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I had already cleaned the throttle body, but didn't realize the two larger holes inside the cover plate feed the fuel injectors. Those air paths were cleaned today by removing this cover plate and injecting throttle body cleaner into the two holes in the back wall of the chamber. Didn't even need to disconnect any hoses. Just remove the two screws and lift off the cover plate. This pict if from my prior TB cleaning and has one hose disconnected. For just the fuel injector air mix passage cleaning, the hoses remain connected.
Had engine idling and injected a whole can of cleaner into the medium sized holes. Engine must be running. Injected via straw for about 4 seconds and chases with compressed air. Each injection causes engine to rough idle and puff out some white smoke from exhaust. Once idling recovered, I would spray again.
BTW, don't spray the little holes in bottom of chamber. Doing that once, immediately stalled my engine.
Post cleaning, a ton of misfire codes needed to be cleared. VSC warning light was also on, but clearing the codes took care of the VSC warning. Now that I have an Android and Torque Pro installed, clearing the codes was super conveniently done without dragging out TechStream. Torque Pro clears the codes with a few screen touches.
Reset ECU and let idle for a few minutes. Then drove some miles to let ECU relearn. Engine feels even smoother. LTFT's are definitely shifting from their pre-cleaning readings. Previously, bank 1 was negative 7 but is now trending towards zero. Bank 2 was zero and is tending slightly positive. Will be a while before they settle, but drive into work was super smooth running and peppy. Felt almost like having a wind pushing behind me.
Last edited by Seattle SCone; 02-17-21 at 04:31 AM.
Got them from LexusPartsnow. Not the cheapest source, but I wanted preformed hoses that match the originals.
The attached PDF's were from somewhere else in this forum. I can't find the original thread.
Crossmatching against the LexusPartsNow got me mostly right. The power steering and 25804 associated lines, I haven't worked on yet.
Actually, I'm still trying to find where T.Fck. 25804 charcoal canister assembly is in the car!!
i appreciate your posts sharing your upkeep. your skills are beyond mine but at least i get an idea of what to look for when talking to my mechanic. thanks.
It turned out to be the ACIS vacuum system that sits underneath the intake manifold along with the starter. It's completely hidden unless one removes the intake manifold. Final identification is at end of this thread https://www.clublexus.com/forums/sc4...component.html
Today's project was Seafoam Spraying the air intake. I used the aerosol can version because I feared hydrolocking the engine with the liquid version. I don't pretend to know whether or not the treatment did anything to the carbon, but yep. Plenty of smoke for about 10 minutes post "hot soak."
The only things I can add about the experience that might be helpful to other SC430 owners...
1. I didn't use anyone to help me maintain 2,000 RPM. Instead, I used a board wedged between the accelerator pedal and front seat to set the desired RPM. Moving the seat forward/backward with its usual positioning switches was convenient way to adjust the pedal depression.
2. Took under 10 minutes to spray entire can into the straw (which had been fed into front of throttle body along with its curved shaper). Hardest part was keeping the dang nozzle depressed for such a long time.
3. Engine increases RPM slightly while Seafoam is being sprayed.
4. After the 30 minute "enthusiastic" drive, I parked and scanned for DTC's. Then, reset the ECU prior to drive home.
5. Only one error code was triggered - a fuel too rich on bank 1. Other than that, not a single other DTC was found on scan
6. O2 sensors were not destroyed. They still have nice swings, but I can see the trims are being relearned. I surmise that based on differences in LTFT's from what I usually see post an ECU reset.
Drive home registered the highest MPG I have seen on the car's computer, 25.0 MPG. That number is to be taken with a grain of salt, but is higher than what I have seen on the same drive home, also post ECU reset. My drive home is about 80% country road / 20% city. It will be weeks before I get a good handle on mileage, but prior to the SeaFoam I was seeing 23.8 MPG. Before its refit over the past few months, my poor SC430 was all the way down to 20.3 MPG on that same drive.
Was Seafoam air intake helpful? Don't know definitively. Even more confounding is the procedure includes a drive which is basically an Italian tune-up. That in itself could change things for the better in a carbonized engine.
At least, It didn't destroy my engine or sensors.
Last edited by Seattle SCone; 02-21-21 at 12:40 AM.
I was told couple years ago by "auto" friend to add a can of SeaFoam to full tank of gas at each oil change... Any truth in this / does it help??? people out there swear by SeaFoam????
I was told couple years ago by "auto" friend to add a can of SeaFoam to full tank of gas at each oil change... Any truth in this / does it help??? people out there swear by SeaFoam????
When I had Corvettes a chevy engineer told me to use Techron every 5,000 miles in any fuel injected motor. I have done this faithfully in all my cars for over 25 years and never had a fuel system problem (I also use only top tier fuel). May be a coincidence but as it is pretty cheap maintenence I will continue to do so. My SC is nearing 130k miles and runs flawlessly.
I have regularly put in a bottle of Techron in my 225k mile SC430 work horse. It has been fed only top tier gas and twice yearly oil changes all its life. Techron noticeably smooths out the idle in a few days post addition.
