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Discussion Starter #1
Hi Guys,
I have a 1995 Ford Bronco with V8 5.0L EFI engine and E4OD trasmission.
The problem started a few weaks ago, the engine braking "disappeared". The speed is about 30-40 mph (~50 km/h) and the car is running smoothly but almost no speed loss (of course without pushing the pedal).
What could be the problem?
thanks in advance,
Zoltan

I am Hungarian, and although my mechanic is very good but you should know that in Hungary there could be around 4-5 Ford Broncos so my mechanic's never seen any before...
 

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Yo Zkonya,
WELCOME!

This is by Ford and similar to your 95; 96 Bronco-F-Series Workshop Manual (PARTIAL)


coastdown downshift occurs as the name indicates, when the vehicle is coasting down to a stop.

Diagnosis by Symptom Index

•No Engine Braking with Overdrive Cancelled
260 — ELECTRICAL ROUTINE
Powertrain Control System
•Electrical inputs/outputs, vehicle wiring harnesses, powertrain control module, coast clutch solenoid
•Run On-Board Diagnostics. This can be done with a Scan Tool or DIY Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19
A helper is good to assist in reading Codes; best is to take a cell fone vid and replay it.
Some basics;
Visual Check
1.Inspect the air cleaner and inlet ducting.
2.Check all engine vacuum hoses for damage, leaks, cracks, blockage, proper routing, etc.
3.Check EEC system wiring harness for proper connections, bent or broken pins, corrosion, loose wires, proper routing, etc.
4.Check the Powertrain Control Module (PCM), sensors and actuators for physical damage; IAC, TPS I see was replaced, etc.5.Check the engine coolant for proper level and mixture.
6.Check the transmission fluid level and quality. See E4OD Fluid Condition Check Below)
7.Make all necessary repairs before continuing
8. Check headlights

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.

Turn off all accessories; radio, lights, A/C, heater, blower, fans, etc. (close driver's door)

Then turn off engine and wait 10 seconds.

Do KOEO test First

Post Code(s) here according to:
KOEO
&
KOER

Service as required. Clear codes, road test and rerun On-Board Diagnostics.

360 — HYDRAULIC/MECHANICAL ROUTINE
Main Controls (Valve Body)
•Bolts not tightened to specification
•Retighten bolts to specification.

•Gaskets damaged
•Inspect for damage and replace.

•Coast clutch solenoid damaged, stuck
•Refer to electrical routine No. 260.

•BS3 check balls missing or valve body separator plate seat damaged
•Inspect for damage. Service as required.

•3-4 shift valve stuck, damaged or misassembled
•Inspect for damage. Service as required
 

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yo,
Have you tried the Self-Test for Diagnostic Trouble Codes (DTCs)?


Idle Air Control Location pic Source: by SeattleFSB (Seattle FSB)
http://www.supermotors.net/getfile/853886/fullsize/idle-air-controller-(iac).jpg

Overview & Testing; "First let me say this little thing has many names. But they all talk about the same item under the hood. Here all the names I’ve had the torture of learning throughout the years: Idle Air Bypass, Idle Air Control, Idle Speed Control, Throttle Bypass Air, Idle Bypass, Inlet Air Controller, Inlet Air Bypass, Intake Air Bypass, Intake Air Control; This is really easy to test. First as with all problems you should gather the trouble-codes from the computer. Follow the codes for testing and repair. If you get a code that points to a problem with the IAB start the vehicle and bring the engine up to operating temperature. Allow the engine to idle without any driver input to the throttle or pedal. Go under the hood, and disconnect the electrical connector to the IAB. If the engine begins to stubble or stalls the IAB is functional and does not need to be repaired. If the engine idle does not change you should remove the IAB for inspection. The IAB can pass and still need repair, or it can fail and not need replacing. The plunger and internal spring can get clogged with dirt and oil. This will slow down the air flow and not allow the IAB to function properly. Remove the IAB and clean it. There are 2 halves to the IAB, and you can not buy just one half, but you can take it apart to clean it. But if the internal solenoid is faulty the IAB needs to be replaced..." SEE & Read More..Source: by Ryan M (Fireguy50) at
http://web.archive.org/web/20101201013829/http://fordfuelinjection.com/index.php?p=39

Removal & Cleaning in a 93 Source: by Bobby (blue) http://www.supermotors.net/registry/media/146158\


