Turbo K Light On And Misfire Through The Inlet

[pip470 61]

Ok so I bought this car as it was local to me, When I drove it back it was clear it had no boost. Put it on a code reader and it said, "boost control circuit" I thought it was a bit vaugue but changed the boost control actuator. I then had boost but the k light and back fire were still present.

 

More about this back fire, If the car is sat at Idle, and you stab the throttle it will some times splutter and sometimes cough back into the inlet manifold,

 

Ive changed the plugs and leads and the fuel filter. I have also put another two ecus on as i thought maybe it just needed the fault code clearing before it could carry on as normal but the light came straight on.

 

 

So anyone got any suggestions on this?

 

Also is the fuel delivery controlled by the map sensor in the ecu?

 

What exactly is the heater element in the idle control circuit needed for (that may be a basic turbo principle but I cant find out anywhere) and will this put a light on if its not plugged in?

 

 

Any help much appreciated. Phill

[Henry Yorke 269 3 Cars]

Sounds like it is running rich. K light will come on if the lambda is picking up rich running and cannot adjust the injectors and fuel enough. Possible weepy injector?

 

Total guesses though

[pug_ham 244 3 Cars]

As above, check the lambda sensor but also TPS.

 

The throttle body heater element won't put the K light on imo, many people don't fit them anyway do they?

 

Not sure if the fuelling is controlled by the MAP sensor, TPS or both contribute towards the signal to the ecu.

 

Graham.

[pip470 61]

Thanks for the replys,

 

I would of thought if the lamba was reading rich then when the diagnostic was plugged in it would of indicated it with a fault code.

 

Ive now taken the engine out, One thing I thought could of been a possible is the actuator rod could of been stuck open. Two reasons really, one is the boost didn't seem a massive amount which I know the standard boost pressure isnt very much. The other is even with the pipe from the actuator removed, it still doesnt give everything, in fact I would say it boosts the same as it did with the pipe fitted. So that would point to a boost leak. With the engine removed ive gone around all the joints looking for any sign of leaking boost with splattered oil as evidance but all the pipes are really clean and the intercooler looks intact too. Its all a bit of a mystery.

 

There is so much to learn about standard ecu's. Well the bonus is its now going in the drag car so i just wont fit the k light. It has some boost but ive just got to work out why its limited.

[mang 3]

Thanks for the replys,

 

I would of thought if the lamba was reading rich then when the diagnostic was plugged in it would of indicated it with a fault code.

 

Ive now taken the engine out, One thing I thought could of been a possible is the actuator rod could of been stuck open. Two reasons really, one is the boost didn't seem a massive amount which I know the standard boost pressure isnt very much. The other is even with the pipe from the actuator removed, it still doesnt give everything, in fact I would say it boosts the same as it did with the pipe fitted. So that would point to a boost leak. With the engine removed ive gone around all the joints looking for any sign of leaking boost with splattered oil as evidance but all the pipes are really clean and the intercooler looks intact too. Its all a bit of a mystery.

 

There is so much to learn about standard ecu's. Well the bonus is its now going in the drag car so i just wont fit the k light. It has some boost but ive just got to work out why its limited.

two things with a little leak you would only loss about 2 psi of boost any more than that you would hear it the other thing is i think you can run these engines without a lambda sensor (xm,406) did the engine go up and down in revs when you first started it?

[pip470 61]

two things with a little leak you would only loss about 2 psi of boost any more than that you would hear it the other thing is i think you can run these engines without a lambda sensor (xm,406) did the engine go up and down in revs when you first started it?

 

 

The engine was still in a 406 when I started the thread. It has a lamba and is plugged in. The idle from start up was perfect, no hunting what so ever.

 

Definatly could not hear a boost leak in the car. If I had more time i would of fitted a boost gauge which would of helped things. However we drove the car with the computer plugged in the diagnostic port and we could see the map sensor reading around 160? at idle and then going up to 450? at full boost.

 

The thing I cant get out of my head is why did it not overboost when i disconected the pipe from the boost control actuator to the wastegate. It should of given everything it had but there was no change. Other than the waste gate being stuck open or a big leak I can not think of any other way it will not overboost.

[Cameron 16]

I always thought backfiring through the inlet meant very lean.

[Tom Fenton 1,542]

Turbo sh@gged?

[mang 3]

while its out check the fins on the turbo some of them might be up the creek if so the turbo would not make loads of boost henc not over boosting