What is a "REAL" boost leak test?

[Dinkpit]

btw, make sure to lube the inj. O-ring before reinstalling them... and check for cracks, breaks..etc.

[howslowcanyougo]

Any comments on this???

If there wasn't a big boost leak "somewhere" I probably shouldn't have a problem with DSMLINK reporting that I'm ok running at a ~18/1 A/F, but when I richen it up to where DSMLINK reports close to 11/1 the car bogs and back fires?

This leads me to believe that the Mas is measuring Air that never makes it to the motor, there by giving the symptom of running ok while that lean?

Does this make sense, or am I way off base?

I'm really trying to diagnose the weak power, strange loud noise and weird DSMLINK reading symtoms to get this car back on base?


TIA.....
__________________

[Alpine TSi]

What kind of MAS are you using?

[howslowcanyougo]

What kind of MAS are you using?

OEM 2G Mas, with the default 2G MAs setting on v2.5 of DSMLINK.

[Alpine TSi]

Ok, so if you were to have a boost leak, since your MAS is before your turbo and IC, you would be losing metered air. Therefore the ECU will add more fuel than is actually needed, which would create problems while under boost, bucking, backfiring, etc... I had a similar problem when my ECU was acting up last summer and I would go under 10:1 with any amount of boost than the car would hate me and buck real hard for a moment until all the unburnt gas got out of the cylinders. Now when you add fuel by richening the sliders on DSMLink, yes you would be adding even more fuel and not helping anything at all, and causing the symptoms you list. So yes, your thinking is correct in your situation. For those of us that have MAF-T's in blow through it doesn't matter because the air doesn't get metered until it going into the TB, so there would have to be a pretty big leak there to cause anything. Not that buying a GM MAS setup is the fix, as it only hides a problem, but just the other scenario, which obviously doesn't apply to you.

Get those leaks taken care of and go from there. Also, are you using a wideband O2? Or are you just going off of the claculation that DSMLink makes for you? If using DSMLink, do you have its individual settings set right? Then also you have to realize it is going off of data that also involves your MAS, which isn't telling the ECU the right info with all those boost leaks. Plus in the end the AF ratio function built into DSMLink is just an estimation, not something I would completely rely on. IE to get the backfiring and such you are now, you are probably going a lot lower than 11:1 like it said.

Hope this helps.

[howslowcanyougo]

Ok, so if you were to have a boost leak, since your MAS is before your turbo and IC, you would be losing metered air. Therefore the ECU will add more fuel than is actually needed, which would create problems while under boost, bucking, backfiring, etc... I had a similar problem when my ECU was acting up last summer and I would go under 10:1 with any amount of boost than the car would hate me and buck real hard for a moment until all the unburnt gas got out of the cylinders. Now when you add fuel by richening the sliders on DSMLink, yes you would be adding even more fuel and not helping anything at all, and causing the symptoms you list. So yes, your thinking is correct in your situation. For those of us that have MAF-T's in blow through it doesn't matter because the air doesn't get metered until it going into the TB, so there would have to be a pretty big leak there to cause anything. Not that buying a GM MAS setup is the fix, as it only hides a problem, but just the other scenario, which obviously doesn't apply to you.

Get those leaks taken care of and go from there. Also, are you using a wideband O2? Or are you just going off of the claculation that DSMLink makes for you? If using DSMLink, do you have its individual settings set right? Then also you have to realize it is going off of data that also involves your MAS, which isn't telling the ECU the right info with all those boost leaks. Plus in the end the AF ratio function built into DSMLink is just an estimation, not something I would completely rely on. IE to get the backfiring and such you are now, you are probably going a lot lower than 11:1 like it said.

Hope this helps.

Thanks much for verifying my thought and troubleshooting process on this issue.

I'm going to fix all the leaks, <have a new 63 mm TB ordered to take care of the TB Shaft and Biss leeks, and then I'll need to buy and install new injector insulators and seals> THEN I can take this AWD A/T car to RS Racing PREPARED for some Dyno/Wideband time.

[A//// Guy]

I wouldnt order a TB, if it is leaking it is very minor, like Ecoli mentioned. Most Boost controlers have a bleed hole that will leak out more than the TB will adn its not a big deal.

If you care that much just order the TB shaft seals and a new BISS screw.

[TheBlizzard]

Have you checked your intercooler for leaks? Just because its brand new doesn't mean that a a weld didn't break open.

[howslowcanyougo]

Have you checked your intercooler for leaks? Just because its brand new doesn't mean that a a weld didn't break open.

I haven't heard any from that area, buy also haven't sprayed it with soapy water yet either? I'll try that as well, Thx.....

[howslowcanyougo]

Is there a cheaper Wideband system that lets you use the wideband O2 sensor as the cars front O2 sensor, or do you have to put in another hole into your O2 housing?
Is there a system that can dump the wideband A/F data off to the DSMLINK as well? What's the best value in onboard Wideband systems right now?

TiA