09 Cobalt SS Aftermarket Turbo Low Boost Level Issue?

[tillman speed]

Have a 2009 Cobalt SS with aftermarket Dejon 5457 turbo and catless downpipe, as well as Dejon intercooler piping, greddy BOV and dejon intake.

Made a base file up with desired air load right below 300, keeping it fairly conservative with a stock timing table. Car just does not seem to be acting right. Boost on the gauge is around 18psi, this last pull the throttle was limited out of nowhere (overboost?? wtf??? I turned it off in the Engine Diagnostics???) and was from 16-22psi (mostly on the low side) and our dynojet boost sensor is jiving with that.... (about 18psi or so on every run). So we're putting down about 300RWHP and air fuels look great.

The actual log shows 255kPa, I'm just confused how we aren't seeing the right pressure?

We're taking our dynojet boost reading from the hose between the turbo and the wastegate selenoid.

Ideas, anyone?

Chris

[Iam Broke]

The ECU runs out of range at 255 kPa I'm afraid. That's a hare under 22.3 psi boost if I calculated it right.When I ran 28-30 lbs of boost I had to depend on the analog gauge on the A pillar for readings.

The wastegate solenoid is bleeding off some of the pressure at your tap IMHO. It controls the wastegate by pulsing the signal through the solenoid to the WG actuator. (dwell) The volume of the line may not be enough to pressurize your gauge and the WG solenoid circuit.

[BackyardTurbo_FTW]

You should change your boost reference for the gauge to the line from the compressor housing to the boost solenoid, this will be an accurate pressure reading.

Looking at your log, which was hard to find a cfg that read most of it, but anyway lol.. the MAP is maxed! If that really is the case, Ive found the overboost disable isnt enough to stop the car from limping. You need to disable 0106 codes and 0234.

I also noticed the LTFT and STFT's are 50% ?? And saw 1.00 Lambda while the MAP was maxed!

I hope these things are from not using your cfg file

[Gimpster]

Ya, thats an interesting log (what I can see of it) for sure. Post up your config if you would so we can see the whole picture

[shabby]

I really wish the config file would be built into the log, is it that hard to implement?

[tillman speed]

Here is the config file. It's one I got off of here a while back...

I turned off those two codes (there was 4 copies of the map sensor code and one of the overboost code). I was also wondering if this config file may be logging a little bit weird???

Let me post another run here shortly... I'll post a custom config file and log as well.

[BackyardTurbo_FTW]

Im viewing even LESS stuff with that cfg. I used the LNF Generic.cfg from the histo/cfg thread and viewed MOST of the stuff in your log.

Using your cfg tho, it looks like the TPS dips mid pull. Are you lifting or is this another case with the beta not working right for the TPS signal??

The trims look "better" with your cfg, still a LOT of STFT IMO during a WOT pull.

[tillman speed]

I didn't lift, so that's why I was confused. I'm gonna download the LNF Generic config and log with that from now on. I'll try throwing a little bit at the MAF frequency in the areas where it needs it. The Dejon intake must be throwing it off some.

[Iam Broke]

You could log it with the LNF SS.cfg file I posted at the top of this forum sticky. It has everything from soup to nuts in it based on many others posted.

[BackyardTurbo_FTW]

The LTFT doesnt look awful at 2%, just apply 1.02 to the whole freq table and thats set.

Then using the LNF Generic, log with the STFT Histogram, drive the car around a bunch then do a few diff WOT pulls. The chart will show you where to adjust the Maff Corr table and dial in the STFT's.


There has been 2-3 people now with the weird TPS and beta thing. I would email Support and tell them about your problem, other people had it corrected quickly!

Edit: I see you're in PA...and have a dynojet. Im looking to dyno again, I'll be in touch

[oldskool]

I'm just curious what everyone thinks of 300whp @ 18PSI on this turbo. I'm sure the OP's goals are much higher than that. It should max out around 400 whp right?

The stock IC is going to start backing up significantly above that power lever BTW.

[BackyardTurbo_FTW]

If you look at the log tho, the boost comes on and fades, then comes back again. The TPS signal goes up and down as well. The timing is VERY conservative IMO. I think he's just trying to get it up and boost right then make some good numbers. Please correct me if that's wrong!

[tillman speed]

Yeah, I'm trying to find out why it's not boosting up more or less.

I've done a bunch of pulls where throttle position stays to the floor but my gauge and dynojet sensor read low (like 18psi). However the PID on the log says 255kpa, so it's a little conflicting. I am going to take the advice on the boost readings and try and see if that corrects it. I will also log with the right config file.

After I get that squared away I am going to modify the stock timing tables. Shooting for 400RWHP, yes.

[tillman speed]

Man, I can't find this generic histogram anywhere. I see the sticky thread and there's a few of them for LNF in there.... LNF Boost 2.0, etc.

[BackyardTurbo_FTW]

I gotchu!

[Iam Broke]

I like this one since I added histograms for tuning LTFT's based on Term2's suggestion to sum the difference of LTFT's & STFT's.
Works well for tuning intakes.

[tillman speed]

Thanks fellas! Will make a pull on the dy-ner now!

[tillman speed]

Using the generic config, I just logged another run... car made 302RWHP but still seems to be hitting 18-20PSI and holds steady.

We took the Dynojet sensor and all out of the equation so it's just the factory boost gauge reading I'm relying off of. This does jive with the kpa reading from the datalog (a flat 235 or so).

Wonder why im only getting a commanded 19-20 psi with the max air load torque and desired air load tables im running asking for 26 psi roughly?

EDIT: Calculated load is 75%? Could it be running off the desired air load cells between 70-80%? Makes somewhat sense...

Calculated load should be pegged at 100% correct as soon as absolute load goes over 100%? Is this because the MAF is so far off?

BTW... thank you both a million times over for the config files. WHAT A DIFFERENCE! I can see what's going on!!

Chris

[wantedSS/TC]

How much for dyno pulls, I'm in Aston as well ..... Backyardturbo and myself are looking for a place ....

[BackyardTurbo_FTW]

Alright, we're looking better! LOL!


The DALs in the tune above are a bit low! I also like to make the 90 and 100 columns the same, just seemed to help! Try 300's up to 5500-6K, then over 300 up top. If you still cant break 255kpa, you may want to try the "pill" mod.

You can also run a lil leaner up top then what you have now, looking at your tune posted above, you are tapering to richer up top. Should pick up a few more HP holding a steady AFR then dial in the timing with that AFR stable!



Edit: I added a screenshot of the MAF Correction Histogram. Add these values to your maf corr table