Replaced ecu caps, engine stumbled again today randomly. Will be replacing plugs (they were done 35k miles ago by PO...) but damn, what else could it be? Cleaning the MAF sensor soon as well. Im starting to think its the TPS sensor? worn out in a tiny tiny area and there is a lack of singal passing thru it at a point?

 

could be one of the coils, have you rescanned for codes since the stumble?

if there was a misfire, there will typically be a record of which cylinder it happened in

 

mine did this..turned out to be the coils. I ohm'ed them out and they failed slightly on one of the terminal tests. so they weren't so bad that the cats were glowing red but they still were bad

 

scanned and no codes. could very well be the coils, Goign to price out a set of new oem ones with plugs. Thanks.
I know the PO ripped one when he was changing plugs and replaced it with OEM, maybe now the others are starting to fail?

IS there a test procedure and resistance values for the coils that I can rule those in or out?

 

for future reference, this would be helpful. Where are these records stored ?

 

records on past recent events are stored in your ECU's memory - you need one of these, as I have mentioned several times

 

a new set of OEM coils is gonna be at least $800 to the door, and aftermarket junky coils are essentially no cheaper


yes, in the service manual,

I would suggest getting the factory service manual set, then you have all of these tests at your finger tips, you can still get the shop manual set brand new (for now) for $160 (which is cheap)

OR

you can always join Toyota Tech Information Service on a 2-3 day pass for $15 and download the appropriate pages, and look at technical bulletins, recreate your orginal factory sticker, and all kinds of fun stuff!

 

160 is good! i saw em for over 200 on ebay.
900...jeez...uh..well goign to test them and replace only the ones (if any) need replacing...

 

the best price I have seen anywhere on the real Lexus coils is $97 each at Lexus of South Atlanta

part number is: 90919-02228

 

Literally no reason to replace them all.

test them, '98-00 coils don't fail often. Just replace the ones that have fallen out of spec.

 

So the problem has returned.

What I did narrow it down to though, it only happens when it snows. It is not temperature related. I drove it one day it was -12 F, clear skies everythign was great. , next day -10F snow-stumbled alot.
Next day +20F, no snow, was fine, next day, +20F, snow-stumbled.

I checked the air filter, it was dry and clean, so its not loading up with snow. I was thinking maybe its the VSC kicking on, but this happens even when coasting, or light throttle with VSC off. So its not wheel spin.

Perplaxing, but..only happens when it snows. Very strange.