Originally Posted by sjrutle

LexusLoyal was your CEL and VSC off on constantly? I have a 01 LS430 with 60K on it, just had the timing belt and plugs replace now getting CEL and VSC. Code was 1305. The CEL and VSC only comes on after car runs about 30mins the longer the light is on it will run rough. I suspect the coil pack.

Originally Posted by abs

I once had an intermittent misfire on a couple of cylinders in a GM 3.8 V6 engine - after replacing ignition modules and fuel injectors I discovered that the upper intake manifold was leaking and allowing a small amount of coolant into the cylinders near the throttle body. The leak was slow so no noticeable coolant consumption was occurring. Also, at high RPMs the I would not get any error codes on my OBD-II scanner. At lower RPMs, I would get the misfire codes consistently. The best way to tell if this is the problem is to pull out the spark plugs and see if they are fouled with a brownish crust on them (residue from the coolant). If they appear clean, this is probably not the issue. If it was bad gas, you would see the problem on multiple banks/cylinders, not just Bank 1. If it was a bad fuel pump or fuel pressure regulator, I'm thinking that more cylinders would be involved . . . Lastly, it is unlikely that multiple coil packs would go bad all at once, although not impossible. A bad tank of gas should impact multiple cylinders in both banks as well.

How many miles on this vehicle? Did you recently have any work done on the car?


Always try simple things first:

1. try a high quality fuel injector cleaner (Chevron w/ Techron is tops)
2. try adding isopropyl alcohol to absorb and burn off any water in the fuel (just in case)
3. check plugs for fouling
4. verify fuel pressure in the fuel rail at varying RPMs are in spec
5. swap coil packs to ensure they are not the culprit
6. last option check for small coolant leaks into the cylinder (due to a failing gasket) by disassembling upper engine

Good luck,

Andrew

Originally Posted by LexusLoyal

I have a 2002 LS430 UL, with 135k. A few weeks ago my check engine light and VSC light came on, also the car began to idle rough, I ran the code and it was P0301, Cylinder 1 misfire. I attempted to troubleshoot the problem myself, i replace the spark plug, the coil, cleaned the MAF, added fuel injector cleaner to the gas tank on two occasions, but none of this helped, it still idles rough and check engine light is still on. Now I'm thinking it may be the fuel injector or maybe head gasket is blown, either way I think I will have to take it into the shop. Does anyone know how much it'll cost to replace a head gasket. What else can be the problem? Can I still keep on driving it?

Originally Posted by Khalusta

Hi Andrew thanks for your message.

I have a 2003 LS430, recently had the starter replaced, i now have engine misfiring codes (all odd numbers on the same bank) and VSC warning. Also CEL flashing during idle in traffic. Under throttle car runs fine.

Is it possible that the mechanic allowed water or debris into the intake manifold during the starter repair which is causing the current issue?