2001 Lexus Estima knock sensor help

[2001 Estima Owner]

So my Estima's automatic transmission won't go into top gear, and starts getting high revs above 80. The check engine light is on. I talked to a transmission guy, who said go see an electrics guy (because from his experience electronics go before the actual transmission), who ran diagnostics that came back with "knock sensor 1 and 2". So it seems because the engine isn't running perfectly well, or the sensors are just thinking it's not running well, the system is hampering the transmission...not sure why. Electrics guy says next step is trying to replace the knock sensors, and I suppose also getting the engine to run better (it's pinging a bit and also a tad sluggish, but nothing outlandish...I mean it seems to be running well as far as I can tell). I dont really understand how all this is related, but someone has told me it's feasible either faulty sensors or just low-power from poorly running engine can cause the engine management to start disabling things. Who knows? (not me!)

So any advice would be appreciated. I love the van, but it seems like a rabbit hole of finding and replacing sensors and things, which will be hard to find anyway, and crossing my fingers it works. Could I sell the van as is, to someone who doesnt mind a slow van? I doubt it, but the car market is crazy nowadays. It's in top shape otherwise. Do I scrap it? Seems like a big waste. Then I need another vehicle. Or are knock sensors easy peasey when you know how? Wow. It's a quandary.

Anyone have experience or know-how?

[2001 Estima Owner]

Update: Van now only drives up to 80km/hr, then accelerator no longer works and van drops speed until 60, when accelerator begins functioning again. This happens about every 10 seconds, so van is now not very driveable in its current state.

[philpreston3072]

Probably a concern if it's pinging. Are you using the right fuel for this car?  Does it require premium unleaded?

[2001 Estima Owner]

2 hours ago, philpreston3072 said:

Probably a concern if it's pinging. Are you using the right fuel for this car?  Does it require premium unleaded?

Trying higher octane fuel is the next thing I am going to try. Someone recommended it. No sure which fuel it is supposed to use; I bought the vehicle imported and it didnt come within any instructions. Ive always just used the most budget unleaded, but not had a problem for the last 8 years or so. I mentioned this to a mechanic and he says it would be better to use good fuel, but can't be the only reason it is acting so poorly. He thinks maybe the engine management module is faulty...so Im looking into sourcing one, if possible.

[campbeam]

I would be inclined to check/clean or replace the spark plugs, air filter.

No harm to also clean the throttle body and the Mass Air Flow sensor.

When was the last time the fuel filter was replaced? Something else to consider. 

[Hiro]

Also, "Lexus" Estima?  Dollars to donuts the importer slapped a set of Lexus badges on what was only ever sold/made as a Toyota...

[Tony Prodigy]

On 4/23/2022 at 9:40 PM, philpreston3072 said:

Probably a concern if it's pinging. Are you using the right fuel for this car?  Does it require premium unleaded?

I was thinking the OP may have got a bad batch of fuel and the system is contaminated. The pinging is a tell tale sign too.

Talk about a rabbit hole. For a DIYer, I'd remove the tank, flush it and the fuel lines, replace the fuel filter, then get the injectors checked. Use 95 RON for starters to get it all up and running and if all goes well go back to standard unleaded. I don't think it requires premium fuel. That would be ridiculous for a Toyota van.

If the knock sensors keep protesting then perhaps have them replaced and go from there.

[2001 Estima Owner]

I have mentioned all the above to my mechanic, and he thinks the transmission management module (or whatever it is called) could be the culprit I think he is trying to get a replacement to swap it out and try. My dad thinks a high voltage cable could be to blame. Thanks for suggestions so far.

[Tony Prodigy]

9 hours ago, 2001 Estima Owner said:

I have mentioned all the above to my mechanic, and he thinks the transmission management module (or whatever it is called) could be the culprit I think he is trying to get a replacement to swap it out and try.

We hope he's right. Does he have a plan B if it doesn't work ?

[2001 Estima Owner]

Update: van no longer runs. It starts and idles fine, but any attempt to use accelerator causes wild backfiring, strong fuel smell, and engine splutters and dies. No way to increase the revs without this happening. Nothing seems to have caused this; it started shortly after having the diagnostic by the auto electrician. He said all he did was check the error codes and reset them, and that couldnt affect the car in any way. I guess the plan now is to wait and see if my original mechanic can find a management module, and hope that does something. I was going to take the vehicle to a mechanic I found who specialises in imports, but now I cant move the car (and he wont come here), that plan has gone out the window. I suppose towing is an option.

[KAA]

Sounds like your only option Mike is to have it towed over, at least then he can do some magic for you to get some answers mate hope it isn't a major issue.

KAA

[2001 Estima Owner]

Update: had a mobile mechanic check her over and he found filthy spark plugs, and after he cleaned a sensor (air? fuel? not sure) the car ran fairly decently. So he thinks Ive had bad fuel, which may or may not be the only problem. He said he's never seen such crud in a system. (So I hope the guys I was paying to for my servicing were actually checking things all these years).  At least Ive got a starting point.

 

Next step: drain fuel. I couldnt put a hose down the fuel tank, so Google tells me using the fuel pump is the next best thing. Im looking for the fuel pump relay. Apparently I can jump that with a wire. I just need to find it. Is it the main EFI relay in the engine bay, or do I need to find a secondary one elsewhere?

 

Once drained, I can get her to a mechanic for changing of the rest. Hopefully.

Edited May 10, 2022 by 2001 Estima Owner

[Tony Prodigy]

On 4/27/2022 at 4:47 AM, Tony Prodigy said:

I was thinking the OP may have got a bad batch of fuel and the system is contaminated. The pinging is a tell tale sign too.

Talk about a rabbit hole. For a DIYer, I'd remove the tank, flush it and the fuel lines, replace the fuel filter, then get the injectors checked. Use 95 RON for starters to get it all up and running and if all goes well go back to standard unleaded. I don't think it requires premium fuel. That would be ridiculous for a Toyota van.

I rest my case..

The transmission guy sent you down that rabbit hole I mentioned. I knew it had to be something simple because this issue just came from nowhere. Generally transmission issues give you advanced warnings and not just simply cave.

Is the fuel pump an in tank type or external ? If there's more crud in the tank, you may need to flush it with some fresh fuel. Put in 10 litres and drain it out again. Don't forget to replace the fuel filter afterwards.

If you want to utilise the fuel pump, you have to bridge out the switching contact points for the fuel relay. I'm not familiar with your particular vehicle, but it should have a specific fuel pump relay. Just look for it and find the corresponding numbers which indicate the normally open/normally closed contacts. Place a bridge wire from the common side to the closed side and the pump should start. You may need to turn either accessories or power on after this to initiate the power circuit.

If that's not something you feel like doing, you can purchase a relatively cheap syphon pump on ebay. I have a couple of these in my kit just in case. I also rigged up an old motorcycle fuel pump with 1/4"" fuel hose when I drained fuel out of another car I have and that worked very well too. Just connected it to a car battery.

If you can find the fuel pump relay, post up a photo of the side which shows the contacts and I can show you which to bridge out.

Edited May 10, 2022 by Tony Prodigy