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Octavia RS, accelerating problem

Chanodc
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Chanodc Apprentice

Chanodc

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First of all, nice forum! :rock:

Well i've just bought an Octavia RS sedan from 2002. What an amazing machine to own, when you're living in non-car-friendly Denmark ;)

I've just noticed that when accelerating, suddenly the engine lose power for just a second and then accelerates again. It feels like the turbo suddenly stop charging, even though it doesn't. And then, after approximately half a second or so, it accelerates fine again. Very frustrating when accelerating.

No error codes in VCDS, thought it might be a mass airflow sensor? Any ideas lads?

Edited by Chanodc
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DBP Experienced

DBP

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Don't think there's any egr valve on this model, 1,8t from 2002. Or am I wrong? :)

There is an EGR valve, you can get rid of it when you do the SAI removal.

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Chanodc Apprentice

Chanodc

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There is an EGR valve, you can get rid of it when you do the SAI removal.

Well there you go, now i'm just a little wiser :) But guys, if the EGR valve would be the problem, wouldn't the car store some kind of errorcode?

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DBP Experienced

DBP

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Well there you go, now i'm just a little wiser :) But guys, if the EGR valve would be the problem, wouldn't the car store some kind of errorcode?

Mechanical valve with no electrical connection so I wouldn't think it would the ability to store it.

I have the same problem as you as the turbo drops off. I will be removing the SAI and all that soon to see if it helps.

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Lofty79 Experienced

Lofty79

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its like a stutter, smooth pull then periodical .. like.. instantaneous pulses then back on power. I bet its more noticeable at about 3rd throttle, on very slight inclines. I also bet it would be associated with a puff of smoke.

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Chanodc Apprentice

Chanodc

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Well DBP, I will definately remove the SAI system then. Do you know if this intervention will affect my OBD tune, or can I just perform the surgery and enjoy my new car without thinking about getting it re-tuned again?

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Chanodc Apprentice

Chanodc

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its like a stutter, smooth pull then periodical .. like.. instantaneous pulses then back on power. I bet its more noticeable at about 3rd throttle, on very slight inclines. I also bet it would be associated with a puff of smoke.

To be honest, I haven't looked in my mirror when this occurs, but perhaps I should try that. Actually, I noticed these small lacks of power during acceleration in 3rd gear doing full throttle!

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Eccentric Toast Rising Star

Eccentric Toast

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This sounds something similar to what I'm experiencing. I get it between 5 and 7 thousand revs the car kinda drops the power for a sec on and off all the way from 5-7, thought it might have something to do with the remap because i just fitted a bigger down pipe and intake pipe and didn't notice it before i did!

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Chanodc Apprentice

Chanodc

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Just thought I would check the air filter, and I realised that it was a little greasy and with a smell of gasoline/oil. Could this have something to do with the SAI system? I definately have to replace it, but I don't know whether to buy a pipercross replacementfilter or if I should go for the CAI filter with a long pipe for front mounting?

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rk696 Experienced

rk696

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The 1.8T doesn't have an EGR valve. What everyone thinks is the EGR valve is actually a combination valve that allows fresh air to go into the exhaust stream to warm the cat up faster. An EGR valve re-circulates exhaust gases from the exhaust back to the inlet to be burnt again.

Chanodc, you may have a sticky N75 valve. If you have a full copy of VCDS, you can log the airflow and boost readings and see if it's a dodgy MAF of what.

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Bodge Experienced

Bodge

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The 1.8T doesn't have an EGR valve. What everyone thinks is the EGR valve is actually a combination valve that allows fresh air to go into the exhaust stream to warm the cat up faster. An EGR valve re-circulates exhaust gases from the exhaust back to the inlet to be burnt again.

Finally someone stepped in to state the truth! Chanodc you were correct, the AUQ engine does not have EGR.

I'd be very surprised if it was the combi valve (part of the SAI system), as there's not much to them.

Do you have a standard engine map/calibration? There are common issues with remapping this car.

Sounds like you need to change the air filter anyway, so like others said just get a standard one.

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Bodge Experienced

Bodge

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What benefit would removing the SAI have when hunting a what appears to be a boost issue ??

It does do anything unless the car is cold does it ?

Yeah Dave, just sits there doing nothing when you're driving. It will only work at cold idle, or on idle to check itself. As soon as you open the throttle it automatically shuts down.

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Chanodc Apprentice

Chanodc

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The 1.8T doesn't have an EGR valve. What everyone thinks is the EGR valve is actually a combination valve that allows fresh air to go into the exhaust stream to warm the cat up faster. An EGR valve re-circulates exhaust gases from the exhaust back to the inlet to be burnt again.

