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My '95 Bronco is losing power after it gets to normal operating temperature. 5.8 with 42k miles, all original. It has been garaged kept, and not a daily driver. The most recent work I have done was, replace the fuel pump with motorcraft replacement. This was about a year ago. Truck was running fine after. It has been sitting in the garage with a battery tender since. I have occasionally started the truck while cleaning it. I haven't been driving it because I am trying to get the time to look for a small freon leak. Can't stand driving in the south Florida heat without ac. Yesterday I pulled out the truck for a drive in cooler weather. When I left the drive, I had full power. I went to get some rec 90 fuel locally, about 10 blocks away. When fueling I noticed the abs light was on. Went home to look for obvious things. I had at one time disconnected the break reservoir electrical connection. This was because of a repair ford had been sending me regarding possible fire due to a short that could be caused. Ford wanted to install a fuse. When I got back home, I turned off the truck and restarted it. ABS light was off and, stayed off. Was excited to take it up on the highway and run her for a bit. This is when my issues began. I got far enough from home to get on the gas. The truck started bucking like it had no power. Note that when I first left the house with the truck cool, I did smoke the tires off the line. The truck was running strong then. I picked up a new motorcraft fuel filter last night because it seemed like it was starving for fuel. I would be a quick install and not expensive. Installed the filter this morning and left for a drive. Had full power for a mile and a half, then the same shit. I came home and checked for anything obvious under the hood, naada. Came inside to check a couple of forums. this took me about 30 minutes. Went back to truck and started to go for a short drive. Before I left I held the brake and put the pedal down. Smoked the tires on my concrete driveway. When I hit the road, i had the same issue in about 1/2 mile. The loss of power only happens after warm up to full operating temps. I am looking for the next best place to start looking. This condition came out of nowhere. Nothing had been done to the vehicle. This truck is so fresh, it still has the original gray painted hoses. Any ideas from anyone would be helpful.
 

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1986 Eddie Bauer 5.0EFI AOD Full length headers Y pipe into single 3" Magnaflow 3" factory exit
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It sounds like something telling the engine that its warm is not working, bad coolant temp sensor or something. Any codes? That would help diagnose so you aren't just throwing parts at a problem. Purchasing a code reader is ALWAYS a good idea as well for the cost.
172140


Even with your Bronco being in such nice shape & low miles, every hard plastic line is still 25 years old & probably brittle & don't be surprised if there are numerous cracks in those vacuum lines causing vacuum leaks. All possibilities, but as stated earlier, it sounds like a sensor to me.

You could test the resistance on a few of the sensors as well to determine if they are good or not.
 

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Yo Tom,
Welcome!
As Rob advised.

Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19 @ Code Reader

PCM stores the Self-Test program in permanent memory. When activated, Self-Test checks the EEC system by testing memory integrity and processing capability, and verifies that various sensors and actuators are connected and operating properly.

Inspect the air cleaner and inlet ducting. Check all engine vacuum hoses for damage, leaks, cracks, blockage, proper routing, etc. Check EEC system including the wiring harness for proper connections, bent or broken pins, corrosion, loose wires, proper routing, etc. Check the Powertrain Control Module (PCM), sensors and actuators for physical damage. TPS, ICM, DISTRIBUTOR, etc. Check the engine coolant for proper level and mixture. Check the transmission fluid & engine oil level and quality. Make all necessary repairs before continuing with SELF TEST.

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test. Run it around to heat the engine up and shift thru all gears including Reverse. Make sure A/C is off and transmission is in Park (automatic); or in Neutral for a Manual & release clutch. Then turn off engine, all accessories/lights (close driver's door) , etc.

Do KOEO test First. Post Code(s) here according to KOEO & KOER.
A helper can assist you by counting the codes. Some use their smart phones to record them.

BEWARE OF FAN, BELTS, PULLEYS, HOT HOSES, IGNITION HIGH TENSION WIRES, AND ENGINE COMPONENTS

Or ask local mom and dad parts stores if they will test it for you.
Or purchase a coder reader such as ROB MENTIONED,, Equus 3145 Innova OBD I Code Reader for Ford EEC IV Engines at Walmart & most parts stores.

