Looking to put a full H&S decat also an STI panel filter on my MY99 2000 Turbo, car totaly standard at the moment,.
By fitting a STI panel filter will this affect the air fuel ratio and cause the engine to run lean.
Does the reduction in back pressure cause turbo lag or should it spool up quicker
Any other helpfull advice would be greatly appreciated

 

The filter won't make a significant difference, BUT the full De-Cat WILL!! That alone may be enough to make the car run lean. You may think it will be safe, but is it really worth the risk!??

 

so i guess I would have to get the ECU remapped

 

I would like to see a substantle amount of supporting evidence of this.
I would guess that 90% of the people on here with a full decat are still running on a standard ECU Map.

For a start the MY92-96 is pretty much limited to ScoobyECU/SubaChip mapping
Hardly anyone maps the MY97-98
And 99> is all ECUTEK and I doubt the % mapped using ECUTEK matches the % running full decats.

 

As Scott says there is only a limited risk with that set up of running lean as it used the MAF sensor to know how much fuel to inject.. so the extra air sucked in and the speeder spool with the decat will again suck more air past the MAF sensor..

You would benefit from a remap and could get a lot more out of the car with a decent map in there though.

As pointed out to me in the past by Scott and having then witnessed it on my own car the worst thing seems to be an induction kit as it seems to screw the load the ECU sees (although I have no idea why?) and it then runs more timing than it should, hence why fitting an induction kit appears to give a huge power increase.. when infact it is just running a different section of the ecu's timing map when it is not safe to do so.

imho of course.

Simon

 

I ran my MY99 for 50k miles with a full decat and panel filter, without a re-map. First it was a 2.5" full Scoobysport then a 3" BPM. Didn't have any problems what so ever. And the current owner had it rolling roaded this year at 255bhp, 248ft/lb with 70k on the clock.

BUT I would advise caution, mostly beacuse I don't want you to damage your car. So considering the cost, I'd plan to get a re-map with the decat to keep your mind at rest.

Dave.

 

Panel filter & exhaust is fine - add huge boost & you might be getting to the edge of the map, though, which is when things could tricky (on top of running a turbo past the edge of its efficiency envelope - ie outputting more heat than air...)

Induction kits can screw up the airflow past the MAF, which means it misreads (air takes a different path to the intended one/ on for which is was calibrated for) & so underfuels. Key thing that's noticeable about this is that spool-up becomes 'hesitant' - time to switch back to a panel filter before things get too hot!

 

Sorry, didn't read the post properly! I thought the car was an STI in which case the car would be more sensitive to the changes, that said, if you speak to the 'experts' on here, they would advise you ran Optimax etc as the de-cat will lean the car out from standard.

 

Should run on Optimax or SUL anyway - the cars' aren't set up for less than 98 even as standard...

 

Cheers for the advice guys, anymore is much appreciated.
just got to make up my mind H&S or the new Scoobysport fulll decat
I know it has nothing to do with this thread but any recomendations

 

Just had a full H&S Decat now - DeCat D/P, Non resonated centre and 3.5" tail BackBox.

It sound awesome - it is quite loud but on full chat sounds unbelievable.....well recommended

This is running on a MY00 Classic

 

get a knock link. £150 for piece of mind. nine times out of ten just get the green light on, but get more activity every now and then with certain temp / humidity so i know to take it steady

turbo should come in about 500 rpm sooner

stevie

 

Nelson,
did you notice much difference with the H&S system
Does the turbo spool up quicker

 

hi mystiv5 has a decat run on oct with oct boost runs about 103 japs fuel is between102 -106 the increse is between 15-25 bhp buy some lagging and rap it around the turbo and down pipe this will keep the heat contianed and make the gasses burn faster less turbo lag about500rpmquicker fit alloyflywheel 600 quid no turbo lag

 

Any chance you could post that again in English washer? Have you given up punctuation for Lent or something?