Chanodc, you may have a sticky N75 valve. If you have a full copy of VCDS, you can log the airflow and boost readings and see if it's a dodgy MAF of what.

Ok thanks, nice to know, important detail :) Well, I have access to a full version of VCDS, so I think I will try reading the airflow and boost, trying to determine whether it's a MAF or what. Thank you for your input! But how do I test the N75 valve?

Finally someone stepped in to state the truth! Chanodc you were correct, the AUQ engine does not have EGR.

I'd be very surprised if it was the combi valve (part of the SAI system), as there's not much to them.

Do you have a standard engine map/calibration? There are common issues with remapping this car.

Sounds like you need to change the air filter anyway, so like others said just get a standard one.

Also thanks to you Bodge. Well former owner got it mapped, but as far as I know, the company had the car at dyno and made a mapping for the specific engine. But i'm not quite sure 'bout this. By the way, I have changed the airfilter, and bought an original from Skoda.

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Longyear Rising Star

Longyear

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Unless I've missed it, what we really need to know from the OP, is whether the car has been remapped.....

[EDIT: Ok, now we know it is remapped, so a definite candidate for PRBSD ('post-remap boost surge disease')]

If so, everything I am hearing sounds identical to the boost surging that "destroyed my June 2012" :)

If there's def nothing showing on VAG-COM, the first thing I'd change personally is the N75 valve. This fixes the issue for some (it didn't for me, and neither did the other 6 things I tried, but a replacement ECU completely resolved absolutely all surging).

You could also potentially look at the MAF, and also if you have any eratic or strange behaviour from your temp gauge, change your Coolant Temp Sensor as a faulty one of those can also cause similar symptoms.

Edited by Longyear
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Chanodc Apprentice

Chanodc

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Unless I've missed it, what we really need to know from the OP, is whether the car has been remapped.....

[EDIT: Ok, now we know it is remapped, so a definite candidate for PRBSD ('post-remap boost surge disease')]

If so, everything I am hearing sounds identical to the boost surging that "destroyed my June 2012" :)

If there's def nothing showing on VAG-COM, the first thing I'd change personally is the N75 valve. This fixes the issue for some (it didn't for me, and neither did the other 6 things I tried, but a replacement ECU completely resolved absolutely all surging).

You could also potentially look at the MAF, and also if you have any eratic or strange behaviour from your temp gauge, change your Coolant Temp Sensor as a faulty one of those can also cause similar symptoms.

I just looked at your thread Longyear, and I really don't hope I have these problems with the ECU. But it was very nice to know that it could also be a posibility! I think I will try changing the N75 valve first of all, and check the hoses in that area. I'm also tempted to look at the temp sensor, as I've noticed small oscillations in the instrument temp. Sometimes the coolant temperature drops just a little below 90 degrees. If none of these will help, I'll try monitor the MAF and get the car remapped at the best company in Denmark. I'm currently in a dialogue with them, and they claim that it's not the first time a mapped 1,8t has behaved like mine does :think:

Edited by Chanodc
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MattVrsmk1 Apprentice

MattVrsmk1

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Not sure if this will be correct but my 1.8t 2003 does the same thing under acceleration when the wheels lose grip the ESR kicks in and stops the engine for a 1/10th of a second or so. The ESR light flashes at the same time.???

I think mine was remapped by the previous owner so maybe the extra torque spins the wheels more.

So I guess it could be normal. Try a lighter right foot that might work. I'm no expert so I'm just guessing.

Matt

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Chanodc Apprentice

Chanodc

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Not sure if this will be correct but my 1.8t 2003 does the same thing under acceleration when the wheels lose grip the ESR kicks in and stops the engine for a 1/10th of a second or so. The ESR light flashes at the same time.???

I think mine was remapped by the previous owner so maybe the extra torque spins the wheels more.

So I guess it could be normal. Try a lighter right foot that might work. I'm no expert so I'm just guessing.

Matt

Matt, no wheel spinning here and no ESR light either. It's not only at full accelerating mine behaves weird, it's also if i'm just accelerating normally. So I don't think thats the reason

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Chanodc Apprentice

Chanodc

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Update: today, i've changed the N75 valve and the coolant temperature sensor. I've driven approximately 8 miles home from work, with some better accelerations! I must say that it helped with the N75 valve, but let's see if it was just 8 lucky miles, or what. Stand by guys - update soon to come :hi:

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