E4OD Transmission Control Indicator Light (TCIL) is a LED with an overdrive on/off switch at end of the Transmission shifter stalk; flashing OD light is an indication of a transmission related trouble code in the Powertrain Control Module (PCM).
Is it flashing while driving?
■●■
ASAP, find out if speed control recall work, if equipped was completed @ Recalls Look-up by VIN (Vehicle Identification Number); or @ Welcome to Ford Owner | Official Ford Owner Site; have VIN ready. While there, see most Ford dealer maintenance/repairs done @ any dealership nation-wide.
"Summary: ON CERTAIN PICKUP TRUCKS, PASSENGER VEHICLES, SPORT UTILITY VEHICLES, AND MOTOR HOMES CHASSIS, THE SPEED CONTROL DEACTIVATION SWITCH MAY, UNDER CERTAIN CONDITIONS, LEAK INTERNALLY AND THEN OVERHEAT, SMOKE, OR BURN. THIS COULD RESULT IN AN UNDERHOOD FIRE."
See this guide by jowens1126 to confirm recall status @ 93 & 94-96 Cruise Control Recalls Repair
Note that the 93 recall is different than 94-96.

1995 Bronco Dealer Brochure @ 1995 Ford Bronco

1995 Bronco Drivetrain, Powertrain Service Manual - Google Drive
&
1995 Bronco Chassis, Service Manual - Google Drive
To switch between folder list & grid views, click the button to the right of the "DOWNLOAD ALL" button in the upper right corner of the window) by HawkDriver

For any Bronco questions or to chat about it's planned modifications or build, it's better to post each seperately in Noobie Bronco Tech Questions. Flame free zone. This will get more attention and you can build up your post count to get into other sections such as Bronco and Ford Parts/Accessories (75 non-padded posts required to participate, due to scammers who preyed on our members).

To save you time and for better responses, please fill out your Bronco info with location, year, engine size, transmission type, transfer case type (manual or electric shift), locking hub type (automatic or manual) info & major mods such as a Lift, etc. .
Bronco info is now able to be put under your user name.
Click your profile button in the top right and go to account settings.


On that first page, named Account Details, scroll down to "Vehicle Info" and type in up to 100 characters.

Now you can simply enter your information in the text editor and click save.

Our Forum FAQs includes for example, How to Use Search and more tips!

➡See Baba Looey's Favorite FSB Links (lots and lots of tech links)
... Includes such as, How do I fix my back window?

Take time to participate in our Full-Size of the Month & later in the year, Full-Size of the Year Contest @ Voting
You will get ideas by those competing.
Al
 

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Discussion Starter #4
It sounds like something telling the engine that its warm is not working, bad coolant temp sensor or something. Any codes? That would help diagnose so you aren't just throwing parts at a problem. Purchasing a code reader is ALWAYS a good idea as well for the cost. View attachment 172140

Even with your Bronco being in such nice shape & low miles, every hard plastic line is still 25 years old & probably brittle & don't be surprised if there are numerous cracks in those vacuum lines causing vacuum leaks. All possibilities, but as stated earlier, it sounds like a sensor to me.

You could test the resistance on a few of the sensors as well to determine if they are good or not.
Hey Rob, thanks for the quick reply. I now that the ecm doesn't read any sensors until the motor is up to operating temps. I believe may have given me a place to start. What do you think about the coolant temp sensor? Since I only drive it until it gets to normal operating temp, then come home, it shouldn't take more than a few minutes to show a cool start again before I go out and try again. Smoke the tires and just a few minutes later, I have the problem. I hope it's something easy. I will only install a ford parts. Trying to keep her bone stock. I had a 96 that I was going to rotisserie, and build to have some real fun. It was stolen some years ago. Someone liked it better than me. This truck is so pristine, I don't want to hurt the value with add ons. I wouldn't have thought the same in the 90's, but these are becoming more rare in like new shape. I hope Ford with the new Bronco comes up with something compete with the new Rubicon's 450 hp coming out. Last that I heard, they were going to offer an e-bronco. That just goes against my grain. I didn't buy my past broncos for gas mileage. I bought them for fun, and meeting people that feel the same. I've got two parents, to see at two different homes for Christmas. I'm trying to do this safely for them. I will be on this right after. I miss driving it. I will give a heads up on what I find. Have a good Christmas, and stay safe. Tom.
 

