Erratic boost

Thomas · 31-05-2006, 00:44

Hi guys, something not quite right with the car. Octavia 1.8T, when driving I feel as if the power just suddenley disapears. The boost usually holds at 12 but now it goes to 14 then 8 then 14 then 8 and so on. It feels like some thing gets stuck and this seems to sap the power, then it sometimes frees up and the power comes straight back. Also I can usually drive at 30mph in 5 gear but now it judders when I do so. Any help will be welcome. Thanks.

cheezemonkhai · 31-05-2006, 11:48

NOt sure but the obvious thing to check are the hoses.

Manguish · 31-05-2006, 11:49

Is it remapped with a boost controller?

Thomas · 31-05-2006, 19:17

Yes it is remapped, no boost controller. Drove it this morning and it was fine, but problem arrose again this afternoon.

texasjohn · 31-05-2006, 20:35

Do you have the stock Bosch diverter valve fitted?

They have been known to fail on chipped cars, the plastic can't stand up to the increased forces.

This of course has NOTHING to do with the fact that I have a Forge-type metal diverter valve for sale in the 'for sale' section!!!

Thomas · 31-05-2006, 20:57

No, when I bought the car it was cracked so had another one fitted, not sure what one, but it is just plastic. If leaking boost is the problem would this also account for it being juddery at low speed?

Manguish · 31-05-2006, 21:39

Hmm.. Mine had the same problem, turned out it was a faulty boost controller. Basically a variable resistor. Replaced it and all was well.

texasjohn · 31-05-2006, 21:47

Quote:

Originally Posted by Thomas

No, when I bought the car it was cracked so had another one fitted, not sure what one, but it is just plastic. If leaking boost is the problem would this also account for it being juddery at low speed?

To be quite honest, I am not sure!

I think that when the DV breaks/cracks, the car has trouble holding boost at the same level (i.e. needle on boost gauge 'wobbles' at WOT)

Thomas · 31-05-2006, 22:11

Hmm.. Mine had the same problem, turned out it was a faulty boost controller. Basically a variable resistor. Replaced it and all was well.

Really, could be whats wrong with mine. No error codes thought, how could I check the boost controller?

Manguish · 01-06-2006, 08:50

I thought you said you didn't have one?

A small k no b you can twist to turn the boost up/down.

If you do find one, simply unplug it and the stuttering will go away if it's faulty. Mine was going open circuit.

Thomas · 01-06-2006, 14:58

Quote:

Originally Posted by Manguish

I thought you said you didn't have one?

A small k no b you can twist to turn the boost up/down.

If you do find one, simply unplug it and the stuttering will go away if it's faulty. Mine was going open circuit.

No I don't, I thought you were refering to some kind of inbuilt, oem boost controller that may have had a faulty resistor.

31-05-2006, 00:44	#1
Thomas Briskodian Join Date: Oct 2004 Location: Westlothian Scotland Posts: 98 Thanks: 0 Thanked 0 Times in 0 Posts	Erratic boost Hi guys, something not quite right with the car. Octavia 1.8T, when driving I feel as if the power just suddenley disapears. The boost usually holds at 12 but now it goes to 14 then 8 then 14 then 8 and so on. It feels like some thing gets stuck and this seems to sap the power, then it sometimes frees up and the power comes straight back. Also I can usually drive at 30mph in 5 gear but now it judders when I do so. Any help will be welcome. Thanks.

31-05-2006, 11:48	#2
cheezemonkhai Briskodian Join Date: Jan 2006 Posts: 13,769 Thanks: 77 Thanked 340 Times in 314 Posts	Re: Erratic boost NOt sure but the obvious thing to check are the hoses. __________________ Cars make CO2 and trees absorb CO2. By driving your car you're feeding a tree and helping the environment.

31-05-2006, 11:49	#3
Manguish Briskodian Join Date: Mar 2004 Location: Newcastle Posts: 925 Thanks: 0 Thanked 0 Times in 0 Posts	Re: Erratic boost Is it remapped with a boost controller? __________________

31-05-2006, 19:17	#4
Thomas Briskodian Join Date: Oct 2004 Location: Westlothian Scotland Posts: 98 Thanks: 0 Thanked 0 Times in 0 Posts	Re: Erratic boost Yes it is remapped, no boost controller. Drove it this morning and it was fine, but problem arrose again this afternoon.

31-05-2006, 20:35	#5
texasjohn Briskodian Join Date: Feb 2006 Location: West Midlands Posts: 1,678 Thanks: 3 Thanked 4 Times in 4 Posts	Re: Erratic boost Do you have the stock Bosch diverter valve fitted? They have been known to fail on chipped cars, the plastic can't stand up to the increased forces. This of course has NOTHING to do with the fact that I have a Forge-type metal diverter valve for sale in the 'for sale' section!!! __________________ Xbox 360 gamertag: TexasJohn74.

31-05-2006, 20:57	#6
Thomas Briskodian Join Date: Oct 2004 Location: Westlothian Scotland Posts: 98 Thanks: 0 Thanked 0 Times in 0 Posts	Re: Erratic boost No, when I bought the car it was cracked so had another one fitted, not sure what one, but it is just plastic. If leaking boost is the problem would this also account for it being juddery at low speed?

31-05-2006, 21:39	#7
Manguish Briskodian Join Date: Mar 2004 Location: Newcastle Posts: 925 Thanks: 0 Thanked 0 Times in 0 Posts	Re: Erratic boost Hmm.. Mine had the same problem, turned out it was a faulty boost controller. Basically a variable resistor. Replaced it and all was well. __________________

31-05-2006, 22:11	#9
Thomas Briskodian Join Date: Oct 2004 Location: Westlothian Scotland Posts: 98 Thanks: 0 Thanked 0 Times in 0 Posts	Re: Erratic boost Hmm.. Mine had the same problem, turned out it was a faulty boost controller. Basically a variable resistor. Replaced it and all was well. Really, could be whats wrong with mine. No error codes thought, how could I check the boost controller?

01-06-2006, 08:50	#10
Manguish Briskodian Join Date: Mar 2004 Location: Newcastle Posts: 925 Thanks: 0 Thanked 0 Times in 0 Posts	Re: Erratic boost I thought you said you didn't have one? A small k no b you can twist to turn the boost up/down. If you do find one, simply unplug it and the stuttering will go away if it's faulty. Mine was going open circuit. __________________

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