brandonfpv

just purchased rx300 with 299,809 miles. it was moldy, leaked oil, misfired like a b, and the exhaust leaks. I fixed the oil leak, and the misfire I only fixed partially. the exhaust im worrying about last, but it definitely needs to be repaired. take a look fellas/females. I need ur help!

LeX2K

Define misfire, how do you know?

salimshah

Welcome! We are exited for you.

Is this going to be a 'project car'?

Do share with us the progress and if you need group advice please be specific about the issue as well as diagnostic codes the vehicle is telling.

I would highly recommend that you address personal safety issues before dealing with drivability and cosmetic stuff. Exhaust leak is a personal safety issue as a leak in exhaust can percolate inside the cabin and CO is a silent killer.

Salim

brandonfpv

guys/gals, I made a stupid decision. I purchased an old Lexus with a lot of issues for $1,100, thinking even if I spend another $1000 I can run it to 400k miles, or realistically just 6 months and id be fine. but issue after issue, im beginning to lose motivation.i am leagues away from where I started, but she's still not road-ready. here's where im at: she misfires so bad that the exhaust gets red hot, but wait, there's more, the exhaust leaks so the insulation behind the heat shield catches fire . she stalled the other day and I couldn't get her to move unless I was higher than 1k rpms. im at my wits end, I need help from like a Lexus wizard. there's most likely a vacuum leak. After taking it to two mechanics, and slightly bettering the issues, they told me I have to fix the exhaust first before they can tackle the misfire. the exhaust guys told me whoever works on that car is "risking themselves". Have I made an extremely bad choice, or will a few more hundred dollars solve my problem ? has anybody seen anything like this before? lol thx in advance

maxSteel

I'm having trouble getting oriented. Is that a broken y-pipe? Is the catalytic blocked?
I wouldn't try to drive it like that. You are gassing yourself and at risk of a fire.

You say it is misfiring, what codes is it throwing? I wouldn't be worrying about vacuum leaks just yet.

brandonfpv

sorry guys, im really frustrated that my post never showed up. I replied and I guess I didnt hit submit. anyways, thanks for the warm welcome.

To answer your question(s) as best as I can, yes that is a broken y-pipe, I believe. the codes she's throwing is p0300,p0301,p0303,p0305, (1,3,5 misfire) p0171(bank 1 lean). after looking on the forums I see that this isn't so common of an issue, but I highly doubt someone hasn't experienced almost this exact thing, because I heard another rx300 the other day and it sounded like dog water too. Now, after taking it to like 3 different places, one guy helped me with the misfire a bit, ripped me off. I took it to another mechanic he said to fix the exhaust before he can't do anything until the exhaust is fixed. the exhaust guy is like shoot thats dangerous I would fix the misfire. at this point im just going to get the exhaust fixed because if im not mistaken, the back pressure can highly affect the engines performance, and since these 1MZ-FE engines have a vacuum system, perhaps the exhaust lacking back pressure has a great effect? but after today, realizing the whole front part of my exhaust is now missing I guess it rotted off, and someone flagging me down for the ridiculous amount of flames coming out of the front bottom of my car is super discouraging. it is sitting at a muffler shop currently. im going to give the guy money to weld a new pipe and this new y pipe for hopefully like 150 bucks. but should I get the aftermarket/fake new one or get a used one from a nearby '99 with 130k miles? I only want this car to last me like a year more max until I can get my next Lexus.

maxSteel

Aftermarket Y pipe should be fine, I don't think they are that expensive.

The guy who says he can't do anything until the exhaust is fixed is right .Can't trust the air-fuel sensors with the exhaust like that.
Bank 1 is the one with the broken pipe. All the misfire codes are bank 1.

It's hard to tell from that video if it's more then just the broken pipe, I was wondering if the cat was clogged too. All that red-hot flaming is kinda unsettling. I guess fix it and then see if exhaust is flowing out the back.

If you are handy you might be able to do it yourself. The bolts go through the flanges (not bolted into them) so if they are frozen solid you can cut them out. New fasteners would be good and don't forget the donut gaskets.

brandonfpv

Ok so apparently knock sensors go bad on this model. In another post there’s a guy who splices the knock sensor wire and pairs them up with the good one. Should I do this? Or it’s unrelated to the knock sensor? Btw guys, someone did a lot of engine work to this. New bank one valve cover gasket, to which there is a broken screw, new coil packs and where there was a coil pack screw someone drilled into it because they must’ve stripped it so it’s leaking air! Do you think this much air getting in will cause this bad of a misfire?

maxSteel

You haven't reported any knock sensor codes, so not an issue.
The coil bolt just holds the coil in place. There is no airtight seal there to maintain.

salimshah

Valve cover casting has threads to accept bolt for the coil pack. The threads do not go thru and thru.

The valve cover has tube to allow the spark plug to go through. The tubes have Oring to make an oil tight seal. If the tube develop a leak oil can come through that, but the oil generally pools inside the tube before spilling over the top. You would also see the coil pack soaked in the down hole.

Please, please do not try random fixes. Stick to the reported problems and any visual clues.

Salim

brandonfpv

Ok. sorry guys, I get a bit frantic/excited this is my first car since my accident, so I keep jumping to conclusions. I will try to be patient.


what is that plunger thing called again

I currently have the aforementioned y-pipe and this attached front assembly shipping to my home. after resetting ECU today, she ran fine. so im thinking this is a sensor issue, whether its o2 or knock, but like you said its not throwing any of those codes, so i'm just curious as to what inevitably leads this vehicle to shoot out flames "like fireworks on the 4th of July" someone who flagged me down said. it drives fine cool, but once its warm, she starts to misbehave. today I got lucky though. I didnt stall or jerk once. thats how I know she still has some life in her. anyways, me and my new mechanic, who has been super helpful thus far for free, determined that whoever had previously repaired this vehicle did a very poor job. they welded a pipe where this flex pipe should be, and it completely decayed off, both from rust and because its supposed to flex, not be welded lol. he knows im young and didnt want to take my money if it was going to be wasted, but he sees my investment and the vision, so he is helping me out. But the fact that it still runs in this condition really shows you the integrity of these engines. Also, is it normal to hear a hiss of air come out from the top of the engine when you pull on that thing that connects to the left side of the air manifold? I dont know what it's called, I'll attach a picture. im just looking in every corner for an air leak, a disconnected wire, etc.. and nothing so far.

do you think the removal of back pressure can actually cause air to get sucked in? i remember on my first car, a Chrysler 200, I removed the muffler to be cool or something, and the performance went down like 3 weeks later. it was gradual, but my friend said it was probably lack of back pressure.. the ecu just gets used to it and overcompensates with something I presume. with the highly computerized and sensor filled Lexus, I dont doubt im straying too far from the issue. I can only hope.
what do u think?

maxSteel

I wouldn't drive it or expend any mental energy on it until the exhaust is solid and free-flowing.
So you need a y-pipe and a flex pipe?

brandonfpv

yeah just those two and the exhaust system should be back to somewhat normal. but the misfire really discourages me. like I said it was fine after I reset the ecu.. you're right though I won't stress over it. ugh I just cant wait til I revive her it has already been months probably hasn't been on the road in like 2 years based on this level of wear. thank you thus far steel n salim I feel like I have a team on my side

brandonfpv

update: just received this pipe, do u think it matters if it was 5 times cheaper than oem?

maxSteel

I replaced my rear cat and resonator with Walker stuff five years ago, it's still fine