibly rubbed the air pipe, it isnt noticeable from the top. Otherwise scopes103 sounds possible to me.

On the EGR, I have always been able to get mine working just by cleaning them. Then you can put a little vacuum on the pipe and should be able to hear it open and close. I dont have to deal with emissions so dont know how I would do on a sniff test, but it will get them working to stop EGR problems.

Most likely the small vacuum hose is clogged with carbon. The little metal pipe is held on with a Phillips screw. From my experience, you will not get it loose with a screwdriver. I have to take vise grips to get a good hold on that screw and break it loose and then use a screwdriver to get the screw out.

The little pipe is going to be frozen into the EGR and it just takes alot of working to get that pipe freed up from the EGR. I use a drill bit with my fingers to get the carbon out and then I use a bit and a piece of wire to get the carbon out of the EGR and then do the vacuum test.

Maybe scope103 can answer your question better about the EGR malfunctioning and causing that problem. I can get pics later for cleaning the egr somewhere in one of my threads.

Here is the pipe I am talking about and where you put the vacuum on it to hear/feel it operate.

huffman102833

Thanks, Terry. Here's the scope for this evening:

-Check EGR vacuum
-Check for vacuum leaks (including plastic tube above fan)
-Picked up noid light to verify that injectors are, in fact, not firing. I'm starting to think that maybe I'm just too lean to fire due to leak.
-Picked up spare AFM to test
-Ohm AFM wires back to ECM
-Re-check all factory splices

Hopefully this will narrow it down some. Again, I really appreciate all the input. I will report back ASAP.

huffman102833

***Update: Solved (hopefully)

-EGR was definitely clogged. I went ahead and removed it, capped the vacuum lines, and made plates to replace. Problem still persisted after doing this.
-Check for additional leaks and didn't find any.
-Tested new AFM with no luck
-Re-checked splices ... As I mentioned previously, about a month ago I cut out the factory splices and re-soldered\heat shrinked\taped them back together. I decided to go ahead and cut them back open to make sure it still looked right. To my surprise, the wires were actually worse than before I "fixed" them.

Apparently, I did not strip the wires back far enough. Also, I think it would have been a good idea to spray them thoroughly with some type of corrosion block. It prob didn't help that I exposed the corrosion to my sweat and the humidity down here before wrapping it back up. I actually found that the large (~12ga) black wire had corrosion running about 8in back towards the ECM. There may be others.

After cutting all this out and temporarily twisting everything back together, the truck ran fine.

My plan is to pull the upper plenum back off this evening and remove all the plastic housing. I'm going to cut the wires as far back as I need to to see bright copper wiring. I'm then going to spray the hell out of it with corrosion block, twist\solder\heat shrink\tape. Hopefully this will fix it for good.

cman1

iTrader: (1)

you probably wont find any more shiney copper wire at this point, just go up as far as you can and splice in 2 new wires. glad you found that...I feel your pain.

osv

x2 ^^

what i ended up doing was cutting the big ground wire back towards the cab, then finally sanding the bare wire enough to get the solder to stick... not an ideal situation, it should be replaced when it's not clean bare copper... mine was black.

since you are going to this extent, you might as well replace the injector plugs well.

shrink wrap is your friend here, as well as some of the space age black electricians tape that places like lowes have... you can first wrap it with the double-sided sticky, then again with the single-sided tape.

and oh yeah, use quality thick shrink wrap, not the cheap thin junk from harbor freight.