Misfire When Engine Is Cold

[ExiledinIN]

I have a 2002 ES300 w/ 46,000 miles. I'm parking the car outside at the moment since I have some projects that are taking up the room in the garage. Night time temperatures are 5-10 deg F. When I start up the car in the morning it is running rough as if it is not firing on all cylinders.

It did this 2 weeks ago, and it threw a CEL. I took it to autozone for them to check the code. The guy said something about random multiple cylinder misfire. Since the engine was running fine, I asked him to clear the code.

However, it started doing the rough start this week.

Typically, I start the car, and it is stumbling around 1000 RPM or less. I gas it past 2000 RPM and it runs fine. I let go of the gas pedal and it falls down to 1000RPM and less. Sometimes, I will just die if I do not give it more gas. I hold the gas in for 1 min and then it is fine.

Has anyone experienced this before?

[monarch]

You need to find out if the problem is ignition or fuel system related. Since no code is being set for a rich or lean fuel mixture, there's a strong probability the problem is in the ignition system. Probably something minor and inexpensive to fix like a partially fouled spark plug or weak ignition coil on one or more cylinders. Switching to premium gas could help reduce propensity to miss.

[Toysrme]

Clean the IAC valve first & check for vacuum leaks.

Then get around to checking your plugs/wires/coils & the fuel system.

[ExiledinIN]

I use premium fuel on my car, so I think I can rule the gas thing out.

There's a nice import garage in town, so I'll check w/ them on a TB cleaning along w/ the IAC valve cleaning as I'm desperatly short of time... Plus it's darn cold in the garage atm!

One other question. With a sticky TB or IAC valve, what causes it to misfire? Not have the correct A/F mixture due to the stuck plate and valve?

The dirty TB and IAC tends to feel more right as the code is for a random multiple cylinder misfire. Whereas a bad plug or coil will always have a misfire where ever that coil or plug is located.

[mburnickas]

I use premium fuel on my car, so I think I can rule the gas thing out.

There's a nice import garage in town, so I'll check w/ them on a TB cleaning along w/ the IAC valve cleaning as I'm desperatly short of time... Plus it's darn cold in the garage atm!

One other question. With a sticky TB or IAC valve, what causes it to misfire? Not have the correct A/F mixture due to the stuck plate and valve?

The dirty TB and IAC tends to feel more right as the code is for a random multiple cylinder misfire. Whereas a bad plug or coil will always have a misfire where ever that coil or plug is located.

You can clean the TB and Ivac in about 25 minute and cost about $4. If you do a search on here, it has come up may times. I did mine this summer, very easy.

Also mabe you have water in fuel? The fuel does not matter, It matters how log it was in there tanks. I am starting to use FP60 in my fuel.

[monarch]

40,000 miles is not enough miles for the TB or IAC to get seriously gunked up (except maybe on a car that has been modified from stock). Therefore I would bet my money something is marginal in the ignition system or that the independent shops that have been servicing your car were sloppy and disconnected or misrounted a hose or wire or left a air intake tube hose clamp loose or tore a hole in the tube by accident or something like that.

I thought new Lexus's came with a 4 year, 50,000 mile bumper to bumper warranty. If so, how come you are not considering taking the car to a Lexus dealer for diagnosis?

[Toysrme]

40,000 miles is not enough miles for the TB or IAC to get seriously gunked up

Minus the carbon, look at how much oil recycles through the front breather & PCV valve.

This was a '99 1mz-fe, pics taking in '03, or '04. All the oil from the front breather get's sucked straight through the IAC/ISC valve on all the engines anytime the valve is in operation.

Heating bakes said oil everywhere where it stands.

[mburnickas]

Minus the carbon, look at how much oil recycles through the front breather & PCV valve.

This was a '99 1mz-fe, pics taking in '03, or '04. All the oil from the front breather get's sucked straight through the IAC/ISC valve on all the engines anytime the valve is in operation.

Heating bakes said oil everywhere where it stands.

I love when you post. You tell it like it is!!!!!!! :) :) :)

So much for the beloved Toyota design. I wish people would face the facts; they are not perfect and call it a day. I think you posted more times on this then my oil debates. :P

If no one has checked it 100 to 1 it is bad. If anyone thinks it is not an issue, they do not have (OWN) these modes years. Mine was not the bad but pretty bad; and it is STOCK.

[ExiledinIN]

40,000 miles is not enough miles for the TB or IAC to get seriously gunked up (except maybe on a car that has been modified from stock). Therefore I would bet my money something is marginal in the ignition system or that the independent shops that have been servicing your car were sloppy and disconnected or misrounted a hose or wire or left a air intake tube hose clamp loose or tore a hole in the tube by accident or something like that.

I thought new Lexus's came with a 4 year, 50,000 mile bumper to bumper warranty. If so, how come you are not considering taking the car to a Lexus dealer for diagnosis?

:chairshot: doh! i'm so used to 3/36 that I didn't remember. I'll call the dealer in the morning.

[Toysrme]

It's worse on the old model engines that had EGR & idle valves, better without the EGR & better on the new ones where it's got just an electronic throttle. - But the same thing is still going to happen.

The two ACIS valves in them now. It's all crazy in there.

Eh I mean it's a stupid thing to argue about, but it's always been a problem on not just these engines, but about every engine. It's just one of those things that tends to happen. (In his case it's just moving the rubber pipe off the throttlebodies & seeing what's going on. Maybe that's the problem, maybe not - but only good comes from cleaning that stuff. :) )

Good deal on the new warranty. I didn't know the upped it either. Handy info! :D

[mburnickas]

I have a 2002 ES300 w/ 46,000 miles. I'm parking the car outside at the moment since I have some projects that are taking up the room in the garage. Night time temperatures are 5-10 deg F. When I start up the car in the morning it is running rough as if it is not firing on all cylinders.

It did this 2 weeks ago, and it threw a CEL. I took it to autozone for them to check the code. The guy said something about random multiple cylinder misfire. Since the engine was running fine, I asked him to clear the code.

However, it started doing the rough start this week.

Typically, I start the car, and it is stumbling around 1000 RPM or less. I gas it past 2000 RPM and it runs fine. I let go of the gas pedal and it falls down to 1000RPM and less. Sometimes, I will just die if I do not give it more gas. I hold the gas in for 1 min and then it is fine.

Has anyone experienced this before?

Call me dumb here but I just went over to the other "lower class" Lexus forum and low and behold you asked the same thing???? I would say pick a forum and call it a day. Based on the site owner over there, you are better off over here!

[ExiledinIN]

I have a 2002 ES300 w/ 46,000 miles. I'm parking the car outside at the moment since I have some projects that are taking up the room in the garage. Night time temperatures are 5-10 deg F. When I start up the car in the morning it is running rough as if it is not firing on all cylinders.

It did this 2 weeks ago, and it threw a CEL. I took it to autozone for them to check the code. The guy said something about random multiple cylinder misfire. Since the engine was running fine, I asked him to clear the code.

However, it started doing the rough start this week.

Typically, I start the car, and it is stumbling around 1000 RPM or less. I gas it past 2000 RPM and it runs fine. I let go of the gas pedal and it falls down to 1000RPM and less. Sometimes, I will just die if I do not give it more gas. I hold the gas in for 1 min and then it is fine.

Has anyone experienced this before?

Call me dumb here but I just went over to the other "lower class" Lexus forum and low and behold you asked the same thing???? I would say pick a forum and call it a day. Based on the site owner over there, you are better off over here!

Yup, as I am new to the Lexus family, I didn't know who would bite first, so trying out both sites....