97 LX450 Struggles to Accelerate After Startup (1 Viewer)

[bonestock]

Been chasing this issue for a minute now on my daily driver and have elected to throw the parts cannon at the truck until it’s running better or ends up with an LS swapped in. Observations below.

After start up (both cold and warm) and putting the truck into Drive (as indicated by my working D light) the truck fails to accelerate and runs awful. By depressing the skinny pedal to the floor the problem is solved. Revs like crazy, takes off like a rocket and runs fine until the process is repeated (parked for variable length of time, startup, Drive selected, crappy engine performance).

The diagnosing of this issue appears to be beyond my limited abilities. To date, I have fired the below ammo from my parts cannon to no avail:

Cap, rotor and coil wire
Fuel Pump Relay
EFI Relay
Fuel Pump
ECU

Parts cannon ammo on deck:

Rebuilt injectors
Used (good) wiring harness
Throttle position sensor

I’m assuming, at this point that it’s either the harness or the TPS.

Tips appreciated and flaming expected.

Appreciate the read!

Edit for ease of read: As for recent work, Jeez... Had the tranny out to do the rear main. Guide button thing on the torque converter was broken and missing and had to source a used one from a buddy. Went back together and ran like a top. Went on a 3day glamping trip in the NE Georgia Mountains and the truck basically s*** the bed on the trail. Short version there is that the coil wire had somehow become partially dislodged from the distributor cap. Replaced the coil wire and ran fine for a few days. Now we are somewhat back to where I started.

Mileage is currently at 193k and all maintenance has been done to the best of my wallet's ability.

 

[Kernal]

Is the MIL (check engine) light on? Have you checked the simple things like a cracked air intake tube, breather, or PCV valve hoses?? Clogged air filter? Have you checked the spark plug wires or spark plugs? Timing? Any recent work performed just before these symptoms first occured, did they start suddenly or did the symptoms get worse over time? Mileage on the vehicle? Past service?

 

[robnicko]

you may also want to check the MAF sensor & its wiring connections. it could need a clean with proper MAF cleaner (do not use CRC or WD40 lubricants - only proper MAF cleaner - CRC do make a cleaner for this)

there is also a fuel pump resistor in the engine bay - check its connections and if you have access to a multimeter check its tolerances as per FSM

Toyota Land Cruiser: Fuel pump resistor - SFI

www.tlacruiser.com

 

[Pierce]

Putting my name in the hat for fuel pressure regulator

 

[bonestock]

Is the MIL (check engine) light on? Have you checked the simple things like a cracked air intake tube, breather, or PCV valve hoses?? Clogged air filter? Have you checked the spark plug wires or spark plugs? Timing? Any recent work performed just before these symptoms first occured, did they start suddenly or did the symptoms get worse over time? Mileage on the vehicle? Past service?

No CEL illuminated. Occasionally, I would get a 301 (cylinder 1 misfire) but, the ECU seems to have resolved that issue. Or, at least, it has not come back in the 160ish miles I have driven since the ECU swap. Intake tube, breather and PCV valve and hoses are all relatively new and in good condition. Air filter is a K&N and was recently swapped with a clean and oiled one I keep on the shelf.

As for recent work, Jeez... Had the tranny out to do the rear main. Guide button thing on the torque converter was broken and missing and had to source a used one from a buddy. Went back together and ran like a top. Went on a 3day glamping trip in the NE Georgia Mountains and the truck basically s*** the bed on the trail. Short version there is that the coil wire had somehow become partially dislodged from the distributor cap. Replaced the coil wire and ran fine for a few days. Now we are somewhat back to where I started.

Mileage is currently at 193k and all maintenance has been done to the best of my wallet's ability.

Putting my name in the hat for fuel pressure regulator

Where is the magical regulator of which you speak? Is it different that the Fuel Pump Relay that mounts to the DS inner fender?

Thanks for the help here guys. This has already cost me a trip this weekend and am soooo ready to get back on the road / trail.

