Engine Misfires - Cel Blinking - Please Help!

[drmull]

I have a '99 with 160k miles. The only trouble I've had was some starting problems from a stuck IACV, which I fixed following the tutorial on this site.

Two days ago my wife filled up (from nearly empty) at a new BP she had never been to. The next day the engine suddenly shudders, the CEL blinks, and it goes into that failsafe mode where it won't shift into overdrive. The codes thrown were P0300 (Random/multiple misfires), P0305 (Cylinder 5 misfire), and P0306 (Cylinder 6 misfire). In addition there was another DTC Pending code on the printout for cylinder 6.

It seems like more than coincidence that this happened right after the fillup. Could it be water in the fuel?? I would have thought maybe it was a coil problem with just one or two cylinders misfiring, but the P0300 code confuses me. Does that mean it detected misfiring from all the cylinders, just not enough from each one to throw an individual code for all of them??

I dumped a can of SeaFoam cleaner in the tank when she got home. With an almost full tank, will that do any good??

I'm really worried about damaging the catalyst from the misfiring - would I be ok to drive it somewhere to get the gas pumped out? Where could I get that done??

I'm frustrated, scared, etc. - sorry for so many questions. I just thought I'd try the water in the gas thing first - I just don't know how to get it out of the tank! Thanks for ANY help -

[tmastres]

To me , this sounds like a failed coil(s) problem. Once a coil goes bad and you drive the vehicle more than a block the vehicle will begin to throw a cascade of other codes because its running poorly and causing other sensors to indicate trouble. If it is a coil, the car will not repair itself so I'm guessing it is still running poorly? The thing I did was to clear the codes with a code reader and then start the car again, the CEL should come on shortly , after it does, turn the car off and read the codes.The first code should indicate the cylinder number failed coil. Replace that coil and see if its running properly.

You may be able to clear the current codes by disconnecting the battery but I'm not sure about that.

If your problem is a bad coil, I'd recommend replacing them all. It's a pain and its expensive ($5-600), but I had 3 coils go bad in an 18 month period . All at different times and all completely randomly. After the third one I just replaced all the rest.

As I understand it the original coil designs were changed at some point to make them more reliable.

(in jest)To the skeptics on the board, no I don't have any documentation to prove this, in fact I may just be making it up :D )

However I do have the old coil part numbers old: 90019-02234 (probably what you have in the RX now)

and the new part numbers: new 90080-19016 (the ones I put in my RX)

[drmull]

Thanks -

Update - I cleared the codes, ran it until the light came on and it did throw one code - P0306 (cylinder 6). I've read posts of people changing coils themselves in minutes. Should I be able to do it on cylinder 6?? Thanks

[lenore]

Cylinder six is a piece of cake, it is the front left cylinder next to the battery. Will take all of 5 minutes....

back is 1 3 5 This is the left side of engine and car

front 2 4 6

this is front of car

[tmastres]

Thanks -

Update - I cleared the codes, ran it until the light came on and it did throw one code - P0306 (cylinder 6). I've read posts of people changing coils themselves in minutes. Should I be able to do it on cylinder 6?? Thanks

You are in Luck, relatively speaking. If I remember correctly the cylinder orientation is

135

246

With the 246 being towards the front of the vehicle.

I shouldn't take more than 10-15 min. If it were one of the rear ones??????? When you have the cover off, take a look where the rear ones are , that's something I don't ever want to do again.

[tmastres]

Hey, is there an echo in here? :D

[tmastres]

nevermind

[drmull]

Hey folks - I switched the #4 & #6 coils and sure enough, it then threw a P0304. So, that surely means the coil, not the plug, is bad right?? Thanks for all your help.

[tmastres]

Hey folks - I switched the #4 & #6 coils and sure enough, it then threw a P0304. So, that surely means the coil, not the plug, is bad right?? Thanks for all your help.

As long as you didn't change the plug as well then I'd say that's the case.

[BillyShaft]

As I understand it the original coil designs were changed at some point to make them more reliable.

(in jest)To the skeptics on the board, no I don't have any documentation to prove this, in fact I may just be making it up :D )

PROVE IIIIITTTT!!1!!

Just because the part number changed and Lexus received lots of complaints doesn't mean that changes were made!

HAR

Good info, T...

[drmull]

The cheapest part I could find was at one of our Toyota dealers for $93. Not too bad!

[BillyShaft]

The cheapest part I could find was at one of our Toyota dealers for $93. Not too bad!

Ewww...are you going to do all of them?

[tmastres]

The cheapest part I could find was at one of our Toyota dealers for $93. Not too bad!

Thats about right. I paid $91 I think from Lexus of Oxnard when I did mine. My local Toyota dealer quoted me over $100 and wouldn't warrant the part if I put in a Lexus!! and not a Toyota, (I kid you not). In any case, I believe they can be had in the $80's if you buy from Sewll Lexus or Park Place in Texas, but then there's shipping and the time till delivery. If you order several and you have a high sales tax rate (as we do here in CA) it can still be cheaper to buy from an out of state dealer, even with the shipping.

