My Leon Jerks when accelerate

tom450

Guest
HI everybody! Im from Argentina and its a pleassure to share a forum with you, i`ve been reading since i bought my Leon FR 2.0tfsi 2007. I know some english, so i will try the best to understand me.
The car is chipped witch 3`downpipe and CAI. The power is about 260bhp.

The problem
2 weeks ago my car started to do a jerking phenomenon during HIGH acceleration (sometimes little explosions too). This not always happens, only sometimes and mostly in middle RPM (mainly between 3000-5000 rpm).
If i accelerate slowly nothing happen, so this only happen when i pull hard the accelerator.
My mechanic changed the fuel filter, check cylinder pressure, turbo and everything seems fine. Also i put fuel from another company and always the high octane one.
I connected with VAGCOM and the engine hasnt any error! if this should be a ignition problem like plugs or coil packs.. Can the computer not generate fault codes, like mystfire o something else??

I can record with a camera what it do or maybe do a Graph with VAGCOM (with the variables you tell me), i dont know.. :wtf:

Any suggestion?
 

WeeG

Active Member
Nov 5, 2008
3,407
4
Largs , Ayrshire
HI everybody! Im from Argentina and its a pleassure to share a forum with you, i`ve been reading since i bought my Leon FR 2.0tfsi 2007. I know some english, so i will try the best to understand me.
The car is chipped witch 3`downpipe and CAI. The power is about 260bhp.

The problem
2 weeks ago my car started to do a jerking phenomenon during HIGH acceleration (sometimes little explosions too). This not always happens, only sometimes and mostly in middle RPM (mainly between 3000-5000 rpm).
If i accelerate slowly nothing happen, so this only happen when i pull hard the accelerator.
My mechanic changed the fuel filter, check cylinder pressure, turbo and everything seems fine. Also i put fuel from another company and always the high octane one.
I connected with VAGCOM and the engine hasnt any error! if this should be a ignition problem like plugs or coil packs.. Can the computer not generate fault codes, like mystfire o something else??

I can record with a camera what it do or maybe do a Graph with VAGCOM (with the variables you tell me), i dont know.. :wtf:

Any suggestion?

Log 015,016 for cylinder missfires on Vagcom and check if during the hesitations there are missfires on cylinder 1-4 if there is change the respective spark plugs and coil packs
 

tom450

Guest
WeeG, minutes ago i logged 015 and 016 channels but Vagcom didnt detected any missfire. I tried 4 times with same results, but i have the doubt if is ok this, Is normal that malfunction recognition is disabled?? Can some channels be disabled so thats the reason for no error detection???

Screen:
i.imgur.com/co1HSY6.jpg
 
Last edited by a moderator:

tom450

Guest
Hi, yesterday i disconnected the MAF sensor but Vagcom didnt detect any fault code after driving 20 minutes, this is normal?
 

manhota

Active Member
Apr 21, 2010
275
0
west mids wolves area
When ur foot is off the accl peddle its disabled when u accl it's enabled. Get some one to sit in the car and moniter it I had on wot 4 misfires on cylinder 3 turned out its the ignition coil starting to fail.
 

tom450

Guest
When ur foot is off the accl peddle its disabled when u accl it's enabled. Get some one to sit in the car and moniter it I had on wot 4 misfires on cylinder 3 turned out its the ignition coil starting to fail.

But if i log the missfire blocks i can see later if in any moment get enabled.. but this dont happen! even at full throttle.. whats the difference in someone monitoring and me alone logging?
 

manhota

Active Member
Apr 21, 2010
275
0
west mids wolves area
With someone else looking while you drive with YOUR EYES on the road you have greatly reduced your chances of crashing your car plus they will see when your misfires occur as they happen as in if your wot at what rpm it's happening at etc good luck
 

Rosskie

Active Member
Apr 20, 2013
162
0
disconnected MAF should have an error. If your not seeing misfires in the logs, then I doubt it misfiring.
 

tom450

Guest
disconnected MAF should have an error. If your not seeing misfires in the logs, then I doubt it misfiring.

Rosskie, Im not seeing misfires in the logs and disconnected MAF didnt generate any error :confused:... I only see fuel consumption increased

Misfire counter can become disabled when the revs are raised. Try it on idle.
I tried too, with same result!


Problem 2 (i think its unrelated to problem1)
Also, today i detected some strange noise like PSSS from intake/turbo when i accelerate smoothly until stops, like a opened valve with reduced boost from turbo, PCV? N75? DV?

I bought this car 1 month ago and i already getting tired..
 

BHP Addict

Back in a SEAT!!
Jan 31, 2006
886
0
Birmingham
May be pcv. At the cheapest option £35ish I'd change it anyway.

I have the psss noise under load. I assume its a very very small hole in a pipe as i have change pcv and dv and neither were the problem.

If your not seeing misfires or removed maf errors then i would check on some one elses software could be your system.
 

v0id

Active Member
Apr 21, 2009
209
1
Leeds
this may sound stupid but have you tried accelerating with traction control turned off?

i have the same problem where it suddenly stops accelerating and jerks back and then goes forward again. doesnt happen with it off - i find the traction control is extremely harsh on the leon. completely destroys all power.
 
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