Rokas

Hello Lexus people,

I'll give you guys a rundown of what led to my current problem.

My car has 220k miles and had barely ever been maintained before. Anyway, I was driving and all of a sudden, I lost like 85% power. I had to drive with hazards because it was so slow.

I thought maybe clogged cat so I took it to the shop, they ran a test and it wasn't. Sent me home saying I need a new timing belt, waterpump (doing these two soon - separate problem), spark plugs, wires, and distributor rotors/caps.

First I changed out the spark plugs. That alone brought enough power back to where I could drive without hazards with everybody passing me. At this point and before, I was getting code p0130. Being a dummy, I changed out that O2 sensor but the code came back. It's not the sensor - it's what's coming out the exhaust.

There is a strong smell of gas from the exhaust. You can smell it inside and outside. It's definitely coming out of the exhaust but also the smell is strong by driver's side tire area although I'm not sure that means anything.

Next, I did the spark plug wires. This helped even further. Then I noticed my throttle was acting weird. It was pretty unresponsive. I was able to floor it a couple times and the throttle was like 60%! Although it's not all the time - another time, it put me back in my seat.

I changed out the fuel filter which was definitely due for a change and that helped even more. However the weird throttle problems persisted...

So throttle problems... I changed the Throttle Position Sensor. This actually helped even further. ALSO, the p0130 code went away and then I got a p0150 (different oxygen sensor). Why did this happen? I think this here might help somebody to figure this out.

But even though it helped, I noticed it was still not as responsive. I then tightened the throttle cable. It was pretty slack.

At this point, the car drives okay. As long as I'm driving with traffic, it's fine. The gas pedal is a lot more responsive. However I still have this fuel problem.

Thankfully, I don't think I'm losing more than like 4mpg but I need to get this figured out. I don't know but I feel like it throws the engine off or even the transmission. I know the tranny was taking longer to shift but that was fixed by the TPS. The only thing left as far as that is that when I put the car in D, it takes a second to go into gear.

Now I'm thinking Idle Air Control Valve. I'm at least gonna clean it.

As far as the fuel problem, where do I start? Are there any more sensors, valves, or "small" things I can look at? I'm just wondering if I have a leak for sure or if the ECU is sending more gas for some reason. At this point, I think it's the former but I need guidance. I'm gonna turn the car on while I follow all the fuel lines to see if I can find a leak but I wasn't able to doing a quick check.

Where are the common places?

I know I need to check the fuel injector O-rings. Can someone post a pic of where the fuel injectors are on this motor? I've never worked on any fuel system.

Anyway, if anyone has any good leads, please let me know. I need my baby back! Well, at least I need her to drive right (and not blow up...). Thanks.

Rokas

Guys, after thinking a little bit and doing some "testing," I think I have a vacuum leak. It's not normal to hear a "tsssssssss" while driving, right? Today I floored it and the air escaping sound was very prominent and was punctuated by even stronger releases of air... Sounded like a blowoff valve. I bought a few different size hoses so I can replace a bunch of them and pray but does anyone have any ideas? My car does have an ACV delete but I really doubt it's leaking air through the plugged valve.

Edit: This would make sense cause vacuum leak = car runs rich so the engine doesn't get damaged running lean.

Yamae

Generally speaking, "vacuum leak = car runs lean" because the additional air goes into cylinders. The air absorbed additionally is not measured by the MAF, you know.

Other than searching the unusual sound source, I'd check the feed back system of the car measuring the ripple voltage of the VCC=5V line first at the MAF or at the water temp. sensor for the ECU because too much ripple causes the A/F ratio extremely rich. I also will check the DC voltage at the water temp. sensor too. A failed sensor keeps the voltage higher than 1.35V and the A/F ratio becomes richer than normal.

One more thing. Your description "Sounded like a blow off valve" reminds me of a tiny explosion in the exhaust line which is caused by the unburned fuel. Too rich causes so.

Rokas

Thank you. Let me ask you - is there no situation where the ECU would realize the car is running lean and overcompensate? I read that an engine running lean can get damaged so a lot of cars are made to run lean in that case? Maybe I'm way off.

Anyway, yesterday I found the source of the hissing sound. I got under the hood and if I pressed the throttle down, there it goes... Pssss... And it seems to be coming from the line coming out of the power steering pump. However I replaced it and made sure it's tight. It seemed to hold up for maybe 15 miles IF IT wasn't in my head but now it leaks air again despite the fact there's PS fluid in there... Am I mistaking it for something close leaking? There's a bunch of metal lines close too but I don't see a problem.

This is what I replaced and the bottom attached part seems to be the source of the sound but I'm not so sure anymore. This is driving me nuts... The car has been running like this for over a month.



See the metal lines in the first picture? Could it be one of those? The problem is that the sound really seems like it's coming from that hose.

I replaced both the temp sensor and temp sender (for the gauge). My MAF sensor IS old however. Could you please spend the time explaining how to do the tests you spoke off with a simple voltage meter (I have ohms, etc)?

Rokas

Yamae, first of all thanks again for your help and second, I was just thinking about your blowoff valve sound comment in regards to the extra fuel. Well, you are right that it causes a similar sound aswell but I'm actually getting both of these. Thank you for helping me remember.

And also, the only reason I'm thinking a vacuum leak is the sole cause of this is because I Googled "Can a vacuum leak make a car run rich?" and the answer at the top of the Google search was that yes because the computer shoots for a rich fuel mixture to prevent damage that it might sustain running in a lean condition.