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1986 Eddie Bauer 5.0EFI AOD Full length headers Y pipe into single 3" Magnaflow 3" factory exit
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No problem, enjoy your Christmas!! All of the EFI component work together, and if one goes bad, all sorts of strange things happen. Thats why I say go buy a code reader, it will be a good purchase, I guarantee it.

Its most likely a simple.sensor thats under $20 & yes, buying Motorcraft parts is your best bet!! It could be an Air intake Temp sensor, or Coolant temp sensor, a Throttle position sensor, its really just a guess which one may be acting up, thats where a code reader comes in handy.

I had a 96 brand new, but it was new, so nothing went wrong with it & I sold it a few years later... I'm more versed on the early EFI Broncos like my 86, but we'll be here to help walk you thru it when you return, there's a lot of knowledge on this site.

If you have a meter that can read ohms, you can measure resistance on each of these sensors & we know what they are supposed to be, so when you find the bad one, it will be way off. Like I said, its probably just one of these inexpensive sensors gone bad after 25 years, which is tough be expected after that long.
 

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Yo,
Check for codes yet?
 

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Discussion Starter #8
Yo,
Check for codes yet?
Yes, thank you. Iv'e been doing things for family while waiting for the 3145 tester, and the 3149 extension cable. Thanks to members for recommending this tool. I started the truck just long enough to get it out of the garage. with the key on engine off, I was able to pull these codes. I got a 111, a code 10, and a code 327. I was talking with innova. I asked them if I could damage the tool or anything else leaving it hooked with the engine running. They said no. So as usual, I left the driveway with the truck running like a scalded dog. 1 minute later, it's running like hell again. The manual doesn't show a code 10. The manual says 111 is system pass, and code 327 says egr valve position circuit below minimum voltage. Any ideas on what would be causing the low voltage for the code 327. At least having the tool, and with some help from this forum, I'll get this resolved. Thanks, Tom.
 

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'92 Ford Bronco XLT
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Hi @Deltatom, that 327 code means the EEC can tell the position of the EGR valve..so you might have a faulty EGR or it could be a bad EVP sensor or possibly EGR valve might also have a vacuum problem. Have you check for vacuum leaks around the EGR? Having said that, I don't think the EGR would cause the bucking or loss of power problems you're describing.
 

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Yo Tom,
Check for codes again because 111 is System Pass and therefore there shouldn't be 327.
As jermil01 advised:
d

DTC -- Damaged EVP sensor.

l Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.

l Install breakout box, reconnect PCM.

l Connect DVOM between Test Pin 27 and Test Pin 46 at the breakout box.

l Key on, engine off.

l Lightly tap on EVP sensor and wiggle harness connector to simulate road shock.

NOTE:

EVP voltage with EGR valve closed is normally between .24 and .67 volt and steady. A sudden change in voltage indicates a fault.

l Is a fault indicated?

Yes

REMOVE and INSPECT EVP sensor connector. If OK, REPLACE EVP sensor. CLEAR Continuous Memory (REFER to Quick Test Appendix, «Section 5A»). RERUN «Quick Test».

No

LEAVE DVOM connected, RECONNECT PCM and GO to «DN91».

DN91 CHECK EEC-IV VEHICLE HARNESS FOR INTERMITTENT OPENS OR SHORTS

l Key on, engine off.

l DVOM connected between Test Pin 27 and Test Pin 46 at breakout box.

-- Grasp the vehicle harness closest to the EVP sensor connector. Shake and bend a small section of the EEC-IV harness while working toward the dash panel. Also wiggle, shake and bend the EEC-IV harness from the dash panel to the PCM.

l Is a fault indicated?

Yes

ISOLATE fault and SERVICE as necessary. CLEAR Continuous Memory (REFER to Quick Test Appendix, «Section 5A»). RERUN «Quick Test».

No

LEAVE DVOM connected and GO to «DN92».

DN92 CHECK VOLTAGE WHILE EXERCISING EGR VALVE

l Disconnect vacuum hose at EGR valve and connect a vacuum pump.

l Key on, engine off.

l Measure voltage between Test Pin 27 and Test Pin 46 at the breakout box while performing the following:

-- Slowly apply 5-10 in-Hg (17-34 kPa) of vacuum to EGR valve, then slowly bleed vacuum.

l Does the voltage increase and decrease steadily from no more than 4.81 volts to no less than .24 volt?

