1KD-VFT engine - no power after prolonged periods of engine braking

[Greasemonkey Lurker Find all posts View Profile Close Greasemonkey]

It happened twice now. Towing with a 2014 Prado face lift with 1KD-FTV a 2.3t caravan in S4 (not in D) as per Toyota recommendations for some two hours up to 100km/h prior to a long hill descend. To look after the brakes, pushed the auto transmission down to S2 and completed a descent at about 60km/h without touching the accelerator, ie full engine braking. Engine was driven up to just below 4000RPM for some 4 minutes it did take to complete the decent. On the scan gauge the cooling water temp sits around 83 degrees when not towing, when towing at around 100km/h on flat ground it goes up to around 85degrees. Fuel consumption goes from some 9 to10l/100km not towing to 14.5l to 16l /100km with van. After the descent on engine braking the cooling water was around 80degrees on the scan gauge. Outside air was around 15 degrees. Transmission temperatures quite cold as oil cooler is fitted. On two occasions now, needing to apply accelerator again on the flat after the decent, the engine has no pull, it feels like fuel starvation. It also sounded a bit off, not grunty, but perhaps a bit pingy and thin. Couldn't clearly hear what the turbo did, didn't check boost values with the scan gauge, but with no exhaust gas pressure it would be low anyway. It idled absolutely smooth, tapping the accelerator in neutral produced a clean response, just no power getting to move. Remaining fuel in the tanks was about 20 litres first time, 50l second time. Fuel filter light has never been on, filter also only changed 5000km ago after it happened the first time and i though it has to be fuel starvation. I inspected the filters (have a 30 micron pre filter) and unrolled the material of the OEM filter, it didn't look bad. The transfer filter is also regularly changed and normally in daily commute drive the tank down to the last 10l, transfer system hence must work. Also no problems with refueling 140liters, no splash back, clean and fast fill. Anyhow, why fuel starvation after a decent where there is low consumption? I never run out of power going up hills with at times pedal flat to the metal, of course one could wish one had more, but I can't feel anything being wrong. On both occasions after the descent things feel wrong, each time I immediately pulled into the first service station and filled up completely. Symptoms gone, power was back. On the second time I carefully listened when removing the filler cap whether there was a huge inrush indicating a strong vacuum, but there wasn't. Is the fuel temp too high with lower quantities in the tank remaining after driving for 3hrs with van in tow? But why would this manifest itself consistently after a severe cool down going down a hill? Why not going up a hill when water temps get up to 95 at times and ambient temps are in the thirties? Have 4000RPM with low injection quantities anything to do with it? Engine has done 80000km. EGR standard, not cleaned yet. Oil catch can fitted at 40000kms. Oil sump pickup grid clean. No issues I'm aware off, except for this engine braking problem.

[Greasemonkey Lurker Find all posts View Profile Close Greasemonkey]

Additional Thoughts: The low fuel warning light did not come on. I believe the sub to main fuel tank is done via a jet tank. If someone could please confirm whether on a 2014 face lift model the jet pump primary flow is achieved with a small electric fuel pump in the main tank or just by the return fuel flow from the injector loop. If the latter, it could be perhaps that when towing at much higher fuel consumption that the return fuel is sufficiently reduced so that a complete transfer of the fuel from the sub tank no longer happens in time of the main tank running low. Going down a hill just might the trigger for air to get finally sucked up, depends on the actual geometry of the pickup. Just speculating. Replaced the transfer filter today, can blow through it with ease, so can't be the reason.

[D4DDave Member Find all posts View Profile Close D4DDave]

Greasemonkey,

I've had this problem with my 2012 1KD-FTV. I never conclusively got to the bottom of it, but in my case there was a low boost code present immediately afterwards. See https://www.pradopoint.com.au/forum/...299-fault-code. I had no cooler at the time and put it down to the auto overheating. I've since installed a transmission cooler and not had a re-occurrence, but have perhaps not pushed as hard with the engine braking either. Sorry this is not that helpful, I'll be interested to know if you find a reason for it.

Cheers,

David.

[Greasemonkey Lurker Find all posts View Profile Close Greasemonkey]

Hi D4DDave, Thanks for your input. I read your write of the situation and it sound just about the same as mine, except that I didn't have a fault code coming up on the scan gauge, nor any light on the dash. I do watch engine water temp, main torque converter and overall auto transmission temps all the time, and in my case they weren't up, in fact a bit on the cool side as when driving in S4 the box pretty much locks up around 65km/hr unless pushed. At 60km/hr going down hill there is plenty of air flow through the radiator, so given only 15 degrees outside things cooled down quite a bit last time it happened. But the symptoms trying to get going again on the flat are exactly the same to yours. Taking it out of S2 on the bottom back up to S4 it started labouring, so pushed it down to S3 again and it sounded OK. Traffic was then stop and go and Prado was very lame, had to take it easy even when moving off in first. Idling and light load normal in sound, no vibrations, just no go past half throttle and engine sound changed. I have ordered a diagnostic tool that enables me to see both tank fill levels, will start checking out that the transfer works OK and keeps up with the increased consumption when towing the van. On the last trip I filled 10 liters from the jerry can into the Prado before making the 300km home trip with only a lunch stop, engine stopped after a 4 minute cool down, so no extended idling while having a bite, so consumption rate pretty much 15l/100km all the way. A jerry can top up due to the slow fill rate would have all gone into the sub tank only. May be the problem was actually the slow gradual climb before the descent, and the decent just causes a delay in a low fuel situation or it has something to do with the fuel pick up location. Do you know by any chance your tank fill level when yours happened? May be it is something to do with the turbo, it would also go quite cold as not much fuel is going through the engine, but air flow is still quite high due to being pushed at 4000RPM. Doing all this on the brakes is no solution either as one still needs to feather them and be ready for a complete stop when needed. In my case the problem didn't rectify itself, it was some 10 minutes of superslow traffic to the petrol station. Next time I will also check what the priming plunger does feel like.

