P1251. The Journey. The Epic. The Fix.

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P1251. The Journey. The Epic. The Fix.

Post by JohanW »

I posted a reply on the other forum because someone else seems to have the same problem. Error code P1251 stepper motor intermittent.

The reply was supposed to be short, but instead I became the below. I was planning on doing a full writeup on the issue here but didn't get around to doing so. So here goes: :siffler:

It took me 5 months and a fair bit of frustration and cash to solve. I was very near to replacing a perfectly working turbo due to a inherent software issue on the 2009-2011 models.

I drive a late 2009 3.0 d4d AT Hilux 4x4. The first error was logged at about 197k km (will need to go look in the freeze frame data). I'm now on 204k km.

P1251 means that the turbo driver ( a small ecu and stepper motor driver in a box located in the glovebox ) is unable to reduce the boost pressure in the intake manifold quickly enough. It does so by telling the stepper motor on the turbo to reduce the pitch of the VNT vanes.

I did the following before I finally found a solution:
1. Replaced the stepper motor/actuator unit on the side of the turbo with one from a accident damaged 2014 d4d. No improvement. ~R1400
2. Replaced the MAP sensor on the intake manifold with a new unit from toyota ~R2500
3. Cleaned the intake manifold and EGR valve. ~R90 (Mr Muscle Oven Cleaner)
4. Made a blanking plate for the EGR valve pipe that fits against the block. ~R80 for oem gaskets
5. Swapped out the turbo driver unit in the glovebox with one from a 2007 fortuner (my dads)
6. Removed the turbo, cleaned the inside with oven cleaner and diesel. ~R450 for new oem gaskets,nuts and cir-clips

All of the above had little to no improvement and the issue steadily got worse. I have a dedicated laptop with techstream which I used to diagnose and reset DLC errors. I have in excess of a 100 freeze frames for this error. This I managed to get due to the vehicle going limp on every single drive towards the end. I was about to replace the turbo before chatting to Kosie Swanepoel from KSD.

7. The solution. A chip with a boost clamp.

Now for the Why:

I have a short exhaust that is very free flowing, makes a fantastic sound and causes the turbo to spool up rapidly. This however causes increased wear on the turbo actuator ring. This ring sits inside the turbo body and controls the VNT vanes. The turbo stepper motor moves this ring about with a little lever. This lever is a close running fit in the actuator ring. With time and use this fit becomes either too loose or too tight due to carbon or wear. This leads to a delayed reaction in boost reduction and ultimately a P1251.
I had this exhaust fitted in May 2016 and did a 12000km trip through Botswana, Nam, Zim and back without issue. Its only in the last 5000km since the trip that the issues have started.

P1251 gets triggered when the boost pressure in the intake manifold is in excess of 225 kpa for more than 3sec after a signal to the stepper has been sent to reduce the pitch. 225kpa being the gauge pressure and is also what gets recorded in the freeze frame data.

The boost clamp simply hijacks the signal that tells the ecu the boost pressure and tells it that the pressure is 224kpa (thumb suck figure since I don't know at what level KSD set this) instead. The signal to lower the boost pressure went to the stepper motor driver/ecu before we even got to the 224kpa level (its threshold is lower than 224 kpa ) so its already busy lowering the boost. This negates the risk of overboost damaging the engine or the turbo by telling the ecu the boost is lower than it actually is.

I have done a ton of reading on P1251 on numerous forums all over the world. It seems to be a common issue on AT models with different exhausts. But there are reported cases where it happens on vehicles with stock standard everything. It also seems to only affect pre 2012 models. The ecu and turbo driver have different part numbers post 2011.

My conclusion is the following: A free flow exhaust can lead to increased wear on the turbo actuator ring leading to delayed boost control. This delay and a too low error condition trigger level leads to a P1251 error and limp mode.

