cold start

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Shrek_95

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I have a 95 5.8l automatic when I start the engine it goes to about 1300rpm then drops to 1000rpm which is normal for warm up then it will drop to 500rpm +/- 100rpm for about 2 min then it will jump back up to 100rpm then to 800 rpm and runs fine after that. I changed the iacv and shot the tps which reads perfect voltage. The gas pedal responds perfect I ran codes and it is coming back with 111 koeo and koer. I can't find any vacuum leaks. And my truck runs rich enough to smell it while driving. Checked spark plus they look new I haven't sprayed any carb cleaner around the intake yet any input would be greatly appreciated.

I'm new to the bronco community and to the 5.8l

 

Rons beast

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Hey Shrek,  Welcome.

Code 111 is a system pass, or no problems detected.

You may want to do the test for vacuum leaks, but I suspect a temp sensor issue. 

On these type of problems you could search for some physical cause, (like a vac leak), but the real culprit is a sensor with odd readings , or a reactive unit that is a bit slow...or fast.  With the 111 code the comp is telling you that it can find nothing that feeds inputs outside the normal range, and all reactive processes are reading active.

The one thing that interests me is that you say the truck runs rich.  If it is the comp would definitely pick up on that.  UNLESS...this is happening only when the truck is cold and in the open loop running mode. 

Open loop is when the engine is running on preprogramed perimeters, and not through the inputs from the system sensors.  This happens when the engine is started cold, or a limp condition.

Perhaps there is a glitch as the comp switches from open to closed loop.  ( examp.: open coolent temp spec 100f, actual coolent temp spec fluctuation between 98 and 101)

On these issues there are other causes that can be frustrating to find until there is a greater disparity for the comp to pick up, and give a code to guide you.

(EGR fluctuation,or sticking, o2 sensor, MAF dirty, IAT, CT sensor, dirty throttle body, dirty intake, Dirty or lazy injector pintel, etc.)

You may want to check voltage through the CTS when cold. ( sorry I don't have that spec on hand), but I suspect it is in range or the comp would throw a code.

Finally go back to basics and check base timing.  Also you didn't mention mileage, but a can of seafoam may be in order. (dirty valves)

I would not try throwing parts at this problem, it can get expensive.These things can cause hair loss and bad eyesight........Sorry I couldn't be more help. 

Good Luck

 
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Shrek_95

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Thank you very much for the info. I have disconnected my map sensor to see if there was a change in the running of my truck but no change until I pulled the vac line off and sealed it the the truck slowly climbed in rpm Webern I hooked it back up it went back to 800rpm. I turned of my truck disconnected the tps restarted it and got the same results as before. I also need the location of the mafs I thought it was supposed to be on the air cleaner but can't find it. And I will have to do research on the other sensors you mentioned thank you again.

 
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Shrek_95

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Also while driving and it gets up to temp the check engine light comes on would the heated oxygen sensor located on the head cause this problem. I still get no codes btw

 

Rons beast

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Does the CEL come on and stay on?   If so one would expect it would have to be storing a code.

If it comes on and goes off, there should be a pending code.

Do you have a code reader?  How are you accessing the codes?

 
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Shrek_95

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I stays on while i'm driving but as soon as I turn the truck off to hook up my code reader the light goes out and does not come back on. And that is what I thought I thought there should be a code some where but everyone it comes back as normal no matter what test I perform

 
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Shrek_95

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Ok I will try that I was looking at my notes and I did get a continuous memory code of 512 which is keep alive memory test fail and could not reset it my book says that is probably from disconnecting the battery. But I will try to hook up my code reader when I get home tonite

 
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Shrek_95

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Ok just did the test I got a 173 code which is heated oxygen sensor failure/rich. But would that cause the cold start problem koeo is still coming back 111 and continuous memory of 512 I just figure out how to clear it I guess i'm to slow on the buttons lol

 
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Shrek_95

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Ok just changed oxygen sensor out there was no change. But if I start my truck and let it idle with the oxygen sensor disconnected it runs fine it never drops below 800rpm. I noticed that I had an exposed wire for the starter I fixed that (temporarily) so that it wouldn't try to start when hooking the battery up could that of shorted the oxygen sensor out. I don't see them crossing anywhere so that could happen. or could I just be buying the wrong oxygen sensor

 

Rons beast

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Hey Shrek,

I recall there being a problem with the ground for the heated O2 sensor.  The heated sensor is the one at the cat. Your Bronc should have 3 one in each exhaust manifold and one at the cat. Which one did you change?

I also believe that the code doesn't necessarily condemn the O2sensor, but indicates that the sensor reading is showing a rich condition beyond perimeters.

