Chasing the smooth running
01-11-19, 11:43 PM
#1
Pole Position
Thread Starter
Chasing the smooth running
Hi All,
So My LS430 which I grabbed a few months ago at a great price but 330,000km/200,000miles, a little rough in some places but overall solid, straight and no rust.
At the start I had to fix a few things - ie, got the ECU talking to the pc and elm32, replaced the nav DVD drive (ali express about $80), filter, oil, replaced all the old and hard rubber air hoses at the top of the engine and both VVT oil control solenoids, sprayed the MAF with cleaner and reset the yaw sensor.
Since then put a few thousand miles of it and generally running pretty well. however, fuel consumption is still on the high side (10-11l/100kms on long gentle highway runs) and there is some intermittent hesitations when accelerating from time to time. Looking at the ECU data the long term fuel trims are fluctuating a bit randomly from pulling fuel when cruising to adding fuel. Either way none of the sensors are obviously bad or throwing codes though there are some strange looking waveforms from time to time from the MAF and the o2 sensors. Occasionally smells like rotten eggs after 'giving it some beans'. So theory aside, my assumption is the o2's are getting lazy with age, the plugs could do with a refresh and the MAF is original and perhaps not at optimum performance anymore.
Coinciding with a trip to USA I decided to take advantage of some goodies from Rockauto to refresh some old parts, establish a baseline on the sensors and find the cause of the highish fuel consumption and hesitations. These include
*new PCV and seal,
*Denso MAF
*set of Denso TT plugs,
*set of Denso O2's
*New cabin filter - completely unrelated to the engine running but way cheaper in the USA than Australia.
In the name of a scientific approach, over the next few weeks, I am going to change one part type at a time and post back the results in case anyone else is having the same symptoms.
The first part changed is the PCV and seal. The old seal crumbled away (much like the other rubber intake hoses I replaced a couple of months ago) and the valve looks pretty cruddy anyway, Second off the rank will be the MAF, followed by the plugs and finishing with the O2's.
So My LS430 which I grabbed a few months ago at a great price but 330,000km/200,000miles, a little rough in some places but overall solid, straight and no rust.
At the start I had to fix a few things - ie, got the ECU talking to the pc and elm32, replaced the nav DVD drive (ali express about $80), filter, oil, replaced all the old and hard rubber air hoses at the top of the engine and both VVT oil control solenoids, sprayed the MAF with cleaner and reset the yaw sensor.
Since then put a few thousand miles of it and generally running pretty well. however, fuel consumption is still on the high side (10-11l/100kms on long gentle highway runs) and there is some intermittent hesitations when accelerating from time to time. Looking at the ECU data the long term fuel trims are fluctuating a bit randomly from pulling fuel when cruising to adding fuel. Either way none of the sensors are obviously bad or throwing codes though there are some strange looking waveforms from time to time from the MAF and the o2 sensors. Occasionally smells like rotten eggs after 'giving it some beans'. So theory aside, my assumption is the o2's are getting lazy with age, the plugs could do with a refresh and the MAF is original and perhaps not at optimum performance anymore.
Coinciding with a trip to USA I decided to take advantage of some goodies from Rockauto to refresh some old parts, establish a baseline on the sensors and find the cause of the highish fuel consumption and hesitations. These include
*new PCV and seal,
*Denso MAF
*set of Denso TT plugs,
*set of Denso O2's
*New cabin filter - completely unrelated to the engine running but way cheaper in the USA than Australia.
In the name of a scientific approach, over the next few weeks, I am going to change one part type at a time and post back the results in case anyone else is having the same symptoms.
The first part changed is the PCV and seal. The old seal crumbled away (much like the other rubber intake hoses I replaced a couple of months ago) and the valve looks pretty cruddy anyway, Second off the rank will be the MAF, followed by the plugs and finishing with the O2's.
Last edited by Aus430; 01-12-19 at 12:28 PM.
01-12-19, 09:45 AM
#2
Love it. Keep us updated I’m interested to see how the numbers change with some new parts
01-12-19, 10:40 AM
#3
Thank You and I would be very interested in what your long-term fuel trims are currently reading versus the finished product. On my '04 the LTFT's are all in the +/- 3% or less range. I have 132k miles with original O2 sensors and MAF (cleaned) with a PCV and new plugs done at time of timing belt/water pump service approximately 4,000 miles ago. Glad you were able to pick up the parts while visiting the US. Have you "tapped" on the catalytic converter to see if you can hear anything rattling around? It could be starting to plug up or go bad? Good luck.
