Lexus ES300 Will Not Hold Idle

[ray]

Today, just out of nowhere my 1996 Lexus ES300 began to stall during travel.
It finally stopped where the battery needed time to gather itself to allow me to start it again.

I do not see a loose connection, or anything obviously causing the issue. When I let it set for a moment (while broke down in a parking lot) I started it up and it drove home fine. The car ran as smooth as butter and did not stall again.

Should I be looking at Electrical? IACV? All else runs fine. I just know that it was hot under the hood but not overheating or anything. I am leaning toward blaming this on how hot it was and something intermittently reacting to it. I did come away with the check engine light though. I think what I will do is cleanup the Idle Air Control Valve. I will go from there and wait for any tips anyone has to offer.

Any suggestions, guys?

Topic

[Wayne]

[quote=”rayg85374″ post=61530]I did come away with the check engine light though.

Any suggestions, guys?[/quote]

Find what that code is for first, would be my suggestion. Fast and free at any local chain automotive shop. That will likely give you your biggest pointer to the issue.

[college man]

I agree that the code will give us a direction to go.

[ray]

What I will do is get the code reading, stop and get some carb cleaner and clean out the throttle body and the IACV.

We will see what happens after the code reading.

thanks guys

[ray]

So i went to the local parts retailer who pulled the codes off my CEL.
Apparently it is an issue involving P1300.

Code definition is cylinder #1 IGf signal does not return from ignitor. This is strange as the car runs smoothly and shows no obvious runability issues. Could this be a coil pack problem? Whatever the case I am letting my local shop run a scope on it to ensure I fix the right thing.

Any guidance from here would be much appreciated as I am not too sharp with electrical and would love to save a trip to the shop…

Thanks guys!!!

[Its me]

The cheapest way to test is to remove the coil pack and inspect it for physical issues, if no issues, move the coil to another cylinder and try that one out. If the problem code moves to another cylinder, chances are you have a bad coil pack.

The bad part is that #1 cylinder is a bit hard to get to on the lexus es300 (but not the worst one). I can’t remember which year they switched to a waste spark system (these are much easier because they fire two cylinders at the same time, but actually, only one cylinder is truly in ignition stroke… hence “waste spark”). This waste spark system actually only works off front coil packs (much easier to work on!)

If you have a newer system, just switch out the front coil packs (2 and 4). Hint, 4 is tied in with 1.

Good luck

[college man]

+++1 on the above. switch #1 coil with another cylinder
to see if the problem moves.

[ray]

I just decided to take it to my local shop and let them scan it. I would love to use the coil pack to test the other cylinders but in this case cylinder one is against the firewall underneath a plenum and throttle body.

I figure I let them tell me what it is, I lift the plenum then do the work. I would imagine there is some labor involved and that would shoot the cost thru the roof. I just hope it plays out to be that simple. Otherwise their diagnosis may require going beyond the surface.

Thanks guys…I will let ya all know what happens.

[ray]

I am also confused when you say 4 is tied in with 1…what does that mean?

[Its me]

OK, it sounds like you have coil packs on all the cylinders. When I reference 4 is tied to 1 is the newer style engine ignition system. I think that it may have been 98 or 99 when they switched from Coil packs on each cylinder, to having only 3 coil packs on the “front” or easy access cylinders.

I will try to explain…

This was a good idea to do IMHO, because like you see getting the rear coil packs out is a bit of a PITA for the DIYer and required removal of the plenum. Now the plenum is not really that hard to remove, takes me only about 20-30 min and the only real pita is getting the EGR tube nuts back in place, but is still a time eater for a tech… Not to mention when trying to do an actual cylinder compression test (this is why a relative compression test with a lab scope is so nice, but that is another story)

On the new system, What they did was make it so the front coil packs also fired the rear cylinders. All there was was a spark plug cable from the front coil packs to the rear cylinders. These packs fired twice, one cylinder got spark during the exhaust stroke, at the same time the other cylinder got spark at the end of the compression stroke.

So, when cylinder #1 is on the end of the compression stroke, cylinder #4 is on the exhaust stroke (balance)… note the pic…

Note, photo, these are the “front” cylinders. Note how they are not like your coil plugs, they have an extra plug for a spark plug line to go to the “rear” cylinders.

Sorry, don’t have any photos with plenum off. I always take the plenum off when putting in the car, but couldn’t find any.

Hope this explains the waste spark system a little better.

Cheers.

[ray]

Thank you for going to great length to explain that to me. So the 1 3 5 cylinders do not have a coil pack and just run off of the auxiliary wires from 2 4 6?

Thanks for the help!

[ray]

So Karl…

Got a call from the mechanic earlier and he was relieved enough to say that the issue arose from the harness/wiring from the front cylinder, first on the left. Apparently it was causing an issue with another cylinder and it is…(you guessed it) a waste spark setup.
So all I have to do is replace a bad connector which apparently caused the whole problem.

So what I will do tonight is splice into the existing wires and clip the new connector on. From there I will let you guys know how it all goes from there. Thanks for the advice that hopefully let to a successful result.

Have fun guys!

[ray]

Hey guys…

Karl you were right it is a waste spark system, first off. I totally forgot I have the additional spark plug wires running to the back of the engine.
Had a diagnosis done on it with the local mechanic to ensure the theory is correct and received the car back a few hours later only needing to replace the harness connector that clips onto the ignition coil pack. It was moving around and accruing moisture.

***Attention, Lexus Owners*** Do not bother calling Lexus for the replacement harness clips because the dealer will try to sell you a whole harness and wiring assembly upwards of $100 bucks. I went to my local Wrecking Yard and grabbed as many as I could find beside the one I needed for the job. Only paid about 5 bucks.

Spliced the wiring, made sure to tightly wind the electrical tape to protect the wiring and popped the new connector on. Runs smooth as butter and starts up like she normally does. Guess it did turn out being something funny like a little electrical issue.

From an experience standpoint, I would say just before going to any extreme, check connections. Check wiring. And use the tactic ToyotaKarl mentioned in the middle of the thread. I went to my local mechanic because I needed to make sure that it was nothing else causing the problem. This series of steps (maybe minus taking your car to a shop) should solve your issue if your running into this problem – generally if you pull a P1300 code.

I hope this topic helped those with an issue where their Lexus ES300 isn’t holding idle!!!

Have fun, guys…

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