Sudden loss of power while accelerating (3 Viewers)

[Jasonazx]

Hello all - I’m trying to resolve an issue we’ve been having every time we drive the cruiser. I suddenly lose power most commonly when accelerating up hill. The engine is still running but there’s no throttle response for a couple seconds, then it comes abruptly back online. I receive no check engine lights while driving or codes when connected to techstream or when performing techstream health check.

Here’s a video I took while driving to show what’s going on:

Vehicle details:
2006 LX 470
~203,000 miles

Major maintenance and repairs performed or issues reported (excluding the more basic maintenance items):

90k - previous owner had timing belt and water pump service done by toyota.

104,000 miles - previous owner reported to Toyota that vehicle would stall out on highway through high elevation passes and smelled like fuel. Toyotas answer was to replace spark plugs.

128,000 miles - previous owner had cooling system flushed and new radiator hoses installed by toyota.

144,000- previous owner took to Toyota as vehicle would not start. Reported that they filled up at a remote gas station. Toyota replaced fuel pump, filter and pump relay. Siphoned gas from tank and added fuel cleaner.

156,000 - spark plugs replaced again at Toyota. No other notes.

173760 miles- previous owner reported to Toyota that vehicle will randomly lose power. Service notes from toyota: drove vehicle several times and could not duplicate issue or make any repair recommendations at this time.

177519 miles - previous owner reported to Toyota that vehicle was getting hot (over 200 degrees when driving) Toyota replaced radiator due to poor flow.

180,000 miles- timing belt, water pump and throttle body replaced at Toyota by previous owner.

183,000 miles- previous owner took truck back to Toyota stating cel and vsc lights on. Toyota noted code p2714 for transmission pressure control solenoid “d” stuck off. Drained transmission and found significant amount of metal in fluid. Toyota replaced transmission.

194,000- I purchased from previous owner listed on mud. Issue of random loss of power occurred within first 1,000 miles of my ownership.

203,000 miles - over the past few weeks I have replaced the fuel pump with a denso unit, fuel filter from toyota, pcv valve and hose, coolant and transmission flush at toyota, new steering rack, all new power steering hoses, front wheel bearings and races, new oem cv axles, all new brakes and brake fluid flush. I also swapped in an accelerator pedal position sensor I purchased from an eBay seller reporting that they refurbish oem sensors to see if that was causing the problem. It’s still happening.

I’m at my wits end with this issue. Great truck otherwise and was taken in for service at either Lexus or Toyota it’s whole life. No rust, no leaks - super clean Arizona and Colorado truck.

I did read on a tundra forum mentioning similar issues. They replaced the knock sensors and repaired some wiring and the problem went away. I’m thinking my next move is to remove manifold and have a peak underneath to see if anything’s chewed up. If wiring looks good then replace knock sensors, have the injectors cleaned and possibly replace the air induction pump. Great time to replace injector o rings, coolant pipe gaskets and starter while I’m in there.

Appreciate any ideas of what this problem could be! @2001LC interested to see if you may have any insight.

Thanks!

Edited to add: I should mention that the loss of power issue during my ownership has been off and on leading up to this past month. I could go weeks without the problem occurring. Over this past month or so I experience the problem every time I drive it.

 

[araco100]

For me seems was as simple as low octane fuel in a 98. Coil packs maybe?

 

[Kamran Khan]

Whoever was previous owner Toyota dealership has certainly ripped him off. There are many things that will cause loss of power but there few basic components that you need to check before moving forward to replace parts and lose money on replacing functioning parts. Check the airflow of air filter, clean the air box. Check clogged EGR system. Check PCV valve related hoses and PCV valve itself. Check the engine blow by, if engine has blow by then do compression test. Check clogged fuel injectors, checking clogged fuel injector on this car isn’t easy but I suggest adding some injector cleaner to fuel tank. Replace fuel filter that is an easy and cheap task to do. Clean IAC valve regardless of if it’s functioning properly or not. Lift up all the 4 tyres and put in neutral gear and release the handbrake and then rotate each tyre by hand to make sure non of the brake calipers are seized. In early Lexus ECU use to leak capacitors that use to cause many problems. Unplug the engine ECU and open it and check that circuit board doesn’t have leaking capacitors. Make a list and check all these components one by one. Check the metal fuel lines and make sure it’s not rusted. That’s all I can think of right now. Clean the throttle body also.

 

[Jasonazx]

Whoever was previous owner Toyota dealership has certainly ripped him off. There are many things that will cause loss of power but there few basic components that you need to check before moving forward to replace parts and lose money on replacing functioning parts. Check the airflow of air filter, clean the air box. Check clogged EGR system. Check PCV valve related hoses and PCV valve itself. Check the engine blow by, if engine has blow by then do compression test. Check clogged fuel injectors, checking clogged fuel injector on this car isn’t easy but I suggest adding some injector cleaner to fuel tank. Replace fuel filter that is an easy and cheap task to do. Clean IAC valve regardless of if it’s functioning properly or not. Lift up all the 4 tyres and put in neutral gear and release the handbrake and then rotate each tyre by hand to make sure non of the brake calipers are seized. In early Lexus ECU use to leak capacitors that use to cause many problems. Unplug the engine ECU and open it and check that circuit board doesn’t have leaking capacitors. Make a list and check all these components one by one. Check the metal fuel lines and make sure it’s not rusted. That’s all I can think of right now. Clean the throttle body also.

