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! Desperated situation Engine stutter on acceleration :(


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Today i was finishing  with testing parts , removing, cleaning, pressurizing the whole air system checking for leaks.

I cleaned the throttle body because it was oil dirt ,i cleaned ,checked almost every part, the n75 it seems to work good , the DV too , at least manually , the vacum/boost hoses are good no leak, what i didnt checked is the combi valve(EGR?) because i should remove the water inlet pipe !? , and the suction spray pump .,the secondary airpump.

The N112 , N249 was working if i  manually applyed the power , the one way valves(checkvalve) are functioning good .

I found that the car now is working better, i got no stutter at all, no hasitating , and after gearchange is more powerfull and the engine not fallback after shift .

So it worth something to fix things ... :) bytheway the car is still misses the horses in my opinion , its not pulling me into the seat in 2,3 gear  as it was long time before !!!!

Some strange thing it was , today when i start  first time the engine , as cold  it was shaking the IDLE , then just somthing (a valve maybe) was activated ,and the car Idle well  after

   Was shaking the idle abowe 800rpm right before coldstart, then when comes back to 800-850rpm the car sound was changing and no more shakes.

I know that the car uses no lambda when its cold , so ...somewhere could be searching the problem.

I was logging a small townrun on my android torque , i dont know sure, but a think i missed to put to log  some more things  ,anyway its seamed to me that the fuel is reach and the boost ...i dont know

I Can send you for someone the log file which is CSV and you can see proty well in excel  so , if someone of you  want to check my log  just tell me and i will send it  for compare/examine :)

Just as much for now ...

Edited by gjenck
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When its a cold start it uses the secondary air pump so that might be what's causing the rpm to be high. You should let the car idle for 90 seconds to let the pump do its thing before driving away or it will judder and jump, as it uses variable valve timing when the pump is running.

Has the work you've done today got rid of the 17705 code?

I'll PM you my email address on Monday if you want to send me any logs as CSV files.

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I have to check with my frend tommorow because my Elm327 wityh android never found the 17705 just my frend VAG box can read .

Anyway i will have to check it !

Yess i would like you to look at my logs i will do tomorow too, yes you can send your mail.

About missfire ...it was just once that error code so i really dont know if i should give importance or not ... anyway i have a relative at a skoda service annd i will ask for coilpack recall .

I also agreed that the car should run clear even at cold start at 1200 rpm too, mostly runs , i will check tomorow also.

Thanx for suggestions...

I;m curiouse that the stutter will come back just at once or not :D

Hope not...

Can be the Combivalve working bad and stucked open and let allthetime pass the exhaust gas to get back to air intake,could be tha case why the power is lower than should be .

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Could be the combi valve. Have you opened up the airbox anytime recently? I remember a thread a couple of years ago with a VRS that had a stuck open combi valve and the exhaust gasses had been going all the way through the secondary air pump (breaking it in the process) then up into the airbox where they had met cold air coming into the box and condensed forming a pool of water in the airbox! How the guys car hadn't sucked in all this water I'll never know!

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Yess i was examining and removing the filter too , no any evidence of condensed water ... but if i think back ,the sieve on the airbox lid , where's the MAF inside has really quite smell of exhaust ... maybe that could be normal . dont know...:)

Tommorow i check for 17705 with vag ,so i will know more then :).

Today also the car was working perfect ...i hope the stutter will never come back again :D

Yess finally i can test the combivalve if i remove the inlet pipe which comming from the combivalve to the airbox .? As removed the car should be like other cars without combivalve :D

Just to be sure ...the combi valve is similar to EGR or it is the same (exhaust gas recirc.) ?

Bye for today ..

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The combi valve opens so that the secondary air pump can pump fresh air from the airbox into the exhaust manifold during a cold start. A lot of people on here remove it and blank the hole off with a blanking plate from Forge when they remove the secondary air pump so maybe that's something you could consider on yours.

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If it is sorted I'm going to say it was the throttle body being dirty, don't try to over complicate things! I would just read the codes every few days for week or so to see if any come back. The 1.8 VAG unit is prone to oil dirt in the throttle body and a well know side effect being a stutter on acceleration and lumpy idle. I would clean it each time you service the car. My wife's fiat also suffers from this issue.