Also something to note. Once a p1251 and limp mode has been logged the next drive will be in a detuned safemode. I would purposely trigger a p1251 in the morning within a few minutes of starting up to get into this safemode on my way to work. This prevents a second error from happening until I reach my office. But on the following drive this detuned safemode would be cleared and a P1251 would be waiting to happen in the most inconvenient place. Interestingly enough even on this third restart after the vehicle would still not be back up to full power. So if you have a P1251 fault code logged your vehicle wont be running on a optimum power level. A techstream needs to clear this error before power levels (and economy) would be back to normal.

KSD fitted my Dastek chip with boost clamp on the 5th of April 2017 since then I have not logged a single P1251 or limp mode. Did a 1600km trip before and over easter up the West Coast and back without a issue.

It seems like toyota solved this issue in the post 2012 models since I'm yet to find one with this issue. Or it could simply be that models post 2012 are yet to get to a age where wear leads to this issue.

I will add more detail in time and some photos. And also post if the error returns...
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Re: P1251. The Journey. The Epic. The Fix.

Post by Mud Dog »

Interesting .... makes sense as well. Don't drive diesel, but I'm sure that other members will find this to be useful. Thanks for the input. :thumbup:
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Re: P1251. The Journey. The Epic. The Fix.

Post by Mars »

Thanks Johan. As usual a nice and detailed post that will undoubtedly help someone in future. What is a boost clamp and does that come as an additional item to the dastek chip?
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Re: P1251. The Journey. The Epic. The Fix.

Post by JohanW »

Mars, the boost clamp is simply a setting on the Chip itself. It intercepts the signal from the MAP sensor and tells the ECU its something lower from a certain threshold level upwards. Its currently set at 205kPa. So even though the actual boost level is 225kPa the ECU is told its only 205kPa. But its only sent a lower value when the actual boost level is above 205kPa. So for any value below 205kPa the actual level get sent to the ECU. A tad low but I intend to go visit KSD again soon for a tweak or two.
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Re: P1251. The Journey. The Epic. The Fix.

Post by Mars »

Lekker lag ek nou vir myself! Dankie
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Re: P1251. The Journey. The Epic. The Fix.

Post by Renart »

My Car : Fortuner /Hilux 2007 3.0D4D AT
Engine 1KD-FTV
KM 190000
Problem Repetive Error P1251/34 and Limp Mode


Hey Johan,
I am just registered to the Forum Hilux 4X4 and I read with great interest your differents posts ( April 2017 ) about Error code P1251.
I Have similar problem :.and Limp mode .suddenly happen at normal drive without special effort , some time, in down town at 1500//1600 rpm = 40/50 km/h Or on road at 70/80 km.

I did make similar checks, as you, and no change .

I inform you that I leave in Madagascar and I am obliged to searchand do everything by myself because a lak of local service .

You say that a good solution is to fit :’’A chip with a boost clamp ‘’.
As in Madagascar we do not have dealer in this accessory , could you give me more details about this Chip/Clamp :
Specifications Data
Brand Name with reference
How to fit it
Dealer where I can purchase it by Internet
Average cost of this Chip/Clamp

Thanks and congratulation again for your good work to find a reply to our problem .

Regards
Real Name Bernard

PS Sorry for my Poor English Writing because I am French and not so familiar with Lhakespeare language !!
BG
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Re: P1251. The Journey. The Epic. The Fix.

Post by JohanW »

Hi Renart

I replied on your separate thread.
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Re: P1251. The Journey. The Epic. The Fix.

Post by JohanW »

Just to update anyone with this issue.

Even with the boost clamp the turbo eventually failed spectacularly. The turbine shaft snapped due to cyclic overloading.

The vanes of the broken turbo were sooted up and sticky. This I think was due to the racechip fitted by the previous owner. This caused slight overfuelling and higher soot levels.

I bought a new turbo from Toyota and fitted it. Expensive yes, but now everything is working as it should again.
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Re: P1251. The Journey. The Epic. The Fix.

Post by Renart »

Hey Johan

Many thanks for your usefull reply I am also thinking to change The Turbone ..
Please let me know if the new Toyota turbo is supply with the Actuator and of course VNT van?

