2007 Avensis Estate 2.0D4D Engine Knock.

[Farming23srx]

Hello,

I'm in desperate need of some Diagnostic help for my Avensis. As much as I could just throw the problem at any who come to this post first, I'd like to tell the history of the car in case it can help with the diagnostic.

This is gonna be a long post (especialy since English isn't my native language) but please bear with me.

 

I've bought this car in the end of September 2022 from a professionnal seller with 166000km. It is a grey Station Wagon model from 2007 with the 2L diesel 1AD-FTV. Seller had full history for the car until 100000km. Car was maintained at Toyota dealership in both France and Spain until 2009 where the engine was changed under warranty by Toyota at 100000km, then no history. 66000km without history is not great but I desperatly neaded a car. Car has been serviced and passed inspection before I bought it, with bills from the garage to confirm. I tested the car before buying (was ~30°C when trying the car out, it's gonna matter later) and appart from some aestetic problem (car has been badly repainted) the car ran fine, no smoke, A/C working, all the usual stuff. Bought the car, made ~150km home with it just fine.

 

Next week October comes in and the first cold wet mornings with it. I start the car in the morning and surprise, no front deffrost and no heater. Turns out guy that had the car before me had cut the tube coming into the heater radiator and had the coolant going straight back into the engine. So I change the tubes and the heater radiator, heater works fine. Rest of the car is fine.

Winter comes with freezing and then I thind out that the car will not keep coolant temp up while driving, car heats up fine when parked but when you start driving temp goes down, this was not an issue when testing the car at 30°C but at 0 things change. I decide to change the thermostat at the next service.

April comes around and it's time for service, so full service I did at 171837km plus some extras. Engine oil, Gearbox Oil, Both Air Filters, Eng Oil Filter, Fuel Filter all Toyota OEM. I also clean the EGR valve, the radiator, and change the leaking rocker cover seal (Since cover is off I check the chain and it looks perfectly fine). While draining coolant (guy had put green coolant), I change the thermostat and I find that he also drilled a 4mm hole in the bottom of the Thermostat so that the engine could not keep the coolant heat up. I also find out that someone has cut the pipe going from air box to the turbo wider and added some rubber to make up for the fact the hose doesn't stay on the turbo since its diameter is now way too big. I add the missing hose clamp on the turbo and find out that it can't clamp down since the hose has been made wider. I manage to make everything work and the car now has full service done and is now keeping coolant temp up when driving with the new thermostat. Great.

 

 

Summer comes around and now comes the fun part, the car is now heating up nicely and the outside temps are going up as well (going above 30°C every day and sometimes above 40). Now that the engine heats up I find that when the engine is hot and if you're driving along at stable speed (with small, steady, stabilized press on the throttle) the engine makes noise, kinda like a rattle or a knocking sound. By driving the car to and back to work everyday (60km to and back) I find that the noise goes away the moment that you let go of the gas pedal, and that it is kind of quieter if you accelerate frankly. The sound also is more noticeable the hotter the outside temp is (above 40°C it's all you can hear and under 7-8°C you can't hear it even with fully warmed engine).

Since I don't have much choice I continue using the car since a problem from the rods or bearings would probably still be noisy when the accelerator is realesed. And then one week mid August the temps stays above 40°C everyday and the engine light comes on with "VSC OFF" and "TRC" light. So I look for a solution and find this forum, I look things up and try the usual things, brake lights, master cylinder sensor connections, and EGR Valve who is still clean from the service I did in April. Since nothing is working I decide to take the car to the dealer but just when I decide to call them, the warning lights go off (it has been 3 days since they came on). I continue using the car and the lights come back one for 2days and them go off again. Then temp drops arround 30°C again and the light never come back.

 

Until 2 weeks ago when it came back on when the outside temperature went above 36°C again (same lights : Engine light, VSC, TRC OFF). So this time I buy a diagnostic tool and decide to read the code myself since Toyota can't take the car in before 2 weeks. By the time I receive the OBD reader 2 days have passed and the warning lights have disapered again. I read the ECU and I get Code P0100 and P0069 are inactive but saved in memory.

 

That takes us to today. The car is nearing 179000km and the codes have not reappered, the engine still knock when fully warmed up, and I can't pinpoint where the problem comes from.

I've tried filming the engine so that you can hear the sound but it is what it is. ->

You can hear the knocking kick in at 0:13 and 0:35 when the engine gets past 1400rpm when pressing the pedal steadily (Rail pressure goes over 450bar at that point when testing parked). 

Noise is less noticeable when I accelerate harder from 0:41 onward but you can kind of hear that it goes away when I let go off the gas.

What you hear at 0:31, 0:41 and 0:46 is the dual weight flywheel that is worn out but the noise goes away when I do the test with the clutch pressed down. The knock on the other hand does not.

I've tested the MAF and MAP sensor the best I could using the Toyota Service Manual and the Denso one but I don't have the equipement to be mesuring and sending 12V to the sensors at the same time so It mostly was a visual check and some basic brake cleaner cleaning.

I've used the OBD reader to monitor all I could while driving and I found that the knocking sound mostly comes on the the Common Rail Pressure gets around 450bar and above, I'd have liked to be able to diagnose the injectors further but my diagnostic tool is mostly limited and buying a 350€ + scan tool or a Techstream license is not something I want to do unless I absolutely have to. I've tried disconnecting injectors one after the other but the knock stays independantly of the injector that I disconnect. I've tried disconnecting the MAF, but it stays the same. I've tried using premium fuel and/or 2 stroke oil in the fuel but the noise didn't even quiet down a little. I've also found out when testing that if you accelerate hard ( flat out ) when under ~1400rpm when driving, the car really doesn't sound happy, I'm having a hard time describing it but it's a mix between an old v8 sound, misfire sound, a loud electrical transformer sound and a big rattle. Since the car doesn't smoke or eat oil or coolant I'm starting to think that it is running "lean" or injecting too early.

I'm thinking about taking the car to a diesel specialist that's not too far away but that's an expensive solution and I'd prefer putting that money into OEM parts rather than into man hours even if it is for a real professsionnal dieselist.

 

I'm hopping someone has an idea about what could be causing this, and frankly any help would be greatly appreciated. If you need any more info just ask I'll gladly give it to you the best I can.

 

In any case thank you for reading all this, and have a nice day.

(Also I'm sorry if you eyes hurt from my terrible writing but I'm trying my best over here.)

Edited September 24, 2023 by Farming23srx
Ortograph Corrections