ignition wires bad?

[SeanAndHis80]

Someone back me up here before I spend the $$$ on ignition wires...

A couple of weeks ago the truck started hesitating - especially after it had rained. Normally I would just replace the ignition wires, but they are expensive on the 80 so I went for the FSM instead.

The code coming up was #6 misfire.

OK so I check the wires with an ohmmeter and found them to be well within spec. They were all in the 17K range - 25K is listed as the max allowable.

I replaced the spark plugs while I was in there and put it all back together. I test drove it, even in the rain and it seemed fine. My wife had the truck and said she felt some hesitation - today in the rain I felt it too. It isn't as bad as it was but definitely still there.

Now they would have been replaced by the PO - and they were genuine Toyota parts.

I am guessing that the insulation is bad regardless of the resistance measurement and that moving them around caused the reduction in hesitation.

Is there anything else I should check before spending the $$$ on ignition wires?

 

[dfmorse]

Sean; something u might try; wait until its dark outside, night time. Maybe u have the beast parked in a garage. Raise the hood, start the engine, and look at the spark wires. If the wires are as old as 136k miles indicates, u might see some glowing or sparking across the wires. This means that wires have outlived their usefulness. I am still amazed that 5mm wires work.

In any case, if they are original wires and cap and rotor, I would change them all to new stuff...

David in Denver

 

[SeanAndHis80]

I had tried that and didn't see any sparks - however I did not take the covers off of the valve cover - so most of the wires were covered.

 

[SeanAndHis80]

No one else? ...I guess it is time to just start throwing money at it then...

 

[cruiserman]

Did you check the cap? All the wires properly seated?

 

[SeanAndHis80]

Yes, I pulled each wire to check the resistance. They came off and seemed to go back on properly. Is there a proceedure for checking the cap?


BTW thanks for any and all replies!

 

[elmariachi]

Yes, I pulled each wire to check the resistance. They came off and seemed to go back on properly. Is there a proceedure for checking the cap? BTW thanks for any and all replies!

At 136k miles I'd change the wires, cap and rotor anyway. Do it one at a time starting with the rotor to see if that's the problem though.

 

[CruisinGA]

changing wires, plugs, cap and rotor at 130k miles is not throwing money at it...

I would do it regardless. Might as well do it now and see if it fixes the problem.


(note: I normally don't suggest the "install this and see if it works" approach)

 

[MH_Stevens]

You should just change the wires, but if you don't want to unless really needed then remove cap and measure the resistance of each lead. It should bge less than 25,000 ohms

 

[CruisinGA]

You should just change the wires, but if you don't want to unless really needed then remove cap and measure the resistance of each lead. It should bge less than 25,000 ohms

Read a little closer. He already did this.

Resistance is not a static value, however...

 

[Mudshack]

I had problems with mis-firing last year this time. It got so bad that I had 3 cylinders mis-firing and fuel being dumped out the exhaust pipe. Ended up being a wiring problem at the firewall. The wires had rubbed raw over the years, and caused a short - hence the mis fireing.

 

[SeanAndHis80]

OK - I replaced the ignition wires, the dealer didn't have a cap on hand so I will wait a couple of days to replace the cap and rotor. So far so good but the road is dry and the engine was hot - so I cannot tell if it worked yet.

It is supposed to rain the next couple of days so I should find out if the ignition wires were the culprit before changing anything else. The truck has been in such excellent shape - I doubt that these were the original wires. ...allthough the actual service history is a mystery to me.

Mudshack - where were these wires passing through the firewall? I would like to check that out.

 

[CruisinGA]

Sean- It is the large wire loom that passes from firewall to head right at the heater valve and beneath the EGR valve. It contains the wires for the fuel injectors, TPS, IAC valve and maybe a few other things. Basically some of the most important engine wires.

I know of another 80 that had the exact same problem with the wiring loom in that same spot.

 

[SeanAndHis80]

Well, it wasn't the ignition wires. The cap should be in this morning and it is supposed to rain heavily today so I will be able to quickly determine if it is the cap and/or rotor.

I'll check the wiring harness by the direwall while I am in there - thanks Bailey/Mudshack. What did you guys do to fix the harness did you repair or replace?

 

[SeanAndHis80]

Well, looks like the cap and or rotor was the culprit. Knock on fake wood trim. Thanks for all the help and suggestions.

 

[landtank]

Sean- It is the large wire loom that passes from firewall to head right at the heater valve and beneath the EGR valve. It contains the wires for the fuel injectors, TPS, IAC valve and maybe a few other things. Basically some of the most important engine wires.

I know of another 80 that had the exact same problem with the wiring loom in that same spot.

The wiring at this point was changed after 95 (i think) and isn't a problem any more.