On the other I am fitting since one year , like you , to found à solution and you are the only one who make a deep analysi s of the problem.
If you like I can make you a long report of my personnal experience in this .
Could you allow me to send it to you personal e.mail and of course I shall keep informed fo the follow .
My Personal mail : b.gorde@moov.mg

Bernard
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Re: P1251. The Journey. The Epic. The Fix.

Post by JohanW »

Toyota supply the complete turbo with the stepper motor.
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Re: P1251. The Journey. The Epic. The Fix.

Post by Renart »

OK Thanks as I will be abroad for three weeks I shall revert to you at this times
Have à good day
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Re: P1251. The Journey. The Epic. The Fix.

Post by pietpetoors »

Johan I see you say
" Made a blanking plate for the EGR valve pipe that fits against the block"

Did you blank off your EGR?
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Re: P1251. The Journey. The Epic. The Fix.

Post by dalkill »

Eish, so my model is prone to this issues even though i don't have freeflow on.

WOuld it be a good idea to do a decarbon on these motors as preventative maintenance.

Looks like members have already done it a bit...
viewtopic.php?t=38537

But i don't think to the extent like this guy:
https://www.youtube.com/watch?v=FBAwmXMAEQs

I would like to one time go for the full monty like the guy in the video, but is that wise.
Won't that loosen up bits of gunk that could foul up engine even further.

Anybody got recommendation of local garage that has done this for a while, and quite experienced doing it, knowing all the pitfalls.
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Re: P1251. The Journey. The Epic. The Fix.

Post by JohanW »

pietpetoors wrote: Thu Apr 05, 2018 8:54 pm Johan I see you say
" Made a blanking plate for the EGR valve pipe that fits against the block"

Did you blank off your EGR?
Toyota uses the EGR circuit as a sort of blowoff valve. This is documented in the form of a error code. Part of my fault finding process was to clean the EGR valve and see if this isn't part of the problem.

Cleaned up the EGR valve and installed a blanking plate with a 7mm hole in it. This limits the amount of muck that gets sucked in but still allows pressure to be vented if the blowoff function is used.

I bought two new gaskets from toyota and shaped a 3mm alu piece to fit.
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Re: P1251. The Journey. The Epic. The Fix.

Post by JohanW »

dalkill wrote: Fri Apr 06, 2018 8:56 am Eish, so my model is prone to this issues even though i don't have freeflow on.

WOuld it be a good idea to do a decarbon on these motors as preventative maintenance.

Looks like members have already done it a bit...
viewtopic.php?t=38537

But i don't think to the extent like this guy:
https://www.youtube.com/watch?v=FBAwmXMAEQs

I would like to one time go for the full monty like the guy in the video, but is that wise.
Won't that loosen up bits of gunk that could foul up engine even further.

Anybody got recommendation of local garage that has done this for a while, and quite experienced doing it, knowing all the pitfalls.
The problem is that the cleaning is all on the intake side. The problem is the exhaust side and the soot buildup in the variable vanes in the turbo.
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Re: P1251. The Journey. The Epic. The Fix.

Post by JohanW »

Some further reading and pickchas of someone that had the same issue and fixed it DIY. He attributes it to rust, but I beg to differ and say that is soot buildup. Most of the assembly is stainless steel so rust in there is hard to believe. Most of the buildup is on these stainless bits.

http://oilybits.blogspot.co.za/2014/02/ ... ntrol.html
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Re: P1251. The Journey. The Epic. The Fix.

Post by JohanW »

O and the racechip that caused the soot and slight over-fuelling is lying in a box and a dastek chip has been fitted with a proper tune and AFR (Air Fuel Ratio).
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Re: P1251. The Journey. The Epic. The Fix.

Post by Renart »

New Turbo-charger on Hilux D DKD-FTV
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Re: P1251. The Journey. The Epic. The Fix.

Post by Renart »

On May 2nd 2018-05-02
Hi Johan

You said that you had change Turbo-charger by a new one , as I think of to do the same I need some more information :
Did you purchase a true Toyota origin from Toyota dealer and under which Reference ? 17201-??????
Or did you purchase one OEM Model Probably Made in China under which Brand Name and reference ?

