Misfire Cyl 1,2,3

[Qis30003]

Hey everyone, I'm a new member to this forum but a Lexus owner for 2 years now IS300/03 5sp 120mil, I enjoy the ride and the power but now just lately i stumbled into a problem which my Mech and I can not figure out.

Here is the the scenario, The Cel was on for the longest time, i got it check it and it was on e-vap codes so i wasn't too concerned about it so i left for a while till one day i was driving on the high-way then the cel came on and started blinking, when i pulled into the closest parking lot i can hear the car stumbling on low rpm and one of my caskets blew on my Greddy cat-back. Turns out the gasket that blew was the on right after the 2 cats. The very next day i brought my car to the shop to get the exhaust fixed thinking that was the only problem i thought i might as well throw in the new clutch, timing belt, water pump and acc belt all at the same time.

After thinking getting all that done my car would run mint again but it didn't it ran even worse for some reason, every time i would clutch the car would want to stall and every time i clutch to change gears it would bounce my tach meter very abruptly, My mech told me to unhook the starter alarm bc that might be causing the problem to that, but to top that off the car was misfiring cylinder 1, 2, and 3. It had trouble driving up to 4000-6000 rpms

I disconnected the alarm/starter and changed the gas with 94octane with lucas injector cleaner and octane booster, the tach worked fine after that and the engine ran a lil bit smother but now the main problem is my cel is still blinking and we checked with the scanner again and the car is misfire in cyl 1,2,3 still,

I changed the sparkplugs NGK Platinum and check engine compressing, results were 200 psi all cylinders, swapped the coil packs around to see if that was the problem, swapped the injectors around, cleaned out the air flow meter, the only thing i can see that was no working well was the signal to the injectors, we hooked up a nod light to check the signal and cyl 1,2,3 the signal was weak and 4,5,6 the signal was much stronger. from here i don't know how to proceed. Oh yeah on the scanner said O2 sensor was reading lean

any advice or tips?? i might think i have to change the ecu but still not certain what the main problem is

and to top everything off does anyone know if i can install and aftermarket deck in my car without losing the stock gps system? the 6 cd changer is broken

[smooth1]

Have you checked the IACV?

[Qis30003]

Have you checked the IACV?

I'm not sure about that but to my understanding IACV is Idle Air control Valve correct? where would i locate that valve?

[smooth1]

Yeah, but you aren't getting any codes off the cel other than misfire 123? The IACV also controls the Vvti. And while we'r e there, the car is timed correctly? I mean your sure it is right? Your mechanic knows what he's doing? You're sure?

[Qis30003]

Yeah, but you aren't getting any codes off the cel other than misfire 123? The IACV also controls the Vvti. And while we'r e there, the car is timed correctly? I mean your sure it is right? Your mechanic knows what he's doing? You're sure?

I'm quite sure just because they took off the valve cover for me and showed me the the dots that are supposed to connect some where near the water pump and the 2 dots that are parallel going vertically up, am i correct? but after you told me about the IACV i went to go look for it and i unscrewed this thing on the throttle body i seen a mechanic play around with once which has 2 Philips screw holding it in right in front of the TB and played around with that, but after i did that the check engine light came off but still idles a lil rough but a lot better but when i drive the CEL starts blinking again

[smooth1]

From your description of the engine, I would venture to guess that your not a tech yourself. You have to resset the ECU. Your probably in limp mode right now. It's a safety mode the ECU goes into to protect the motor from further damage. But the issue is if you resset the ECU< you also erase information that was logged so the proper tech can find out what and why this is going on. My advice is to take it to someone who specializes in Toyota/Lexus. The 2JZGE motors and ECU's have been around long enouph now that any competent tech should be able to diagnose and fix your issue. With out being able to check over the work that was done to the motor, and look at the adjustments and read a scanner we're just shooting at pigeons in the dark here. This could be as simple as a vacuume hose that wasn't put back on tight and fell off, or your timing belt jumped , or your IACV is stuck or not working, etc. etc. etc.

[Qis30003]

From your description of the engine, I would venture to guess that your not a tech yourself. You have to resset the ECU. Your probably in limp mode right now. It's a safety mode the ECU goes into to protect the motor from further damage. But the issue is if you resset the ECU< you also erase information that was logged so the proper tech can find out what and why this is going on. My advice is to take it to someone who specializes in Toyota/Lexus. The 2JZGE motors and ECU's have been around long enouph now that any competent tech should be able to diagnose and fix your issue. With out being able to check over the work that was done to the motor, and look at the adjustments and read a scanner we're just shooting at pigeons in the dark here. This could be as simple as a vacuume hose that wasn't put back on tight and fell off, or your timing belt jumped , or your IACV is stuck or not working, etc. etc. etc.

Your right i'm not a tech, but I am about to give up on this and send it to another mechanic to find out what is wrong with my car, but i'm pretty sure it's one of the problems you mentioned, thanks for the help. but about my last question do you know if i install an aftermarket deck in my car would it disable my existing oem gps?

[smooth1]

For your stereo issue, I don't think they are connected to each other, so you should be fine. You might want to look up DCfish here on the forums. He's an authorized vendor for Lexus OEM electronics. He may be able to help you out there.

[Qis30003]

For your stereo issue, I don't think they are connected to each other, so you should be fine. You might want to look up DCfish here on the forums. He's an authorized vendor for Lexus OEM electronics. He may be able to help you out there.

Thanks a lot you were a lot of help