Rav4 enters limp mode on occasion

[TomPrem]

Hi,

I've stumbled upon this forum while googling an issue with my car and seeing lots of great posts and answers I thought asking is worth a shot.

Firstly, I don't remember the obd error codes, I'll try to collect them tomorrow. There were at least 2 common ones and sometimes an extra.

Secondly, codes may not be that informative since I've been to Toyota ASO and a couple of mechanics and I just lost money with them. However, here's the breakdown of my problem.

1. Mileage - 200k km. Limp mode observed for the 1st time at around 170k a couple of years ago. 

2. Does it happen often? Not really, there are periods of up to 4 months without a single occurance and sometimes check engine fires up a few times in an hour (very rare)  or a few times a week (most common).

3. Restarting the car fixes the issue and it feels lik the car regains some of its hidden power...however the 2nd part may be biased. A qiuck restart doesn't help. The car needs to be turned off for at least 4-5 seconds.

 

Now, it's not easy to cause it to enter limp mode. The conditions which highly increase the chances is: 

- When you go for an extended period of time a little uphill on 5th gear (nearly exclusively for the past year) once in a while on 4th gear. It never happened when going up a steep hill but I've never done it on 5th gear...so who knows. It happens mostly several seconds since the start of the hill when I'm at a bit lower RPM - around 2-2.4k). It's usually preceeded by a very short feeling of the car lacking power, as if it could not accelerate but it doesn't loose power. It's hard to explain but I can now mostly forsee the limp mode occurance at that point. 

- I've had several occurances in the same place (once 3 days in a row!) when I go uphill like 60-70m, decelerate, turn left, accelerate softly for like 300-400m and change a drive lane in order to go on a highway. At the point of changing lanes or within a couple of seconds after I just get limp mode. Had it nearly daily for a month, rarely on other occasions and now it's been 3 months without an occurance.

 

Toyota ASO checked the car, said they had no idea what's wrong, changed a part for the heck of it and cashed in big time. I hate them.

I went to 3 mechanics who had no idea and were having hard time recreating the limp mode (at that time it was happening at a bit different conditions, about that later), 4th one pointed to one of the valves at the engine. I don't know which one, it was over a year ago but the new one from Toyota costed something like 300 pounds. He found a refurbished one, replaced it and the car was working without issues for a couple of months. 

Later, when it started to occur once again it remained untill now just the way I described earlier. I'll explain briefly how it differed earlier below.

At the time before valve replacement, limp mode was never occuring on 5th gear and I don't recall it happening on 4th either. It was most commonly observed on 3rd gear when going uphill. At that time it was happening not when I was accelerating softly but the other way round - stepping on the gas pedal when going a little uphill, basically accelerating while joining the highway, was the way to obtain an error. But it usually took like half an hour of trying to get it. I never got an error below 4th gear since, and I only got it 3-4 times on this gear in the past year (actually past 2 months, never happened before).

Sometimes I feel like the car just lacks power, it accelerates as if it wanted but couldn't, especally in the 1900-2500 rpm range but it doesn't enter limp mode.

 

So, the car is old but in a good condition. Maintained well, low milage for the age, never done anything hardcore, had the clutch changed at around 115k if I remember correctly and just this annoyingly hard to pinpoint issue haunts it. 

I'll be very grateful for ideas and assistance with this problem of mine. I'll try to fix the codes from the past 6 months or so tomorrow.

Best regards

[Hybrid21]

Hi to Tom, the best way forward is to analyse the fault codes to give you an idea where to start, otherwise you will be changing parts needlessly.

Do you have an obd reader ?

[TomPrem]

Hi again, 

I'm sorry for the late update, been a busy week so I went to the mechanic today.

The error code is 34(2) - it's the model released just before the code system overhaul. Both the mechanic and uncle Google say it's Turbocharger related error.

Here's the list of things that had been done in the past:

1. Turbocharger regenerated - upon this change things got better for a few weeks and then returned on higher gears (described in my OP)

2. Fuel filter changed

3. Used fuel additives to clean the system

4. Valves changed (VSV and SCV I think)

5. EGR cleaned

 

The mechanic tested the car in a single way - with OBD attached he pushed gas pedal to the ground on neutral gear and the preassure was going up to nearly 190 kPa immidiately, while in his oppinion it should reside below 90 kPa.

 

[TomPrem]

I'm sad nobody could provide any sort of input in this case.

So here's something which so far works for me....

In an "almost a state of desperation" I had given a shot to the idea which many months ago would have put my Rav4 in limp mode. I first heat up the engine a bit. I noticed that while boosting the RPM on neutral some black smoke had been getting out the exhaust. I then took the car for a ride. I basically tried to make it go into limp mode. High RPM, making turbo kick in, high load uphill, highway. I burned like a third of the gas tank and never gotten the limp mode. Now it's been 3 weeks and I had not gotten limp mode even once. There's no hesitation when I step on the gas pedal anymore (allright, once in a whil there's a little, but barely any). I now regularly put the engine (turbo) under stress and so far so good. 

Hope this might help somone. 

[Smani]

Hi Tom, 

Is the DPF regenerating ok?

Had the same issue with a Ford Kuga for years!  It kept resetting itself just like your RAV4, after turning off and back on in few minutes.  Ford and independent garages never gave me the diagnostic, spent a fortune with both just for waste of money and time. Lost completely the confidence in the car, afraid to push it for overtaking in motorways.  Then when it never reset again, put in a different independent garage and they said the exhaust pressure sensor was not working, and this was inhibiting the DPF to regenerate, as consequence it was completely blocked.  New sensor, they tried to clean the DPF unsuccessfully and a new one had to be in as well.

Why it had to take to that stage to someone diagnoses properly, god knows.

That issue brought me to Toyota hoping never hearing this again from this brand 😟.  Hope you get it sorted.

 

[TomPrem]

Hi Smani, thanks for your input.

I haven't been driving much this car lately, but I clocked in several houndred km, both city and highway. I haven't gotten any limp mode since the last post. I believe it's an inherent issue with TDI engines and comes up as an issue to calmer drivers who rarely put the car under "unnecessary" stress.

And yeah Smani, I was afraid to test things on highway and especially while taking somebody over on two-way streets as I knew stress causes the limp mode to kick in. However I just decided to have a go after I heat up the engine, stressed it a little on neutral near the house and only then I took it to the highway to put it under some serious stress in the evening, when there's little traffic.

 

Cheers guys.

[Cyker]

Thanks for reporting back on how you got on!

Hmm, so the good ol' 'Italian Tuneup' still works 'eh!  

I must admit that wouldn't have been my first recommendation based on the reported symptoms, but I forget people don't drive like I do...   

It's funny how many seemingly unrelated issues are caused by deposits building up in the engine due to it not getting hot enough! I must admit I'm surprised you had all those issues but didn't develop any DPF-related problems, which is the usual warning flag that the diesel engine needs to be taken on a good thrash to get it good and hot.

[TomPrem]

Half a year and several thousand km later I have not experienced limp mode a single time. I felt a delay when accelerating a few times but a brief excessive load on engine and they go away.

No need for special tools, costly part replacement or regeneration in my case. Or even fuel additives.