SOS...Sensors?? - Ford Bronco Forum
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post #1 of 19 (permalink) Old 04-25-2017, 11:03 PM Thread Starter
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SOS...Sensors??

Hey guys, pulling into my driveway today and my bronco died! Started it up again and pulled forward 20 feet and it almost died again, and when i put it in park the idle was really irregular and kinda rough. TPS? IAC valve? MAP sensor? i know its gotta be a sensor...i had just done a complete tune up and fluid flush, re-timed it and made sure it was running sound. Any ideas can help.
Thanks.

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post #2 of 19 (permalink) Old 04-25-2017, 11:11 PM
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I would start with the easy stuff and make sure you didn't knock something loose when you were doing the tuneup. Maybe you loosened a connector and it finally fell off? Then start checking the common sensors by making sure they have the correct values. IAC, and TPS are known to go bad. Is your fuel pump working? That maybe weak as well. I imagine some others will chime in, but start with the easist stuff and go from there. Report back what you find and hopefully we can help you.

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post #3 of 19 (permalink) Old 04-26-2017, 08:53 AM
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Maybe fuel issue, filter?
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post #4 of 19 (permalink) Old 04-26-2017, 09:23 AM
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Yo fsb86,
Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

Some no code usual suspects by Ford;
Vacuum leak, see my leak diagnosis link in post #11
Air filter, is it relatively clean?
Air inlet atop radiator support to filter box and to throttle body; look for obstruction; damaged tubing
Inspect plug wire routing using decal afixed to radiator support or underside of hood.
Fuel quality; Oxidized fuel often turns darker over time and may even smell sour. You can check stored gasoline by pouring some into a clear glass container and comparing it side-by-side with known fresh gasoline. If your old sample looks noticeably darker than the fresh gas, you have strong evidence the gas has gone bad.
Electrical connectors; inspect at battery & grounds, coil, firewall, PCM, etc. especially those with broken locking tabs.

You can pull IAC to see if it or it's passageway is clear.

See my partially recovered Bronco web site ...Will need to clean up dead links & add many more new links some day. Thanks to Mr. Schwim!
THANKS to ALL WHO SERVE!

Last edited by Quader1; 04-26-2017 at 09:52 AM. Reason: Fix URL
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post #5 of 19 (permalink) Old 04-26-2017, 09:56 AM Thread Starter
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So i haven't had a chance to work on it, but i will definitely get to it this weekend, but i just wanted to let you know what i've done to it. I did plugs, wires, rotor/cap, air filter, cleaned out my throttle body, replaced inline and intank fuel pumps, replaced my fuel filter, and made sure all my injectors were functioning properly. Made sure i had no loose grounds, no loose wires, and no corroded/exposed wires. Thats why i thought of sensors. I had an '02 f150 4.2 v6 and had a sensor/computer problem and was at a loss. Don't want to give up on my bronc just yet. I have been 4wheelin a lot more lately so I will definitely go through and check to see if a connection has come undone studleyjay126. As far as fuel filter, i got a motorcraft one from rockauto for my tune up so I'm pretty sure i can rule that out woodguy. Miesk5 I did all the electrical so i was sure its not a short somewhere, just a faulty sensor(hopefully). As far as vacuum leaks, that was my next guess. So i will diagnose this weekend and let you all know.
Btw i'm 19 and just started working on this thing a month ago so besides what i have already ruled out, it could be anything regardless as to what i have done, so any ideas beyond what i have said are very helpful.
Thanks a ton you guys.
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post #6 of 19 (permalink) Old 04-26-2017, 10:02 AM Thread Starter
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I would also like to add that the guy removed all the emissions ie. air pump etc. for a full exhaust kit he had put on it. So i know it will obviously throw codes

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post #7 of 19 (permalink) Old 04-28-2017, 10:29 AM Thread Starter
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Quote:
Originally Posted by miesk5 View Post
Yo fsb86,
Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

Some no code usual suspects by Ford;
Vacuum leak, see my leak diagnosis link in post #11
Air filter, is it relatively clean?
Air inlet atop radiator support to filter box and to throttle body; look for obstruction; damaged tubing
Inspect plug wire routing using decal afixed to radiator support or underside of hood.
Fuel quality; Oxidized fuel often turns darker over time and may even smell sour. You can check stored gasoline by pouring some into a clear glass container and comparing it side-by-side with known fresh gasoline. If your old sample looks noticeably darker than the fresh gas, you have strong evidence the gas has gone bad.
Electrical connectors; inspect at battery & grounds, coil, firewall, PCM, etc. especially those with broken locking tabs.

