hi all, problem with me mates fiesta rs turbo. his car wasn't boosting very strongly at all and when i fitted a gauge was barely making 5psi ( it's totally standard by the way ) so i fitted him a new actuator today and when i first drove it it was spot on but the boost was 0.8 bar and when we got onto the highway the overboost cut in when we were in 4th. let it cool down and then adjusted the actuator and it was pretty much spot on ( peaked at 0.6 psi and then held at 0.5 ) trouble is the ignition kept cutting when the car came on boost ( it felt like the overboost cutting in again but it happened straight away as soon as the car came on boost, on other rs turbo's i've only ever known the overboost cutting in when there was more load , i.e when planting your foot in fifth or running full throttle in third or fourth ) the car does run on the hot side and i would imagine a little hotter still now the turbo is doing as it should, which makes me think it could be heat related? i know you can get missfires etc with excessive heat but would it cut the ignition?

any pointers would be great people and solutions even better !!!

thanks for your time

 

are you sure your boost gauge is accurate, because my mates fezzy was only hitting 9 psi and the ecu cut in a very harsh limiter, ok now the ecu has been chipped.

 

its possible that you havnt connected the vacume houses back up properly.
this may cause the turbo to over spin.
the standard chip wont like any thing over 10psi.
it is also possible that the actuator is not the correct type for your car.
as a last bit of advice, you will only really get an accurate reading foot to the floor in 3rd or 4th, the car also has to be at normal operating tempreture.
if this still doesnt work then i would saggest checking the amal valve (little brown device with vacume hoeses going into it, i think its near the master cylinder on fiestas). if this is faulty it will cause your to become 'confused' (for want of a better word) under boost.
hope this helps mate

lee

 

cheers mate

vacuum hoses are all fine, actuator seems fine to be honest
amal valve is near airbox and haven't really checked

thanks

 

i would say your boost gauge maybe out mate, mine is 2 psi lower than the car boosts, u need a nomad or something as good to try and get a decent reading.

i had the problem when mine was standard, kept cutting out on boost, thought it was a misfire, changed everything, my boost gauge said 8 psi, i thought it was correct, turned out i was hitting the boost limit, as i used a nomad gauge and it was hitting nearly 11psi!!

 

thing is it's my mate's car so i'm just trying to help him out, he's got a TIM gauge and it does look a bit shit to be fair, but i have now set the actuator to below standard boost and it still does it?

does anyone know if a faulty amal valve would cause the overboost protection to cut in early or at the wrong time??

 

it would if the hoeses are on in the wrong order?
it may be that the ecu or amal valve are faulty, you wouldnt be able to tell.
a clever way of actually testing just the wastgate (actuator) is to use an air pump. connect it to the actuator vacume hose and start pumping air, you will be able to see the wastegate opening then you simply look at what pressure of air you are using. i used this method to set up a 2 stage boost control and found it really easy.
*you could just disconect the amal valve and temporeraly put a bleed valve in its place this way you can easyly adjust the boost whilst setting it up.
hope this helps

 

hi mate had a similar problem with my mates fiesta turbo, it would start and run fine but as soon as you tryed to hit boost it would try to cut out and generally jump about, had a good look at it and it turned out that the crank shaft position sensor wiring had corroded and when hitting boost would cause the engine to tilt backwards pulling the wires apart! soldered in a new bit of loom and a new multi plug and has been sweet ever since could be worth a look.

 

thanks peeps, i removed the amal valve and plumbed the pipe straight from the turbo housing to the actuator but it still had the problem , put his old weak and worn actuator back on and the problem has stopped but the car is slow as fook, guessing it could be the actuator we tried. were unsure as to whether it's a standard actuator or uprated. what would happen if you use an uprated one to run less than 10 psi?

will check his CPS thanks mate?