[ccsdaddyx2]

My lexus rx 300 is sending a code saying that there is a problem with the egr valve.I called the dealership and they said it doesn't have an egr valve. Could anyone help me with this? When I drive it runs a little rough also when I'm on the highway at 60mph the rpm stays at 4000 really high.

[TxGreaseMonkey]

. Change the platinum spark plugs, using the exact brand and plug no. that came with the car (likely NGKs). Gap plugs to .044 inch.

. Check for vacuum leaks on all emission control hoses.

. Start using 5W-30 full-synthetic engine oil; e.g. Mobil 1. This will improve performance, engine life, gas mileage, and reduce emission control sludge. Change every 6,000 miles or 6 months, whichever comes first.

. Clean Idle Air Control Valve/hoses, throttle plate, and throttle body. Ensure all ports are clean. Change air filter, if it hasn't been replaced in the last 25,000 miles.

What exact code was thrown?

[CaptainRich]

Good question, tx. What was the code?

[ccsdaddyx2]

[QUOTE=CaptainRich;1412667]Good question, tx. What was the code?[/QUOTE

it was my wife who got her car checked at an oriley's so they didn't give her the code. The man just said it was an egr valve code so I got it checked myself at an autozone. They said it was sending a random missfire in cylnders 4 and 5. so I changed all the plugs today and cleaned the throtle body. Now the car won't start at all... I think I might need to clean the iac valve and hope that will fix the problem. Checked every connection and its good. Any help with this would be great.

[TxGreaseMonkey]

For random missfires, on cylinders 4 and 5, replace the coil-on-plugs:

While we find your parts, please enter your ZIP Code at PartsAmerica.com

[ccsdaddyx2]

Well I got the car to start now but it still runs a little rough. There is still the check engine light blinking while I drive but didn't have time to get it checked. I could only spray electric parts cleaner through the slot in the throtle body to clean the iac valve and that worked to get it started. Coils or new iac valve? The car runs fine at rpms and just a little rough on the idle.

[TxGreaseMonkey]

Misfires are coil-related. Either the coils are not properly installed on cylinder 4 and 5 or they are likely bad. Did you ensure the plugs were gapped properly (.044 inch)? This can also cause misfires. It's also important to lightly coat the porcelain and electrode with dielectric grease. Good technique is more important than ever on modern-day cars.

[ccsdaddyx2]

Misfires are coil-related. Either the coils are not properly installed on cylinder 4 and 5 or they are likely bad. Did you ensure the plugs were gapped properly (.044 inch)? This can also cause misfires. It's also important to lightly coat the porcelain and electrode with dielectric grease. Good technique is more important than ever on modern-day cars.

When I changed the plugs I pulled the 4 and 5 coil and put them easily accessible in the front got the car scanned today at the local auto zone still the same code on the lexus form at club lexus people having the same problem as me they say to clean the iac valve to fix the rough idle.

[ccsdaddyx2]

I just don't think that it's the coil because they look fine no burn spots or signs of getting hot.

[TxGreaseMonkey]

Yes, cleaning the IACV should definitely help the idle. Not sure it will cause the misfire codes to go away--it's certainly worth a try, however.

[TxGreaseMonkey]

You can't tell by looking at most bad components that they are bad. This is especially true with ignitors and coils. The proof will be if misfire codes return or not, after cleaning the IACV.

[ccsdaddyx2]

Yes, cleaning the IACV should definitely help the idle. Not sure it will cause the misfire codes to go away--it's certainly worth a try, however.

It was the coil packs.
I changed the two and all is good.