DTC 411 Idle speed system not controlling idle properly (generally idle too high); "...DTC 411 indicates a dirty/ bad or connector issue w/Idle Air Control valve (IAC). inspect it for crap. Some can be cleaned. But our's shouldn't since the TSB says; "...Cleaning is not required on sludge tolerant throttle body designs released for 1991 and newer model years...." in Idle Air Control (IAC) Sludge; Poor Idle TSB 91-25-07 for 85-92 Bronco & F Series & many others; "...Hard cold starts, hesitation and stalls on initial start-up or during idle or decel may be caused by sludge in the throttle body and/or idle by-pass valve. Sludge deposits or oil film on the throttle body bore and plate or the idle air by-pass valve may cause one or more of the following conditions. Hard Cold Start, Stall On Initial Start-Up, Stall During Idle, Stall During Decel, Rough Idle, Rolling Idle, Hesitation During Acceleration. A new idle air by-pass service kit (F2PZ-9F939-A) is now available for service use to correct sludge contamination concerns of the throttle bore and plate only. It eliminates the need to clean the majority of past model throttle body applications. Cleaning is not required on sludge tolerant throttle body designs released for 1991 and newer model years..."
Source: by miesk5 at FSB

DTC 412 Cannot control RPM during KOER self-test high RPM check. "...indicates that during the Engine Running Self-Test, engine rpm could not be controlled within the Self-Test upper limit band. Possible causes: Open or shorted circuit. Throttle linkage binding. Improper idle airflow set. Idle Air Control (IAC) solenoid contamination. Items external to Idle Air Control system that could affect engine rpm. Damaged IAC solenoid. Damaged Powertrain Control Module (PCM). Turn the key "OFF", connect a tachometer. Then start the engine and disconnect the Idle Air Control (IAC) harness connector. Does the rpm drop or engine stall? If it does, turn the key "OFF" and disconnect the IAC. With an Digital Volt/Ohm Meter (DVOM) check the resistance of the IAC solenoid. It should be between 6.0 and 13.0 ohms. Due to diode in the solenoid, place the DVOM (+) lead on the VPWR pin and the (-) lead on the IAC pin. If it is not within specification, replace the IAC solenoid..." miesk5 Note; Ford says the range is 7-13 ohms
Idle or Noise Problems & Troubleshooting; including HIGH IDLE Conditions; "...For high idle problems, try unplugging the IAC motor. If the idle drops, its usually due to an input signal to the computer which results in the computer raising the idle speed. If this is the case, look at all of the computer inputs to make sure everything is up to par. If the engine RPM does not drop when the IAC motor is disconnected, then either the IAC motor is not functioning properly, or, there is a vacuum leak in the engine. Stop the engine, remove the IAC motor and block off the passages. Restart the engine to see if there is any change in engine RPM. An idle speed higher than base idle specs indicates a vacuum leak. If the engine RPM is at base idle specs, then the IAC motor is bad. Resistance specs are 7-13 ohms. A good resistance reading does not necessarily mean that the IAC motor is good. Occasionally, an IAC motor will become weak, and will actually bypass too much air, causing a high idle condition even though everything else is operating properly..."
Source: by Mike N
 

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Discussion Starter #5
Unfortunatelly I do not have a code reader, but I will try to get one asap and I will try to read the info.
but all the informations given were very useful for me so I printed everything and I'm going to the garage to discuss these things with my mechanic. (Actually I am chemist I know a lot of things about materials - mainly nanomaterials - but almost nothing from engines...)
thanks a lot,
Zoltan

Could you please give me advice about a good but not expensive code reader I could by from the eBay?
 

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yo,
You can test for Code(s) with a short jumper wire or paperclip.
 

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Discussion Starter #7
4 month later... the engine was partly rebuild, new rings, new bearings, etc.
the sound is much better, the rpm is ok, only minor proble, that the chekc engine light is sometimes on, sometimes off. No error code. what could be the problem?
thanks
 

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Just skimmed this post, so I may have missed it, but could your torque converter just be disengaging? That could cause a problem and would make sense as to why it would drive when you hit the pedal.
 

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Discussion Starter #9
Same as when I posted those links - did you read them yet?
yes of course I read them. I bought a code reader (innova 3145) and I read out the codes. As I said since that we worked a lot on the truck (changing cylinder rings, all the bearings, etc.) and it is not easy from Hungary - you know I have to wait 2-3 weeks for every pieces, since the mechanics are not familiar with this car here...
The last couple of days the code reader was not able to read the engine codes; before the KOEO test the code reader checks the solenoids, this step was ok, but after that no signal.
5 minutes ago I was able to read the codes manually, I suppose that some cables are oxidized and there is no contact.
the codes:
539
539
1
332
536
332
536
thanks,
Zoltan
 
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