1995 Bronco 5.8 low idle speed stall after warm up

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Skinner95

New member
Joined
Sep 8, 2015
Messages
33
Reaction score
0
Location
Delaware
I am having a tough time diagnosing a rough idle and stalling issue with our 1995 FSB 5.8.

It will start and run at fast idle absolutely fine but when the engine makes the transition to low speed idle after about 45-120 seconds it more often then not begins to misfire and  stall.

At times this does not occur and the Bronco runs like it just came off the showroom floor with surplus power and torque to smoke the tires.  

When this does happen ( more often then not ) you can drive the Truck but you have to play devils advocate with pedal flutter at idle until it begins to settle out a little after full warm up if at all... While driving you can feel a pronounced lack of power during acceleration and while cruising you can notice a missing through the engine.

As indicated above ,When it goes through the starting process properly it runs flawlessly so I am more inclined to think it is something Stupid Simple. If it were a coil, Pick Up Module, ECM, it would do this All The Time  not just after idle kick down and then not self fix and run fine..... .

Have done several days of diagnostics from OBD readings to fuel pressure testing.

Easier to say what has been done this far to resolve the problem... Fuel pressure leaked down, traced to stuck fuel injector REPLACED and fuel pressure regulator, REPLACED Both test  GOOD, Fuel Flow, GOOD,  TPS,  REPLACED, Idle Mix Valve ,REPLACED, Vacuum leaks tested and found at canister REPLACED & GOOD, Ignition Wires REPLACED, Spark Plugs REPLACED, Air Filter REPLACED, Fuel Filter REPLACED, EGR valve came up bad during last test and REPLACED

***.... I know someone here has had this problem and probably replaced a $19.95 part ... We did fix some underlying fuel issues but Cm'on Just short of scrapping the Fix Or Repair Daily and going back to the CK Blazer...LOL...

 

Rons beast

Active member
Joined
Dec 13, 2007
Messages
1,537
Reaction score
13
Location
Florida..in my mind , sitting on the beach
Hey Skinner,

Welcome and sorry you have this problem that makes you loose hair.

Question: After everything was replaced have you cleared any codes, run the truck for 10 miles or so and rechecked for codes?

Sometimes these things will give a code somewhat unrelated to the actual problem.  The issue is the problem part is creating a condition that throws a code or 2..or 3.

Tell us what the codes are now since you did the parts replacement, and we will go from there.

Good luck 

 
OP
OP
Skinner95

Skinner95

New member
Joined
Sep 8, 2015
Messages
33
Reaction score
0
Location
Delaware
Sorry

I was slightly detained today...

The only code I have coming up is

538

This is after all the indicated repairs had been made and the truck driven for 1/2 hour.

I performed the OBD test again today and have the same code.

 
Last edited by a moderator:
OP
OP
Skinner95

Skinner95

New member
Joined
Sep 8, 2015
Messages
33
Reaction score
0
Location
Delaware
Code 538 comes up as invalid cylinder balance test due to throttle movement during test...

 

Rons beast

Active member
Joined
Dec 13, 2007
Messages
1,537
Reaction score
13
Location
Florida..in my mind , sitting on the beach
If you clear the code does the CEL come on and the same code come back?   What happens after clearing the code and driving the truck at least until it's warmed up?

(I'm trying to determine if this is a hard code or an anomaly.)  What type of code reader are you using?

 
OP
OP
Skinner95

Skinner95

New member
Joined
Sep 8, 2015
Messages
33
Reaction score
0
Location
Delaware
The code was cleared  prior to each time the test has been performed this code only comes up when performing the KOER test on a Ford OBD I from Innova

Was getting several codes and have performed all repairs to eliminate them. Low egr was found to be the canister rusted through at the attachment bracket on the bottom of canister.

Only thing that I can not resolve is this rough idle and stalling issue. Drove the truck yesterday and ran like crap going out... Ran perfect going to another location then like crap again on the way back. Brief stops in between...

 

Rons beast

Active member
Joined
Dec 13, 2007
Messages
1,537
Reaction score
13
Location
Florida..in my mind , sitting on the beach
Since there aren't any codes to trace to a rough idle and stalling issue I only have guesses. 

1-MAF sensor....there is a procedure to check the unit, unfortunately I don't have it.  I will see if I can find them or someone else here can chime in if they do. This part is too expensive to just change and hope.

2-coolant temp sensor that is out of range. (again a guess.)   I had found one that was causing problems on a Ford truck and no code was set.

3-fuel pump relay intermittent rapid failure.

4-since the code refers to throttle movement ...could the TPS be installed incorrect or it could  be defective even if new.

Good Luck

 
OP
OP
Skinner95

Skinner95

New member
Joined
Sep 8, 2015
Messages
33
Reaction score
0
Location
Delaware
Rons Beast,

I Thank You for your help and I am taking your advice to heart since I have been fighting this issue so hard.

I did have this issue  before about a year ago and done several part swaps with no success then one day it quit and did not rear up again until the past few weeks...

TPS issue Understood Unfortunately This would be the second unit thinking the same thing... Did not do an actual resistance test Just replaced it.as far as installing incorrectly it is a fairly simple install but I guess I could have missed something?

..

Will try the MAP sensor and the Coolant temp sensor The Fuel Pump Relay was swapped out even though during the fuel pressure test there were no indications of loss of pressure or lower pressures noted.

