It’s only a few months old. I never had any problems with the battery since I replaced it

 

Timing isn't a good reference point on performance. Running full OEM timing only says your car is OK. If it's really running well, you should be running a lot less than factory full timing. Combustion chamber efficiency is directly related to full advance timing, and a good combustion chamber runs about 7 degrees full advance. More advance means your efficiency is crap, and you're applying a bandaid for a poor combustion chamber design.

 

The advance was probably related to the e30, but I was running the same fuel with the tune so it’s an objective measure. I’ll see this spring what it runs on 93. I imagine it’ll go down some.

 

Quick update: I did a boost leak test and there was quite a big leak at the blow off valve area, which is now fixed. However, the car is still having the same issues. If anything, it’s running way more lean now than before and I can barely go into boost. Anymore than 10% throttle and the car will start jerking repeatedly and it seems to do it anytime boost vacuum reaches 0 and is about to go into boost. I plan on getting my fuel filter looked at later this week and will report back the results.

 

Did you install the kit yourself?

 

No I didn’t, I had a local performance shop do it for me. There weren’t any shops in my area is familiar with Lexus let alone a supercharger install and I’m not the most mechanically inclined unfortunately.

 

Can't remember the last time I heard of anyone pulling out a clogged up dirty fuel filter in a newer Lexus IS.

Joe Z

 

Right? I’m just desperate for answers at this point.. it definitely seems fuel related I’m not sure what else it could possibly be.

 

i have an sc isf and diagnosed multiple issues and installed myself. The maf is extremely sensitive. Check all of your piping and connections even the smallest leak will cause mayhem. Make sure your BOV is set correctly and is functioning properly, test the boost air line to the bov and make sure it is clear. A bad maf sensor will cause a ton of bogging issues as well. If you fixed a leak, reset your ecu the fueling will be all over the place when its used to a running with a leak. If rafi sent you a map to correct the issue might want to go back to a base map without any revisions. Did the shop need to extend the wires for the maf when it was installed? I would check their work, if its crimped or soldered poorly that will make a voltage drop in the readout of the maf sensor. Im going to bet on an air/boost leak somewhere and it makes sense that it has gotten worse over time. If you have an air oil separator even a tiny leak from that will cause multiple issues and difficult to diagnose as its a vacuum.

 

I’m not SC but I can say with certain that what the @dcguy says is 110% true! I had a bad MAF sensor a while back and my car ran like absolute trash. I could not figure out what was wrong for a while either because it would not throw a check engine light. Near redline it bogged and would shake. When I drove the car normal though it would have no issues. At WOT between 5k rpm until redline is where I had issues. Either it wouldn’t be able to redline or it would shake, bog and lose power, etc. eventually I tracked it down to the MAF sensor. Mine was clean and looked fine. I ordered a Denso one off rockauto and after installing it all my problems were gone immediately after installing it.

 

What led you to figuring out it was the MAF?

 

Things I checked: fuel pump, fuel pump filter, spark plugs, ignition packs, wiring, RR tune, fuel, I also did a compression test. Eventually I just unbolted the MAF to look at it and it visually looked fine. I honestly can’t remember what made me order a new MAF but at that point I’m sure my mindset was what do I have to lose.

 

Did you do another boost leak test after fixing that leak?

 

was going to suggest resetting the ecu after the boost leak but you beat me to it.

 

Okay I went ahead and ordered a new Denso one from rockauto. Really hoping it’s something as simple as this!