frikinyankee

Hey all,

Chasing down a running issue. 86 4runner 22re. Truck runs, but sometimes it runs kinda bad, lacks power, pulsing idle. But overall not terrible. Could it be the coil? I spoke to someone knowledgable and they say it either works or doesn't, and even said he's never seen one fail. Do you agree?

My coil primary tests at 1.4ohm, and secondary 13.5k. So according to the FSM I'm out of spec on primary test, manual says it should be 0.5-0.7. BUT then when I see the ACCEL coil for this truck it advertises 1.4 ohms. So is that resistance value fine?

snippits

I have seen some coils fail over the years. If it's leaking or seeping oil, then it definitely needs to be replaced.

frikinyankee

Leaking coil? You mean the distributor/pickup coil? I was referring to the ignition coil

snippits

Ignition coils like the one on my 92 pickup have oil in them. One like linked below that fits my truck. It says it's either oil filled or epoxy filled.


https://amzn.to/2JxYvqV

frikinyankee

Huh! I didn't know there was liquid in coils, interesting. Don't think mine is leaking though

Co_94_PU

iTrader: (-1)

If it's a Toyota coil, yes that's out of spec like your manual said. High resistance and high voltage makes high heat, this is cyclical the more heat the more resistance .. Back to the beging heat resistance heat..

To much voltage is hard on the ignitor, it's why we have specs for high tension (sparkplug) wires and spark gap limits.

frikinyankee

So what coil would you recommend for replacing the faulty one? The ACCEL one sold at O'Reilly's for this truck advertises 1.4ohms, and that's off spec...

Could this higher resistance cause it to run badly? Or is it just good until it fails / run vs no-run issue...

old87yota

One thing to note, many common multimeters are not super accurate reading that low of resistances because the small resistance of the test leads themselves start to matter.

This means that you are reading the resistance of the test leads in addition to the coil. For most measurements, this does not matter, but for very low resistances, it can skew your measurements.

Just as an example, my "free" (with coupon and another purchase) Harbor Freight multimeter measures anywhere from 0.6 to 1.0 ohms with just the leads touching. This resistance, plus the resistance I am trying to measure would show up on the screen.

On a multimeter that allows you to compensate for this you can touch the test leads together and "Zero" the resistance reading, which should give you the true resistance value you are measuring right on the screen.

I am not necessarily saying your coil is good, because it can still be bad, but just wanted to point out a possibility.

I would look for other possibilities first before throwing a new coil at it.

snippits

For my 92 pickup with 22RE, I would roll with Standard Motor Products UC12 Blue Streak. Standard T Series UC12T is their cheaper competitive line, but I would still use it if needed.

frikinyankee

I don't really have reason to believe my tester is not working correctly, but yes I can imagine a wrong reading would mess things up

@snippits, the coil you talk of is also not advertised as having same primary resistance as the FSM suggests...

If manual says it should have 0.5-0.7... then why are the aftermarket brands advertising coils for this truck with resistance that's more than 1ohm?

snippits

Where do you see the primary resistance rating of the Standard UC12? I can't find it.

I just checked the primary resistance of the coil cold on my 92 pickup.

Extech EX330: 0.7 ohms to 0.8 ohms cold was jumping back and forth

Actron CP7677: 0.7 ohms cold

frikinyankee

For the UC12 resistance summit racing commented on one of the questions in this listing
https://www.summitracing.com/parts/smp-uc12x
saying: The primary resistance is 1.3 to 1.5 ohms and the secondary resistance is 7700 to 9500 ohms.

Seems strange... i guess if people are putting these in their trucks than the primary resistance can't affect the performance that much? Or other factors at play...?

Thanks for checking that! I believe i read somewhere that post-89 truck coils have different specs than the older 22re's? Not by much though... Anyways it's lower than advertised, that's strange?

snippits

Yes I see that.

I found some that are close to the FSM range. The one linked at O'Reillys is epoxy filled, so it does cost more. Amazon is lots cheaper.

https://www.holley.com/products/igni...ck/parts/8145C

https://www.oreillyauto.com/detail/b...ion+coil&pos=4

Paul22RE

This NGK specs correctly. Rockauto has it for $28. Is the OEM a Nippondenso coil or this NGK?

https://www.autozone.com/ignition-tu...5_558418_17367

frikinyankee

Thanks for all the research guys, really appreciate it

In theory... what would happen if the coild specs were off? We're talking about more overheating if the resistance is higher.. does that affect performance at all, or is it just a question of works as it should until it fails?

RJR

@AKWheeler is correct - unless you have a 4-wire ohm meter capable of making Kelvin ohms measurements (these are NOT sold at Harbor Freight or auto parts stores), you can't reliably differentiate between a .7 ohm coil and a 1.4 ohm coil. Your measurement error is greater than that. You can get closer by touching the two test leads together, noting the reading, and then subtracting that value from the reading you get while measuring the coil. That's the manual version of AKWheeler's "zero" function. It will be a somewhat more accurate measurement, but still not great because the contact resistance between your test leads will be different than the contact resistance from test lead to coil lead.

I would view that coil measurement spec (.5 to .7 ohms) as more of a "is the coil intact or not" kind of a test. There's no reason for the coil resistance to age and slowly get higher. It's just a length of copper wire, and the resistance won't change over time or with use. You could have internal connections that fail, but normally that would show as significantly greater resistance and/or intermittent resistance readings.

My guess is, had you measured this same coil when it was new from the factory with the meter you have now, you would have measured the same 1.4 ohms as you see today. In other words, I doubt the coil is bad.

frikinyankee

Yes thank you for those comments, you guys are right, when I touch the tester leads alone they give 0.8 ohms resistance by themselves... so if i subtract that from the 1.5 i was reading, I'm on spec. So I'm gonna go ahead and agree that the coil is not where I should be looking...

I'm gonna look back under the hood, write down everything I've eliminated as a problem, and I guess start a new thread... thank you guys!