Yes

Unable to duplicate and/or identify fault at this time. For further diagnosis using the EEC-IV monitor box or Scan Tool, REFER to «Section 7A».

No

REPLACE EVP sensor. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test
 

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Discussion Starter #11
Yo Tom,
Check for codes again because 111 is System Pass and therefore there shouldn't be 327.
As jermil01 advised:
d

DTC -- Damaged EVP sensor.

l Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.

l Install breakout box, reconnect PCM.

l Connect DVOM between Test Pin 27 and Test Pin 46 at the breakout box.

l Key on, engine off.

l Lightly tap on EVP sensor and wiggle harness connector to simulate road shock.

NOTE:

EVP voltage with EGR valve closed is normally between .24 and .67 volt and steady. A sudden change in voltage indicates a fault.

l Is a fault indicated?

Yes

REMOVE and INSPECT EVP sensor connector. If OK, REPLACE EVP sensor. CLEAR Continuous Memory (REFER to Quick Test Appendix, «Section 5A»). RERUN «Quick Test».

No

LEAVE DVOM connected, RECONNECT PCM and GO to «DN91».

DN91 CHECK EEC-IV VEHICLE HARNESS FOR INTERMITTENT OPENS OR SHORTS

l Key on, engine off.

l DVOM connected between Test Pin 27 and Test Pin 46 at breakout box.

-- Grasp the vehicle harness closest to the EVP sensor connector. Shake and bend a small section of the EEC-IV harness while working toward the dash panel. Also wiggle, shake and bend the EEC-IV harness from the dash panel to the PCM.

l Is a fault indicated?

Yes

ISOLATE fault and SERVICE as necessary. CLEAR Continuous Memory (REFER to Quick Test Appendix, «Section 5A»). RERUN «Quick Test».

No

LEAVE DVOM connected and GO to «DN92».

DN92 CHECK VOLTAGE WHILE EXERCISING EGR VALVE

l Disconnect vacuum hose at EGR valve and connect a vacuum pump.

l Key on, engine off.

l Measure voltage between Test Pin 27 and Test Pin 46 at the breakout box while performing the following:

-- Slowly apply 5-10 in-Hg (17-34 kPa) of vacuum to EGR valve, then slowly bleed vacuum.

l Does the voltage increase and decrease steadily from no more than 4.81 volts to no less than .24 volt?

Yes

Unable to duplicate and/or identify fault at this time. For further diagnosis using the EEC-IV monitor box or Scan Tool, REFER to «Section 7A».

No

REPLACE EVP sensor. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test
Thanks for the heads up. I was going to test voltages, and resistance readings on the egr valve position sensor. As far as corrosion, not likely. This truck is kept in a climate controlled garage. Backed out pins would be unlikely, as I have not been in the engine bay except to check the battery tender, and using the code reader. Where did you get your breakout box. Being able to check readings from sensors with the pcm connected would be ideal. Thanks, Tom.
 

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yo Tom,
I don't have a break-out box (BOB), however others here have purchased it with related overlays on e bay.
So, as I mentioned in another thread here; in place of the break-out box, go to the EEC connector pin instead; Substitute EEC connector pin Number for breakout box number
EEC IV Connector Pin Diagram



Source: by Fireguy50 (Ryan M)

EEC IV Connector Pin LEGEND Bronco & Ford Truck & Van: 4.9, 460, 5.0, 5.8;
Source: by Ryan M (Fireguy50) at Ford Fuel Injection
 

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Discussion Starter #14
yo Tom,
I don't have a break-out box (BOB), however others here have purchased it with related overlays on e bay.
So, as I mentioned in another thread here; in place of the break-out box, go to the EEC connector pin instead; Substitute EEC connector pin Number for breakout box number
EEC IV Connector Pin Diagram



Source: by Fireguy50 (Ryan M)

