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jazzmaster
jazzmaster, ASE Certified Tech
Category: Ford
Satisfied Customers: 2951
Experience:  ase certified--32 yrs experience
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I have a 86 f150 5.0 not firing the back half of the dizzy

Customer Question

Hi I have a 86 f150 5.0 not firing the back half of the dizzy 8154 wires pulled no change and no codes
Submitted: 1 year ago.
Category: Ford
Customer: replied 1 year ago.
I got on it getting on the freeway i noticed that the tach stopped at 3000 even though the revs were still increasing. It shifted and then started shuttering and i limped it home. I ran the code scanner and got 11 both KOEF and KOER. The 86 wont do a balance test so I pulled plug wires 1 at a time and had no change in the running with 8, 1, 5, 4 off. It does start but wont get up the drive way.
Expert:  Lou P. replied 1 year ago.

Have you removed the cap and checked for arcing ? Sounds like a distributor cap issue. Check that or replace and let me know. :) Lou.

Customer: replied 1 year ago.
I have not seen or heard any arcing until I pull off the wires
Expert:  Lou P. replied 1 year ago.

That doesn't matter. The spark had to go somewhere. I say at least try it and see what happens. Same with the rotor.

Customer: replied 1 year ago.
Try what?
Expert:  Lou P. replied 1 year ago.

Replacing the distributor cap and rotor

Customer: replied 1 year ago.
Ok but they have about a thousand miles on them
Expert:  Lou P. replied 1 year ago.

Ok that's good info so the issue happened after the new parts ?

Expert:  Lou P. replied 1 year ago.

And never think cause a part is new that it is ok. New means nothing lol

Customer: replied 1 year ago.
No i put very few miles on the truck since then. Its been running great until I jumped on it getting on the freeway. It was reving fine but the tach stopped at 3000 but the revs still were increasing till it shifted and then started stumbling and bairly limped home
Customer: replied 1 year ago.
Odd to me that a factory tach would stop counting revs at high RPM but continue to work after they went down. Wondering if its the module or something. Odd also that these cylinders are all at the back of the Dist in order
Customer: replied 1 year ago.
Also on the way home it would intermitenly hit on all eight and run good for just a minute then stumble and shake again.
Expert:  Lou P. replied 1 year ago.

That is my thinking. Since the wires are all in one spot that tells me distribute issue. Weather it be cap or rotor or pickup coil.

Customer: replied 1 year ago.
Ill go get a cap and rotor. Weird it does arc to those plug wires when i hold them just away from the terminals might be a tad weak though.
Expert:  Lou P. replied 1 year ago.

What else did you change before this happened ? And why did you change parts ?

Customer: replied 1 year ago.
New cap and rotor no change.
Expert:  Lou P. replied 1 year ago.

Did you see my last post ?

Customer: replied 1 year ago.
No its not updating till i refreash. Last year I Just did a tune up wires, plugs, cap and rotor. I was thinking since its a 86 and does not have sequencel fuel injection, can you tell me which injectors fire at the same time, could one be shorted and cause the other injectors that fire at the same time not to fire as well
Customer: replied 1 year ago.
We have Church gotta go, ill try you when we get back.
Expert:  Lou P. replied 1 year ago.

Ok so the injectors would not be the issue as each bank would be affected on the whole bank. Not as random as your cylinders. Did you go over the firing order ? I'll send it to you just for you to double check.

Expert:  Lou P. replied 1 year ago.

Here. It's just worth a look.

Customer: replied 1 year ago.
Thats the firing order for a 5.0 HO not the f150
Customer: replied 1 year ago.
Also its strange that its all four corners of the engine. Is there a limp home mode?
Expert:  Lou P. replied 1 year ago.

You said you had the 5.0 in your description ????, ok I will opt out. My apologies. Maybe another expert can help. Lou

Expert:  jazzmaster replied 1 year ago.

hi, do you still need help with this ?

do you need the firing order for the truck or do you have that and feel the firing order is right ?

Customer: replied 1 year ago.
I do but im not all that impressed with the help so far. I think I just want a refund
Expert:  jazzmaster replied 1 year ago.

well, let me try to help first and then if you want a refund -no problem..jazzmaster

there is no limp home mode .

This may be either the distributor or a weak coil issue

do you have bat voltage at the coil with the key on ?

also, do you have at least 9.5 volts on the other small wire at the coil when its running .

the pick up coil in the dist may be bad as well..please let me know ..thank you

Customer: replied 1 year ago.
Wont get a chance to work on it again till next week will our chat stay open? My book says "if the problem is bad enough the EEC IV will switch to an alternate mode allowing only limited operation so the vehicle can get to a repair facility" the fact that it has killed all four corners makes me think that it is in this mode. It is firing at the cap when i hold the wires just away from the terminals on all 8 cylinders I also tried spraying starting fluid in the throttle body while reving the engine and it smoothes out. Also it is not running rich so i think it is not pulsing fuel while 8,1,5,and 4 are getting spark. I did find the wires on the #1 injector to be frayed i seperated them and taped them off fo now.
Customer: replied 1 year ago.
I pulled the pos lead on the battery and turned on the lights then reconnected and started the engine, no change. How long fo you need the batt disconnected before the computer clears? If it is in a "alternate mode" how do you put it back?
Customer: replied 1 year ago.
what is HLOS mode?
Expert:  jazzmaster replied 1 year ago.

http://www.revbase.com/BBBMotor/TSb/DownloadPdf?id=23128

this pdf will explain the hlos mode .

this basically just shuts off the injectors and allows the motor to run .it is not really a limp home ,thus doing what it does when you sprayed starting fluid .

