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Help! By Cars Poorly


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Hi all,

My car does not seem to be running 100% of late and on a couple of occasions the car has sort of misfired when traveling at reasonable speeds when I've needed to accelerate sharply. It sudden splutters badly as if Ive slammed the brakes on for a brief moment before accelerating back to normal.

Hoping some genius on here can tell me a little bit more about a fault that has appeared on my cars ecu. "P0105 Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction" is the exact code and description. Has anyone else had this or knows a bit more about what this entails costs wise etc.

The cars dash warnings lights (TRC Flash/Engine Light) have gone now and the car is running ok now... (until it happens again).

Many thanks in advance,

Kaz.

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Black standard box. Found some better search results on google as I had little joy on here. Sam had an issue like this and he replaced the vac sensor. You about Sam? Part number how much is this part? Oh and is it easy to fit? Cheers all.

Oh, what happened to your IS dude? Just noticed your signature....

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Black standard box. Found some better search results on google as I had little joy on here. Sam had an issue like this and he replaced the vac sensor. You about Sam? Part number how much is this part?

The vacuum sensor is 89421-20190 and is around £200, so you're going to want to be pretty sure this really is at fault before swapping it !

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Ouich...£200...

The piggy back is soldered, I will have a close look tomoz to make sure the solder is still good and the ECU is secure. I was guessing at it being the vac sensor as Sam said that seemed to cure his....if im honest i have no idea what it is... :duh: :shutit:

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Do you think it may be a good idea to remove the pre-cats from the manifold?

Someone may correct me, but I don't see how that could be connected since the vacuum sensor is measuring the pressure before the air goes into the engine, and your pre-cats are after the engine. Sorry if I'm misunderstanding you though and you're asking an unconnected question.

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Do you think it may be a good idea to remove the pre-cats from the manifold?

Someone may correct me, but I don't see how that could be connected since the vacuum sensor is measuring the pressure before the air goes into the engine, and your pre-cats are after the engine. Sorry if I'm misunderstanding you though and you're asking an unconnected question.

lol, yeah sorry, it was a little random. Im just googling and it seems that removing the pre cats is a good idea in general for forced induction cars. Im a little concerned now after reading about it that they can often break up and cause issues with the engine.

Back to the PO105 Is it possible to just clean the vac sensor?

If I replace the Piggy back ECU with another one I have spare somewhere, and then erase the error code from the ECU, will it come straight back on if its not sorted it?

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lol, yeah sorry, it was a little random. Im just googling and it seems that removing the pre cats is a good idea in general for forced induction cars. Im a little concerned now after reading about it that they can often break up and cause issues with the engine.

I do remember reading about that, yes, but hasn't that only been on cars where the charger has been pushed a fair bit above the stock TTE setup ?

Back to the PO105 Is it possible to just clean the vac sensor?

If I replace the Piggy back ECU with another one I have spare somewhere, and then erase the error code from the ECU, will it come straight back on if its not sorted it?

I don't know if you can clean it, but I can't see it hurting to try. At least you can see whether there's something obvious blocking it up.

The manual talks about needing a couple of trips to work out if an error is a real one or not but this doesn't square with what I've seen, which is that the error can come up straight away again. So I'm not completely sure, but I think it's quite likely to come back up again immediately if there's still a problem.

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Im not sure how others have come to the conclusion its the vacuum sensor. The OBDII just tells me the code. Not exactly specific really. Some say its the Piggy back going faulty.

I don't really know where to go from here without having to take it to Lexus and them pull my p*nts down parts/labour etc.

The car has spluttered, misfired a few times before and no warning lights have come on until the other day, why is that?

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Im not sure how others have come to the conclusion its the vacuum sensor. The OBDII just tells me the code. Not exactly specific really. Some say its the Piggy back going faulty.

I don't really know where to go from here without having to take it to Lexus and them pull my p*nts down parts/labour etc.

