Injector wiring harness?

H

Heyduke

New member
1999 4Runner, V6/AT/4WD - Wondering if the wiring harness to the injectors is available new, if so does anyone have a p/n? I couldn't find it at Toyota Parts Deal dot com.

I'm still battling a misfire (P0300, 0301, 0304) after replacing and swapping a bunch of parts... currently it appears that a couple of the 'refurbished' 5Omotorsport injectors might be the problem (swapped new coils to different cylinders, code remained the same), but most reports here seem favorable...

I've tried to avoid digging back to the injectors, but after swapping coils and the code didn't move the Magic 8 Ball says it's the injectors. So my next step is to move the injectors from Cyl's 1 & 4 to 3 & 5 and see what happens. Hopefully the codes will then read P0303 & 0305, and I can replace (warranty?) those two easier than the driver side injectors.

What a PITA

Thanks
 
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I'm not sure if there is a separate wiring harness just for the injectors. I believe its all part of the main wiring harness for the engine.

I have a complete 99 engine wiring harness in my garage right now. I'll look when I get home.
 
thegipper said:
I'm not sure if there is a separate wiring harness just for the injectors. I believe its all part of the main wiring harness for the engine.

I have a complete 99 engine wiring harness in my garage right now. I'll look when I get home.
Click to expand...

You are right, it is a complete harness. They feed into the engine harness that bolts on the side of the valve covers which then connects into the ECU through the firewall.

It's doable to replace the wiring harness but it's a lot of work not to break any connectors that are old and brittle. If there's any damage to the injector wiring, it'll be right at the connector though. The rest of the wiring harness is very well protected. I'd swap the ECU before the wiring harness.
 
Since you've already replaced injectors, it's highly unlikely you got two bad ones.

A few more questions:

1. Did you replace all o-rings with brand new ones, not re-using any of the existing ones?
2. Have you done a leak-down test to make sure it's not a stuck valve or bad piston rings?
3. Have you measured the valve clearance making sure the intake and exhaust valves are in spec as what's listed on the under-hood sticker?
 
To add to the post above, you should be able to ohm out the intector harnes from the pin at the Ecu to the pin at the injector if you still suspect wiring. Might help to have another set of hands to move the injector harnes around while you watch the multimeter.
 
I agree, but...

1) the 5-O injectors come with new o-rings

2) Haven't done a leak down test yet, but it runs perfectly... until it doesn't. I've gone 100 miles with out trouble, until I shut off the motor for a few minutes, then the misfire. The exhaust doesn't stink of raw gas when it's happening.

3) When I did the VC gaskets I checked valve clearance on the lobes I could get under, they were all fine, I didn't check them all. But again, no weird noises/clatter.... Hmm, if one of the valves is tight already and the heat soak from sitting causes some expansion, valve can't close... something to consider.

I haven't tried listening to the injectors when it's misfiring, I'll see if I can check that tomorrow.

Nate- thanks for the info on ohm-ing the wires - I'll dig thru the FSM to see if I can find the pin locations

I've bounced this off a couple local mechanics, they suggest checking the fuel pressure regulator and fuel pump. I'm hoping to find someone to check these out before swapping injectors.

It's frustrating, but I really like this vehicle, and with all the new parts under the hood, when it's not missing it runs great. I hope I'm not hurting it too much when it's not happy.

Thanks for the feedback!
 
Heyduke said:
I agree, but...

1) the 5-O injectors come with new o-rings

2) Haven't done a leak down test yet, but it runs perfectly... until it doesn't. I've gone 100 miles with out trouble, until I shut off the motor for a few minutes, then the misfire. The exhaust doesn't stink of raw gas when it's happening.

3) When I did the VC gaskets I checked valve clearance on the lobes I could get under, they were all fine, I didn't check them all. But again, no weird noises/clatter.... Hmm, if one of the valves is tight already and the heat soak from sitting causes some expansion, valve can't close... something to consider.

I haven't tried listening to the injectors when it's misfiring, I'll see if I can check that tomorrow.

Nate- thanks for the info on ohm-ing the wires - I'll dig thru the FSM to see if I can find the pin locations

I've bounced this off a couple local mechanics, they suggest checking the fuel pressure regulator and fuel pump. I'm hoping to find someone to check these out before swapping injectors.

It's frustrating, but I really like this vehicle, and with all the new parts under the hood, when it's not missing it runs great. I hope I'm not hurting it too much when it's not happy.

Thanks for the feedback!
Click to expand...

Looks like you've tackled the easy ones. It's highly uncommon to just have one valve out of spec and the rest fine, it's usually several so you probably would have noticed something out of line in your measurements.

If my memory is any good, when looking at the ECU, I'm pretty sure the injectors are the wires on the top row on the left-hand connector, going from left to right. First 6 wires should be it. Not all years might be the same though, but that should give you something to start with.

The fact that it only throws a code when hot rules out the injectors in my mind, actually. Just helped another member diagnose a P0301, and his wire to the injector was damaged and it stumbled and misfired badly right at startup. Your problem is a sensor/ECU if it only acts up sometimes. The MAF does a whole lot more than people realize, have you given it a good cleaning by spraying both the sensor wire and the IAT wire with carb cleaner/MAF sensor cleaner? Also, have you replaced your air filter lately? Lack of air flow or inaccurately metered air will mess with the injectors.

Also, do you have any way to read your fuel trims? It could be throwing a code due to being too lean or rich. Hence the MAF cleaning suggestion. Don't buy any more parts though, all this can be done with some diagnostics.
 
i know first hand what a pita this is I had the same exact issue few years back I replaced the injector with a remanufactured one but the problem persisted and so swapped the injector again and it was the remanufactured injector that was the culprit. bit the bullet in the end with a oem and issue resolved but mine was specific to p0301.
 
