2002 Lexus LS430 - 200,000 miles
- Oct. I replace all ignition coils and spark plugs.
- Nov. I get a p0121 code, I replace the TPS and calibrate it to 15.3%. It has settled to 14.9% with power on, engine off if that matters.

Shortly after replacing TPS, I get the p0303 code. It would idle poorly at stop signs, red lights, etc. but drive decent enough. I've switched out the coils 3 and 5. When I start the car, the engine idles badly with flashing CEL with code p0303. I checked the spark plugs and coil for cylinder 3 which all seemed fine.

Could all this be coming from a faulty TPS? Any way to check for bad fuel injector?

 

Were you able to get spark plug #3 to spark, as illustrated below?

 

Check the wiring for the coil pack. Sometimes the wiring pulls loose from the coil pack connector.

 

The spark plugs are Denso, and literally bought a month ago. Perhaps there was a dud in the bunch. I'll put a replacement in soon and let you know, thanks.

 

I've tugged on each four connecting wires which seem snugged in there well. I'm aware alot of members have had this issue with their connectors.

I'll be very happy if I were to fall victim to that particular issue. Hopefully a new connector solves the problem.

 

Update: I'm a dumbass, I clipped the connector on cyl. 5 but forgot to do so for 3 and it gave me code p1310. After checking my work, no codes after driving for a good 15 min. or so.

Appreciate RW and 911 for their suggestions. While inspecting the 4 wires from each connection, they all seemed in good condition. I sprayed some CRC electrical cleaner on them.

Apparently the connector housing was faulty even though there was no apparent signs of damage. Would have never guessed it to be the problem, and was going to chase the injector instead. I'm going to change all coil connectors and advise everyone to do the same, thank for everyone's input.

 

 

Thanks for the reply, I edited my previous post and everything seems fine for now...