Paging @Jboyd

 

[CalnSam]

front o2 sensor did this to me, you can watch the live data on a scan tool to verify

 

[BILT4ME]

No CEL illuminated. Occasionally, I would get a 301 (cylinder 1 misfire) but, the ECU seems to have resolved that issue. Or, at least, it has not come back in the 160ish miles I have driven since the ECU swap. Intake tube, breather and PCV valve and hoses are all relatively new and in good condition. Air filter is a K&N and was recently swapped with a clean and oiled one I keep on the shelf.

As for recent work, Jeez... Had the tranny out to do the rear main. Guide button thing on the torque converter was broken and missing and had to source a used one from a buddy. Went back together and ran like a top. Went on a 3day glamping trip in the NE Georgia Mountains and the truck basically s*** the bed on the trail. Short version there is that the coil wire had somehow become partially dislodged from the distributor cap. Replaced the coil wire and ran fine for a few days. Now we are somewhat back to where I started.

Mileage is currently at 193k and all maintenance has been done to the best of my wallet's ability.


Where is the magical regulator of which you speak? Is it different that the Fuel Pump Relay that mounts to the DS inner fender?

Thanks for the help here guys. This has already cost me a trip this weekend and am soooo ready to get back on the road / trail.

Paging @Jboyd

You can do what you like, however, get rid of the KN filter and the oil it comes with.

First, KN filters allow larger dirt particles through their filter than a stock Toyota Paper Filter. This is NOT a good thing.
Second, the oil from the KN filters is known to screw with MAF units, particularly of this vintage. Clean the MAF and get rid of the KN.
Third: Don't buy into the hype that KN filters will increase HP of your engine. There are other sites that have proven this on a dyno and the computer adjusts for all the air/fuel ratios anyway, making it more of a moot point.
Fourth: Maybe get into the FSM and work through the "troubleshooting" section of it to determine the root cause of your issue. Yes this takes time, however, it will take less total time and less total $$$$ than the hunt and peck method you are following now. As helpful and big of A-Holes as we can be, we are not there and cannot see exactly the results you are getting. So, follow the written plan from Mr. T high above.

As it was written, so shall it be done.

 

[bonestock]

As it was written, so shall it be done.

I'll kill the K&N and go with a paper filter. Clean the MAF with proper cleaner and go from there with the FSM. I ahve a model-correct paper copy and should use it for more than a place holder. Thank you for the input.

front o2 sensor did this to me, you can watch the live data on a scan tool to verify

Did it not throw a code when there was a fault with your O2 sensor?

EDIT: Some extra info, the ScanGauge2 is showing the fuel system going from open to closed somewhat regularly. Open on startup, closed once at somewhat normal operating temp. It goes from closed to open when deaccelerating and back to closed when accelerating again. I assume this is normal. I am also monitoring my TPS (Throttle position sensor) on the Scan Gauge. It seems to track equivalently on the ScanGauge relative to how far I am pushing the skinny pedal.

 

[BILT4ME]

I'll kill the K&N and go with a paper filter. Clean the MAF with proper cleaner and go from there with the FSM. I ahve a model-correct paper copy and should use it for more than a place holder. Thank you for the input.


Did it not throw a code when there was a fault with your O2 sensor?

O2 sensors don't always throw codes.

I was having horrible gas mileage issues so I started watching my UltraGauge with it set to just have up the O2 sensor readings. I was amazed as I watched one sensor track up and down, then freeze at one setting for 10 minutes, then start randomly jumping again.

I installed a new sensor and immediately increased my gas mileage 30%. (For those doing math at home, I went from 8 MPG to about 11 MPG.)

 

[bonestock]

O2 sensors don't always throw codes.

I was having horrible gas mileage issues so I started watching my UltraGauge with it set to just have up the O2 sensor readings. I was amazed as I watched one sensor track up and down, then freeze at one setting for 10 minutes, then start randomly jumping again.

I installed a new sensor and immediately increased my gas mileage 30%. (For those doing math at home, I went from 8 MPG to about 11 MPG.)

The ultra gauge will show you values on just the O2 sensors? I don't think the ScanGauge will do that...

 

[BILT4ME]

The ultra gauge will show you values on just the O2 sensors? I don't think the ScanGauge will do that...