01-12-19, 12:39 PM
#4
Instructor
I also recommend replacing the engine air filter and engine coolant temperature sensor, it's underneath the air intake box on the right hand side. Also do a cleaning of the throttle body plate - don't push the plate by hand, it is controlled by a precisely calibrated motor. Put a brick on the accelerator pedal while the ignition is ON to open up the plate.
Also consider replacing the VVT oil control valves, accessory belt, thermostat, water pump, timing belt, radiator support cushions, the 2 engine mounts, and the transmission mount, and if you open up your throttle body, the gasket should be replaced as it is specified as a non-reusable part. Also retorque the head gasket bolts to spec, some people have reported them becoming loose after 200,000-300,000 miles, causing minor oil leaks.
Use your ELM32/OBD2/TechStream to verify that the accelerator pedal position sensor responds smoothly, and likewise for your throttle position sensor.
If you still have engine efficiency problems after this, try a fuel system additive (see https://www.bobistheoilguy.com/forum...&Number=261713 for cleaners that won't damage the nylon debris filter), and consider opening up your fuel pump and replacing the filter anyway. Also try adding Marvel Mystery Oil to the crankcase, someone on these forums said they eliminated the rotten egg smell by using MMO. If you are going to do these items, try to do it prior to changing O2 sensors and prior to an oil change.
You can also test your fuel injectors by removing each one from the block, but leaving them connected to the fuel rail, and using TechStream to turn on each injector and spray into a test tube. Any tube filled lower than the rest means that injector is bad. However, it's easier but more wasteful and expensive to simply replace all the injectors (and o-rings).
The o-rings on the 2 fuel pulsation dampers at the top of the engine near the firewall may develop very small leaks during cold temperatures and high fuel pressure. Replacing the o-rings and/or the dampers themselves can help you get your LTFT closer to zero.
Also consider replacing the VVT oil control valves, accessory belt, thermostat, water pump, timing belt, radiator support cushions, the 2 engine mounts, and the transmission mount, and if you open up your throttle body, the gasket should be replaced as it is specified as a non-reusable part. Also retorque the head gasket bolts to spec, some people have reported them becoming loose after 200,000-300,000 miles, causing minor oil leaks.
Use your ELM32/OBD2/TechStream to verify that the accelerator pedal position sensor responds smoothly, and likewise for your throttle position sensor.
If you still have engine efficiency problems after this, try a fuel system additive (see https://www.bobistheoilguy.com/forum...&Number=261713 for cleaners that won't damage the nylon debris filter), and consider opening up your fuel pump and replacing the filter anyway. Also try adding Marvel Mystery Oil to the crankcase, someone on these forums said they eliminated the rotten egg smell by using MMO. If you are going to do these items, try to do it prior to changing O2 sensors and prior to an oil change.
You can also test your fuel injectors by removing each one from the block, but leaving them connected to the fuel rail, and using TechStream to turn on each injector and spray into a test tube. Any tube filled lower than the rest means that injector is bad. However, it's easier but more wasteful and expensive to simply replace all the injectors (and o-rings).
The o-rings on the 2 fuel pulsation dampers at the top of the engine near the firewall may develop very small leaks during cold temperatures and high fuel pressure. Replacing the o-rings and/or the dampers themselves can help you get your LTFT closer to zero.
The following 2 users liked this post by StanVanDam:
BustaLS430 (01-19-19),
robbyboy32 (02-17-19)
01-12-19, 01:41 PM
#5
Pole Position
Thread Starter
01-12-19, 03:34 PM
#6
Lexus Champion
Hi All,
So My LS430 which I grabbed a few months ago at a great price but 330,000km/200,000miles, a little rough in some places but overall solid, straight and no rust.
At the start I had to fix a few things - ie, got the ECU talking to the pc and elm32, replaced the nav DVD drive (ali express about $80), filter, oil, replaced all the old and hard rubber air hoses at the top of the engine and both VVT oil control solenoids, sprayed the MAF with cleaner and reset the yaw sensor.
Since then put a few thousand miles of it and generally running pretty well. however, fuel consumption is still on the high side (10-11l/100kms on long gentle highway runs) and there is some intermittent hesitations when accelerating from time to time. Looking at the ECU data the long term fuel trims are fluctuating a bit randomly from pulling fuel when cruising to adding fuel. Either way none of the sensors are obviously bad or throwing codes though there are some strange looking waveforms from time to time from the MAF and the o2 sensors. Occasionally smells like rotten eggs after 'giving it some beans'. So theory aside, my assumption is the o2's are getting lazy with age, the plugs could do with a refresh and the MAF is original and perhaps not at optimum performance anymore.
