steady acceleration makes my car faster...!

kpm197

Active Member
Jan 29, 2012
118
0
Hi
I have a minor issue where under acceleration my car can be quite sluggish, like its lacking a turbo.
I noticed today that if I accelerate gradually and hold the revs at 3000rpm for a couple of seconds and then floor it, its very quick.
Would this behaviour lend itself to any theories?
Thanks

('05 FR 180bhp)
 

nathan_20vt

Active Member
Mar 30, 2013
365
0
Kings Lynn, Norfolk
Hi
I have a minor issue where under acceleration my car can be quite sluggish, like its lacking a turbo.
I noticed today that if I accelerate gradually and hold the revs at 3000rpm for a couple of seconds and then floor it, its very quick.
Would this behaviour lend itself to any theories?
Thanks

('05 FR 180bhp)

Hi mate I have this problem but does not seem to play up all the time can be fine for a day or two then will play up from time to time but can hear the turbo spinning up fine. I've read on here that the n249 bypass can help so I'm going to try that and see if anything comes of it. Hope that helps?
 
It's lag in the pipework / cooling system.

If you just floor the acellerator pedal, the turbo spools and it takes time to pressurise the pipework, intercooler etc. If you're sitting at 3000rpm the turbo will already be spooled and prividing "boost", when you floor it then, the system is already "full" as it were, so less lag.

I noticed this a lot when I fitted a large GReddy FMIC to my GlanzaV. Small displacement engine with a TMIC going to a large FMIC with extra pipework it suffered a bit more from lag, but if I kept it "on boost" it responded much better than c/w the TMIC.
 

kpm197

Active Member
Jan 29, 2012
118
0
hi, i should have said the whole rev range. if i accelerate hard from 1k to 6k its very slow, even in the 3k-6k range. if i hold it at 3k and then accelerate hard, its much quicker.

i can feel it sometimes around 1k. i'll just start to pull away and you can feel a slight jerk and it doesnt rev as free. it feels like the throttle is harder to press and its not breathing as easy.
 
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kpm197

Active Member
Jan 29, 2012
118
0
im going to check the turbo intake pipe isnt collapsing/split, make sure the diverter valve is working and then do the bypass, if only to get rid of other pipes that may otherwise be split.
 

W11TTX

Active Member
Apr 23, 2012
950
3
Cheshire
Mines the same with that as well, sometimes you get a good pull of boost low down setting it then it caps it and goes again like its hesitating. And same as you described feed the throttle in it goes like **** but just plant it to the floor and it seems to hold back through the rev range.
 
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W11TTX

Active Member
Apr 23, 2012
950
3
Cheshire
I'm thinking or well wondering if it either one of the other hoses is collapsing to the change pipe or throttle body as iv got a forge tip or if its a faulty actuator ?
 

leon cupra r

Back in an LCR!
Nov 10, 2009
902
0
Barnsley
Have you logged EGTs and IATs to see if these are playing a part? Full rev range wide open throttle runs will induce more heat than a 3k-6k run...

Also in agreement that it's probably just perceived differences due to boost.. Full rev range runs where acceleration is eased in as revs increase will stop you feeling it as much as the 'punch' from an engine at 3k revs ready to generate instant boost.
 

kpm197

Active Member
Jan 29, 2012
118
0
hi

i did the bypass and its more responsive. it didnt fix the problem though. what it did do is make the issue more pronounced when it happens. a split second after i start to pull away you feel it hesitate. almost like someone flips a switch. it drives smooth as butter, just slower.

i checked pipes as well and no apparent splits.

i noticed if i dont drive the car for a couple of days the problem goes away for one run until i switch the engine off. when it does run well, it runs well as long as the engine is running- i did 40 miles the other day in one go and the car felt great. its like something gets set when you start the car up and that is how its going to behave for the entire journey.

i dont have vag-com. i have the torque android app which i can log engine parameters. i've logged IAT, MAF, throttle position, engine load, boost, etc so i can see what the engine is doing at any given time but i can't see too much different between when its running great and when it isnt. think i read somewhere the leon 180 doesnt have an egt. could be wrong, but it didnt log anything for this sensor anyway.

i can log gps/kml map points as well so ill try logging these with the other sensors and make a mental note of when the car hesitates.

the biggest pointer i have at the moment though is the fact the car is much better when its not been driven for a couple of days.

thanks
 

nathan_20vt

Active Member
Mar 30, 2013
365
0
Kings Lynn, Norfolk
I've found an air leak from one of the pipes that run under the inlet manifold but don't think it would be related as that is the breather system, I could be wrong tho? Have you tried a smoke test or have you just visually check yours
 

kpm197

Active Member
Jan 29, 2012
118
0
hi, no i haven't done a smoke test yet.

however i did get an EPC light, traction control light and P0221 code. i checked connections on throttle body and pedal and looks ok, i also checked ecu plugs and no water or corrosion.
 

greck999

SLOW work in progress....
Jul 10, 2009
396
1
Rugeley, Staffs
Read somewhere that the N75 can cause boost hesitation and the feeling of on-off boost under acceleration.
I think tOm changed his and it felt so much better.
Mine does this. It's something I would look at.

Sent from my GT-I9300 using Tapatalk 2
 

kpm197

Active Member
Jan 29, 2012
118
0
i had a look at the n75 today.
i get resistance of 31ohms across the pins (on both cold and hot engine) which i gather is within the normal operating range.
but when i turn ignition on and check voltage at the connector i'm only getting 0.6v. i read it should be 12v. it could be that my multimeter is too slow, as i gather the 12v is pulsed to the n75. but then it could be a bad earth.
i'm going to trace the cable back to the ecu and see what i get there.
annoying as i had all the wipers and scuttle panel off at the weekend, got to do it all again now.

incidentally, i drove the car with the n75 disconnected and it didn't feel any different... no engine light.
 

leon cupra r

Back in an LCR!
Nov 10, 2009
902
0
Barnsley
You won't get an EML for disconnecting N75... well not immediately anyway.

It should feel noticeably slower with it disconnected as you will only run 5 psi boost
 

W11TTX

Active Member
Apr 23, 2012
950
3
Cheshire
Did you get to the bottom of this? Only bringing this thread because I disconnected my maff tonight it drove better and pulled harder on full throttle than steady acceleration?
 

kpm197

Active Member
Jan 29, 2012
118
0
i was going to update earlier today but forgot password. took it into a garage on friday and got a call an hour later saying they took it for a test drive and it was fine. said they had reset the throttle body. i went to pick it up and it absolutely flew like a crazy horse, its like a different car. monday now and its still running really well. there is something that doesnt feel quite right, like sometimes it feels more powerful then others, but its much faster all the time. the throttle feels really light and responsive too. i still get the occasional p0221 code (throttle/ pedal position) usually first thing in the morning, i just turn it off and start again and it goes away.

the mechanic remarked he thinks it needs a new throttle body, not sure if he saw something on vag-com, but for now the problem seems to have all but disappeared. its booked in for the 18th september at the moment and they will keep it for 3 days and take it home to see if they can see the problem. will update the thread when/ if it goes back in.
 
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