Engine 850: B5234T/2.3/20v/T5: engine back fireing hold back ,

[powernut]

Originally Posted by stuartsharp

You might be adjusting the wastegate rod the wrong way. Shortening it (making it looser) will cause overboosting because the rod doesn't have enough reach to open the flap. Adjusting it to make it longer will get the wastegate opening sooner.

ive turned it outwards so it simply sits on the peg, if i wind it in it boosts evern highter /

Just had another thought - if the ECU senses you are overboosting, it will cut fuel to protect the engine. Maybe this could be some of the reason for your misfiring symptoms? I know you have a remapped ECU, but there must still be a limit in there?

[powernut]

Originally Posted by PNuT

you probably need to speak to someone in the know about boost pressure.... maybe due to pulling half the weight you can get away with running 1.5 bar?????

i can get it to boost to 1.5bar no problem but after it its over 1.2ish starts back fireing and when i deaccelerate it back fires out of pipe which it only used to do when giveing it some hard up hill boot/

Originally Posted by powernut

ive turned it outwards so it simply sits on the peg, if i wind it in it boosts evern highter /

Assuming it's the same type of turbo as you had before, it seems that you must have a problem with the boost control solenoid or the wastegate actuator itself. I would bypass the boost control valve, and any manual valve you may have in there, leaving a direct connection from turbo pressure hose to wastegate

Your boost should then be very weak. If you can still get 1.5 bar there's gotta be a problem with your turbo!

[powernut]

Originally Posted by stuartsharp

Assuming it's the same type of turbo as you had before, it seems that you must have a problem with the boost control solenoid or the wastegate actuator itself. I would bypass the boost control valve, and any manual valve you may have in there, leaving a direct connection from turbo pressure hose to wastegate

Your boost should then be very weak. If you can still get 1.5 bar there's gotta be a problem with your turbo!

right if i discontect the bcs its runs crap so ill run the turbo pipe from the houseing to the wastegate and ill go see what happerns thanks matey big help

[powernut]

Originally Posted by powernut

right if i discontect the bcs its runs crap so ill run the turbo pipe from the houseing to the wastegate and ill go see what happerns thanks matey big help

right tryed that runs crap to be honst,now only time is holding back is on high boost it sputters and i can see the boost gauge needle pulling back ,if i keep the engine floored it steadly over comes it so it carnt be mutch surely/

What sort of pressures are you getting?

The point of the exercise was to prove that wastegate could do it's job without the control solenoid taking over. Without the solenoid, the wastegate should open very early and the boost pressure achieved should be very small i.e. performance should be poor.

If it's still overboosting and then holding back, something is wrong with the turbo.

[Chris_Rogers]

Or the actuator or wastegate.

What happens if you force the wastegate open?

[powernut]

right all i know is it only holds back at 1.2bar of boost if a disconect the bcs it runs crap hardly any boost so thats fine ,no codes,but i notice as the engine boosts up and hits approx 1.2/1.3bar evern thow the boosts there it dosnt seem over powerfull evern thow pressures there, i can see the boost needle in the dash flickeing forward and backwards ,if i keep the engine floored its trying to clear its self ,but wont hit the rev limiter ,i turned the actuator out another 2 turns and i can get low boost output but the engine dosent feel quick,(basicly theres boost and the engine pulls but it dosent have that clean powerfull lift if any of u volvo t5 poeple know,?

[bob13]

Hi powernut, If it is just on high boost i would look at the ignition, start with the plugs and work back. Had a simler prob once. New leads and plugs and all was fine. I think i have mentioned before about plugs, but if the boost is to high for the plugs they may be beening 'blown' out, try a smaller plug gap.