I am new to the zone and need some help. I have a 1993 Bronco 5.0 F.inj 130k.About 1 month ago truck started to run rough,take longer to start and hesitate a lot.Since we purchased it over a year ago we decided to do a tune -up, Cap,rotor,plugs,air and fuel filters, wires looked clean and in good condition so i did not change them.Verified timing to specs with spout out and truck still had same symptoms just not as bad for a few days.I then thought in tank fuel pump could be issue so it was changed, still same things.I then did a self test on the eec and found no codes with KOEO or CM.What suggestions does anyone else have before i dump anymore into this Bronco?
1993 running rough
- Thread starter RJF
- Start date
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BroncoJoe19
Active member
I agree, if you could give more info that may be helpful.
Before one checks for codes, one should thoroughly check for vacuum leaks. A vacuum leak could cause your problems and won't necessarily show up when one pulls codes.
Did you check your coolent fluid level and bring her up to operating temp before you pulled codes?
Could be bad wires.
One test is to spray a little water on them in relative darness and look to see if there are any arching/sparking.
Make sure that you do not wear any loose clothing or jewelry that could get caught in any moving parts.
IF the wires were ever removed, and replaced. SOme of them are suppossed to be twisted, or routed in a particualr fashion, or they could arch within the wires and one would get missfires, without seeing any external arching.
Miesk5 posted info about this and a link on how they should be routed Some time this June or July in response to a thread started by BillyToppless The title was something about needing a fireing order, or changed wires.
Here is the post... it was easier to find it thant to tell how to look for it.
http://broncozone.com/forums/index.php?s=&...ost&p=78014
The last thing I can think of off-hand is clogged or misfiring injectors, I think if they were misfiring, they would throw codes, but if they opened but no fuel got through, I don't think there is a OBD I code for that.
Before one checks for codes, one should thoroughly check for vacuum leaks. A vacuum leak could cause your problems and won't necessarily show up when one pulls codes.
Did you check your coolent fluid level and bring her up to operating temp before you pulled codes?
Could be bad wires.
One test is to spray a little water on them in relative darness and look to see if there are any arching/sparking.
Make sure that you do not wear any loose clothing or jewelry that could get caught in any moving parts.
IF the wires were ever removed, and replaced. SOme of them are suppossed to be twisted, or routed in a particualr fashion, or they could arch within the wires and one would get missfires, without seeing any external arching.
Miesk5 posted info about this and a link on how they should be routed Some time this June or July in response to a thread started by BillyToppless The title was something about needing a fireing order, or changed wires.
Here is the post... it was easier to find it thant to tell how to look for it.
http://broncozone.com/forums/index.php?s=&...ost&p=78014
The last thing I can think of off-hand is clogged or misfiring injectors, I think if they were misfiring, they would throw codes, but if they opened but no fuel got through, I don't think there is a OBD I code for that.
Hesitiation at start or after stop and go.It is not idling real smooth but not to bad.It hesitates after starting to move then picks up fine until you level out at about 40,there it will miss,after excelerating to above 45 it kind of smooths out and runs better.
I checked for Vac leaks first and everything appeared good.Coolant level is good, i recently put new waterpump,hoses and radiator in this truck as well.Truck was at operating temps when KOER codes were ran.
I did not do a water test on the wires but after each change of plug i did visually look at each wire connrction at plug and they all looked clean and in tact,i also checked conneection at dist cap as well.The only connection that looked a little corroded was at the coil itself, i did clean it up and reuse.I saw the link and the forum on the plug wires and it is routed about the same way.
How can the injectors be cleaned? The only other thing i was thinking about is ignition coil,TFI Module or Distributor stator? What are your thoughts on these?
yo!
I get some long crank times about once a year on a cold engine; ambients range from 40 to 75 deg F; so extremely cold temps are not da issue; same other sim thAngs to RJF, no DTCs, ign looking good, etc.
Now, I read a TSB for the 94-96's about Long Crank Times may be traced to a sticking Idle Air Control (IAC) valve, TSB 97-9-5 and I am 99% sure that is my problem. See the TSB at end of my post
for RJF, since his Bronco is 93.
Here is what Ryan writes... he was talkin' about Self Testing DTCs then went on with;
"...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..."
Here is his info on; Idle Air Bypass (IAB) 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
I get some long crank times about once a year on a cold engine; ambients range from 40 to 75 deg F; so extremely cold temps are not da issue; same other sim thAngs to RJF, no DTCs, ign looking good, etc.
Now, I read a TSB for the 94-96's about Long Crank Times may be traced to a sticking Idle Air Control (IAC) valve, TSB 97-9-5 and I am 99% sure that is my problem. See the TSB at end of my post
for RJF, since his Bronco is 93.
Here is what Ryan writes... he was talkin' about Self Testing DTCs then went on with;
"...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..."
Here is his info on; Idle Air Bypass (IAB) 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
BroncoJoe19
Active member
If you run the KOER self test, that would give a functional test of the IAC.
BroncoJoe19
Active member
How can the injectors be cleaned? The only other thing i was thinking about is ignition coil,TFI Module or Distributor stator? What are your thoughts on these?
Sorry... I can't give you a difinitive answer on these, other than maybe. Hopefully someone with more experience will answer these questions for you.
Howto clean injectors.
http://broncozone.com/forums/index.php?s=&...ost&p=78524
You might want to do a fuel pressure test. Although you have a new pump, if you have a weak ground, it may be a little flaky, and your lines may be underpressured.
Sorry... I can't give you a difinitive answer on these, other than maybe. Hopefully someone with more experience will answer these questions for you.
