Help Mk5 GTi Underpowered

N3_OLP · Post by **N3_OLP** » Tue Mar 04, 2008 11:22 pm

Hi, was wondering if any1 no's what is up with my car. I have a mk5 polo gti, standard they are spose to be 125bhp. Mine is standard (other than lowered) and its feels really slow. Not much pull on accleration and take ages to get to any sort of speed. I was going along with my friend in a bmw 316 coupe and other friend in a fiat punto 1.4 and i couldnt even pull away from them? Just wondering if any1 had any ideas on what it could be as there are no engine fault codes

Any help would be great

Cheers

Luke

Tim_GTi · Post by **Tim_GTi** » Tue Mar 04, 2008 11:24 pm

hhmmm so you've checked for diagnostic faults using vagcom?

When was the last time you cleaned the throttle body, tyre pressure, oil change and service?

N3_OLP · Post by **N3_OLP** » Tue Mar 04, 2008 11:27 pm

Tim_GTi wrote:hhmmm so you've checked for diagnostic faults using vagcom?

When was the last time you cleaned the throttle body, tyre pressure, oil change and service?

Yeh, i went to the garage today to have the cam shaft and craft shaft sensors replaced. So there are now no engine fault codes. I fought maybe the throttle body maybe come up. I dont really no much about cars, if there a thread or could you tell me how to clean it does i dont even no where it is located,lol.

Bepe · Post by **Bepe** » Tue Mar 04, 2008 11:35 pm

was it the camshaft position sensor that you had to get replaced? if do how much was the sensor?

N3_OLP · Post by **N3_OLP** » Tue Mar 04, 2008 11:37 pm

Bepe wrote:was it the camshaft position sensor that you had to get replaced? if do how much was the sensor?

On my reciept it just says camshaft sensor. It was Â£20.55 + VAT

Tim_GTi · Post by **Tim_GTi** » Tue Mar 04, 2008 11:43 pm

You remove the air panel filter on the top of the engine, which exposes the throttle body,. clean it out using a cloth then get someone to start up your engine and rev it so the butterfly shutter opens, spray a heavy amount of Carb Cleaner (from halfords) into it.

Pics of the throttle body before and after cleaning

N3_OLP · Post by **N3_OLP** » Tue Mar 04, 2008 11:48 pm

Thanks for your help. I will give this ago friday because i have the day off work. Do you think this will be effecting my preformance that much tho?

Tim_GTi · Post by **Tim_GTi** » Tue Mar 04, 2008 11:55 pm

It's worth doing to rule it out, but I wouldn't have thought it would effect performance that much. It does help though

N3_OLP · Post by **N3_OLP** » Tue Mar 04, 2008 11:58 pm

Tim_GTi wrote:It's worth doing to rule it out, but I wouldn't have thought it would effect performance that much. It does help though

Yeh i will give it a go anyways. Prob take it down TSR Preformance and stick it on the rolling road. I would bet that its putting out round 70-80. Really isnt preforming. Will put an update in as soon as its done. Thanks for your help.

Luke

Tim_GTi · Post by **Tim_GTi** » Wed Mar 05, 2008 12:01 am

Yeh let us know how you get on, will be interesting to find out the problem

andyg · Post by **andyg** » Wed Mar 05, 2008 12:08 am

I had the EXACT same problem with mine. Really gutless at lower revs, car didn't pick up any sort of pace untill it hit 4500rpm

Got most of the sensors replaced too. The solution for me (albiet a bit of a bodge) was to ground the VVT actuator, this means that the VVT is on constantly. Instead of from 3000rpm onwards. My GTi feels MUCH faster than before. I've beaten a few mini coopers and they have the same spec so I'm happy at that.

Let me know how you get on, I bet your VVT is not being activated though.

PS. I had mine on the rolling road at the time and it was putting out 100 bhp. Turns out the VW dealership who sold me the car had disabled the engine warning light bulb too.

N3_OLP · Post by **N3_OLP** » Wed Mar 05, 2008 12:19 am

andyg wrote:I had the EXACT same problem with mine. Really gutless at lower revs, car didn't pick up any sort of pace untill it hit 4500rpm

Got most of the sensors replaced too. The solution for me (albiet a bit of a bodge) was to ground the VVT actuator, this means that the VVT is on constantly. Instead of from 3000rpm onwards. My GTi feels MUCH faster than before. I've beaten a few mini coopers and they have the same spec so I'm happy at that.

Let me know how you get on, I bet your VVT is not being activated though.

PS. I had mine on the rolling road at the time and it was putting out 100 bhp. Turns out the VW dealership who sold me the car had disabled the engine warning light bulb too.

Yeh if its the VVT (not that i actually no what that is,lol) is it cheep enuf to get fixed? With it always open is there any side effects? petrol consumption etc?? What warning light is tht? would this come up with VVT errors?

andyg · Post by **andyg** » Wed Mar 05, 2008 12:35 am

VVT stands for Variable Valve Timming. There is an actuator that opens at solenoid when you get to around 3000 rpm (I think it might also be linked if you have your foot flat on the floor too). When the actuator is activated it lets oil pressure from the engine advance the cams. This creates an increase in performance at higher revs.

http://en.wikipedia.org/wiki/VVT Wikipedia article explains it in detail.

I took my car to 2 VW specialists (JBS and one in Manchester) they both couldn't find the route cause, all they did was repace sensors, reset the fault codes and shrug their shoulders.

I then took the car to a VW/Merc specialist: The VVT worked if they shorted the circuit, so it seems like the ECU wasn't turning it on. I asked them to turn it on manually and provide me with an overide switch (which they did). I now have a switch under the bonnet where I can turn the VVT off if need be.

As for fuel consumption: not noticed any difference, I get around 300 miles to a tank. Damage wise: its been this way for a year and it passed its MOT last week at a VW dealership. Not had any other problems (touch wood). One thing is that the car is jumpy at lower revs, when idle it will idle no problem, but setting off from 0 - 15mph can sometimes have hiccups. There could be more unburnt fuel going into the exhaust (and therefore fcuking the CAT) but I'd rather have a fast polo and a broken CAT than a slow polo that feels like a tank.

I reccomend you at least look into it. Or perhaps show the garage my replies.

My opinion is that the car is in "limp mode" where the ECU will switch off stuff like VVT. Not sure how to get it fixed "properly" But I can't afford any more repairs (it cost me Â£600 to get this far!!)

Make sure you keep me posted, I'd really like to know if you find a fix what it was.

N3_OLP · Post by **N3_OLP** » Wed Mar 05, 2008 12:50 am

O ryt, that helps explains thing brill, cheers. I will defo show them your reply's, got a funny feeling it could save me a hell of alot of cash. TSR is a specialist VW garage so if they no what it is them i defo let you no. If they dont no what it is and it is the VVT then i wil try and get them to do the same switch thing for me. Thanks for help, looks like my is going to spend some more money in the garage. Can feel my wallet getting lighter by the second.

nogwuy · Post by **nogwuy** » Wed Mar 05, 2008 7:06 am

may also be worth checking out the MAF (mass air flow meter) had very simular symptoms on my mk3 golf gti, turned out to be this.