this is really bugging me now, engine is running perfect but holds back on boost badly, even on 0.3 bar! as soon as turbo should be coming in it just holds back and makes a constant misfire kind of noise, defo not detting or lean, what could cause a problem under load(on boost) ? have replaced inlet, ecu, fuel ecu, metering unit, fuel pump, coil, leads plugs, cap and arm and amal valve. any help would be great

 

Do you have bailey dump valve? As my old one would wedges it's self open and I'd have no boost. Any small airleaks? Exh gasket ok? Is the turbo it's self ok?

 

Knock sensor fucked?

 

yeh i was thinking that have ya had the engine out at all and knocked the crank sensor, i ahd a calibra do that

 

It's MFI there is no crank sensor lol

 

check for air leaks?

 

oh....gd boy, i know that lol

 

i have this problem too lol, was fine then just started doing it after i changed my rad randomly enough

 

yep i have exactly the same problem too...really bugging me now it just randomly started happening

 

poss air leak or the green wires to the coil is a classic, would especially be looking at the green wires if car had a rad change!

 

mines a xr2 conversion, so green wires are on the bulkhead, i'll have a look at them, where do they go to? one goes to rev counter i know that and thats working fine, isnt it just a earth? also i havent got a plug for the yellow sensor on the bottom of the inlet, what does this control? where do air leaks normally occur from as i checked boost pipes and little hoses on top of inlet

 

Is it definitely just on load? Can you make it 'misfire' when revving it on the spot? If you can then it could be valve bounce. In which case you want new valve springs. Seen this before on an RST engine and it seemed like it was only doing it under load but giving it a good rev in neutral produced the same 'miss'. Valve springs changed and it was sorted

 

sometimes does it when reving on the spot but only when you jus come back from running it, but my engine has only done 600 miles since full build so shouldnt be the valve springs surely, jus seems to me that its massivly rich on idle but no fuel on boost

 

main air leaks are the vacumes from the ecu to the inlet, you shouldnt get valve bounce if its just bin built, but yours might be the case the the valves aint bin seated? have ya still got an amal valve on it

 

Sounds like fuelling in that case, check your throttle position sensor is set up and working properly. Should click as soon as throttle opens. Also there's the fuel pressure sensor on the metering unit that can go faulty and won't enrich the mixture. Sounds like it needs a good setup tbh

 

Mind used to do that as well. I was told it was the coil side of things?
Got a group A one fitted and havn't had the problem since. Not 100% if thats the fix though, may have just been coincidence.

 

ive been told it could be my fuel pump running enough pressure to run the car on idle but not under load, my fuel pump is very noisey so would make sense

 

had experience with the boost sort of "blowing the spark out". New coil and higher temp range plugs it was sorted for good. Why not try the higher heat range plugs first because it does sound like detonation unfortunately.

 

yeh cossies do that a lot, and turbo's running high boost, dunno about .3 bar though, but grpa coil and a set of new plugs sounds like a gd idea, what boost pipes have ya got as i had one on mine and it was worn and use to suck itself closed and restrict boost

 

well, checked the pressure from the pump and all ok, though it is noisey, so checked the pressure under load and it was way out, 2 turns of the pressure reg on the metering head and that sorted it perfectly, i put ford 071C plugs in to just to make sure the spark wasnt being blown out the other day, goes very well now and my coldstart might even start working properlly now,

 

funilly enough, it was my fuel pump lol, it died bout 20 mins ago, o the joy of rs turbos thn have to expect it, there old

 

could be worse i spend over 500quid on bits cos my turbo wasnt fueling to find out the cut off switch was broke lol

 

^ haha same as me spending over £400 on new parts and testing components and it turnt out to be a squashed vacuum hose to the ecu.

Its always the simplist little things, but you never think to check them!

 

yeh like my m8 years ago put a set of really nice oz's on his turbo cab looked the bollocks till he took it down the road and both back wheels were really wobbling so he took em off and gave em away a week later we found out that the screw for the rear drum was sticking out :-(

 

well it werent the fuel pump, fook sake, but it isnt runnin lean on boost its over fuelin and runnin on 1 cylinder after 5 mins driving, doesnt matter how fast or slow you drive it, then if you leave it 5 mins it'll start and run sweet idle perfect but then again when you set off after few miles she does it all over again. Get huge flames from the exhaust and it constantly pops and bangs

 

Got exactly the same problem... do you still know the solution for yours?
cheers