Habu4

Although my vehicle is an 2003 SC430, the problem may be better classified as a 430 problem. At 65,000 miles the engine developed a stumble or miss on light throttle input. The dealer could duplicate the problem but not find the cause. I changed location where I purchased fuel and the problem stopped only to reappear withing a few hundred miles. The miss occurs w/wo cruise control activated on any slight road elevation or hill. It will also occur on initial light throttle input from a stop. Except for a K&N air filter, the engine is entirely stock and serviced from new every 5K miles at the dealership. Any ideas out there?

scdroptop

iTrader: (1)

Habu4-welcome to CL! First of all, I am sorry to hear about your miss on the engine.

I'll start of to say that our CL Forum has some geniuses on here (I am not one) and this topic has surely been covered---try a search if my post or others is not helpful to you.

This could be numerous things...plugs, injectors, O2 Sensor and obviously something more serious and very very very rare as a seized valve, but I doubt it would be back to "normal" again if that was the case.

A few other small things that I would check are your gas cap, and obviously you already changed gas so I would have checked that too.

Dealers sell a fuel injector/induction cleaning service that is a couple of notches better than just buying the $10 bottle and pouring it into your gas tank where they actually suck out the deposits.

Check air filter too. An extremely dirty air filter or clogged (leaves, etc) could cause a miss or I've even had a filter improperly installed (backwards causes it to "suck in") could do it too. Check your K&N and clean it. Do you have the right sized K&N?

Here is a description for the fuel injection cleaning...I've had it and it worked GREAT...my car had a LOT more pickup in it. $149 at most dealers.

Protect your engine from carbon build up. Stop and go driving along with additives in our fuel can cause carbon build up in your engine. Regularly performed induction service can keep your engine performing properly and reduce the carbon deposits in your engine. Our technicians will do a visual inspection of the fuel delivery system and perform a fuel induction service on your vehicle. Your vehicle will be inspected, road tested and washed after completion of service.

Habu4

Gas cap checks OK. Air filter checks OK. I'm off to the dealer for fuel injection/induction cleaning. I'll let you know. Thanks.

howdybob22

Could be time for a little tuning up maintenance (MAF and Throttle body cleaning, changing of spark plugs, and fuel injectors cleaning as mentioned). Do keep us update as what the root cause.

Regards,

scdroptop

iTrader: (1)

GL-and please keep us posted. I am going to do the induction cleaning as well.

Habu4

I had the fuel induction service six weeks ago by the dealership. Seems to pereform better but no change in engine miss - obviously not the problem. Full tune-up done at 60 K miles but spark plugs not indicated until 90 K. Fouled plug would cause miss across entire power range. I am still mistified. Any more ideas?

scdroptop

iTrader: (1)

I would go to another Lexus dealer for a second opinion for sure.

ed lee

I have an 06 and it had the "Miss" every now and then. Mostly when I start from stop light. I told dealer on a service and he said it was a computor thing and normal.

I just had 30k service recently and sofar it has not happened. Wish me luck.

johnnyreno

Plug wires you can thank me ; later

VVTiBob

Interesting.... misfires should show up on as an error code and stored in the ECU and readable by the Lexus Scan tool or DTS. I agree with SC, sounds like it time for a second opinion from a fresh set of eyes. Besides the spark plug wire as mentioned, another possibility is a lean fuel to air ratio .... but honestly intermittent problems are difficult to diagnose.

Habu4

Lexus service has had the vehicle for a week. Scan tool found two cylinders missing intermittently while driving. They will install all new plugs and test drive again next week. K&N filter is out; replaced with OEM filter, although that in itself did not solve the problem. To their credit they are working hard to solve this, probably because I also have an ES that is serviced there! I'll keep you posted.

VVTiBob

Thanks for the update.... we all learn from each other!

willhickey

iTrader: (1)

that guy said the wires he has the best opinion yet..... worth a shot . when i had a bad wire it did the same thing and got progressively worse

TJW98LS

iTrader: (1)

Any update with this?

My LS430 started to do it not long ago. I cleaned the Throttle Body, and it seemed to do the trick for about 5K miles... then did it again. Since then, it has gotten worse. Could it be the coilpacks or wires? I changed the plugs because of the problem, and nothing happened.

Habu4

This is a note of appreciation to all my friends at Club Lexus regarding a 430 engine miss. Some of you cost me a little money but your hearts were in the right place and my SC430 is better for your advice. I was very close to selling the car.
Three weeks ago I left the car with my service shop at Lexus and picked up a loaner. The tech used the car daily and took at least one trip of a couple of hundred miles, all with the scan tool connected. He was able to duplicate the miss and diagnose the cause. The answer: a faulty Engine Control Module (ECM). Although out of warranty, Lexus has agreed to pay for the replacement ECM.
Again, thanks to all of you for your advice.