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I was out for a play this afternoon and checking what boost the engine makes i found on the bar digital gauge is was reading 1.9bar holding and sometimes 2.0 for a short period in 5th and 6th gear. Is this right for a standard AAN.
Craig
Audi A6 AEL 5cyl Quattro breaking.
Audi A5 3.0tdi Quattro Stage 2
07947385043
Nah it should be more like 2.1-2.2 bar on the UrS4s guage - thats absolute pressure.
Subtract nominally 1bar from absolute to get boost pressure. The figure quoted above is for UrS4 in factory trim with standard software when its in overboost mode i.e in 4th or higher from 2000rpm then floor it - should see max boost around 4000rpm then it starts to tail off towards redline.
Max boost not in overboost mode is approx 0.8bar (1.8bar on the UrS4 digital guage)
Its perfectly normal to see 1.9 on the digital guage if ambient air pressure is low - but not *too* low as the altitude sensor tells the ECU to back off boost so as to prevent the turbo from overspinning in thin air in a desperate attempt to generate boost.
If you cannot get the AAN or ABY to generate ~1.2bar on factory software then there is a problem... Either the TPS isn't giving a proper WOT signal to the ECU, or there is a small boost leak, or the WGFV is incapable of being modulated rapidly enough to allow that amount of boost to be generated. Other less likely causes are a faulty altitude sensor, faulty MFTS (which is telling ECU that water is too hot and to prevent overboost mode), faulty MAF, faulty MAP (inside ECU) or faulty air or water temp sensors.
Hmmm, I've never seen mine go above 1.7 bar on the gauge. Despite just fitting a new WGFV, S3 DV and tightening a loose turbo hose clip that I found.
I'm betting that there's still a small boost leak methinks. I still can hear a slight hiss under spool-up of the turbo with the window open.
I guess it's time for the good old pressure test and if needs be maybe a set of Samco's :mischeif:
But, I did check the throttle travel recently, with the acc. pedal fully down the throttle at the housing can be turned a further 1/4" or so until it hits the stop. Is this normal or should it be right at the stop with the pedal down?
mine's the same pete i got a max of 1.9 bar once
but i can't get it t go above 1.7 bar now
i'm gonna do a boost leak test when i've got
time.but try and not blow my maf up
1. SHORT SHIFT KIT
2. PORSCHE CAYENNE CALIPERS
3. H & R SPRINGS
4. BILSTEIN SHOXS
5. NEW BUSHES AND HP2 STRUTS
6. UPRATED HIGH OUTPUT COIL PACK
7. ,3" turbo back s/s/ exhaust
8. fmic fitted
@PeteRR - yours is automatic and I honestly dont know if they run the same boost profile. If you can send your ECU over I'll certainly investigate FOC - and then we'll know better if that ECU can accept a homefried upgrade as I've never touched an S4/S6 with a slush box before.
Your throttle should go all the way to the stop at WOT - if it doesn't then the ECU doesn't think you are wide open !
Though not!, Cheers Paul.
I set about getting to the ECU to find the part numbers etc last weekend. Took the panels off to reveal the ECU and low and behold it's actually a Nothelle modified jobby.
Trying to find out the spec. now.
Though I feel the car doesn't go quite as well as it should (still drives lovely though). 90% sure it's a boost leak.....
Ahhhhhh OK - then I imagine 1.7bar is indeed rather low for what they intended. Good chance of a boost leak alright, but tighten your throttle cable 1st !
Will do Paul.
I actually set it like that as it was hanging high at idle occasionally due to the cable not allowing the throttle switch contacts to close.
I should of just set the switch! Just hoping there's enough adjustment in the TPS to set it, and the cable properly.
Before I chipped my s4 I was seeing 1.3 on the digital
gauge and 2.0 on overboost.
With my 280bhp chips the car hits 1.3 under normal acceleration and 1.7 wot but this is in 2nd right through to 6th and the boost does not back off. I fitted a new boost gauge last week (autometer phantom) which reads in psi, the most I've hit at wot is 10 psi which shows 1.7 bar on the digital display.
I had the wastegate adjustable screw freed up last week so I plan to screw it down a few turns and see if I can increase the psi a wee bit
100 Avant S4 :bow:
HP2 struts with S6 calipers
Stage 1 MTM Chips :chit:
Stromung Exhaust System :bow:
Bosch 005 Fuel Pump
Lowered 30/40mm H&R Springs
Turbosmart Kompact BOV
Autometer Phantom Boost/Volts guages
gauge and 2.0 on overboost.
With my 280bhp chips the car hits 1.3 under normal acceleration and 1.7 wot but this is in 2nd right through to 6th and the boost does not back off. I fitted a new boost gauge last week (autometer phantom) which reads in psi, the most I've hit at wot is 10 psi which shows 1.7 bar on the digital display.
I had the wastegate adjustable screw freed up last week so I plan to screw it down a few turns and see if I can increase the psi a wee bit
I think you'll find you have a problem! From what you've said your car is running worse performance with the chips than in standard trim! By those figures you're not even running standard boost! You may only be running mechanical boost which is determined by the wastegate spring alone. Is your wastegate frequency (wgfv) valve plugged in? Winding up the wg spring is not gonna help you one bit!! With so called 280bhp chips I would expect you to be seeing up to 2.4 on the digital guage! Whose chips are they??
'93 S4 Avant now back on the road complete with new shiny go faster bits.
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Just hoping there's enough adjustment in the TPS to set it, and the cable properly.
I think you'll find you have a problem! From what you've said your car is running worse performance with the chips than in standard trim! 
By those figures you're not even running standard boost! You may only be running mechanical boost which is determined by the wastegate spring alone. Is your wastegate frequency (wgfv) valve plugged in? Winding up the wg spring is not gonna help you one bit!! With so called 280bhp chips I would expect you to be seeing up to 2.4 on the digital guage! Whose chips are they??
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