Hi Guys, My mk3 GTi 16v seems like its holding back a little low down in the revs. If i'm just cruising in 3rd or 4th gear and put my foot down slightly the engine seems to judder a little. The car has only done short journeys before i bought it so am wondering if the throttle body needs cleaning out as it could be full of sh**e. I have replaced the FPR-Inlet vac pipe and the one on the PCV valve as these where perished and had small holes in them. The ECU vac pipe is really thin and breaking down where it comes out of the throttle body so this one could do with replacing too. What do you guys think? TIA
Oh OK . I'll probably have a look at the weekend as need to replace a split breather pipe aswell. Just wondered if anyone had anymore things to look at whilst i'm looking over it at weekend. Cheers Nick
do the vac hoses. it wants 3mm id stuff definately stick a bit of oil down the FPR too, mine was stuck and caused me lots of head scratching. whip a spark plug out, if theyre black and sooty you definately have problems. it should be cappachino colour
Thanks Matt. How do i oil the FPR? Where are all the vac hoses that need replacing? I've done 3 pieces already and then i ran out of vac hose.
syringe the oil in there. when mine was first on the rr it confirmed the massive dip in torque i felt between 2k-3krpm. basically the timing was being knocked back so that could only be a few issues. after a bit of head scratching that cured it. there are only 3 vac hoses, ecu, fpr and pcv. it can leak from the vac hose that goes to the airbox though. also, if the pcv diaphragm splits, thats a leak too. vac leaks are what typically cause the plugs to go black as it richens the mixture up
My breather pipe that comes out of the block and goes to the PCV has a massive split in it so i guess this would cause some issues aswell. Got another on order from VW but won't be in till tomorrow. Thanks for your help Matt truly appreciated
the breather hose shouldnt cause a performance issue but its obviously not good, its a cheap fix too. when youre replacing that, be careful of the coolant hose that goes to the head, the flange is only plastic and you tend to end up trying to shove it out the way if the flange breaks its far too much effort to replace
I think it may have been split for a while as everything surrounding the pipe like the alternator are covered in oily crud from the split pipe. Will be careful when replacing it now that i know about that mate .
Yeah vac pipes are the things to fix... especially the ECU one. mine was rotten through where it passes through from the engine bay to the ECU compartment as leaves had gotten in there and i had my own composting heap i used 4mm ID silicone vac hose with a 2.5mm wall as my OEM vac pipes were 4mm?. I have about 1.5 metres left over if your interested. Have you opened up /gutted your airbox? Thats makes a difference, especially in throttle response. I put the venturi trumpet back in the other day after i read that it helps pressurise the air heading into the inlet track... didn't work...took it out again later that day as it feels so restrictrive and i lost my instant throttle response.
lol. I thought so. Might be pyscological though... its noiser on acceleration without it. Its 40mm one end... and protrudes to close to the opposite side of the airbox for it to be any good for airflow in my opinion. My airbox its slighty different to yours though as i have a ram feed in the front grill creating pressure... and yours enters the back of the airbox through the hot air hole so it might suit the flow of air in yours.
http://www.bolhuijo.com/airflowtest/ I attached the AFM & airbox assembly to the rig and began taking readings. The first thing I tried was to remove that intake horn / velocity stack thingy inside the airbox that looks like it might restrict airflow. If you've removed yours, you should probably find it and stick it back in there. The flowbench shows a pressure difference of .1" for horn vs. no horn configuration. Air flow is measurably better in the stock configuration with the horn in place. you know it
That link doesn;t work... but i assume its not specific to the mk3 golf airbox. Maybe in some scenarios a suitible horn can improve pressure... but i have a 72 mm air intake so i think there is no sense going down to 40mm when the inlet opening is 60mm anyway, especially as the trumpet sticks out so much. Anyway... its not like we are debating huge (any) power increases
if im feeling geeky though, i might gtech the difference... see if you can represent it in a torque plot
Clean all the harness/ECU earths & sensor connections including the ECU connector- Normally makes a positive difference & smoother running. Clean the engine n harness too as that will give a 'guaranteed' 15BHP
a dyno proven 15bhp? AT THE WHEELS? WOW! (youre right though, getting the earths and wiring cleaned up helps as the ecu relies on values from various sensors etc)