Also, I could have SWORN that for 10 miles or so after I installed the new hose, the car WAS running good and didn't seem to be making that hissing sound but the problem is that I can't replicate it and I can't really say my car wasn't just running exceptionally well at the moment... It also doesn't make sense to me why it would hold up for 10 miles or so but not longer. The clamps are on there good.

aptoslexus

Check your fuel trims with an OBD reader. Sounds like you have a rich condition. I would check the intake and MAF for any obstructions.

Htony

How about compression test, blow down test? How did old spark plugs look like?

Rokas

Would the AutoZone reader be able to tell me this info? I only have a code reader - it doesn't tell me anything else.

Also, what is the proper way to clean the MAF sensor on a 95? It's a little weird how the shape is. I assume the sensor is inside. Can I use throttle body cleaner or brake cleaner? I know if there's any residue left, that's bad. Out of 5 LS400s at the junkyard, none are above '93.
​​​​​​


Htony,

The old spark plugs had a good amount of carbon on them. One of them had a little bit of fresh oil which wasn't there after I replaced them. This is what a 220,000 mile spark plug looks like! The previous owners apparently thought all you need to do is change the oil... Sometimes...

Guys, I'm gonna try the starter fluid method of finding the leak but if it's letting air out, how is the starter fluid supposed to get in? I'm just trying to understand. I know the idle should bump up a little if you hit the spot.

Some time later I'm gonna take more pics of the surrounding area and hopefully someone notices something. I would hate to pay a mechanic to do something simple that I feel like I'm overlooking.

The problem really sucks... It's almost like the constant "psssss" while I'm driving directly corresponds to power loss... The more throttle, the more air escaping sound. I should tell people it's a supercharger...

jaaa

Your car is at the age where the EGR pipe would crack and be leaking. It can be loud, but you should be able to smell some exhaust smell if it's loud enough.

aptoslexus

A lot of code readers will also give you other information, including fuel trims. I don't have any experience with the Autozone reader, but it should. I recommend picking up a bluetooth OBD II dongle from Amazon or Ebay and pairing it with an OBD app for your phone or tablet like Torque Pro. That shouldn't cost more than $25 or so. The fuel trims should be close to 0. If they deviate quite a bit plus or minus, you know you've got a problem. You need a special cleaner for MAF sensors. Don't use anything like brake cleaner.

Rokas

Oh thank you! I'm definitely gonna order one. Perfect.

And Jaaa, you might be right. I know that the problem could be that EGR pipe and I'm seriously hoping not. I'm just wondering, can the crack simply be welded? I need to get my timing belt and waterpump replaced soon and I should be close to the pipe to replace that aswell, yes? Well not me - I'm gonna pay a mechanic cause I work a lot and I can't do it myself right now. But yeah, this happened after winter and here in Florida, the weather was up and down - cold one week, hot the next, cold again so it very well could have cracked.

Thanks for all the help.

Rokas

Hey guys, I'm back after checking some things and making a little progress.

1. It wasn't the EGR pipe. There's no cracks.

2. EGR Valve - where is it? On a 95, is it on the left or right side of the engine when looking at it from the front of the car? I was gonna clean it but when I started undoing the hose, coolant started coming out so I'm obviously looking at the wrong part, right? It was the part on the right side of the engine (driver side).

3. I found and replaced a fuel line that was actually cracked past the clamp. I did that yesterday and I have now driven a good 50 miles and there is still no check engine light. Now, there still is a problem but it seems changing the hose did SOMETHING.

Now, it accelerates a little better and I can actually give it some good throttle in second gear without it ******ting itself. Also, now I smell fuel in the cabin only sometimes, typically at a red light. Before I changed the hose, it was ALL the time.

I don't know what the chances of having two fuel lines mess up at the same time is but I'm gonna replace every one I can if it doesn't rain today.

Is the EGR Valve the part that has a saucer-shaped thing with a small hose connected to it on the left side of the engine (passenger)? I'll figure that out myself soon here.

Guys, I can't shake the feeling that whatever this problem is, is just something simple. Wish me luck... It sucks driving what feels like a 150hp LS400. ;(

Random: my back seat was torn up like crazy so I did my own upholstery and turned it into a bench seat. Let me know if you like it. I'm posting a tutorial on my website soon (I don't know if I can post links).

spuds

Nice rear seats are a dime a dozen at the auto wreckers here.....

Rokas

Yep... Still waiting. The last 3 that fit my year were torn up and they just had 3 93s with great seats but I couldn't find any info as to if they fit.

Rokas

Anyone got ANY suggestions?

Can it even be the crankshaft sensor?

Like I said, when I give it some good throttle, depending on the gear, it ****s out. In first, it starts going slower until I let off... In second, I have to wait for the RPMs to build up a little and then I can hit it a little - the engine revs up faster but still ****e. I can push the pedal all the way down in some cases and it's still accelerating at a slow pace.

Does a 95 have a pedal position sensor?

If I floor it in 3rd or 4th, it doesn't know what to shift to until I let off a little and then it takes off pretty well BUT still with a loss of power.

Someone point out the EGR valve please. If I remove just the black motor (I assume) attached to it, will it give me access to clean it? Like I said before, my EGR valve seems to have coolant running through the bottom and that makes no sense to me. I'm comparing pictures of the part online with what I have and I'm stumped.

Also, my RPMs are low at idle. Like at 250rpm. Maybe IACV? I just changed out the TPS but should I try adjusting it? I put it in how the old one was.

I'm about to take this to a shop and get ripped the hell off unfortunately if I can't figure it out. There is an audible sound of air escaping as I drive and like I said, I know the area it's coming from but there's nothing but a vacuum hose I replaced and fuel lines that look to be in good shape (no corrosion).