My 2003 with 234k miles started running into this weird issue out of the blue where itll struggle to go up hills especially in cruise control. Itll downshift way more than it has to just to struggle to go 70mph. On top of that when hitting the gas after a complete stop the car seems to not want to accelerate at all. I tried resetting the ecu or whatever by leaving the battery disconnected overnight and no cel came on after that but the problem is still there. I used to have check engines lights for the evap system and the egr valve, but then theres stored codes that arent triggering a light which are c0200, c0205, c1223, and c1336.

I cleaned the maf sensor, flushed all of the fluids, replaced my air filter, ran a fuel induction clean with wynns products that had no smoke out the rear, im running 93 with ethanol and have only ever ran premium gas, and Im mostly straight piped as you can hear. My throttle position sensor seems to be reading properly, same as my maf sensor, o2 sensors, and knock sensors. Spark plugs and ignition coils were all replaced about 20k miles ago, i have a minor oil leak from my valve covers and a bad power steering fluid leak from the lines to the reservoir. Im not running any performance parts whatsoever.

Is there something obvious im missing that could be causing my issue? Does anyone have any ideas as to what i should take a closer look at or try to do? Im at a loss as i cant seem to find anyone who has dealt with the same problem that wasnt fixed by everything i already did.

 

The intake manifold Jaz variable length runners to improve low end torque but if the VSV wears out, they could end up stuck and hurting performance without triggering a CEL.

 

If im understanding correctly my egr valve is part of that runner switch system. Ive had the failing egr cel for the past 50k miles and the car ran fine then up until recent.

So do you think the rest of the system possibly already fell through and quit on me? Any idea how i could test if my runners are switching properly?

 

There isn’t any EGR valve your car. It’s on the back of the intake manifold

 

I have an intermittent p0402 code for excessive flow in the exhaust gas recirculation system. It was my understanding that that meant i had a bad egr valve. And when i searched for an egr valve location online for my car it showed this piece circled in the image where i currently have a vacuum leak due to the plastic hose connector snapping. If its not an egr valve then what is it? And could it be related to my problem? It drove perfectly fine with that vacuum leak for like 40-50k miles before hand

 

This thread will explain it better than I can- https://www.clublexus.com/forums/ls-...ocedure-7.html

 

Also, in the interest of ruling out possibilities-
What brand of coil and spark plugs did you replace with 20k miles ago?

 

I cheaped out and got a-premium coils and iridium spark plugs (attached picture). I understand the forums sentiments on non oem parts but it was all i could afford at the time when i had a misfire. My misfire back then was only a single cylinder but the car could barely run and tried rattling the whole car apart. I dont believe my issue could be the ignition stuff or misfire just because of how different it is compared to back then, but i could check that out tonight

 

[QUOTE=Chip532;12059384]I cheaped out and got a-premium coils and iridium spark plugs (attached picture). I understand the forums sentiments on non oem parts but it was all i could afford at the time when i had a misfire. My misfire back then was only a single cylinder but the car could barely run and tried rattling the whole car apart. I dont believe my issue could be the ignition stuff or misfire just because of how different it is compared to back then, but i could check that out tonight
QUOTE]
$137 for plugs AND coils.
I think you just found the problem.
This is 1000% oranges and apples compared to the single misfire.
Parts like this are made to fit but are nowhere near the standard of performance necessary to run properly.
You’re probably lucky to get 20k miles out of them.

 

[QUOTE=bradland;12059391]Not to sound dumb, but im not too bright and i dont understand what you mean on your oranges and apples comment. I would like to say though that i dont believe in this forums sentiments on oem parts vs aftermarket. I will check these parts however just because its easy enough to do, and i can try swapping over whatever coils and plugs with my old functional oem ones i have still and see if theres any performance difference.

Is there anything else youd recommend i try checking out while im under the hood next?

 

[QUOTE=Chip532;12059410]You had 8 (likely) original coils which rarely fail without extenuating circumstances like excessive heat or oil contamination.
1 of the 8 went bad, possibly from tube seal leakage, so you replaced all 8 with junk coils and also 8 junk spark plugs.
The new parts (all 16 of them) are barely doing their job from day one, emphasis on BARELY. Oranges and Apples.

If you don’t believe the “sentiment” of ClubLexus collective knowledge base, why are you here asking for advice?
You’re more than welcome to continue buying cheap parts, it’s your car and your money.
Usually after the 3rd or 4th failure is when people realize you would've spent less buying genuine parts in the first place.

Buy 1 decent coil from Rockauto, and 1 correct spark plug, then put the old parts back in to at least get the car running correctly.
When one coil goes bad you don’t have to replace all 8.
1 Wells (brand) coil is currently $32, Wells is a division of NGK.
Also buy 1 Denso 3297, or NGK 4589, no exceptions.
UZ engines are very finicky about coils and spark plugs.

 

[QUOTE=bradland;12059444]The old coils were all original never replaced, and when the one went bad it left me stranded out of state. I went to replace all 8 so i could avoid a similar situation in the future as i wasnt gonna stay trusting 200k mile coils. The spark plugs were a while i was in there situation but i did replace iridium plugs for iridium plugs. Doesnt matter if the plugs werent oem manufactured if theyre practically the same inside and out. Spark plugs are very simple components after all and theyre easy to replace and cheap no matter what so i dont mind if i have to replace plugs a slight bit more often.

I disagree with the forum sentiments on replacement parts needing to be oem or theyre trash parts. I can still however show up to the forum to ask for knowledge on the cars systems, functions, and repair tips/secrets. Like i said I'll still be checking the trash parts as you call them so im still listening to yalls advice.

Also i understand im in a top tier lexus car so i shouldnt cheap out on parts but sometimes we find ourselves in a rough patch and just need to buy what ya can to get by.