Your New Turbo-charger, is it directly Fitted with electronic Actuator? or the actuator was separately delivered with” little lever/rod to link it to VNT vanes , and of course to avoid the loosing of it between both end ?

In the meantime did you change MAP sensor ( On Air Filter ) and ECU “ Turbo Driver “ located behind glove box .with original Toyota reference : 89878-71010 or 89878-71070 ?

Thanks in advance for your reply

Renart/Bernard from Madagascar
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Re: P1251. The Journey. The Epic. The Fix.

Post by JohanW »

Renart wrote: Wed May 02, 2018 11:16 am On May 2nd 2018-05-02
Hi Johan

You said that you had change Turbo-charger by a new one , as I think of to do the same I need some more information :
Did you purchase a true Toyota origin from Toyota dealer and under which Reference ? 17201-?????? Purchased from a Toyota dealer with a part number. Came in a toyota box.
Or did you purchase one OEM Model Probably Made in China under which Brand Name and reference ? Original Toyota from Japan

Your New Turbo-charger, is it directly Fitted with electronic Actuator? or the actuator was separately delivered with” little lever/rod to link it to VNT vanes , and of course to avoid the loosing of it between both end ? Completely assembled with actuator and rod. Bolt loose old turbo, bolt on new one.

In the meantime did you change MAP sensor ( On Air Filter ) and ECU “ Turbo Driver “ located behind glove box .with original Toyota reference : 89878-71010 or 89878-71070 ?
My father drives a Toyota fortuner with a identical 3.0 D4d. During the diagnosis period I swapped my turbo driver ecu (unit behind glove box) with his. They are identical down to the part number. My turbo driver ecu worked without issue in his and his in mine. Still got P1521 with his turbo driver. I did the same with the MAF. The MAP sensor I however replaced with a new unit from toyota. This was also unnecessary and I still got P1521. In hindsight I should have swapped it out and tested before buying a new one.

Thanks in advance for your reply

Renart/Bernard from Madagascar
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Re: P1251. The Journey. The Epic. The Fix.

Post by Renart »

Ref Fortuner /Hilux Engine D4D – 1KD-FTV
Hey Johan ,
Since one an half year I had problems on my Turbo driver with Intermittent Limp mode and P1251 default.
I did all the same check as you without any result.
Recently, by chance I found information in Australia at following address:
https://cdn.shopify.com/s/files/1/0865/ ... 427acf.pdf
Which is self-explanatory

I opened insulated pipe as show on first picture and I found some wires used and rubbed which makes intermittent short circuit and burnt the Turbo driver.

Of course I replace and insulated the wires, and now everything is OK.
It is also the reason why this default happen around Km 80000/100000.
Please spread this information to everybody in order to help all friends who have the same problem

Best regards to everybody and thanks for your help and good information
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Re: P1251. The Journey. The Epic. The Fix.

Post by JohanW »

Great news Bernard. I will have to go check my harness too now. Maybe there is something hiding for me too. I replaced my intercooler with a front mount one. It could be that this shifted that harness and is still masking the issue.

Since I replaced the entire turbo last year October I've yet to have any issues again.

I'm going to attach the pdf on this thread for future reference in case that link dies one day.

Thanks for sharing!
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Re: P1251. The Journey. The Epic. The Fix.

Post by HiaceSparky »

Hi there Johan, thanks for detailing all your findings and additional info.

One of my Toyota Hiaces has a similar recurring P1251 DTC. It only occurs when accelerating while turning left. I presume and will check to day that it will be the cable rubbing issue.

But I am wondering if (with your knowledge of the Turbo) if you think the actuator linkage/Stepper Motor or the Turbo Actuator Ring if worn, might be the problem?
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Re: P1251. The Journey. The Epic. The Fix.