For experiment purposes I tried turning the AC on and off... When switched idle runs smooth then goes back to rough after a few seconds turn off and the same anomaly occurs

I do not know the connection routing for the TPS thinking it may be connection but then the missing issue is very precise in timing so thinking connection issue would be inconsistent.

Again this problem is part of the start up procedure and occurs when fast idle kick down occurs . if it begins to idle rough I turn it off restart the engine and it will run fine then after it goes through the fast idle kick down it begins to idle rough again. this occurs no matter what the operating temp is and again when it does not happen the truck runs like new...

.

If someone knows the system procedures of this vehicle when it first starts then as it warms up goes to step 2 where it begins to idle down but runs rough  I may be able to track down the culprit

Just got a code 51 ECT sensor

 
OP
OP
Skinner95

Skinner95

New member
Joined
Sep 8, 2015
Messages
33
Reaction score
0
Location
Delaware
Replaced the ECT Sensor and the Air Temp Sensor

O2 Sensor Map Sensor still the same results...

Done a manual cylinder check with all 8 cylinders having a noticeable effect when plug wire removed at idle so we know all 8 are firing...

I have a second bronco same year model engine etc. Should I swap out the ECM

 

Rons beast

Active member
Joined
Dec 13, 2007
Messages
1,537
Reaction score
13
Location
Florida..in my mind , sitting on the beach
At this point If everything about the vehicles are the same, I would do that swap.  I beginning to thing it may be ECM. On first start the ECM is supposed to run on an open loop at preprogramed parameters. Then upon sensing engine warm up it is to go to a closed loop running state giving engine commands according to engine demand.

Good Luck

 
OP
OP
Skinner95

Skinner95

New member
Joined
Sep 8, 2015
Messages
33
Reaction score
0
Location
Delaware
Had to do a site visit for a work project this morning so I took the Bronco and it ran flawlessly this morning... Got to the jobsite 15 Min away and shut it down... Went to head back and after re start it began doing the same routine so when I arrived back to the office I ran the KOEO test and came up with the standard 111 , 10 , then code 113 came up.

Ran the KOER test and again got the standard connection code then I got a 173 , and 583 code.

Ran a second test to confirm the codes and only came up with the 538 code

While running the KOER test the connect the unit I am using has a black square to indicate communication of codes. I noticed it was flickering then it would flash a few times to indicate communication then start to flash as if it were loosing communication again. then came on solid.

I checked the connections at various locations and all seem to be fine. when I turned off the code reader the engine went into fast idle briefly then went back to normal idle.

Again I Don't Know...LOL... I will try the ECM swap with the other Bronco to see if that makes a difference.    

 
OP
OP
Skinner95

Skinner95

New member
Joined
Sep 8, 2015
Messages
33
Reaction score
0
Location
Delaware
Also have the SRS dash light flashing now with a 34 and 54 but I don't believe they are associated with the ECM ?

 

freedomgirl

New member
Joined
Sep 15, 2015
Messages
15
Reaction score
1
Location
Rochester NY and Naples Florida
Hi

You guys are killing me and getting me very excited. I have a 92 with a 5.0 and I'm going crazy with the same issue....i did new plugs wires distributor, new egr valve and tube, new air filter new pcv. I am having an additional problem with oil getting into the air filter from the breather tube. Pretty saturated after just a thousand miles. Can't wait to hear what you figure out.

 

Rons beast

Active member
Joined
Dec 13, 2007
Messages
1,537
Reaction score
13
Location
Florida..in my mind , sitting on the beach
Hey Skinner,  Check all your grounds. Body to frame...battery to engine/frame...etc. These old trucks are known for the grounds getting corroded and loose. The management system may be intermittently searching for ground.

Sorry I didn't get to that earlier.

(Welcome freedomgirl)

 
OP
OP
Skinner95

Skinner95

New member
Joined
Sep 8, 2015
Messages
33
Reaction score
0
Location
Delaware
I hear you on that...

I will do a once over on the common grounds.

Hi freedomgirl

 

freedomgirl

New member
Joined
Sep 15, 2015
Messages
15
Reaction score
1
Location
Rochester NY and Naples Florida
Thanks guys! Glad to be here and really happy to have found you. Skinner95 do you have a breather tube going from the motor to the air filter box? If yes, does it spit out quite a bit of oil?

 

Bully Bob

TOP GUN
Moderator
Joined
May 23, 2004
Messages
3,844
Reaction score
12
Location
Boulder City, Nevada (Las Vegas area)
Hi Freedomgirl..,

Can you supply a pic of that oil sucking hose. ?  That just doesn't sound right. Where on the eng. does this

hose come from..?  (sounds like a PO add-on)

Ron & Skinner may get a clue from a pic.

 

freedomgirl

New member
Joined
Sep 15, 2015
Messages
15
Reaction score
1
Location
Rochester NY and Naples Florida
Thanks Billy. I will upload pic tomorrow. Just another thought on this problem. Could it be the map sensor? I was messing around with it tonight as i was checking all my connections and when i pulled off the vacuum hose and choked it off with my finger it didn't stall out. Didn't run perfect, but better. I just don't know. Perplexed

 

Members online

No members online now.

Latest posts

Forum statistics

Threads
22,509
Messages
135,880
Members
25,108
Latest member
Utahstroke
Top