Thanks again for the info!

The air filter is less than 6 months old - WIX paper, and the MAF was a new Denso item ~9 months ago... so I haven't suspected it yet. Is the IAT wire part of the MAF sensor?

I do have a scan gauge II which I think can read the fuel trims thru X-gauges... I just haven't made the time to figure out how to program it.

One more tidbit of info, when I checked the 5-O injectors before installation all were reading ~16ohms cold, which is already on the high side of the resistance specs I could find. All my old ones were ~17.5+. I used a heat gun on the old ones to simulate 'operating temps' and all the old ones were ~20-22ohms, hot. But no 'smoking gun'.

In prep for tearing into the injectors again I did order a new ECT sensor, so if I have to get that deep again I'll swap it also.

I'm going to carry my stethoscope with me and next time it starts misfiring I'm going to try to listen to the injectors I can access...

Again thanks for the feedback and moral support :o)
 
I'm tearing into it today (heat index 106*).

Last night I loaded the 4 x-gauge commands for fuel trim shown on the scangauge site, long and short. Only LF1 & SF1 show any data. At idle, with the misfire happening, LF1 shows 17, SF1 shows 0. When I revved i to ~2500 FL1 dropped to ~-4 +/-, SF1 never changed... I have no idea what this means, or if trims 2, 3, & 4 should be showing anything.

I swapped coils again and the codes are still P0300/0301/0304.

While I'm in it I'm going to check valve clearance on all the valves.
 
Heyduke said:
I'm tearing into it today (heat index 106*).

Last night I loaded the 4 x-gauge commands for fuel trim shown on the scangauge site, long and short. Only LF1 & SF1 show any data. At idle, with the misfire happening, LF1 shows 17, SF1 shows 0. When I revved i to ~2500 FL1 dropped to ~-4 +/-, SF1 never changed... I have no idea what this means, or if trims 2, 3, & 4 should be showing anything.

I swapped coils again and the codes are still P0300/0301/0304.

While I'm in it I'm going to check valve clearance on all the valves.
Click to expand...

Replace your EFI fuse. I had a p0301 misfire. Got injectors serviced by WitchHunter. Changed spark plugs and wires. Then while I was just sitting around crying, I didn't want to look at the CEL anymore and pulled the EFI fuse. Swapped it with the spare one I had in the box. No more CEL for over 500 miles and no misfire (that I can tell!)
 
Dug in deep yesterday, found one bad 5-O motorsport injector... #1 cylinder, something like 140 ohm, and floating a lot. Installed one of my "good" originals, I put the suspect #4 injector, which ohm-ed OK at 100*F into cyl #3.

I checked the passenger side valve clearance, all were perfect - amazing @200K miles.

Put it all back together, it started right up and purred like a kitten (whew!) Drove 30 minutes, ran great, came home let it sit 15 minutes, started up misfiring (grrr!)

I listened to 1 3 & 5 with the stethoscope, #3 sounded different...

This AM I checked resistance at the pass. side injectors, at 80*F all were in spec. Took it for a spin, came home, let it sit, #3 is ~.86ohm, the other two in spec...

2 smoking guns... two bad 5-O motorsport injectors...

After it "cools" off a bit, I'm going to swap #3 with another "good" original injector. I tested it by baking it @250*F for ~30 minutes.

I keep telling my self I've saved major $$$ doing it my self, and now I can strip the top of the motor with my eyes closed.

Also my old multimeter died on me yesterday, so I don't trust the #'s it was giving, but the results were consistant, where it was reading ~16.6, my new one reads 14.4-ish, which is much closer to spec.

I think I'm making some progress...
 
I replaced the other suspect 5-O motorsport #3 injector with one of my old ones, so far 2 drive cycles, with restarts 15-20 minutes later, the problem hasn't resurfaced.
 
Heyduke said:
Dug in deep yesterday, found one bad 5-O motorsport injector... #1 cylinder, something like 140 ohm, and floating a lot. Installed one of my "good" originals, I put the suspect #4 injector, which ohm-ed OK at 100*F into cyl #3.

I checked the passenger side valve clearance, all were perfect - amazing @200K miles.

Put it all back together, it started right up and purred like a kitten (whew!) Drove 30 minutes, ran great, came home let it sit 15 minutes, started up misfiring (grrr!)

I listened to 1 3 & 5 with the stethoscope, #3 sounded different...

This AM I checked resistance at the pass. side injectors, at 80*F all were in spec. Took it for a spin, came home, let it sit, #3 is ~.86ohm, the other two in spec...

2 smoking guns... two bad 5-O motorsport injectors...

After it "cools" off a bit, I'm going to swap #3 with another "good" original injector. I tested it by baking it @250*F for ~30 minutes.

I keep telling my self I've saved major $$$ doing it my self, and now I can strip the top of the motor with my eyes closed.

Also my old multimeter died on me yesterday, so I don't trust the #'s it was giving, but the results were consistant, where it was reading ~16.6, my new one reads 14.4-ish, which is much closer to spec.

I think I'm making some progress...
Click to expand...

Wow, that's terribly unlucky. 2 bad injectors in a batch of 6... that's quite a bummer. Not just to have 1 go bad initially, but then 2 replacements go bad.

Have you contacted them for a refund?
 
It's par for the course for me, I can't tell you how many times I've had the weirdest problems with stuff, whether it's a PC, 2-stroke motorcycle, or semi-modern car with limited OBD.

I haven't contacted them yet, but I will soon. I'd prefer a refund at this point, but I'll bet they will want to replace the bad ones.

The up-side --> I made it thru another hot-restart without issue today at lunch.

That's three!
 
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