Impreza STI V5 rough running

[TomLeTiss]

Good evening,

I have recently purchased an Impreza STI V5 but it has some running issues. Hot or cold it appears to be running on number 1+3 cylinders on low rpm, if you rev through this then it seems to “clear” whilst the revs are high. It does splutter getting up there though. I have tried new plugs, new HT leads, new MAF and new coil. I have compression tested and all seems fine.

 

any ideas? 
 

cheers

Edited March 11, 2020 by TomLeTiss

[t5nyw]

does your engine symbol amber fault light go on when ignition is switch on, then go off once starts up?

did it do this from day you bought it?

have you fitted exhuast or induction to it?

has the car been remapped? not sure if that year can be!!

have you any fault ECU codes?

most common issues are air leaks

have you an atmosperic dump valve.

check all vacuum pipes for cracks/leaks

check all boost pipes for leaks & splits

swop 2 injectors

two other sensors can play up,

the temperature sensor for ECU, not the one for gauge. can run like choke fully on. okay ish when very cold but much worse when warm

and the exhaust sensor, runs closed loop with no throttle and correct burn from exhaust sensor.

when throttle put down open loop, burn controlled by Program Map.

 

Tony

Edited March 12, 2020 by t5nyw

[TomLeTiss]

does your engine symbol amber fault light go on when ignition is switch on, then go off once starts up? ——— Yes, engine light comes on then goes off as it should

did it do this from day you bought it? ———yes it has done

have you fitted exhuast or induction to it? ——— the car has an exhaust, front mount Intercooler, “induction kit”, silicone hoses

has the car been remapped? not sure if that year can be!! ——— from research it appears it CAN be remappped but I don’t believe it has been

have you any fault ECU codes? ——— had a MAF fault code, new GENUINE MAF fitted and code cleared

most common issues are air leaks

have you an atmosperic dump valve. ——— yes, due to front mount Intercooler

check all vacuum pipes for cracks/leaks

check all boost pipes for leaks & splits

swop 2 injectors

two other sensors can play up,

the temperature sensor for ECU, not the one for gauge. can run like choke fully on. okay ish when very cold but much worse when warm

and the exhaust sensor, runs closed loop with no throttle and correct burn from exhaust sensor.

when throttle put down open loop, burn controlled by Program Map.

[t5nyw]

13 minutes ago, TomLeTiss said:

did it do this from day you bought it? ———yes it has done

has the car been remapped? not sure if that year can be!! ——— from research it appears it CAN be remappped but I don’t believe it has been

most common issues are air leaks

have you an atmosperic dump valve. ——— yes, due to front mount Intercooler

swop 2 injectors

two other sensors can play up,

the temperature sensor for ECU, not the one for gauge. can run like choke fully on. okay ish when very cold but much worse when warm

and the exhaust sensor, runs closed loop with no throttle and correct burn from exhaust sensor.

when throttle put down open loop, burn controlled by Program Map.

okay, if no leaks found, and parts are good, looking for something not obvious. hard to tell which route to go without seeing car.

it does sound like decribe when anti lag or launch control engaged. trying to boost when stationary!! overfeulling!!

By the way,  when reving engine car stationary, you should not pull/see any boost, only vacuum.  If you do, thats the fault, turbo boost actuator fault , boost soleniod pipes wrong way or relay normily open and closed (vise versa) pull relay, see if runs smooth statically.

 i would try and prove boost actuator, as above near imposble to do stationary, unless you frig bost relay.

1) boost actuator, it maybe not working properly, put pipe on actuator suck very hard and see if moves okay, think towards the windscreen

a) Turbo actutor Not adjusted right, or sometimes original pipe have a restrictor, brass pin with small hole through and lost in pipe replacements.

b) leaks pipes on wrong way round.

C) closing two early or too late and incorrect fueling. Opening when stationary.

2) common dump valves

a) inspect, you could test blank off but thats VERY Dodgy, dont go over 4Krpm or kill engine.

3) ECU Temp sensor, running with choke on.

4) Fit first exhaut sensor

5)  2 injectors, dribbling but unlikey.

hope this helps.

Tony

ps we are enthusiasts trying to help, we are not mechanics and not aware of your capability