The car has spluttered, misfired a few times before and no warning lights have come on until the other day, why is that?

To make sure on what the problem could be, take your black box off for a few days, re-set the ecu, and see if you are still having problems mate.

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Im not sure how others have come to the conclusion its the vacuum sensor. The OBDII just tells me the code. Not exactly specific really. Some say its the Piggy back going faulty.

I don't really know where to go from here without having to take it to Lexus and them pull my p*nts down parts/labour etc.

The car has spluttered, misfired a few times before and no warning lights have come on until the other day, why is that?

To make sure on what the problem could be, take your black box off for a few days, re-set the ecu, and see if you are still having problems mate.

Thing is though, it only does it when I suddenly nail the pedal down, even then it only does it once in a while. I think I have a spare black ecu some where as I know in the past I had an issue with the car turning off as soon as I touched the acc pedal.Once replaced it was fine, until now.

I can see the Vac Sensor, doesnt look to hard to get at and clean. Gotta be worth a go to.

Thanks for the idea Gord, don't have a huge amount of confidence in touching the ECU and removing the piggy back box. Im gonna need to take the charger belt off aswell aren't i?! D'oh!

Is there anyway of testing the Vac Sensor?

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P0105 is connected with the vacuum sensor according to the technical manual. You can read the troubleshooting procedure here. The procedure to test the vacuum sensor is here.

Bear in mind though, that your car is supercharged, so you're forcing more air in to the air intake (and therefore past the vacuum sensor I presume) than normal, and the manual doesn't cater for that. The TTE black box is there, I understand it, to stop the engine cutting the revs because it thinks there's a problem, so it has to fool the ECU somewhat.

Given that the TTE black box is unreliable, and the similarity of your symptoms to others with a dodgy black box, I think it's highly likely that's where the problem is. But it's still worth cleaning the vacuum sensor, yes, since that should be pretty easy.

You won't get a warning light for every single little problem the car has, the ECU will decide if it's serious enough to put the light on. So your car may have had small issues before but now it's got worse.

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P0105 is connected with the vacuum sensor according to the technical manual. You can read the troubleshooting procedure here. The procedure to test the vacuum sensor is here.

Bear in mind though, that your car is supercharged, so you're forcing more air in to the air intake (and therefore past the vacuum sensor I presume) than normal, and the manual doesn't cater for that. The TTE black box is there, I understand it, to stop the engine cutting the revs because it thinks there's a problem, so it has to fool the ECU somewhat.

Given that the TTE black box is unreliable, and the similarity of your symptoms to others with a dodgy black box, I think it's highly likely that's where the problem is. But it's still worth cleaning the vacuum sensor, yes, since that should be pretty easy.

You won't get a warning light for every single little problem the car has, the ECU will decide if it's serious enough to put the light on. So your car may have had small issues before but now it's got worse.

Thank you very much. Thats put my mind to rest a little. If I can just find my black box...

Will update topic for others.

Many thanks.

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Cool, cheers guys. Just thrown me a little as other replaced the vacuum sensor. I have a spare black box so will get it changed. Im also wainting to hear back from TTE as im hoping they will send me another one as replacement spare.

Cheers again...

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To close the topic off. *UPDATE*

After contacting TTE they agreed that it was most likely the Black Piggy back ecu thats failed. Unfortunately, these are no longer free. They quoted me €299. Lucky for me, I found a brand new I had which Florian sent me after my previous one went bang.

Installed this and ran the ODBII scanner and no DTC codes are shown. Car is now running tip top again!

Cheers guys.

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Great news, well done ! :D

TTE now do a Silver Box, which is supposed to be slightly better than the old Black Box.

Im awaiting a reply from them again. I explained to them that the last one I had was free so I was somewhat shocked by the price they are asking for. Will see what they say. I will ask them how much the Silver one is. Whats the difference? Does it let the revs go higher? 200rpm extra?

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