As mentioned, truck has all new Toyota oem brake components including calipers. Brakes function perfectly. Air filter is new and no issues with restriction. I cleaned maf and double checked throttle body (replaced by previous owner not long ago), and it was spotless. I ran fuel treatment a few months ago. I also mentioned I have replaced the pcv valve and both ventilation hoses as well as the fuel pump and filter. The truck runs perfectly most of the time so it’s not like it’s a low on power issue. It goes from feeling amazing and pulling great to a complete cut out (minimal to no throttle response) for a second or two and then the throttle comes back online abruptly and everything’s normal. It’s like an electrical or sensor issue.

I planned on cleaning injectors professionally as a next step when/if I pull the intake manifold. Other than that, I will double check fuel lines, and check for blow by. There is not an iac valve on 100 series vehicles. I’ll report back after that.

Edit: truck idles great. No issues at idle and I’m able to apply throttle while in park with no issues through the rev range.

 

[Jasonazx]

For me seems was as simple as low octane fuel in a 98. Coil packs maybe?

I thought about this, but wouldn’t a coil pack cause more of a rough idle and low power output? Same thing with a bad maf. I’m having a complete loss of throttle response (engine is still running but not taking input from pedal), and then in a matter of seconds it comes back like everything’s normal.

 

[94SRUNNER]

I see you replaced the fuel pump and filter. Did you replace, both filters; the pre-filter in the tank and the filter in the engine bay?

 

[Ayune]

It’s like an electrical or sensor issue.

When it happens is there any correlation to weather or outside temperature?

I don’t see that the Throttle Position Sensor (TPS) was replaced or checked.

 

[Zjohnsonua]

Is it happening around a repeatable speed or throttle input?

 

[Kamran Khan]

As mentioned, truck has all new Toyota oem brake components including calipers. Brakes function perfectly. Air filter is new and no issues with restriction. I cleaned maf and double checked throttle body (replaced by previous owner not long ago), and it was spotless. I ran fuel treatment a few months ago. I also mentioned I have replaced the pcv valve and both ventilation hoses as well as the fuel pump and filter. The truck runs perfectly most of the time so it’s not like it’s a low on power issue. It goes from feeling amazing and pulling great to a complete cut out (minimal to no throttle response) for a second or two and then the throttle comes back online abruptly and everything’s normal. It’s like an electrical or sensor issue.

I planned on cleaning injectors professionally as a next step when/if I pull the intake manifold. Other than that, I will double check fuel lines, and check for blow by. There is not an iac valve on 100 series vehicles. I’ll report back after that.

Check ECM/ECU and if it’s drive by wire accelerator then check those sensors that communicate between accelerator and throttle body, maybe it’s a loose wire or a sensor that starts acting after the engine gets hot. Try to borrow a known good throttle body from someone that has the same car and give it a try.

 

[Jasonazx]

When it happens is there any correlation to weather or outside temperature?

I don’t see that the Throttle Position Sensor (TPS) was replaced or checked.

It happens regardless of what the temperature is. The entire throttle body (inclusive of sensor) was replaced by previous owner by Toyota when they did the timing belt service at 180,000 miles.

 

[Jasonazx]

Is it happening around a repeatable speed or throttle input?

It seems to be occurring between 2-3,000 rpm’s from what I can tell. I don’t think speed of travel is correlated as it will happen from a stop while accelerating up to around the 3,000 rpm mark or when changing lanes and needing to accelerate to pass (already at higher rate of speed).

 

[Jasonazx]

Check ECM/ECU and if it’s drive by wire accelerator then check those sensors that communicate between accelerator and throttle body, maybe it’s a loose wire or a sensor that starts acting after the engine gets hot. Try to borrow a known good throttle body from someone that has the same car and give it a try.

I will definitely do this. I did change the accelerator position sensor and that didn’t fix it, but maybe it’s a wire up the chain somewhere.

 

[Jasonazx]

I see you replaced the fuel pump and filter. Did you replace, both filters; the pre-filter in the tank and the filter in the engine bay?

I did not replace the sock in the tank, just the pump. The sock looked pretty decent though. Unfortunately the pump is different on an 05-07, so unless big bucks are spent from toyota we’re only getting the denso pump part #950-0210 (tip from @jerryb). The entire assembly was also replaced by Toyota at 144,000 miles, so maybe that’s why the sock looked pretty good.

 

[ih8everything]

I had the same problem a few years ago on a road trip, 100+ degrees outside. It did it probably 10+ times in the span of a few hours of driving. I think it may have just been a bad batch of fuel or something it ended up working itself out. Haven't had the issue again since. So probably not the same problem you are having.

