What would keep triggering (pre-cat) O2 sensor fault codes?

steevie wonder

The silver bullet
Apr 20, 2007
60
0
Midlands
Hi,
I have a problem with my AGU 1.9t.... It keeps throwing up O2 sensor and misfire codes.....
I've changed the (PRE-CAT) O2 sensor and it still keeps happening! I've changed the MAF and crankshaft sensors too in case it was them...but no change at all!!
Have had leak test done and all turbo, breather pipes are fine....

Something is causing the mixture to keep changing causing the occasional misfire.

Any thoughts and ideas very much welcome!!!

Steve
 
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ibiza_95

1.8T MK2 Conversion
whether it helps or not mate i dont know, but my mk3 ibiza runs revo, and i was told by the previous owner that the second o2 sensor is pretty much redundant, but needs to be plugged in for the ecu to be happy... always has the second o2 fault code on the ecu though...

as i say might be useless info, just what ive been told
 

steevie wonder

The silver bullet
Apr 20, 2007
60
0
Midlands
Hi,
I have a problem with my AGU 1.9t.... It keeps throwing up O2 sensor and misfire codes.....
I've changed the (PRE-CAT) O2 sensor and it still keeps happening! I've changed the MAF and crankshaft sensors too in case it was them...but no change at all!!
Have had leak test done and all turbo, breather pipes are fine....

Something is causing the mixture to keep changing causing the occasional misfire.

Any thoughts and ideas very much welcome!!!

Steve

Development.....

I can now hear what sounds like the downpipe blowing......

I'm guessing the air being sucked in when on the overrun is sending the sensor wild!

Does this sound about right?

Engine feels a touch more laggy too, is this likely to be caused by the same problem?

Steve
 

caney

Full Member
Apr 24, 2005
600
0
Is the downpipe blowing all the time or just worse when cold? Just had my downpipe removed and repaired as one of the welds had split nearly all the way round! I didn't get any codes just blowing sound when cold.hope you get it sorted mate:)
 

steevie wonder

The silver bullet
Apr 20, 2007
60
0
Midlands
Is the downpipe blowing all the time or just worse when cold? Just had my downpipe removed and repaired as one of the welds had split nearly all the way round! I didn't get any codes just blowing sound when cold.hope you get it sorted mate:)

Yeah, it sounds (a lot) worse when cold.... But has certainly got worse over the last week! At this rate if it is the weld on the downpipe it'll fall off before the weekend!!....
It's causing havoc with the fueling! Popping and burbling like a ba$tard all the time!! Sounds great, but can't be good on the cat!

Steve
 

caney

Full Member
Apr 24, 2005
600
0
Yeah, it sounds (a lot) worse when cold.... But has certainly got worse over the last week! At this rate if it is the weld on the downpipe it'll fall off before the weekend!!....
It's causing havoc with the fueling! Popping and burbling like a ba$tard all the time!! Sounds great, but can't be good on the cat!

Steve
Are you attending inters? Got anyone local that can whip the dp off and fix it?
 

steevie wonder

The silver bullet
Apr 20, 2007
60
0
Midlands
Are you attending inters? Got anyone local that can whip the dp off and fix it?

Yeah I have access to a full workshop and can do it myself...just need to find the time!

Did you get your downpipe from Jabba?
I have a feeling mine is a Blueflame (supplied by Jabba), in which case any lifetime warrenty will not apply as they've since gone down the $h!tter.

Is your TT the one with the TVR wheels?

Steve
 
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caney

Full Member
Apr 24, 2005
600
0
Mine is a full jbs set up using an owens turbo,thats neils car with the tvr wheels which goes quite well so i' ve been told:)
 

steevie wonder

The silver bullet
Apr 20, 2007
60
0
Midlands
this is relatively common I am hearing :(


Where the crack has appeared suggests it is more of a stress fracture rather than a heat related issue.

Having spoken to Owens this morning they have suggested a brace needs to be fitted to support the underslung turbo..... Something thay have suggested to a lot of people already.

I'm just hoping this hasn't damaged anything else in the housing, i.e. the spindle etc.:(

Steve
 

ibizacupra

Jack-RIP my little Friend
Jul 25, 2001
31,333
19
glos.uk
having run IHI's for a few years, unsupported, including race use for a couple of years, none of them cracked from not being supported. sure they all warped as IHI's do... but I have seen an Owen setup fracture and almost fall off its 3 bolt flange face..

Can you adapt the std support brackets off k04's to suit?
 

steevie wonder

The silver bullet
Apr 20, 2007
60
0
Midlands
having run IHI's for a few years, unsupported, including race use for a couple of years, none of them cracked from not being supported. sure they all warped as IHI's do... but I have seen an Owen setup fracture and almost fall off its 3 bolt flange face..

Can you adapt the std support brackets off k04's to suit?

Hi Bill,

I don't know what the support bracket looks like for the ko4 turbo.....sorry.

Steve
 

caney

Full Member
Apr 24, 2005
600
0
What size housing you using mate? I have a virtually new .64 owens housing as a spare:)
 

caney

Full Member
Apr 24, 2005
600
0
having run IHI's for a few years, unsupported, including race use for a couple of years, none of them cracked from not being supported. sure they all warped as IHI's do... but I have seen an Owen setup fracture and almost fall off its 3 bolt flange face..

Can you adapt the std support brackets off k04's to suit?
Owens turbo way bigger/ heavier than the ihi's Bill which is the problem i think. Happened to wilko twice and a couple of tt's. Top mount is the only way to do it imo.
 
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