EEC IV Connector Pin LEGEND Bronco & Ford Truck & Van: 4.9, 460, 5.0, 5.8;
Source: by Ryan M (Fireguy50) at Ford Fuel Injection
Hello Miesk. I started basic troubleshooting of the EVP sensor. I got these readings with my meter. I tested the EVP both cold, and full operating temperature. Cold; Sig Return to VREF 4.98vdc, VREF to EVP 4120 ohms, and EVP to Sig Return was 634 ohms. The readings when the engine was at full operating temp was; SIG RTN and VREF voltage 4.92vdc, VREF to EVP resistance was 4090 ohms, and resistance between EVP and Sig Return was 640 ohms. I don't think there is anything that looks like a bad EVP. I used the referenced testing peramiters that Seattle FSB had posted. I pulled a one time code of 334, which is defined as a closed valve voltage high. This one time code seems a little strange as I had pulled a couple 327 codes which say EGR circuit below minimum voltage. I am going to check fuel pressures tomorrow. I will be borrowing a fuel pressure guage. A customer of mine has a tranny shop. He says that we can try his code reader. He's not familiar with mine, but his is for obd 1 & 2. It's a high end reader, and he says it's worth a shot. He's a customer of mine. He suggested checking the coil by using a cold pack like you would use on a sore back to keep the coil cold. He has suggested this because of the issues I am having when the engine gets to operating temps. I can now see the favors start to add up. I think this is going to have the cold pack on my forehead. LOL
 

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It could be the egr solenoid letting vacuum thru all of the time. This would cause the fault in the position indicator, & it would run like shit at idle. Start it, & unplug the egr vacuum line, see if it has vacuum at idle, it should not. If it does, I suspect that solenoid is stuck open.

If that is the case, you could cap that vacuum line temporarily until the replacement solenoid comes in & it should run fine.
 

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Discussion Starter #16
It could be the egr solenoid letting vacuum thru all of the time. This would cause the fault in the position indicator, & it would run like shit at idle. Start it, & unplug the egr vacuum line, see if it has vacuum at idle, it should not. If it does, I suspect that solenoid is stuck open.

If that is the case, you could cap that vacuum line temporarily until the replacement solenoid comes in & it should run fine.
Hey Rob. I checked that the other day. I was wondering why there was no vacuum at idle. This is a good thing to know is not the problem. Process of elimination. I just borrowed a snap on code reader, and fuel pressure guage. This will hopefully eliminate two other possibilities. Have a good one, Tom.
 

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Ahhh, ok, good to confirm that is not the problem. It may be the EGR gummed up causing that code then, which is not a big deal if it doesnt open at all. Just if it is stuck open at at idle it causes a problem.

I was getting my EGR system working & just for kicks I hooked a direct vacuum to the EGR to see what happened & it opened up and immediately the engine stumbled pretty bad & ran horrible.
 

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Discussion Starter #18
Ahhh, ok, good to confirm that is not the problem. It may be the EGR gummed up causing that code then, which is not a big deal if it doesnt open at all. Just if it is stuck open at at idle it causes a problem.

I was getting my EGR system working & just for kicks I hooked a direct vacuum to the EGR to see what happened & it opened up and immediately the engine stumbled pretty bad & ran horrible.
I borrowed a fuel pressure gauge, and a snap-on code reader. The adapter for the fuel pressure gauge didn't fit the port on my fuel rail, and the snap-on code reader wouldn't work past entering vehicle information. I wasn't given the proper power cord, and tried to do the testing with a 9v battery that I installed in it. Tomorrow is another day. Have a good one.
 

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You can pull codes manually by counting flashes, I did that a few times, but I hated it so much I bought the code reader I put above. You can search this site on pulling codes manually.
 

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You can pull codes manually by counting flashes, I did that a few times, but I hated it so much I bought the code reader I put above. You can search this site on pulling codes manually.
Yes, I agree. I have the innova 3145, and the 3149 extension cable. For some reason my friend, who owns a very reputable transmission shop, hadn't heard of the one I have. I'm just going to keep eliminating things one at a time. I get the right adapter for the fuel pressure gauge. I'll also ask him if the top end reader that he didn't loan me will give any more definitive info. Possibly he'll have a chance to do that at the end of the day, over a couple of 🍻. I'm determined to do this right, instead of throwing parts at it. The best that I'll get out of this is knowledge.
 
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