You can pull IAC to see if it or it's passageway is clear.
Quote:
Originally Posted by WoodGuy View Post
Maybe fuel issue, filter?
Quote:
Originally Posted by studleyjay126 View Post
I would start with the easy stuff and make sure you didn't knock something loose when you were doing the tuneup. Maybe you loosened a connector and it finally fell off? Then start checking the common sensors by making sure they have the correct values. IAC, and TPS are known to go bad. Is your fuel pump working? That maybe weak as well. I imagine some others will chime in, but start with the easist stuff and go from there. Report back what you find and hopefully we can help you.
Hey guys! so i took my bronco to work today as i dont really commute but a few miles to work, it ran fine! started good, idle was clean, and throttle response was normal. I do live in nevada and its starting to get warm here, would that effect it? Also im checking the fuel filter and the sensors later today since those are easy to check and will get back to you on that. wondering if a fuel injector going out would do that? or would it miss and i'd definitely know that?

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post #8 of 19 (permalink) Old 04-28-2017, 04:15 PM
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Yo fsb86,
Typically heat negatively affect the ICM, especially on the distribuormounted units. The top three leads (for PIP signal) can lose continuity with the back plate (ground) on the module when the unit is hot. You should consider a remote mounted TFI. If your TFI is failing from heat, it can give off computer codes 14 (PIP) and 18 (SPOUT).

Examine all wiring harness and connectors for insulation damage, burned, overheated, loose or broken conditions. Ensure that the TFI is securely fastened to the front fender apron.

Same for vacuum hoses especially @ back of intake manifold where the TAD Valve is located. And onpassenger side @ TAB Valve.

pic by SeattleFSB.

See my partially recovered Bronco web site ...Will need to clean up dead links & add many more new links some day. Thanks to Mr. Schwim!
THANKS to ALL WHO SERVE!
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post #9 of 19 (permalink) Old 05-02-2017, 09:40 PM Thread Starter
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UPDATE: I got called into work this weekend so i didn't get to dive into it just yet, but i did get a chance to do an icm reset on my iac valve. Its been running a little better but i noticed something i hadn't noticed before, when my foot is even the slightest bit on the throttle it runs fine, but when I'm going around 20-55mph and i coast it started to have a stutter, like a hiccup. Wondering if that could still be my iac valve?

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post #10 of 19 (permalink) Old 05-02-2017, 09:48 PM Thread Starter
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Quote:
Originally Posted by miesk5 View Post
Yo fsb86,
Typically heat negatively affect the ICM, especially on the distribuormounted units. The top three leads (for PIP signal) can lose continuity with the back plate (ground) on the module when the unit is hot. You should consider a remote mounted TFI. If your TFI is failing from heat, it can give off computer codes 14 (PIP) and 18 (SPOUT).

Examine all wiring harness and connectors for insulation damage, burned, overheated, loose or broken conditions. Ensure that the TFI is securely fastened to the front fender apron.

Same for vacuum hoses especially @ back of intake manifold where the TAD Valve is located. And onpassenger side @ TAB Valve.

pic by SeattleFSB.
?

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post #11 of 19 (permalink) Old 05-03-2017, 08:55 AM
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Yo,
I wrote that in response to your statement, "... I do live in nevada and its starting to get warm here, would that effect it?..." in your post #7.

See my partially recovered Bronco web site ...Will need to clean up dead links & add many more new links some day. Thanks to Mr. Schwim!
THANKS to ALL WHO SERVE!
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post #12 of 19 (permalink) Old 05-03-2017, 09:25 AM
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It could be a handful of different sensors, but I'd look at vacuum lines on a 30+ year old truck that lives in a dry climate.
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post #13 of 19 (permalink) Old 05-03-2017, 11:38 AM Thread Starter
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Quote:
Originally Posted by miesk5 View Post
Yo,
I wrote that in response to your statement, "... I do live in nevada and its starting to get warm here, would that effect it?..." in your post #7.
sorry bout that, i was just trying to tag you so that you could see that i responded, didn't mean to tag you in that way though. I did go through it yesterday and made sure that all my lines were good and that i had no leaks. I contacted the guy i bought it from and he said that he had put all new hoses on it because he thought it had a vacuum leak when he had it. SOO i went through it to make sure anyways. Didn't find any leaks whatsoever. I'm gonna put a volt meter to all my sensors this weekend to make sure they're all working right. I also have a problem with my exhaust. I don't have a leak anywhere, but when i roll my windows down at all it almost gasses me out. I'd like to add that the exhaust pipes end flush with my rear bumper, gonna put turndown tips on it this weekend to see if it helps, also to give it a better look.
Thanks.
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post #14 of 19 (permalink) Old 05-03-2017, 01:08 PM
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Yo,
No problem.
Do the self test.
Try this Key On Engine Off Wiggle Test Procedure
1.Hook up a VOM or Scan Tool.
2.Turn the ignition key to the ON position.
3.For VOM, activate, deactivate and reactivate Self-Test to enter Continuous Monitor Diagnostic Test Mode (DTM). For Scan Tool, enter DTM, then enter wiggle DTM.
4.Tap, move, and wiggle the suspect sensor and/or harness. When a fault is detected, a Continuous Memory DTC will be stored in memory and indicated as follows:
•Check Engine (CEL) Lights
•VOM: Needle Sweep

