Runnin Good Then Running Bad!

[wyattearp101]

Greetings, have a 1995 5.0 litre, 127,000 plus miles on it. Motor is strong but as temp gets to normal, it will hesitate ,or sputter as I try to hold a steady speed....

If You hold the brake and rev the motor to 2500 rpm I get the same response. I have suspected the fuel was not being burned ( Lack of correct fire??) Replaced the coil, did tune up ect...... even had mechanic check timing... Im thinking issue with distributer but i dono!!! Also as I reach normal operating temp, I'll get a clatter as I put any load on the engine. Any ideas????????

 

[Stomper4x4]

Try a new fuel filter. When they start to clog, they can let enough fuel through for idleing, etc.....but when the motor is revving, the partial clog doesnt let enough fuel through for the higher RPM's.

 

[Txquadhunter]

does it seem like it's flooding out? my 86 302EFI use to do the same thing. it turned out to be a heat sencer in the intake that tells the motor when it's up to opt. temp. when it goes out it'll tell the motor it's still cold and add more fuel. I'm sure it's one of the sencers doing this. if you got a auto zone near you stop by there they'll hook a code scanner up and scan for error codes for free.

 

[kikenhorse]

Good info... Did not know they would scan at all let alone free!!

 

[azrockrat]

check your fuel filter and if that is not it pull the codes from the puter

 

[wyattearp101]

I did the code scan, and did'nt give any info relating to the issue, and the fuel filter had been changed out less then 8k miles ago so i'm still lost for the problem, and a heads up on the Auto zone free scan, they use an OBD II scanner thats good for 96 and newer cars ( emmissions Testing for those states that do this) and the tester will only give a code if an item is flagged, eg. EGR valve!!! the EGR valve may actually be good and another problem may be causing it to throe a code. The Scanners the shops use cost around $ 3500.00 retail, thats why they get up to $100.00 for a diagnostic test. The OBDII scanner Autozone does for free you can by from them for $125.00. Ant other Ideas ?????

Thanks>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

 

[Txquadhunter]

less then 8K on fuel filter can be like 500K. tanks over time will get crud and build-up over time which can **** thru the lines at any time. even more so if ran low on fuel. i keep spares in all my trucks for those times. the 2 i take offroad clods filters qhicker then anything from the roughness of the trail knocking rust and whatever else clingin inside the tank. so never hurts to spend the few bucks on new filter to see. not sure where ya re but it sure don't cost that much to have a shop put on a computer in my area. last mine was it in cost me $115 that was computer scan, 3 new sencors, few other lil things and labor. which was before i learned how to pull my own codes and haven't had to as of yet, but comes in handy knowing how.

also here is the way to get error codes yourself.

http://www.therangerstation.com/OBD_I.html

 

[Gunner]

ummmm on changing that fuel FILTER thing i had this same problem with my 86 bronco so i changed out the FILTER and still had the problem so i traced the hole fuel line and found two more filters. so all in all i had three fuel filters going from the tank to the engine. i dont know if factory did this or previous owner but i took all three of those things out and put one larger fuel filter and i run great now.

 

[amcabbott]

try the oxygen sensor they are only designed to last 50,000 mls You may have more then 1 some do some do not depends where it was built replace them all. check for a vacume leak (e.g.r. valve? air intake rubber hoses could crack with time, bad gasket on throttle plate) as a leak will play **** with your m.a.p. sensor neither will bring on a code. if the truck runs better cold thats because the computer is running in open loop (open loop is a set of perimiters built into the computer) till it warms up then switches to closed loop ( closed loop is the computer running off data collected by the sensors)

 

[myers]

It sounds like your computer is having a hard time switching from closed loop to open loop. I would venture to bet it's either an o2 sensor or a coolant temperature sensor

 

[Broncoholics]

My 89 Bronco had a problem simular and found it was the valves in the heads.

Before we had leaded gas, now its all unleaded. The valves will get hot and burn holes or in my case recessed theselves 1/8 - 1/4" up inside the head causing a leak. This makes the truck run bad. I did a compression test and it came out OK. I then did an Air Leak Down test and found it wouldn't hold air pressure. I could actually hear the air leaking into the upper galley of the engine. I took off both heads and had case hardened valve seates installed and it ran like a new engine!

 

[wyattearp101]

Thanks for all the tips, some of these I've already done some not, I'll get back after further checks

 

[ron753]

check your exaust system sometimes if it is starting to stop up this will cause the problem the best way i found is while it is running put your hand close to the exaust pipe and see how much exaust is comming out if there isn't much comming out most of the time it's the catal. converter

 

[BRONCO JIM]

HEY GUY,I KINDA HAD THE SAME THING WITH MY MOTOR,AND IT TURNED OUT TO BE THE WATER TEMP SENSOR. ABOUT 17 BUCKS AT AUTOZONE,BUT I WOULD ALSO CHECK YOUR DIST. TIMING,AND DO CHANGE THAT FILTER,I VE HAD THEM CLOG IN 1 K,.GET A HAYNES BOOK,AND A VOLT,OHMS METER,AND YOU CAN CHECK YOUR OWN CODES,THEY RE LISTED IN THE BOOK,AND IT DESCRIBES HOW TO DO IT VERY WELL. SAVES $$$$$$ OVER SHOP WORK !

 

[Dan 2663]

I have the same with my 1990. After its warmed up it idles and drives like it has a mind of its own. I am tracing down the problem, error code 84... EGR but I hear a hissing from down by the cats up to the bellhousing, I think it might be a vaccum leak from the smog pump or related things inwhich affecting the EGR system causing the code 84. my EGR valve, EGR sensor and EGR vaccum selnoide seem to check out fine when I test them.

Any other ideas.....maybe the smog pump has a valve. My exhaust fumes arevery

strong, more so than usual..

Dan

 

[1993 Bronco driver]

My '93 is doing the same thing. I can hear the fuel pump struggle, so I assumed it was a filter. Some owner before me placed a non-standard filter inline. Now I cant get the duck bill connectors to disengage. No room between the filter and the coupling to get the tool in.

Anyone have any ideas how to fix this? Besides replacement of fuel lines?