Howto clean injectors.
http://broncozone.com/forums/index.php?s=&...ost&p=78524
You might want to do a fuel pressure test. Although you have a new pump, if you have a weak ground, it may be a little flaky, and your lines may be underpressured.
Joe,
it is one of the EEC IV & OBD II quirks; "The IAB can pass and still need repair" as Ryan noted and the TSB states; "...Replace the AC Valve (IAC/IAB...) with a revised AC Valve if no Diagnostic Trouble Codes (DTCs) are present."
Figured I'd throw the IAC in because removing & cleaning it is a no $ check.
it is one of the EEC IV & OBD II quirks; "The IAB can pass and still need repair" as Ryan noted and the TSB states; "...Replace the AC Valve (IAC/IAB...) with a revised AC Valve if no Diagnostic Trouble Codes (DTCs) are present."
Figured I'd throw the IAC in because removing & cleaning it is a no $ check.
BroncoJoe19
Active member
Miesk5,
I noted that he had NOT run a KOER, and in your response to cleaning it, he stated within your post.
"IAB was clean and working properly as explained in broncolink above.Good thought though."
Do you have links on how to test the TFI module? I know some parts stores will do it for their customers.
Can they get flaky? or are they work- or not work components?
RJL,
Here is a list of grounds for a '92 - '96 bronc you may want to check them... could cause intermittent problems, flaky fuel pump, flaky PCM etc.
I took a look in my Haynes manual.
They list 10 separate grounds... A-J.
A. Starter mounting bolt
B. Right front of Engine compartment near the battery
C. Lower left front of engine
D. Right front of engine compartment on upper radiator support.
E. Left front of engine compartment Upper radiator support
F. Bottom of cowl panel
G. Rear of left fender apron
H. Behind bottom of right cowl panel
I. Left rear corner of cargo area near rear lamp assembly
J. Under center rear of vehicle on rear cross member.
I noted that he had NOT run a KOER, and in your response to cleaning it, he stated within your post.
"IAB was clean and working properly as explained in broncolink above.Good thought though."
Do you have links on how to test the TFI module? I know some parts stores will do it for their customers.
Can they get flaky? or are they work- or not work components?
RJL,
Here is a list of grounds for a '92 - '96 bronc you may want to check them... could cause intermittent problems, flaky fuel pump, flaky PCM etc.
I took a look in my Haynes manual.
They list 10 separate grounds... A-J.
A. Starter mounting bolt
B. Right front of Engine compartment near the battery
C. Lower left front of engine
D. Right front of engine compartment on upper radiator support.
E. Left front of engine compartment Upper radiator support
F. Bottom of cowl panel
G. Rear of left fender apron
H. Behind bottom of right cowl panel
I. Left rear corner of cargo area near rear lamp assembly
J. Under center rear of vehicle on rear cross member.
Ty Joe, I missed the reply.
Yes, TFI testing Links are in my site under;
IGNITION;
Ignition System;
Thick Film Ignition (TFI);
Troubleshooting
Yes, TFI testing Links are in my site under;
IGNITION;
Ignition System;
Thick Film Ignition (TFI);
Troubleshooting
BroncoJoe19
Active member
A MAP sensor should throw a code.
You may want to see post 5 and post 6 of this thread.
http://broncozone.com/forums/index.php?s=&...ost&p=77312
They can be tested, so you do not have to go parts changing on a hunch.
Also, it could be your TPS. Does it seem to be related to a particular range of throttle, and not necessarily related to RPMs?
There is a testing proceedure for the TPS, where one checks for approx 5 volts from the computer, and that it should return between 0.5 - 1.0 volts at idle, and nearly 5.0 at wide open. There should be a smoothe transition from 1-5 volts as one opens the throttle.
Unfortunatley I recently read that 90% of the time the TPS is in the first 10% of its range, and it can get flaky, and not be decerned with a volt meter, but should be checked with an ocilloscope. Yeah... right
You may want to see post 5 and post 6 of this thread.
http://broncozone.com/forums/index.php?s=&...ost&p=77312
They can be tested, so you do not have to go parts changing on a hunch.
Also, it could be your TPS. Does it seem to be related to a particular range of throttle, and not necessarily related to RPMs?
There is a testing proceedure for the TPS, where one checks for approx 5 volts from the computer, and that it should return between 0.5 - 1.0 volts at idle, and nearly 5.0 at wide open. There should be a smoothe transition from 1-5 volts as one opens the throttle.
Unfortunatley I recently read that 90% of the time the TPS is in the first 10% of its range, and it can get flaky, and not be decerned with a volt meter, but should be checked with an ocilloscope. Yeah... right
Last edited by a moderator:
A MAP sensor should throw a code.
You may want to see post 5 and post 6 of this thread.
http://broncozone.com/forums/index.php?s=&...ost&p=77312
They can be tested, so you do not have to go parts changing on a hunch.
Also, it could be your TPS. Does it seem to be related to a particular range of throttle, and not necessarily related to RPMs?
There is a testing proceedure for the TPS, where one checks for approx 5 volts from the computer, and that it should return between 0.5 - 1.0 volts at idle, and nearly 5.0 at wide open. There should be a smoothe transition from 1-5 volts as one opens the throttle.
Unfortunatley I recently read that 90% of the time the TPS is in the first 10% of its range, and it can get flaky, and not be decerned with a volt meter, but should be checked with an ocilloscope. Yeah... right
Problem solved, it was a bad ignition coil.$17.00 and it ran much better and cranked right up.