Engine Running Wiggle Test Procedure
Special Note:
•The Engine Running Wiggle Test may be activated any time the engine is running.
1.Hook up a Scan Tool .
2. Key off.
3.Start the engine.
4.For VOM, activate Self-Test, deactivate and reactivate Self-Test to enter Engine Running Continuous Monitor DTM. DO NOT shut the engine off. For Scan Tool, enter DTM, then enter wiggle DTM.
5.Tap, move, and wiggle the suspect sensor and/or harness or drive the vehicle. When a fault is detected, a Continuous Memory DTC will be stored in memory and indicated as follows:
•Check Engine (CEL) Lights
•VOM: Needle Sweep
....

Can you grab a vacuum gauge and check level; at idle & at different RPMs; with Air Conditioner on on And off, if equipped.. climate control uses vacuum too.

Any black exhaust smoke?

See my partially recovered Bronco web site ...Will need to clean up dead links & add many more new links some day. Thanks to Mr. Schwim!
THANKS to ALL WHO SERVE!
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post #15 of 19 (permalink) Old 05-03-2017, 04:42 PM Thread Starter
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Quote:
Originally Posted by miesk5 View Post
Yo,
No problem.
Do the self test.
Try this Key On Engine Off Wiggle Test Procedure
1.Hook up a VOM or Scan Tool.
2.Turn the ignition key to the ON position.
3.For VOM, activate, deactivate and reactivate Self-Test to enter Continuous Monitor Diagnostic Test Mode (DTM). For Scan Tool, enter DTM, then enter wiggle DTM.
4.Tap, move, and wiggle the suspect sensor and/or harness. When a fault is detected, a Continuous Memory DTC will be stored in memory and indicated as follows:
•Check Engine (CEL) Lights
•VOM: Needle Sweep

Engine Running Wiggle Test Procedure
Special Note:
•The Engine Running Wiggle Test may be activated any time the engine is running.
1.Hook up a Scan Tool .
2. Key off.
3.Start the engine.
4.For VOM, activate Self-Test, deactivate and reactivate Self-Test to enter Engine Running Continuous Monitor DTM. DO NOT shut the engine off. For Scan Tool, enter DTM, then enter wiggle DTM.
5.Tap, move, and wiggle the suspect sensor and/or harness or drive the vehicle. When a fault is detected, a Continuous Memory DTC will be stored in memory and indicated as follows:
•Check Engine (CEL) Lights
•VOM: Needle Sweep
....

Can you grab a vacuum gauge and check level; at idle & at different RPMs; with Air Conditioner on on And off, if equipped.. climate control uses vacuum too.

Any black exhaust smoke?
I'll have to take some time to do all of this because I'm always short of time. But no smoke at all haha no black or whites smoke, really clean exhaust.

86' Bronco, EFI 302, 4" RCL on 33's
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post #16 of 19 (permalink) Old 05-03-2017, 07:08 PM
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Yo,
Ok, check for a fuel leak inengine bay at fuel pressure regulator, fuel rail, schrader valve test port and injectors. Then under driver seat area at fuel filter. Move back following both fuel retuen and supply and vapor lines to the tank and atop tank , etc.

See my partially recovered Bronco web site ...Will need to clean up dead links & add many more new links some day. Thanks to Mr. Schwim!
THANKS to ALL WHO SERVE!
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post #17 of 19 (permalink) Old 05-16-2017, 09:17 AM Thread Starter
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Ok guys i checked everything you said, and everything i could possibly think of, even all my grounds. After that i pulled the iac valve just for the hell of it and turns out it was plugged up with carbon and dirt. SOO i took some carb cleaner and worked it really hard, and then drowned it in carb cleaner to drain out all the soot. Runs like a top! it idles much cleaner, and it idles pretty low (at around 650rpms). Thanks guys for all your help! You never know what it'll turn out to be.
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post #18 of 19 (permalink) Old 05-16-2017, 09:58 AM
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Quote:
Originally Posted by fsb86 View Post
Ok guys i checked everything you said, and everything i could possibly think of, even all my grounds. After that i pulled the iac valve just for the hell of it and turns out it was plugged up with carbon and dirt. SOO i took some carb cleaner and worked it really hard, and then drowned it in carb cleaner to drain out all the soot. Runs like a top! it idles much cleaner, and it idles pretty low (at around 650rpms). Thanks guys for all your help! You never know what it'll turn out to be.
Yo,
Great & thanks for the update!!

See my partially recovered Bronco web site ...Will need to clean up dead links & add many more new links some day. Thanks to Mr. Schwim!
THANKS to ALL WHO SERVE!
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post #19 of 19 (permalink) Old 05-16-2017, 10:12 AM
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Aftermarket fuel pumps can be scary. First this first Fuel, Spark and Air. Check those three first ALWAYS
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