Low boost td5

[TD50WA]

Td5 d2, alisport intercooler, boost box, Bruce Davis ecu, standard size tyres, auto.

Car goes alright, seems to make plenty of go with no smoke.

Egt max 700ish.

VDO manual boost gauge peaks at 18-19psi
Nannocom instrument reading .91-.93
Nannocom testing shows max 185kp.

Waste gate wound up to only 5 threads left with no apparent effect on readings. WG moves freely when tested.

I thought the boost should be higher than this?

Suggestions?

Cheers all.

[strangy]

Depending on the boost box.
Both TD5 Alive boost boxes fitted to D2s in our family indicated less on the Nanocom, the more the boost was wound up.

You gauge will be a better guide.

[TD50WA]

Cheers, but is 18-19psi at the manifold low, considering I have all but wound up the WG?....I thought it should be around 22 odd?....maybe more?

Kev

[sierrafery]

Hi, when you say "Nannocom instrument reading .91-.93" is that "turbo presure"? cos this means the AAP reading is 92-94 to result 185 absolute pressure which is low(i mean the AAP)... and if the AAP reading is not good(sensor fubar'd) the ECU limits the boost to 1 bar...read ambient pressure on live data

[TD50WA]

My understanding of the nanocom, and I might be wrong here, is that on the instrument reading, the boost pressure is direct from the manifold?

Is that in bar, I guess, so .98 bar, but that's only 14.2 psi and my boost gauge is at 18-19psi...?

But according to previous post, with a boost box , the nanocom readings are suspect.....boost gauge is more reliable, so is 18-19psi at manifold low or ok?

Cheers
Kev

[TD50WA]

Hi, when you say "Nannocom instrument reading .91-.93" is that "turbo presure"? cos this means the AAP reading is 92-94 to result 185 absolute pressure which is low(i mean the AAP)... and if the AAP reading is not good(sensor fubar'd) the ECU limits the boost to 1 bar...read ambient pressure on live data

Which sensor is fubar'd?

[sierrafery]

My understanding of the nanocom, and I might be wrong here, is that on the instrument reading, the boost pressure is direct from the manifold?

Is that in bar, I guess, so .98 bar, but that's only 14.2 psi and my boost gauge is at 18-19psi...?

But according to previous post, with a boost box , the nanocom readings are suspect.....boost gauge is more reliable, so is 18-19psi at manifold low or ok?

Cheers
Kev

so... nanocom reads the MAP output through the ECU which is altered by the boost box, the problem is that nanocom converts the reading into "turbo pressure" by extracting the AAP reading from the MAP reading normally and above all this it converts it in bar too... the boost box should let the reading up to 240KPa absolute pressure which in reality is the AAP(ambient pressure) + boost (turbo) pressure in KPa

your reading is .98 bar and as the wastegate is shortened it must be more than that unless the fueling it's limited by the ECU and that's a default mode if the ECU "thinks" the AAP sensor is fubar'd...so if the ECU is on that default mode it will manage things as to keep the boost at 1 bar(.98 can be considered so cos it's not 100% accuracy there)

the real 19 psi reading of the gauge = 1.3 bar and this boost is normal for a non-tuned engine but what ever real boost would be there the ECU doesnt know that tdue to the boost box...(you'd get this boost on a standard Td5 without boost box and shortened wastegate rod)

to not complicate things and confuse you cos maybe i can't explain well here's the short story

read fault codes first to see if you dont have an ambient pressure related fault code...if no fault code read ambient pressure on that "testing" or fueling mode where you got that "Nannocom testing shows max 185kp." if you see what i mean

AAP sensor is that sensor in the airbox and according to your readings and the fact that the boost is so low with shortened wastegate rod is very suspect so you must rule out that AAP sensor

Input/Output
Connector C0158 pin 8 of the ECM supplies the AAP sensor with a 5 volt power supply. The pressure output from the
AAP sensor is measured at pin 10 of the ECM connector C0158, the temperature output from the AAP sensor is
measured at pin 31. The earth path is via pin 30 of ECM connector C0158.
The AAP sensor can fail the following ways or supply incorrect signal:
l Sensor open circuit.
l Short circuit to vehicle supply.
l Short circuit to vehicle earth.
l Contaminated sensor element !!!
l Damaged sensor element.
l Resistance in wiring harness.

In the event of an AAP sensor signal failure any of the following symptoms may be observed:
l Altitude compensation inoperative (engine will produce black smoke).
l Active boost control inoperative.
l Turbocharger boost pressure limited to 1 bar (14.5 lbf.in 2/psi ).
l EGR altitude compensation inoperative.
The MIL will not illuminate in an AAP sensor failure, and the ECM will use a fixed default value from its memory.

i hope you understood what i meant cos this situation is very like when your turbo pressure is limited to 1 Bar(.98) by the ECM so the fact that the wastegate is shortened doesnt help much as long as the fueling is reduced.

read "ambient pressure" and report back

[strangy]

Cheers, but is 18-19psi at the manifold low, considering I have all but wound up the WG?....I thought it should be around 22 odd?....maybe more? Kev

You should be able to get those numbers.
Condition/kms on the turbines of the turbo is a consideration.
How is the boost modulator?

[TD50WA]

Depending on the boost box.
Both TD5 Alive boost boxes fitted to D2s in our family indicated less on the Nanocom, the more the boost was wound up.

You gauge will be a better guide.

I'll try to adjust the WG up some more.

This is what mine is doing as it was reading .98, then I wound the WG up a bit and the reading went down to .92, the boost gauge went up slightly.

So can any of the readings on the nanocom be trusted due to the bbox?

The boost modulator indicates it's working - readings on nanocom increase as throttle increases?

I have removed the egr, the car has just under 200k on it, the exhaust manifold is possibly leaking a tiny bit as some sooting can be seen, my egt probe also leaks a bit around wire, not thread, so I guess these issues will also effect final boost attainable?

[sierrafery]

nanocom reads exactly what the ECM gets from MAP... the reading is altered by the boost box but the engine management is based on that input...
IMO from that point of view you can trust nanocom, it doesnt take readings from the sky...it shows you what the ECM gets and the fueling calculations/estimation of air mass in the cylinders is in relation with it if you see what i mean.... i just wanted to help you but if you insist to neglect the AAP thing your choice... the wastegate is a simple port where the extra boost goes to the exhaust if it opens so even if you clog it completely or weld it as long as the engine/turbo doesnt deliver enough boost due to the management you'll not get more boost at the inlet and tha't's what you see on that gauge... i'm trying hard to tell something in english but that's the best i can, just be convinced that i want to help