[Greasemonkey Lurker Find all posts View Profile Close Greasemonkey]

Found another post with a similar thing, no solution:

https://www.pradopoint.com.au/forum/...-loss-of-power

[D4DDave Member Find all posts View Profile Close D4DDave]

Greasemonkey,

In my case there was no check engine light either, and whilst the P0299 code was present when I pulled over immediately after the symptom manifested itself, it was not present 30 mins later at the end of my drive (and I didn't clear anything). In what time frame did you check with the scan gauge, or does it display codes immediately as they occur?

Agree with there being plenty of ram air through the radiator and auto cooler at the speeds we're talking about. I have noticed that even in S4 though, the TC temperature goes up when backing off on the throttle and coasting even on flat ground. It's as if the TC immediately unlocks in such conditions. I also don't believe the TC locks in S3, S2 or S1, including in an engine braking situation, regardless of how high the revs are (i.e. a long way from stall speed). But having said all this, surely the heat generated can't be significant compared to when ascending hills? The lazy gear changes I experienced seem strange though. Did you experience this?

I can't see how it's fuel starvation. I'd imagine your experience of the symptoms disappearing after re-fueling is a coincidence, and the reason for the recovery being more one of timing and the opportunity for things to cool down. In my situation, the first time it happened we were only ~100kms from home so I'd imagine my tank was close to full, but I can't recall for sure. On the second occasion I would have had about 1/4 to 1/3 of a tank.

I'm not sure what the priming plunger will reveal. My experience is that when operating the plunger when the system is in a normal state (i.e. no air in the system, and not immediately after previously priming), it doesn't have the same resistance as it does immediately after priming anyhow. In other words, even when the system is in a normal state, operating the plunger results in it becoming hard to depress after several presses, even though there's no air in the system.

Please post back if you find anything!

Cheers,

David.

[brogers Advanced Member Find all posts View Profile Close brogers]

I'm not sure you need to downshift manually out of S4 and go to S3 or S2 to get engine braking....if you leave it in S4 and as you descend and apply the brakes a couple of times the transmission seems to downshift anyway...I regularly tow a caravan or a camper trailer, and I have a scan guage, but I dont manually downshift the transmission...perhaps try leaving it in S4 and you just need to apply the brakes a couple of times and it may downshift...maybe try that...for what its worth.

[Greasemonkey Lurker Find all posts View Profile Close Greasemonkey]

Hi Dave and Brogers,

I believe the only gears that can work in conjunction with a locked up torque converter is 4 and 5, five only under light loads and above 80km/h (just by feel). Gears below will always have slip, including when applying engine braking, hence the temperatures also coming up. Yes it is correct, that touching the brakes will down shift, but quite late, too late in my opinion to look after the drum brakes on the van. I really like to keep them as cool as I can to have maximum reserves when I really need them. Dave you are correct, the plunger on a primed system will go hard very quickly, what I'm looking for is anything that might be confirmed sufficiently different to normal. On both occasions it happened to me it was with 30 to 50l of fuel remaining. Coincidentally this appears to be also the typical fuel amount when people stop due to a fuel transfer issue. So I will check fuel levels with the diagnostic tool when it arrives. I don't think this is transmission related, my temperatures are cold, self protective functions should only come in at high transmission temps. The other post mentioned the symptom went away after stopping and starting the engine. In my case engine was stopped and started due to the refueling. So yes, also something to test before doing anything else next time, may be something resets with a restart.

[Greasemonkey Lurker Find all posts View Profile Close Greasemonkey]

Some progress made... Can now check the main tank fuel level with the X-gauge directly while driving (and towing). It should give me a good idea on the next trip with the van whether it could be a main tank fuel level issue. At present when not towing I can see the fuel transfer working as it should. If also OK while towing with only 1/3 of fuel remaining, than at least one possible explanation can be ruled out.

[roadblock Junior Member Find all posts View Profile Close roadblock]

Anyone experiencing P0299 code, please take a look at this post... https://www.pradopoint.com.au/forum/...417#post741417

Regards,
Roadblock

[nateees Lurker Find all posts View Profile Close nateees]

Some progress made... Can now check the main tank fuel level with the X-gauge directly while driving (and towing). It should give me a good idea on the next trip with the van whether it could be a main tank fuel level issue. At present when not towing I can see the fuel transfer working as it should. If also OK while towing with only 1/3 of fuel remaining, than at least one possible explanation can be ruled out.

Hey Greasemonkey, couldn’t see any further posts after your last post on this issue back on Aug 2018. My 2010 kakadu is having what seems like the exact same problem as yours… no power when towing after around 45min of drive time when the car gets to any incline it simply just doesn’t sound right. After I stop and drive next day it appears to be fine but then 45mins or so later it happens again but only when towing!

Did you find yours was related to fuel levels from main tank when towing on incline? I read you got a diagnostic tool to check this and you said it was fine when driving normally but can’t see you comment on how it was towing and with a decline / incline. This issue is really worrying for me, has made me lose a lot of confidence in the car when towing the family caravan which is not even over 1.5T.

hoping to hear more about your issue and how you went and if it was resolved?

cheers