Coinciding with a trip to USA I decided to take advantage of some goodies from Rockauto to refresh some old parts, establish a baseline on the sensors and find the cause of the highish fuel consumption and hesitations. These include
*new PCV and seal,
*Denso MAF
*set of Denso TT plugs,
*set of Denso O2's
*New cabin filter - completely unrelated to the engine running but way cheaper in the USA than Australia.
In the name of a scientific approach, over the next few weeks, I am going to change one part type at a time and post back the results in case anyone else is having the same symptoms.
The first part changed is the PCV and seal. The old seal crumbled away (much like the other rubber intake hoses I replaced a couple of months ago) and the valve looks pretty cruddy anyway, Second off the rank will be the MAF, followed by the plugs and finishing with the O2's.
So My LS430 which I grabbed a few months ago at a great price but 330,000km/200,000miles, a little rough in some places but overall solid, straight and no rust.
At the start I had to fix a few things - ie, got the ECU talking to the pc and elm32, replaced the nav DVD drive (ali express about $80), filter, oil, replaced all the old and hard rubber air hoses at the top of the engine and both VVT oil control solenoids, sprayed the MAF with cleaner and reset the yaw sensor.
Since then put a few thousand miles of it and generally running pretty well. however, fuel consumption is still on the high side (10-11l/100kms on long gentle highway runs) and there is some intermittent hesitations when accelerating from time to time. Looking at the ECU data the long term fuel trims are fluctuating a bit randomly from pulling fuel when cruising to adding fuel. Either way none of the sensors are obviously bad or throwing codes though there are some strange looking waveforms from time to time from the MAF and the o2 sensors. Occasionally smells like rotten eggs after 'giving it some beans'. So theory aside, my assumption is the o2's are getting lazy with age, the plugs could do with a refresh and the MAF is original and perhaps not at optimum performance anymore.
Coinciding with a trip to USA I decided to take advantage of some goodies from Rockauto to refresh some old parts, establish a baseline on the sensors and find the cause of the highish fuel consumption and hesitations. These include
*new PCV and seal,
*Denso MAF
*set of Denso TT plugs,
*set of Denso O2's
*New cabin filter - completely unrelated to the engine running but way cheaper in the USA than Australia.
In the name of a scientific approach, over the next few weeks, I am going to change one part type at a time and post back the results in case anyone else is having the same symptoms.
The first part changed is the PCV and seal. The old seal crumbled away (much like the other rubber intake hoses I replaced a couple of months ago) and the valve looks pretty cruddy anyway, Second off the rank will be the MAF, followed by the plugs and finishing with the O2's.
NGK Ruthenium sparkplugs offer benefits.
See:
https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/904773-ngk-ruthenium-hx-spark-plugs.html
01-14-19, 12:11 AM
#7
Pole Position
Thread Starter
Results so far:
PCV
Ok so the result from the new PCV & seal was no change in LTFT behaviour. It needed changing anyway but wasn't the cause.
Moving on to phase 2 - MAF
Readouts for the old MAF sensor
The install was fine - 2 screws and about 2 minutes to swap. Fired her up and she is running smoothly.
Initial garage data from new MAF is interesting - haven't been for a drive yet so the jury is still out but it is looking promising
So the new MAF is now adding fuel at idle and subtracting it above 20% TPS. The opposite of what the old sensor was doing! Also, the difference between the two banks is smaller and a lot less jumping around of the Long term trims.
Looking forward to taking her for a decent drive tomorrow to see what the result is - will report back soon.
Cheers
P.s. Please forgive the underscores above, I was trying to make a table but the formatting disappeared - Is there anyway to include a table of data in this forum? If so please PM me.
PCV
Ok so the result from the new PCV & seal was no change in LTFT behaviour. It needed changing anyway but wasn't the cause.
Moving on to phase 2 - MAF
Readouts for the old MAF sensor
LTFT___________________ B1________ B2
Idle (closed throttle):_____ -6 to -3%___ -4 to -2%Cruising : _____________-5 to +3% ___-4 to -1%
Above 20% TPS:________ +2%________ +3%
The new MAF.Above 20% TPS:________ +2%________ +3%
The install was fine - 2 screws and about 2 minutes to swap. Fired her up and she is running smoothly.