See if you can trace the wires for the heated O2, and be sure they are not broken or chafed. While you're at it check all grounds especially the ground at the engine block. (just a thought...bad grounds can cause all sorts of odd things)

I'm going to look for more info on the O2 ground problem. (someone else here may have it handy)

and let you know.

 
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Shrek_95

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My truck only has one oxygen sensor right at the y pipe as potter my vin. Auto zone gage the oxygen sensor last night so i'm going to get a new one tonite and I will run the wires also thank you

 
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Shrek_95

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Shot ask the grounds I could find shot for continuity in all 4 wires for the oxygen sensor everything checked good on that side I guess i'm going to try a new oxygen sensor

 

miesk5

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yo Shrek,

This is from

1994 PCED OBDI-A
Diagnostic Routines Symptom Flow Charts — Chart 7
Unique Idle Concerns   —Fast Idle

a16145b.gif

Check for vacuum leaks;

Vacuum Leak Symptoms, General; "...Too fast an idle speed; A rough idle or stalling; Hesitation or misfiring when accelerating

Vacuum Leak Test; On an idling engine check for vacuum leaks using a~3' garden hose section. On COLD ENGINE only, use propane torch w/rubber hose attached, UNLIT, when it gets to the the leak the RPMs will rise

  See Vacuum Leak Test @

http://broncozone.com/topic/23994-90-58l-getting-continuous-code-33-and-running-code-44/

 Post #20

Sensor, Idle Air Control (IAC), Idle or Noise Problems & Troubleshooting; "...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..." READ MORE; slow to load,

http://web.archive.org/web/20100919152357/http://carquest.com/common/downloads/partsTechEnginett3q00.CQ.pdf

Read Strategies by Ryan M @ http://web.archive.org/web/20130816075931/http://oldfuelinjection.com/?p=64

Start / Crank
This is the start.... The EEC needs to senses several things to start an engine:
* Power to EEC and fuel pump(s)
* Slow and irregular PIP signal from the distributor
* MAP low and irregular
* TPS is closed
* HEGO shows lean

Read; Cold Start & Warm Up,

Cold Drive-Away; The Throttle Air Bypass (IAB, AKA Idle Air Control (IAC) etc.)

will be controlling idle, we need a nice smooth idle...Idle will increases 100-200RPM if the ECT or ACT is over 225F. This RPM increase will help burn the rich mixture cooling the combustion chamber. The faster RPM speeds up the accessories, specifically the water pump and fan. Belt fans will speed up )

 ===============

DTC 173 system indicates rich

  • Possible Causes:Fuel injectors.
  • HO2S.
  • Secondary Air Injection (AIR) system.
  • PCV/Hose.
  • Vacuum.
  • Canister Purge Solenoid Valve (CanP/CPRV):
  •  
  • HO2S always rich could be caused by Moisture inside HO2S harness connector resulting in a short to power.Key off.
  • Disconnect the suspect HO2S from vehicle harness.
  • Inspect both ends of the connector for damaged or pushed out pins, moisture, corrosion, loose wires, etc. Service as necessary.

 

Rons beast

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Hey Shrek,

My Bad, I looked up with Actron and code 111 relates to IAT or Intake Air Temp sensor.  They are easy to change and available at parts stores for under $20.00

code 173 relates to a fuel trim malfunction bank 2....My question is if you only have 1 O2 sensor, how does the comp determine a malfunction in bank 2?

Was your truck engine modified?  exhaust changed? engine swap?

 
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Shrek_95

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I don't know how it would know if bank2 is running rich everything I looked at said 111 is everything checks normal and 173 in both my books says oxygen sensor fail/rich. I bought the proper oxygen sensor today

 
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Shrek_95

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I do only have one oxygen sensor I think it is crazy to. I'm going to have to do research on the iat sensor to see where it is. I got the part number from ford for my hego I will do a vacuum test this week. If I use choke cleaner will it react the same as a propane torch in the way that it will raise my rpm if there is a vacuum leak

 

miesk5

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yo,

IAT Sensor Location
(5.8L
(Part of 9424)

Lower Intake Manifold

v4795g.gif

Item Part Number Description 1 — ECT Sensor Location
(Part of 9424)

2 9F593 Fuel Injector

3 9C968 Fuel Pressure Regulator

4 9D280 Fuel Injection Supply Manifold

5 9D930 Fuel Charging Wiring

6 Fuel Return Tube (Part of 9F792 Assembly)

7 IAT Sensor Location 5.8L (Part of 9424)

8 Water Temperature Sender Location (Part of 9424)

9  FuelPressure Relief Valve (Part of 9F792)

 
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