I do seem to remember a thread at the time of people having a similar condition and no one was able to pinpoint exactly what it was. Maybe try searching a bit and see if anyone on that thread was able to find a solution.

 

[Jasonazx]

Is it happening around a repeatable speed or throttle

I had the same problem a few years ago on a road trip, 100+ degrees outside. It did it probably 10+ times in the span of a few hours of driving. I think it may have just been a bad batch of fuel or something it ended up working itself out. Haven't had the issue again since. So probably not the same problem you are having.

I do seem to remember a thread at the time of people having a similar condition and no one was able to pinpoint exactly what it was. Maybe try searching a bit and see if anyone on that thread was able to find a solution.

I hear ya. I have been searching exhaustively and am finding the same thing. I’ve replaced all the common causes, so it has to be something abnormal (chewed up wires or knock sensors) is my bet. I may run fuel cleaner or sea foam through it one more time just in case.

 

[100serieslover]

Have you checked your O2 sensor functionality and fuel trims? I'm not suggesting that these are the problems, but they could provide more information to help you narrow down the source of your issue.

 

[Jasonazx]

Have you checked your O2 sensor functionality and fuel trims? I'm not suggesting that these are the problems, but they could provide more information to help you narrow down the source of your issue.

That was one of my next steps. I’m newer to techstream so I need to figure out how to properly perform the test. Any advice? I found these instructions: https://f01.justanswer.com/JACUSTOMER-ma2fkznv-/1c2b6a31-0e77-423f-8f96-8c6beffe816a_monitor.pdf

 

[100serieslover]

That was one of my next steps. I’m newer to techstream so I need to figure out how to properly perform the test. Any advice? I found these instructions: https://f01.justanswer.com/JACUSTOMER-ma2fkznv-/1c2b6a31-0e77-423f-8f96-8c6beffe816a_monitor.pdf

I've not gone to Techstream yet, my normal OBDII code reader has the capacity to read those things I mentioned. So I'm afraid I'm no help with Techstream. Sorry.

 

[2001LC]

Since RPMs drop, I don't think it's transmission or TQ.

The "bump" just before video end. Is interesting. If associated with cut out and return of power, and not some bump in the road.

I had knock sensor wire cut, in an 01LX. Did not have noticeable engine effect other than CEL and dash lights.
You can look under intake manifold from front, and may see signs of nest under there. If one found vacuum out and look closer from front, possible with snake camera

Some thought:
If only does during or just after getting wet (rain, snow or car wash), could be a clue.
Make sure ground wire near heater Tee securely plugged in. Same goes for MAF, and all wire blocks.
Throttle body. Sudden power or motor cut out, closing and open butterfly.
VVT control. Wrong oil weight can effect them.
Cam sensor either main or VVT sensors.
Crank sensor.
Timing belt tension issue.
Look over wire housing engine and transmission very closely. Don't miss alternator connection.
Coil(s) misfiring.

Getting to repeat while tech stream hook-up and recording my yield clues.
Check for DTC as soon as it happens, without turning key off.

 

[Jasonazx]

Since RPMs drop, I don't think it's transmission or TQ.

The "bump" just before video end. Is interesting. If associated with cut out and return of power, and not some bump in the road.

I had knock sensor wire cut, in an 01LX. Did not have noticeable engine effect other than CEL and dash lights.
You can look under intake manifold from front, and may see signs of nest under there. If one found vacuum out and look closer from front, possible with snake camera

Some thought:
If only does during or just after getting wet (rain, snow or car wash), could be a clue.
Make sure ground wire near heater Tee securely plugged in. Same goes for MAF, and all wire blocks.
Throttle body. Sudden power or motor cut out, closing and open butterfly.
VVT control. Wrong oil weight can effect them.
Cam sensor either main or VVT sensors.
Crank sensor.
Timing belt tension issue.
Look over wire housing engine and transmission very closely. Don't miss alternator connection.
Coil(s) misfiring.

Getting to repeat while tech stream hook-up and recording my yield clues.
Check for DTC as soon as it happens, with turning key off.

I will definitely look into those items. That “bump” was power coming back online and noise from the driveline being shocked as it abruptly came back online. We have some front diff bushings to replace for sure. It occurs under any condition (wet, dry, cold, hot). Using 5w-30 Mobil 1 synthetic. Oil and filter just changed 1500 miles ago. Interestingly enough, previous owner reported problem back at 173,000 miles as shown above and Toyota could not get problem to replicate. Now it’s occurring just about every drive which should make it easier to diagnose. Throttle body assembly is clean and fairly new being replaced by previous owner at 180k.

We did have a p0011 code for bank 1 (camshaft position timing) about a year ago, but it quickly went away and hasn’t come back since. I believe we changed the oil and reset ecu. No longer an issue, and it ran fine even with the code on.

Does anyone have a tutorial or quick step by step on how to record in techstream for this specific issue? Assuming I go into the engine and ect utility and then what?