ryman91

To whomever would like to assist in diagnosing these issues:

2003 Lexus GS 300 base

1. Just swapped all spark plugs to NGK (3764) BKR6EIX-11 Iridium IX Spark Plug
2. changed valve cover seals
3. changed wiring for sparkplug/coilpacks and clips
4. changed intake plenum gasket


Issue:
After replacing these items, I noticed several things:
1. AC wouldn't work right - although this may be due to something else possible over pressurization or not enough freon. I am diagnosing now with a new set of gauges to check that today (7/17).
Question: Are any of the hoses that are needing to be disconnected to reach the valves related to the HVAC system?
2. Car sputters randomly at idle and low/medium-low RPM. - With the MAF sensor being replace (new) within the last 6 months im almost certain it cannot be that. I even took it off and used electronics cleaner on it yesterday (7/16), still happens. I'm thinking it could be either electrical wiring to spark plugs? Or, and i don't believe it to be the spark plugs but misfires?
Question: Can the order the coil packs were in affect the timing or something else? I had them in order but mixed them up when someone helped me with the replacement of the wires.

Also - noticed after driving immediately - shortly after replacement of said items and with the HVAC (AC) fan on , i could hear pitched sound related to RPM varying up and down. Haven't heard it lately but could this be a symptom of a vacuum leak or something to do with the Intake plenum gasket? The gasket should be straight forward, got the replacement part from ebay (link below). There is a air/hiss sound that i can attach a video of but i wasn't sure that was Im 99% positive i got all the hoses re-attached, added more coolant to the said level.

https://www.ebay.com/itm/Fits-1993-2...53.m2749.l2649 -- intake gasket
-- spark plugs
https://www.autozone.com/external-en...414_11985_6534 - valve cover seal
Thanks in advance to anyone that wants to help.

captainva

iTrader: (1)

Double check that all of the hoses are reattached correctly. It definitely sounds like you have a vacuum leak. Also check that the insulation didn't fall off your coil pack wires. I had to fix mine because all of the insulation fell off one pair when I replaced my valve cover gasket due to it being old

TrueGS300

Do you have a way to watch live data? You need to see STFT and LTFT to see if its lean. This will be how you know there is a vacuum leak if it cant be found visually. Did you replace the plugs for any of these symptoms, or are they new just since doing them? On mine, I replaced the hoses for the EVAP purge valve and PCV valve because they were so brittle. I also replaced the PCV vale and grommet because it was cracked and coming apart. There are many potential vacuum leaks, so I also suspect that something is not connected, misconducted, or a brittle line has been damaged and letting in air.