Yes. That's part of the reason I went with that brand.

UltraGauge OBDII Scan tool and Information Center

UltraGauge is both an OBDII Scan Tool and an Information center that displays selectable engine gauges, such as RPM, Speed, Coolant Temperature, Boost, Distance, Fuel Pressure, Mass Air Flow, and more. UltraGauge displays mileage gauges including Instantaneous MPG, Average MPG, gallons per hour...

www.ultra-gauge.com

 

[BILT4ME]

The ultra gauge will show you values on just the O2 sensors? I don't think the ScanGauge will do that...

Pics of the Fuel Pressure Regulator for reference

The a pic of my UltraGauge and where it is mounted. It is not currently showing the O2 sensors, as that is not on my normal page.

I normally monitor voltage, engine temp, mileage. The gauge I have here is an older version and the new ones have better page selection features so you can better select what parameters show up all the time. I also use it to track fuel mileage (after I corrected it for tire size)

 

[bonestock]

The Fuel Pressure Regulator looks original. Whether I need this now to fix my issue or not, It's good to have one on hand I assume. Thanks OUQ.

 

[alia176]

Been chasing this issue for a minute now on my daily driver and have elected to throw the parts cannon at the truck until it’s running better or ends up with an LS swapped in. Observations below.

After start up (both cold and warm) and putting the truck into Drive (as indicated by my working D light) the truck fails to accelerate and runs awful. By depressing the skinny pedal to the floor the problem is solved. Revs like crazy, takes off like a rocket and runs fine until the process is repeated (parked for variable length of time, startup, Drive selected, crappy engine performance).

The bold part got my attention and makes me think transmission slipping due to low fluid.

Let us know if the ATF is low and if the problem goes away after topping off.

 

[bonestock]

The bold part got my attention and makes me think transmission slipping due to low fluid.

Let us know if the ATF is low and if the problem goes away after topping off.

All messages are toped off

 

[fresnoLC]

How are your front drive flanges? Could be a combination of engine trouble and broken flanges. When you rev it the viscous coupler locks and takes off? Just something to check I guess.

 

[Lextronix]

^He wont have a viscous coupler.

This is frustrating I'm sure, it seems like you have been hitting this issue from all the logical angles. Parts cannon isn't a bad approach when base lining is the name of the game as long as you hold on to the replaced parts as spares. Just my opinion as fellow parts cannon enthusiast!

I have a good spare fuel pressure resistor if you want to give it a try. Might be able eliminate one of the two FPRs mentioned above that haven't been replaced already. Alternatively, a quick visit with the multimeter would eliminate it too. It lives near the driver side hood hinge.

 

[alia176]

The fuel pressure regulator can be simply bypassed by pulling the vacuum hose off its nipple, then plugging up the vacuum hose so it does not suck in air. There's no harm in doing this, some of us have been doing it with the MAF from Landtank.

As far as the fuel pump resistor, why not just bypass the resistor and run it at High speed? This is done all the time for people who are wanting more fuel delivery for whatever reasons.

I like them free and easy!

 

[bonestock]

This is frustrating I'm sure, it seems like you have been hitting this issue from all the logical angles. Parts cannon isn't a bad approach when base lining is the name of the game as long as you hold on to the replaced parts as spares. Just my opinion as fellow parts cannon enthusiast!

I have a good spare fuel pressure resistor if you want to give it a try. Might be able eliminate one of the two FPRs mentioned above that haven't been replaced already. Alternatively, a quick visit with the multimeter would eliminate it too. It lives near the driver side hood hinge.

Thanks for the bucking up! I could use it honestly. I’m getting confused a bit. I’ve replaced the fu pump rest in the driver side hinge area on the inner fender and I’ve ordered a Fuel Pressure Regulator. I’ve never heard of a Fuel Pressure Resistor before. Would you mind posting a pic or 2 here?

Thanks!

 

[bonestock]

As far as the fuel pump resistor, why not just bypass the resistor and run it at High speed? This is done all the time for people who are wanting more fuel delivery for whatever reasons.

Never heard of this. Is the a write up available? Also sounds like a good way to test.