jkmfab

I am a service manager and having a hard time figuring out this problem. Customer brought us a 2000 lexus gs300 and it had a blown out waterpump. We did a waterpump, timing belt, component kit, tune up, etc on it and when reassembling, the car would crank, backfire out of the intake and then die after about 5 seconds. We verified timing, vvti operation, cam and crank sensor wavelengths, and did a cylinder leak down test. We found several bent intake valves so we warrantied a head job on it, since the tech felt like he may have let the cam slip and the valves hit. After the head job, no leaks in the valves. still the same problem, crank, start for 5 secs, backfire through intake. We have since did a ecm pinout, check the anti theft system, Checked all the sensors on the car. ecm is putting out everything it should be at every pin. It still acts like it is out of time, not sure what to do from here. We dissassembled the vvti and inspected the gears inside and all works great. I have not replaced the vvti actuator or dissassembled it yet. what do yall think?

jj14

Hi jkmfab, you are probably in the wrong section of the forums. This is for the 4th generation (2013) GS. Maybe one of the admins can move this thread to the appropriate subforum?

GS4_Fiend

iTrader: (22)

You got a severe lean misfire. Check fuel pressure

jkmfab

oh yeah, no codes, fuel pressure is within 2 psi of spec

GS4_Fiend

iTrader: (22)

I forgot to mention to check fuel volume also, fuel pressure itself doesn't verify your getting enough fuel. Make sure you got the firing order correct. Check the coil pack secondary side, make sure the boots does have carbon tracking. Make sure you are using dual tip spark plugs and the insulator are not cracked. Bad ignition wires plays a role too.

maximus54

iTrader: (4)

Did the engine run before you did the service? What was everything that was replaced ie. Cam seals. crank seals? You said you did a tune up, did you change the spark plugs?

jkmfab

yes it ran fine, just pouring water out, we did a head job on it, cam seals, crank seal, etc. we checked it with a inline fuel pressure manifold, shows volume and pressure. But please keep helping, maybe we can figure this out with your help

jkmfab

parts replaced-spark plugs,3 ignition coils, cam sensor, crank sensor, head gasket, upper gaskets, key transponder, ignition coil igniter,
parts tested properly via lexus service software- ecm pinout test, coil feeds and grounds, all sensors

GS4_Fiend

iTrader: (22)

What are the fuel trim numbets for STFT AND LTFT?

jkmfab

i cant keep it running long enough to get good readings on both but short term jumps to around 4-6

GS4_Fiend

iTrader: (22)

Are you sure timing is good? Is the VVT-solenoid working?

maximus54

iTrader: (4)

When he put the vvt-i gear back on did he turn it all the way to the right to get the timing right?

oslouie

Plugs on the coils tight?

jkmfab

how do i check the vvti solenoid, i cant find a true component test in mitchell. its all oil pressure actuated, yes it was turned to the right, yes plugs are tight on coils

GS4_Fiend

iTrader: (22)

Use a power probe and apply power to it. Use caution