This trial of Seafoam in the air intake is a new experience for me. When I cleaned my throttle body, there was carbon buildup. It is reasonable to presume there is carbon buildup further in the air intake manifold. I wanted to see if the process yields any difference. Next debate is whether I should do an early oil change post the tx. I'll examine the oil today and see if it has darkened post the Seafoam. Was past midnight when I completed the Seafoam. Did it at night to avoid alarming neighbors with smoke of Seafoam burning off.
BTW, Torque Pro on my Carlaoer Android was absolutely fantastic for scanning DTC's and clearing codes. No laptop needed at far end of drive.
[Edit: Oil looks the same as prior to Seafoam spray tx.
Couldn't help myself. Needed to life the car to do the two power steering vacuum hoses anyway. So went ahead and change oil & filter while she was up. A bit early at 3,000 miles, but it was browning.]
Last edited by Seattle SCone; 02-21-21 at 09:56 PM.
Drove it 189 miles. 23.5mpg. Really enjoying the fixed car. Ran behind a lc500 today and had to think hard about having one of those instead of mine.....
if he offered to straight trade of course. I would pony up $20k cash and mine. Tops.
had a faster car more than 50 years ago. 58 vette. Removeable hard top convertible.
A little follow up post a multistep cleaning with Techron in tank, CRC throttle cleaner in injector air mix passages, Seafoam aerosol induction cleaning, and subsequent oil/filter change....
Before doing the above, my long term fuel trims were (bank 1/ bank 2)) idle values of -6.5 / 0.5 and 65 mph cruise at 0 / 0
That indicated my left bank was running rich at idle.
Post the Techron in tank, CRC throttle cleaner in injector air mix passages, LTFT's had changed to -2.7 / + 0.5 idle, cruising values still about 0/0
So, that seemed to improve airflow into bank 1.
Add the Seafoam aerosol induction cleaning, and subsequent oil/filter change and driven about 75 miles....
This morning, the idle LTFT was 0 / 0, cruise was 0.1/0.1
Yes, that was in closed loop mode with engine fully warm after a 20 mile drive into work.
I think the process has improved the airflow for bank 1 based on LTFT's values going towards ideal lambda.
Bank 1 LTFT once more trended negative. So, I repeated the air mix passage cleaning with CRC throttle cleaner. This time I ran an entire can into the medium sized passage of the air mix chamber. Put about 2/3 of the can into the bank 1 side while keeping RPM's around 2,000. Usual blast 2 second then allow engine to recover routine. Bank 1 LTFT is a lot more neutral again and idle is even smoother. Those air mix passages for the injectors are a lot more important than their small size suggest. If you clean the throttle body, don't neglect cleaning the air mix passages.
Having continual fuel trim data display is teaching me more about the engine. Without the OBD data display, I'd be happily driving, unaware that the ECU was needing to compensate for correctable issues.
Attached is how the car sounds (with its Magnaflow Catback exhaust) while getting the CRC intermittently sprayed into its air mix passages. Pedal is held steady. The drops in RPM are while the CRC cleaner is sprayed.
Headphones recommended!
Last edited by Seattle SCone; 02-25-21 at 11:58 PM.
A little follow up post a multistep cleaning with Techron in tank, CRC throttle cleaner in injector air mix passages, Seafoam aerosol induction cleaning, and subsequent oil/filter change....
Before doing the above, my long term fuel trims were (bank 1/ bank 2)) idle values of -6.5 / 0.5 and 65 mph cruise at 0 / 0
That indicated my left bank was running rich at idle.
Post the Techron in tank, CRC throttle cleaner in injector air mix passages, LTFT's had changed to -2.7 / + 0.5 idle, cruising values still about 0/0
So, that seemed to improve airflow into bank 1.
Add the Seafoam aerosol induction cleaning, and subsequent oil/filter change and driven about 75 miles....
This morning, the idle LTFT was 0 / 0, cruise was 0.1/0.1
Yes, that was in closed loop mode with engine fully warm after a 20 mile drive into work.
I think the process has improved the airflow for bank 1 based on LTFT's values going towards ideal lambda.
When I cleaned my throttle body, I also cleaned the air mix passage, but didn't do so while the engine was running. I'll have to give it another go while it's running. At any rate, I need to figure out what is causing me such low MPG. My drive is 100% hilly city, but I have been getting anywhere from 8-16 MPG. My plan is to clean the fuel injectors and replace bank 1 02 sensor 1. Bank 2 was bad when I first got the car, so I only replaced that side. I'm also going to set up a screen today in torque pro to monitor my long term fuel trims. Thanks again for all your helpful posts @Seattle SCone
i replaced my climate control unit with a replacement i got at a wrecker.
the old unit worked fine but it bothered me that the display had missing pixels “outside temp”.
the swap took less than 10mins and no tools thanks to this forum!
Had her lifted for some other work. Took advantage of the situation and cleaned the under covers and quite a few other components under the car. Turtlewax Wet'n Black spray and microfiber towel did a nice job after Windex.
Silly, I know, but was pretty happy with getting old grime removed.
02-16-21, 07:27 AM
Cleaned Air Mix Passages for Fuel Injectors