I still think you have an issue with the dist pick up coil .the ignition module can be checked at many auto parts stores -just to see if it is good or weak .

please check the ignition coil for those voltages ,as I stated .the one wire will have 12 volts or battery voltage and the other wire will have 9.5 volts or so and will kind of pulsate .

computer won't clear until the problem is fixed .

Also, check the wiring ,if you found frayed wiring ,there could be more .

check at the eec and fuel pump relays for corrosion as well.

if the coil isn't showing the voltages ,it may be weak -the 9.5 voltage should pulsate a little

so,please let me know ,after you get a chance to check it out ..thank you ...jazzmaster ..

Customer: replied 1 year ago.
Had a little time after Church today, With the key on I had 12.5 volts on both wires off the coil. Running. They both bounce around from 13.5 to 9.5 no pattern just erratic. I pulled plugs on dead cylinders plugs look great dry and clean. It is firing the plugs it just seems to be not getting fuel. The arc between the plug and the wire is the same on the dead cylinders as on the working ones. All the wire connectors are good even the injector wires that are not under the upper manifold. Best i can see the wires under the upper manifold may be shot. I dont understand why the insulation is comming off at the injector plug wires. They are not corroded but several strands of wire are severed. I am pulling the upper manifold next
Expert:  jazzmaster replied 1 year ago.

yes, that is what I thought ,the one side of the coil should have battery volts but the other side will change around as you see .

I would think that a critter got into the wiring ,they love the insulation ......so you either have to fix that wiring to the iectorsectors or replace some the wiring .

then you will need to make sure all the injectors are firing right and it could have made the ecm bad if these shorted bad enough

Customer: replied 1 year ago.
Replaced two injector connectors one shorted one frayed some animal teething. Traced all wiring under hood No other wire damage. Replaced upper intake gaskets cleaned Butterflys, replaced PCV valve and hose. No Change. Got a EGR code and put the vacuum hose back on that I forgot. No codes No Change. How to I tell if it fried the ECU?
Expert:  jazzmaster replied 1 year ago.

did you check to see if those injectors are firing/pulsating while cranking the motor over after you fixed the wiring .?

Expert:  jazzmaster replied 1 year ago.

sometime the ecm will have a burnt smell to it .

if there is no pulsing ground on some of the injectors the ecm is most likely bad .the ecm controls the ground pulse to the injectors and I find that a lot of times the ecm is bad when the wires get shorted ..also, check all the fuses to make sure none are blown ..jazzmaster ..

Customer: replied 1 year ago.
The other guy saids its not the injectors because it would affect the whole side not random like your problem. I just found out that one bank is all four corners 8,1,5,4 like my problem and the other is the four inner cylinders. That dude Lou knows less then I do. So since it is one of the two banks that is not working are there any other things that could be causing this?
Customer: replied 1 year ago.
I have not since the repair . When i started testing i had battery on both sides of the #1 injector, that was after I split apart the shorted wires. I will test them tomorrow.
Expert:  jazzmaster replied 1 year ago.

1` 4 5 and 8 come from the same terminal ( # *****) at the ecm .that is the tan/orange wire -this is the ground(pulsating ) source for those injectors .

The injector will show bat positive on both wires when the wiring is connected to the injector with the key on.

the only thing that would cause those injectors not to work is a bad ecm !

and maybe a shorted injector -which is possible also...

you can use an ohm meter and check the resistance of each of those injectors is should show around 12.0 -17.0 or so for each on

when you measure the resistance make sure the injectors are disconnected (wiring connector )

or you can disconnect the injectors and check the continuity between the tan/red wire and the tan /orange wires of the connectors .

also, you can check the continuity from the tan/orange wire at the injector to the ecm terminal # *****

if the resistance shows bad on one of the injectors or more then those a bad

if the continuity is bad from the wiring at the connector to the ecm then it is a wiring issue

if the continuity is showing between the tan/orange wire and tan/red wire at the injector (1458) disconnected then the ecm is at fault ..

I am sure you will find one of these things is not right .-but usually if you had an injector wire shorted on one of those injectors that the ecm is fried ..thank you ..jazzmaster ..

Customer: replied 1 year ago.
Had a very little time today so i figured id pull the ECU. The book said it was behind the driverside kick panel. Spent hour pulling the four extreemly long cover screws behind the E-brake only to find a nice empty hole that would fit an ECU. Checked online and its supposed to be above the gas pedal. I'll look tomorrow.
Expert:  jazzmaster replied 1 year ago.

ok,

Customer: replied 1 year ago.
Pulled the ECU its a E6TF-AB1A is the E6TF-ABA the same?
Expert:  jazzmaster replied 1 year ago.

it should work .does the ecm smell like an electrical burn

Customer: replied 1 year ago.
No, I looked inside nothing obvious.
Expert:  jazzmaster replied 1 year ago.

it doesn't always smell electrical or look bad

Expert:  jazzmaster replied 1 year ago.

if the ecm came out of a truck similar to yours it should work