Post by Renart »

Sorry I have no Idea of your problem , But P1251 DTC could appear for different reason and put Engine in Limp mode .
In my case the rubing wire make à short circuit to Stepper motor and Burnt the Turbo driver.
In my case the difficulty was that the short circuit was intermitent .
In your case if the stepper motor is still runing well that mean that the short circuit does not affect the linking wire of the Turbo driver.
I the limp mode occurs when turning left only that mean that the whole engine is little moving and occurs a temporally limp mode .
I advise you to search inside all the harness ... In my case I find a flat rubing on external part of the harness involved.
Good luck in this .

PS: Check with a simple jump wire between to top connector4 (female ) to bottom 5 (female ) on the connector on botom of the steering wheel and in case of turbo default circuit , including turbo driver, the Default was 34 by ligthing ( 3 lights anf 4 lights ) in place of the sign of limp mode .If it is different that mean that the default is on an other place .
Hopping to help you .

Sorry for bad writing english but I try to be more simple
Best Regards Bernard
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Re: P1251. The Journey. The Epic. The Fix.

Post by Toughtimes »

HiaceSparky wrote: Wed Aug 07, 2019 1:45 am Hi there Johan, thanks for detailing all your findings and additional info.

One of my Toyota Hiaces has a similar recurring P1251 DTC. It only occurs when accelerating while turning left. I presume and will check to day that it will be the cable rubbing issue.

But I am wondering if (with your knowledge of the Turbo) if you think the actuator linkage/Stepper Motor or the Turbo Actuator Ring if worn, might be the problem?
G’day mate, have you had any luck fixing the hiace with p1251? Ive got the same problem, located in Perth, will pay you for any info. Its had a new turbo and actuator from turbotech, new turbo driver / ecu, new egr valve and vacuum switch thats part of the egr. New airflow meter, new map sensor, new intake pipe, cleaned the intake manifold and egr cooler and it still over boosts flagging p1251. Any info be much appreciated please, Thanks Dan
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Re: P1251. The Journey. The Epic. The Fix.

Post by Issi786 »

Hey guys. I have a p1251 dtc on a 2012 fortuner 3 d4d. It's very consistent. If I floor the car even while in park it will go into limp mode at around 4500 rpm or if I'm driving and I floor it n it kicks down hard it will go into limp mode guaranteed. It does not miss it. But if I Rev it gradually no limp mode. As long as u are not hard on the gas the car drives very well.

I have tried a lot to resolve this issue and all has failed :
1) recond the turbo from the car
2) checked egr and intake and it was clean
3) swapped step motor from my hilux
4) swapped maf and map from my hilux
5) swapped turbo drive from another fortuner
6) fitted a whole other turbo with new step motor supposedly better calibrated(not!! Just cond cos I was desperate )
7) tried another turbo drive
8) had it by a very good auto lec to check
9) another accelerator peddle
10) lastly another ecu. Had it cloned and still the same problem.

Now after a lot of research and testing I see that my map sensor reading seems to be the problem. It's not the map sensor or the wiring. It's the ecu.

With the ignition on and engine off any map reading should be around 85kpa(atmospheric pressure) in my area (mpumalanga) . And it is so on my hilux. But the fortuner reads around 185kpa. Even when the engine is running it will also be in the 185kpa region. I think that's where my overboosting issue is coming from.

It's both the original ecu and the second hand cloned ecu that give high map reading. If I plug the ecu into the hilux an turn ignition to on position the hilux also reads 185kpa as map reading. So the issue is definitely on the ecu.

Could it be that the fault was copied while cloning was taking place?

Secondly do u guys think the the map sensor reading would cause my p1251 dtc?

Any assistance would be appreciated.
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Real Name: Andrew

Re: P1251. The Journey. The Epic. The Fix.

Post by AndrewSpark »

Hi....is there a shortened or easy flow exhaust fitted ?
Issi786
Newbie
Posts: 4
Joined: Sun Feb 16, 2020 2:14 pm
Town: Machadodorp
Vehicle: 2012 fortuner 3.0 d4d
Real Name: Ismai

Re: P1251. The Journey. The Epic. The Fix.

Post by Issi786 »

Nope. Seems to be standard. Cat converter been removed. The box for the cat is still there but it's empty. No chip no modification as far as I know
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