Occasional power loss and spluttering in 3rd/4th gear

[Son of Quatto]

Took her out today.On heavy acceleration the car is fine in low gears . Third gear and particulary fourth around 4500rpm(80-90mph) the car will occasionally splutter(bit of smoke) losing power then be fine again. Would a crack in the exhaust manifold cause this problem?

[snuffy]

Has it been out in a lot of rain ?

[daddysumo]

Son of Quatto said:

Took her out today.On heavy acceleration the car is fine in low gears . Third gear and particulary fourth around 4500rpm(80-90mph) the car will occasionally splutter(bit of smoke) losing power then be fine again. Would a crack in the exhaust manifold cause this problem?

When did you last replace/gap the plugs ?

[hollowpockets]

Fuel pump been upgraded?

[Mike Tuckwood]

Sounds like the spark is being blown out, could be a variety of reasons for that, have you noticed any increase in boost level on the gauge?

Mike.

[daddysumo]

Mike Tuckwood said:

Sounds like the spark is being blown out, could be a variety of reasons for that, have you noticed any increase in boost level on the gauge?

Mike.

Agreed , that why I asked about the plug gaps with all this nice cold air about, !!

[Son of Quatto]

I ordered some new plugs about two months ago from Chrisopher Neil. They were changed so as new. She hasn't been in the rain at all and garaged. I only do about 20 miles a week in her.

Edited by Son of Quatto on Saturday 20th February 21:51

Edited by Son of Quatto on Saturday 20th February 21:52

[Mick S]

What turbo boost pressure are you getting. Sometimes when mines been stood for a while during winter months it can over boost and then causes a sudden mis (as if the engine cuts out)due to hitting the ecu limits on boost pressure. Normally after about 30 miniutes of use it all settles down. If its just a slight mis I'd go with the plug theory.

[TuxMan]

Check the gapping on the plugs mate , should be 36thou , wonder if they have set them a bit big !!

[snuffy]

Son of Quatto said:

She hasn't been in the rain at all and garaged. I only do about 20 miles a week in her.

Ah, well water has been in problem with mine on a few occasions - but not in your case then. Oh well, worth a guess.

[daddysumo]

Mick S said:

What turbo boost pressure are you getting. Sometimes when mines been stood for a while during winter months it can over boost and then causes a sudden mis (as if the engine cuts out)due to hitting the ecu limits on boost pressure. Normally after about 30 miniutes of use it all settles down. If its just a slight mis I'd go with the plug theory.

What engine cut on boost pressure ?

[RobP]

If the cut-out/spluttering occurs only after the car is hot then you might have a problem with the low pressure fuel line (bit between tank and the pump) collapsing under full load. A few of us have had this and replacing the low pressure line with high pressure fuel pipe makes the problem disappear. As others have said check plugs first, but if the problem persists then consider the fuel line.

[Son of Quatto]

thanks for all the advice. Will get my plugs checked. Like someone said this weather does no favours for running a Noble weekly.

[Mick S]

daddysumo said:

Mick S said:

What turbo boost pressure are you getting. Sometimes when mines been stood for a while during winter months it can over boost and then causes a sudden mis (as if the engine cuts out)due to hitting the ecu limits on boost pressure. Normally after about 30 miniutes of use it all settles down. If its just a slight mis I'd go with the plug theory.

What engine cut on boost pressure ?

The ecu has limit settings for boost pressure, If the boost exceeds this then you can have a brief cut out. Thats why when most people fit after market boost controlers they end up having problems when they dial in more boost pressure than the ecu is set for. I have noticed on mine that when its been stood for a good few weeks it can occationally on full boost cut out for a fraction of a second which feels like a big mis. (Boost guage hits close to 1 bar, but I'm unsure how accurate the guages are). After a few miles everything settles dowm. I was told that the ecu adjusts to cope with different fuel grades and atmospheric pressures at various altitudes by a turbo tunning whizz kid. Now I'm no expert on turbo's and ecu's, but this was an comment made to me by someone who is.

[ThatPhilBrettGuy]

Mick S said:

I was told that the ecu adjusts to cope with different fuel grades and atmospheric pressures at various altitudes by a turbo tunning whizz kid. Now I'm no expert on turbo's and ecu's, but this was an comment made to me by someone who is.

Well he isn't.

The standard Noble ECU does not adjust for different fuel grades etc.

[sjc]

ThatPhilBrettGuy said:

Mick S said:

I was told that the ecu adjusts to cope with different fuel grades and atmospheric pressures at various altitudes by a turbo tunning whizz kid. Now I'm no expert on turbo's and ecu's, but this was an comment made to me by someone who is.

Well he isn't.

[roi354]

sjc said:

ThatPhilBrettGuy said:

Mick S said:

I was told that the ecu adjusts to cope with different fuel grades and atmospheric pressures at various altitudes by a turbo tunning whizz kid. Now I'm no expert on turbo's and ecu's, but this was an comment made to me by someone who is.

Well he isn't.

yeah that tickled me too

[YellowShed]

+1 tickled!!!

YellowShed

[Adrian W]

YellowShed said:

+1 tickled!!!

YellowShed

What do you know about Turbo's and ECU's and stuff

[TuxMan]

Adrian W said:

YellowShed said:

+1 tickled!!!

YellowShed

What do you know about Turbo's and ECU's and stuff