Initial garage data from new MAF is interesting - haven't been for a drive yet so the jury is still out but it is looking promising
LTFT _________________B1________ B2
Idle (closed throttle) ___+2.34%_____ +3.91 (both trims very stable)Cruising ______________N/A________ N/A
Above 20% TPS ______-7 to -8% ___-5 to -6%So the new MAF is now adding fuel at idle and subtracting it above 20% TPS. The opposite of what the old sensor was doing! Also, the difference between the two banks is smaller and a lot less jumping around of the Long term trims.
Looking forward to taking her for a decent drive tomorrow to see what the result is - will report back soon.
Cheers
P.s. Please forgive the underscores above, I was trying to make a table but the formatting disappeared - Is there anyway to include a table of data in this forum? If so please PM me.
Last edited by Aus430; 01-14-19 at 12:20 AM. Reason: Formatting
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bradland (01-14-19)
Trending Topics
01-15-19, 01:07 PM
#8
Pole Position
Thread Starter
So Results so far from the MAF swap over a longer drive - aircon on as we are having quite a warm summer at the moment.
LTFT at idle are now stable 0%. Both banks.
Under load -4% to -2% generally with occasional -6% under higher throttle situations - (thoughts are perhaps leaky or blocked injectors)
Overall a bit smoother though I still feel that there should be a little bit more power there.
Fuel consumption now dropping below 10l/100 to about 9.5l/100
I feel this is still a little high but happy with the drop of about 1-1.5l/100 in fuel consumption
Next step new Plugs. Won't get time to do this until the weekend, though am thinking about running some fuel injector cleaner through the remaining tank first so could be next weekend.
LTFT at idle are now stable 0%. Both banks.
Under load -4% to -2% generally with occasional -6% under higher throttle situations - (thoughts are perhaps leaky or blocked injectors)
Overall a bit smoother though I still feel that there should be a little bit more power there.
Fuel consumption now dropping below 10l/100 to about 9.5l/100
I feel this is still a little high but happy with the drop of about 1-1.5l/100 in fuel consumption
Next step new Plugs. Won't get time to do this until the weekend, though am thinking about running some fuel injector cleaner through the remaining tank first so could be next weekend.
01-15-19, 06:36 PM
#9
not sure why you are not happy with the mileage. 10l/100km should be average city driving with slightly better mileage hwy. I am at 12l/100km here in winter time and am pretty happy especially at -15 to -25C temps we're having
01-16-19, 02:12 AM
#10
Pole Position
Thread Starter
Good point caddylover. It is cold where you are! I would be ok with 12l/100 in those conditions given the fuel required to get up to operating temps! It's closer to +30 to +43C so very hot here with yet another record breaking heatwave going on here - lots of airconditioner use.
I am happy with 10l/100 given than it is way better than the 12-13l/100, even the 16l/100 I got during one tankful when I started out with this car a couple of months ago - shot vvt solenoids and various leaky cracked air hoses and all.
It's just that I know it should be better given the LS430 is an aerodynamic ULEV vehicle and all. Like this guys LS430 and what some other people have been getting on this forum. Even the official government fuel figures for the time (which granted can be taken with a large grain of salt given they are made in a laboratory) have the highway coming in at 7.6l/100. Given my use is generally 80% highway, I will be happy when it's closer to the 8.5-9ish l/100 ballpark
The other side of this project is a seat-of-the-pants feeling - It feels like the computer is holding the car back sometimes. I can feel the power coming and then being taken away again. The new MAF has made a big improvement, but there are still some funny patterns in the LTFT's and some intermittent hesitations, so something else is out of balance.
I'm hoping for a similar improvement again when the new O2's go in. Even if there is no improvement, at least the readouts won't be suspect.
In the meantime, I have taken StanVanDams suggestion of putting some fuel cleaner through before replacing the O2's. In this case, as we don't have Seafoam or Marvel Mystery oil in Australia, I am using some Subaru Upper engine cleaner that seems to be well regarded around here.
Anyway, stay tuned - more results coming soon.
I am happy with 10l/100 given than it is way better than the 12-13l/100, even the 16l/100 I got during one tankful when I started out with this car a couple of months ago - shot vvt solenoids and various leaky cracked air hoses and all.
It's just that I know it should be better given the LS430 is an aerodynamic ULEV vehicle and all. Like this guys LS430 and what some other people have been getting on this forum. Even the official government fuel figures for the time (which granted can be taken with a large grain of salt given they are made in a laboratory) have the highway coming in at 7.6l/100. Given my use is generally 80% highway, I will be happy when it's closer to the 8.5-9ish l/100 ballpark
The other side of this project is a seat-of-the-pants feeling - It feels like the computer is holding the car back sometimes. I can feel the power coming and then being taken away again. The new MAF has made a big improvement, but there are still some funny patterns in the LTFT's and some intermittent hesitations, so something else is out of balance.
