89 5.0 with a miss

Aroby0618 · Oct 24, 2017

What's up guys. I just received an 89 with a 5.0 in it that has a miss in it. I went to pull the rotor cap to look for corrosion or what not and noticed that the #1 plug wire is on the post to the drivers side of the post marked #1 and it follows firing order with all being 1 post to the clockwise position of what I would call their normal post.

Maybe this is a manufacturer issue with the cap. I don't know, but thought I would come ask some of you bronco experts that may have seen this before.

I do have an 89 f150 here I looked at yo make sure I was not crazy and it is lined up #1 to the post marked #1.

Has anyone seen there or no a common problem some one would do this to for a reason?

Rons beast · Oct 25, 2017

Hey Aroby, Welcome.

I think the distributor was removed at one time and not clocked properly when installed. If the timing is correct and the wires are in order that is not the cause of the miss. You will have to isolate the cylinder that is missing and go from there. It sounds like some inexperienced hands had worked on the truck before. You may have to sort out other things but that is much of the fun for many of us. Congrats on your new Bronc and good luck.

Aroby0618 · Oct 25, 2017

Thank you sir. That was my first guess but it never hurts to ask for a second opinion.

A "34 year mechanic" owned this before a friend bought it and I ended up with it. So I thought may be there was something he had done there.

I have good spark at the plugs, if I have time I'm going to swap the fuel rail over from the f150 that runs fine on the next day or 2.

Are there any common issues past the basics with these engines that days misfires?

miesk5 · Oct 25, 2017

Yo Aroby0618,

The #1 plug wire as you described bothers me.

Would you consider re-stabbing the distributor?

See http://www.fuelinjectedford.com/page71

Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

Some basics;

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.

Run it around to heat the engine up and shift thru all gears including Reverse.

Make sure A/C is off and transmission is in Park (automatic); or in Neutral for a Manual & release clutch.

Then turn off engine, all accessories/lights (close driver's door) , etc.

Do KOEO test First

Post Code(s) here according to: KOEO & KOER

...

Without a DTC;

Are plug wire routed as shown on decal atop radiator support?

See http://www.supermotors.net/clubs/superford/registry/5180/32495

Vacuum leak, see my leak diagnosis link in post #20 @ http://broncozone.com/topic/23994-90-58l-getting-continuous-code-33-and-running-code-44/?p=125535

Aroby0618 · Oct 29, 2017

It threw no codes at all with any of the test. The distributer being off really concerned me also.

I narrowed it down to being the number 8 cylinder by pulling plug wires and then confirmed by unplugging injectors that I could get to.

The next step I am going to take is to go ahead and start tearing the engine down and see what is going on.

Rons beast · Oct 29, 2017

What does the #8 plug look like?

Aroby0618 · Nov 1, 2017

Its brand new. From the previous owner. It also has a new plug wire going to #8

Rons beast · Nov 1, 2017

Have you hooked up a vacuum gauge to engine vacuum? What does the needle do?

Aroby0618 · Nov 5, 2017

Sorry for the delay been working. Its still at about 18 psi with little fluctuation

Aroby0618 · Nov 5, 2017

Also I went ahead and restabbed the distributer to eliminate that. Nothing changed. I put my multimeter to work on the injectors and they read the close to the same down the 5678 side. I will be pulling the valve cover and checking on valve movement and measure it to see what I got

Rons beast · Nov 5, 2017

If the vacuum gauge is steady the valves and internals should be good. Try switching the #8 plug wire with another wire to see if the missing cylinder changes.

I'm thinking the the problem is the plug wire. Better to do the easy stuff before getting into the engine.

Aroby0618 · Nov 6, 2017

I have tried sealing the plug wires. The previous owner had replaced the #8 wire with what appears to be a new wire. The other 7 are accell wires that don't appear to be very old. It has a new coil on it. I agree with the easy stuff. I'm just running out of options.

miesk5 · Nov 7, 2017

Yo,

Have to ask about tge plug wire routing since I didn't see an affirmative reply.

Service Bulletin Number: 90-4-14 Bulletin Sequence Number: 009 Date of Bulletin: 02/90
NHTSA Item Number: SB011916
Component: ELECTRICAL SYSTEM:IGNITION:OTHER PART Summary:
SPARK KNOCK OR ENGINE MISS CAUSED BY INDUCTION CROSS FIRE-THIS OCCURS BECAUSE OF MISROUTED SPARK PLUG WIRES-FIRING ORDER OF 5.0L ENGINE THAT 8 SPARK PLUG FOLLOWS #7 SPARK PLUG-PLACING WIRES #8 AND #7 NEXT TO EACH OTHER AT SEPARATING BRACKET M AY INDUCE CROSS FIRE-CHECK POSITIONS OF #7 AND #8 SPARK PLUG (ASF-42-C) WIRES AN D REROUTE CORRECTLY IF REQUIRED-ALL 1987-90 FORD BRONCO/E150,250/F150,250 TRUCKS

upper case is by Ford.

Aroby0618 · Nov 7, 2017

Sorry got auto corrected. Tried switching the plug wires. I have made sure they were separate so that no cross firing is occurring.

miesk5 · Nov 7, 2017

Yo,

No problem friend!

For other no codesingle cylinder misfire see http://www.aa1car.com/library/misfire.htm

For a 96, so iggie the trouble codes.

89 5.0 with a miss

Aroby0618

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miesk5

96 Bronco 5.0

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96 Bronco 5.0

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