[drmull]

OK guys -

The trouble goes on. I replaced the coil on cylinder 6 and everything was great - for a day. My wife drove it this morning and the CEL flashes with the car "lunging" and not wanting to shift. This happens intermittently - fine for a couple of minutes, then bam, stumbling. She limped it home. It's only throwing one code this time - P0301 pending. I cleared that and ran it again to be sure. Same result - P0301 pending. I can feel the engine missing. Is that possible that two coils could fail at the same time? Why did cylinder one not show up when it was first throwing multiple codes? Is there something else going on? This is extremely frustrating. Thanks for your expertise & help.

BTW - do I have a chance of replacing the cylinder 1 coil by myself? At least I can see it!

[BillyShaft]

If your problem is a bad coil, I'd recommend replacing them all. It's a pain and its expensive ($5-600), but I had 3 coils go bad in an 18 month period . All at different times and all completely randomly. After the third one I just replaced all the rest.

I have read that it is common for coils to fail domino-like as they get to failure age.

:(

[lenore]

Something else to consider, putting the coils back on the plug, take a flashlight and look inside the core of the coil. The spring may have compressed or be corroaded. I found that using some electrical contact cleaner will help. Also the plugs may have built some corrosion on the connector end. They should be cleaned with some emery paper and than lube with electrical cleaner. I also add some dielectric grease to the inside of the boot of the coil to eliminate moisture and hopefully arcing. Arcing can cause a very rapid failure of the coil pak if it is between the coil and plug....

[tmastres]

I certainly don't claim to be a mechanic, just an average DIY guy but it seems very possible that its another bad coil. Do the symptoms seem the same as before when the first coil went bad? You mentioned that the car ran fine after you changed out the original offending coil so I think we can call that fixed and look at this as a separate and new problem. When I experienced coil failure, I don't remember any intermittency (intermittentness?) in the symptoms, it seemed to be running consistently poorly. I might suggest doing the same switcheroo you did originally with the 4&6 coils to see if it cylinder misfire code changes cylinders with the coil. Access to the # 1 cylinder isn't easy but at least you don't have to maneuver any tools in that tiny space (like when you're changing the plugs). I have XL sized hands and I was still able to change all the back coils myself by just taking my time and using a LOT of patience (for which I'm not known :D ).

FYI- I just checked my notes and my second coil went bad 3 months to the day that my first one went bad and then I had a whole year before the third one went. The timing of the failures seems random enough to me and personally, I don't see why the second one couldn't or wouldn't fail only a few days after the first one. I realize its a very frustrating experience, especially when its the wife or kids that end up stuck somewhere, thats why I went ahead and changed all of my remaining original coils, I simply had no way of knowing when or where they were going to go out next. If this does turn out to be another bad coil, I'd say bite the bullet, change em all and make an afternoon out of it under the hood. That's just me and it took 3 failures to get me there so hey.

[drmull]

I swapped the new coil (cyl 4) with the suspect one (cyl 1) and, sure enough, it threw P0304. I'm really hoping this is the last one for a while. It wasn't so bad getting the coil out of #1 - I only removed one end of that vacuum hose and pushed it out of the way. If I have to completely remove it to do #3 I'm in trouble. I couldn't see (in a mirror) exactly how to remove the hidden end...just squeeze the little clip & yank?? It seems to connect to a steel fitting on that end. If #3 or #5 go quickly I may chicken out and let my local Lexus guys (not the dealer) do it. I had enough patience for #1 but just barely!

If I were to try, though, do I have to remove the throttle body to facilitate removing the #5 coil?? Thanks, tmastres.

[lenore]

Please read my other post, beware of corrosion....it can cause havoc on the coil paks...

[tmastres]

I didn't have to remove the Throttle Body to change the coils, it wasn't easy but I pushed prodded and jammed that #5 coil in there. If you can fit your hand in the hole between the TB and the intake you can get at the 5 and 6 coils. It certainly isn't easy (or comfortable) but its possible. There were times when I was sure I wasn't going to get it in there but I eventually did.

I wouldn't blame anyone for wanting to let someone else get dirty for this job but the coil costs are high enough and if you can save a few hundred bucks, hey, why not. There are some things on these vehicles that I just wouldn't try, its just a frustrating and difficult vehicle to work on, for me at least.

I would concur with Lenore on the dielectric grease, its simple and it certainly can't hurt.

Lastly, if you're not going to replace all the coils I'd at least get an extra one and keep it in the car. As you've seen the front ones are fairly easy to replace and the failures are so random you never know when its going to go, or where you'll be when it does.

[drmull]

lenore- I did read your post and promptly forgot to check inside the latest bad coil for corrosion. I'm unable to check the back plug tips. I'll pull the latest bad one again (now up front) and have a look. Thanks.

Will the "QD Contact Cleaner" at Ace Hardware work??

Cleaner

[lenore]

Yea that cleaner should work great....

[drmull]

I checked the spring on an old vs. new coil. The new one looks like copper, the old one seems to be a little more "silvery". Is that what corrosion on copper looks like? Thanks

[lenore]

Sometimes the corrosion looks like a white powder, or grayish look. If it is corroaded a little scrapping with a screw driver will tell you, if it knocks off it is probably corroded. The contact cleaner will sometimes desolve it.