I'm hoping for a similar improvement again when the new O2's go in. Even if there is no improvement, at least the readouts won't be suspect.
In the meantime, I have taken StanVanDams suggestion of putting some fuel cleaner through before replacing the O2's. In this case, as we don't have Seafoam or Marvel Mystery oil in Australia, I am using some Subaru Upper engine cleaner that seems to be well regarded around here.
Anyway, stay tuned - more results coming soon.
01-18-19, 09:10 PM
#11
I'm from Melbourne and yeah, it's CRAZY hot, been above 45 degrees C (113F) every day for a week so far.
So i'm using AC flat out and it's doing very well, I'm also getting 10.2-10.8 L/100km (22.5 MPG)
I think I may have a bad cat as it smells like rotten egg under heavy load.
I'm looking forward to seeing ways to reduce the fuel consumption if possible.
So i'm using AC flat out and it's doing very well, I'm also getting 10.2-10.8 L/100km (22.5 MPG)
I think I may have a bad cat as it smells like rotten egg under heavy load.
I'm looking forward to seeing ways to reduce the fuel consumption if possible.
01-21-19, 02:38 PM
#15
Pole Position
Thread Starter
So a little update, Having put about 300kms on it the readings have adjusted slightly from first installed, but the consistency is amazing compared to the old sensor.
Readouts at idle at___ +3 bank 1, +1.4 bank 2
Readout under throttle -4 bank 1, -5.8 bank 2
Definitely, more power everywhere and smoother, though strangely there is a slight & irregular misfire/stumble in reverse gear at idle! remains (it is totally smooth at idle in Park, neutral and drive so why reverse?). My gut feeling on this one is it will disappear when the new plugs go in however we shall see...
Over the weekend we had a day or two of reasonable temperatures which meant being able to drive without A/C and not being cooked alive! (Love the LS AC - so powerful with front and back circuits switched on)
On a stretch of highway cruising, I was able to experiment a bit with switching the A/C on and off. Judging from the instantaneous readout, AC adds about 1.5l/100 to the baseline fuel use is. This would indicate I am now running in the low 8l's/100 on the highway without AC (woo hoo).
Next step: As soon as this current tank of fuel with cleaner gets low, I'll put the upper engine cleaner treatment through and new oil/filter change to see what, if any, difference that makes.
Damian@f1 , I too get the rotten egg smell after 'spirited driving'. It is still present after the new MAF, sadly, although anecdotally it seems to be less than before (that could be placebo effect/wishful thinking).
The rotten egg smell seems to be a common issue on these vehicles judging by the number of threads about it. Which may be a case of 'they do that' by design. Before replacing the Cats though, an exhaust backpressure test would seem to be a good idea to identify if they are actually blocked. If it gets to cat replacement stage, for me at least, I'll be having a chat with the local exhaust shop about options.
Readouts at idle at___ +3 bank 1, +1.4 bank 2
Readout under throttle -4 bank 1, -5.8 bank 2
Definitely, more power everywhere and smoother, though strangely there is a slight & irregular misfire/stumble in reverse gear at idle! remains (it is totally smooth at idle in Park, neutral and drive so why reverse?). My gut feeling on this one is it will disappear when the new plugs go in however we shall see...
Over the weekend we had a day or two of reasonable temperatures which meant being able to drive without A/C and not being cooked alive! (Love the LS AC - so powerful with front and back circuits switched on)
On a stretch of highway cruising, I was able to experiment a bit with switching the A/C on and off. Judging from the instantaneous readout, AC adds about 1.5l/100 to the baseline fuel use is. This would indicate I am now running in the low 8l's/100 on the highway without AC (woo hoo).
Next step: As soon as this current tank of fuel with cleaner gets low, I'll put the upper engine cleaner treatment through and new oil/filter change to see what, if any, difference that makes.
Damian@f1 , I too get the rotten egg smell after 'spirited driving'. It is still present after the new MAF, sadly, although anecdotally it seems to be less than before (that could be placebo effect/wishful thinking).
The rotten egg smell seems to be a common issue on these vehicles judging by the number of threads about it. Which may be a case of 'they do that' by design. Before replacing the Cats though, an exhaust backpressure test would seem to be a good idea to identify if they are actually blocked. If it gets to cat replacement stage, for me at least, I'll be having a chat with the local exhaust shop about options.
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Tharper1 (01-25-22)