Fuel injectors

Tiny
TMCINTOSH11
  • MEMBER
  • 2002 FORD EXPLORER
  • 4.0L
  • 6 CYL
  • AWD
  • AUTOMATIC
  • 239,000 MILES
I recently found out that I have a problem with my SUV it is the xlt model that is related to the fuel injection circuit. I am not sure if it a harness or the injector itself but I just need to know how I go about getting to the injectors and harness for this model and if there is anything important I need to know when attempting to replace one of the two if not both if I decide to. It is giving me the P0201 code. By the way, thanks!
Sunday, April 30th, 2017 AT 5:14 PM

41 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Before you get into that be aware that it can be any of the things listed causing the problem. This includes air leaks, like engine grommets or holes in duct work leading to engine, or vacuum leaks. See pictures for testing it still can be a bad PCM as well. Disregard first two pictures.
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Monday, May 1st, 2017 AT 7:20 AM
Tiny
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Ok I'll check those out too, thanks!
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Saturday, May 6th, 2017 AT 5:30 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 49,990 POSTS
Hello,

I have found some wiring diagrams and a couple of guises to help you get the problem fixed.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

and

https://www.2carpros.com/articles/how-to-check-wiring

Please run some tests and get back to us so we can continue helping you.

Cheers, Ken
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Monday, May 8th, 2017 AT 5:06 PM
Tiny
TMCINTOSH11
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I have an update on the injector circuit problem, I ran a few test and I replaced the injector harness, so far nothing has changed, it accelerates a little better but for the most part it's still running rough at times and it's all pointing to the injector itself. I wasn't able to check for air leaks yet, I'm still trying to find a cheap and effective way, I was thinking of running smoke through the brake booster air line to check that, I also pulled the codes again and this is what came up:
P0301 cylinder 1 misfire
P0171 fuel system too lean (cylinder 1)
P0201 cylinder 1 injector curcuit malfunction
P1131 lack of HO2S-11 switching
That's all I have for now, I'm going to test the compression in cylinder 1 tomorrow to make sure that's ok, let me know what you guys think, thank you!
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Thursday, June 22nd, 2017 AT 5:23 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 49,990 POSTS
Hello,

P0201 cylinder 1 injector circuit malfunction

Will cause the other codes. Did you test the injector?

Here is a guide

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Please let us know what happens.

Cheers, Ken

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Thursday, June 22nd, 2017 AT 5:51 PM
Tiny
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I ran some test on the injector today (what I could), the first test was with a long screw driver and I did hear the clicking noise plain as day, I did the same with a different injector and I noticed a different sound of clicking, I didn't know if that mattered or not.
I also used a multimeter with the ohms setting with the ignition off, the harness gave a reading of 172.2, injector gave no reading.
So what should I do next? Thanks for your help!
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Sunday, June 25th, 2017 AT 12:13 PM
Tiny
HMAC300
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Sunds like the harness is bad should only be 5 ohms from injector to pcm. Tan wire and violet wire to ground should be same. Also check for wire to be rubbing engine on block that may be problem. Also check resistance of injector should be 11-17 ohms or around there.
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Sunday, June 25th, 2017 AT 12:49 PM
Tiny
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The harness I checked was a brand new one I put on last week that made no difference in performance. I tried to check the injector itself but it didn't give a reading, I'm an amateur at using multimeters, I've never had to use them before, the wire isn't up against anything but the throttle body cover. I heard if there is no reading on the injector then it has an open in the circuit but I'm not sure. If the reading on the harness is high could it be the wiring? Thanks for replying!
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Sunday, June 25th, 2017 AT 2:01 PM
Tiny
HMAC300
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Yes the reading shold be what I gave in previous reply or its'grounding out. Use your old harness and hook to injector take an ohm reading that way it should be close if no reading then the injector may be bad.
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Sunday, June 25th, 2017 AT 3:38 PM
Tiny
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I ran another test this time with a probe light, while the engine was running I connected the red wire of the light to the positive battery post and the light to the left side of the harness and the light lit up, I then put the black wire of the light to the negative battery post and connected the light to the other side of the harness and no light at all. So now it seems like a bad ground somewhere, what should I do next? Could it be a bad pcm or the wiring? Thanks!
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Wednesday, June 28th, 2017 AT 7:19 AM
Tiny
HMAC300
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It cold be either if you check the wire back to pcm and it reads 5 ohms or less then it's the pcm probably but that you shold have verified first as a mechanic has to program the new one to your vehicle. Check the tan wire to pin #2 on pcm if no reading or h igh on ohms then it s wire
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Wednesday, June 28th, 2017 AT 9:33 AM
Tiny
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So would I have to disconnect the harness from the pcm? I'm not sure which one it is because I tried to follow the wires from the injector and they go down behind the motor and as far as I can tell it goes into the top harnessvon the pcm. I thought there would be another connection harness between the pcm and the injectors but I think the wires go straight into it, not sure. I don't suppose that cleaning some ground wires would help. Thanks!
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Wednesday, June 28th, 2017 AT 3:30 PM
Tiny
HMAC300
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Yes you disconnect the harness on the pcm and be careful not to bend any pins. Removing and reinstalling harness. The plastic connector will be marked by numbers where wires are just make sure it's the correct color and number to check which I have given you previously. Use dielectric compound when re installing for better contact. Usually sold as bulb grease on counter at auto parts for around $2
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Wednesday, June 28th, 2017 AT 4:43 PM
Tiny
TMCINTOSH11
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Ok I'm going to give it a try this weekend, I'll let you know what I find out, this is kind of new territory for me, I'm worried about bending the pins now that you mention it, I can't tell you how much I appreciate all your help, I feel like I'm really close to finally finding the problem, I'll get back with you this weekend with the results and see where to go from there, Thank you!
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Wednesday, June 28th, 2017 AT 7:11 PM
Tiny
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By the way I have a couple more questions, since I'll have the harness off the pcm to test it, would it be a good idea to try some crc contact cleaner on the pins? And would I apply the dielectric grease on the pins or around the pins? Thanks!
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Thursday, June 29th, 2017 AT 7:19 AM
Tiny
HMAC300
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Don't bother with crc just put the grease when you can on pins
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Thursday, June 29th, 2017 AT 8:12 AM
Tiny
TMCINTOSH11
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Im trying to get a reading on the pcm harness and Im having any luck, I don't think my multimeter pin won't fit down far enough to get a reading, I also couldn't get a readind on the pcm itself, am I doing something wrong? I took a picture of the pins and the harness to show you where Im at, is the battery suppost to be disconnected? Let me know, thanks!
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Sunday, July 2nd, 2017 AT 8:09 AM
Tiny
HMAC300
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If your multimeter won't fit you'll need something that will like either a pin or maybe a paper clip to take the reading.
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Sunday, July 2nd, 2017 AT 8:27 AM
Tiny
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Ok, I got a thin piece of copper and put it in the pin hole of the harness and it didn't give me a reading at all, I also had the battery disconnected, does this mean it's the wire? Thanks
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Sunday, July 2nd, 2017 AT 8:39 AM
Tiny
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I guess Im gonna assume it's the wiring since I didn't get a reading on the harness, I put it all back together after I put a dab of dielectric grease on the pins, it still runs the same. So should I be looking for a separate harness for the injectors or do they go straight into the pcm? Thanks!
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Sunday, July 2nd, 2017 AT 10:24 AM

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