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The combi valve opens so that the secondary air pump can pump fresh air from the airbox into the exhaust manifold during a cold start. A lot of people on here remove it and blank the hole off with a blanking plate from Forge when they remove the secondary air pump so maybe that's something you could consider on yours.

Strange thing , maybe i'm wrong but as i know the combi valve is a kind of EGR (exhaust gas recirculation) so the exhaust gas going back trough sec air pump into the airbox filter ... another clue that i had the maf sensor hard smell of exhaustr gas ! ... and i tought that the car also reuses the exhaust gases at enginebreak thats how i can have 0.0 fuel consumption during .

Maybe i should remove the sec air pump pipe which going into the airbox , and i will see what he doing :)

Another thing is that yesterday i was clearing the error codes , as i found the same 17705 and another N75 open circuit , i think somehow this error came up when i was repairing , disconnecting ...i hope !! I didnt remember if i was igniting when it was removed things like n75 ... so the car going well in my opinion and i will check for error codes after 2-3 days later .

So anybody who can compare/examine my android torque Log are welcome and i can send it just give me your mail.

It is nicely showing in excel this .csv file maybe i can compare also with someone to be sure about fuel consumption , and boost.etc.

If i examined right my boost now is around 1 bar , the fuel trim is ....i take a look and will come back with results...

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It's not an EGR, that's on diesels.

It works the opposite way to what you thought, it puts fresh air into the exhaust at a cold start, and the variable valve timing makes the exhaust valves open longer so you get post-combustion in the exhaust header and it warms up the exhaust system and cat quicker.

I've PM'd my email address if you want to send me CSV files. It sounds like the car is working ok at the moment now though?

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It's not an EGR, that's on diesels.

It works the opposite way to what you thought, it puts fresh air into the exhaust at a cold start, and the variable valve timing makes the exhaust valves open longer so you get post-combustion in the exhaust header and it warms up the exhaust system and cat quicker.

I've PM'd my email address if you want to send me CSV files. It sounds like the car is working ok at the moment now though?

Yes . i think you have right , because if i cold start the engine and turn off the engine , i hear after a strange noise like maybe the sec. air pump stopping (3-4 sec) so .

Strange thing remain why the maf housing sieve is smell like exhaust gas ?

I'm not exactly understood what the fresh air makes in the exhaust ? feeding another combustion in the exhaust with gases which wasn't combusted ?

Word after words ...the car it works well now , without stutter , hesitation at all , pulls quite good , maybe missing horses i dont know , maybe eats still much , ... but today i readed the error codes and i found 1 error still, the 17705 pressure drop between turbo and throtle valve (check D.V. !) P1297-35-00-

:D

So the leak error is still there which i had all the time :) :( .

After all that searching for leak , i think i dont have any phisical leak as i pressur tested the system. I only found a very very small leak maybe at the turbo itself but anyway i think i have boost enough how i saw in torque app.(the boost build only after the turbo soo ..)

Maybe sometimes not working or the dv or N75 ... still mistery :o

(I have to check the suction spray pump, again check the PCV valve as it was a bit leaking , and measuring the wiring to , n249,n112,n75 , so i still have choices :)

I reinstalled the torque program and i will send you tommorow the logs , as i wanted to make new logs. Last 3 days the program made strange logfiles , missing boost pressure , nonsense datas on some pids , maybe because i put a lot of sensor pids to log .

I check and i can send you from my older ones ...

Thanx for now...

Edited by gjenck
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Someone can tell me why my idle stutter mostly at cold start , when the revs fallin back to 750-800 ,i hear (i think) the SAI turning off and the idle starts to work perfect !

I still on getting a log in torque app about boost , hp ... anyone suggest in which gear/revs should i make the log ???

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if you want to log the boost (requested and actual) 3rd gear will suffice (2k revs -> red line)

if you want to log the maf values and use them to approximate your hp and torque go for 4th gear (2k revs to red line)

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  • 5 years later...

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