Cruze running a bit lean

[Xnitro67]

Been trying to figure this out for a while now and all I hear is fuel pump but no symptoms and trims 0 out under load or highway but that was before the tune. I watch long term and it sits about 10-15 at idle but there are no vacuum/boost leaks as I've tested that. I have however have found an exhaust leak at the turbo/cat. Also if I reset the mpg during highway I can see it's still good but idle or city drops to like 26 and used to get 31ish (pcvfixkit). I've also tested cylinder compression and that was fine. Fuel pressure is fine 43 idle which is in range but at rail I've found it at 40? Only reason the cat was removed was from a misfire from a bad coilpack but got p0420 2 months later on the aftermarket cat then trims started to go up and still is after I got a hold of a working oem cat. I did however got a p0171 lean during highway but fuel cleaner fixed that but not trims. Also to note trims tend to 0 out in park or neutral.

[Xnitro67]

current logs and tune file. the small one is just at idle

[sbarisic]

Overboost/underboost distabled, turbo overspeed limiting removed, wastegate DC increased to 99%, knock airmass set to 1 across the whole range, MAF diagnostics disabled and on top of it all, up to 6 degrees of timing removed while a ton of it was added in high load low RPM areas.

This is a horsepower delete map. Throw this in the trash and start from scratch.

[Xnitro67]

thats what zzp must be doing then. as i dont know on how to tune would like to start then i can do it myself. ill install the stock file but of course ill have to get the plugs back to .028 and to get another log file on stock. and no wonder the ltft tend to be worse now

[Xnitro67]

i got the stock file put back instill runs good just long term likes to jump everywhere but only evens out at neutral or park even during highway its nuts im surprised it hasnt popped a p0171. when iv watched these before they actually 0 out on cruising speeds. i uploaded 2 logs with stock tune. Anyone know how to turn off o2 or closed loop?

[sbarisic]

No need to turn off primary O2 or closed loop, that's a dangerous game when you don't have a wideband.

What is the difference in the internal diameter in the pipe where the MAF sensor is located compared to stock? I also recommend you get a MAF sensor cleaner spray and clean it, in case you put too much oil on the air filter. In the meantime, try this. I rescaled the MAF curve by +20%

Be careful on wide open throttle, i cannot tell from the tune file if power enrichment will engage or not. That should be one of the parameters in the log file.

Frayer_13_Cruze_A6_ZZPcai.hpt

[Xnitro67]

I installed the stock file back in. All I'm wanting to do if the exhaust leak is causing issue or not. Also I tried maf cleaner did nothing but unplugging the maf mad the car run better even fuel trims went 0. Currently I don't recommend wot as from what zzp says I have too much exhaust back pressure on wot causing floating valves but not sure if real but makes sense.

[Xnitro67]

Here's an update on something. I noticed on my scan tool reading fuel trims without purge is actually better. So waited till car was warmed up and unplugged the purge valve and put in drive and noticed the trims didn't go rising. Then plugged it back in and put it in in drive and what do you know they go up.

[sbarisic]

You don't see valve float below about 6000 RPM on these engines. Not even with a bigger turbo.

bar_150.jpg

This is a dyno with a K04-049 unit with the rev limit raised to 7000 RPM, 1.5 bar flat to the redline, everything else but the fuel system stock. It doesn't make any power above 180 hp at the crank, no matter how much air you shove into it.

For reference, this is at 1.3 bar

bar_130.jpg


Stock turbocharger simply does not make any power above 1.2-1.3 bar, and you most definitely can not hold it that way to the redline. 0.8-0.9 bar max. More than that and you cook air, losing power to knock retard and heated air.

[sbarisic]

Here's an update on something. I noticed on my scan tool reading fuel trims without purge is actually better. So waited till car was warmed up and unplugged the purge valve and put in drive and noticed the trims didn't go rising. Then plugged it back in and put it in in drive and what do you know they go up.

Hmmm, does the purge valve properly click when the car is idling and is plugged in?

Also, if the internal diameter of the original intake differs to the diameter of the cold air intake, you will need to scale the MAF anyway. Probably not by 20% tho.

[Xnitro67]

To about the maf and Cai thing I never had issues with it after installing when this issue been going on I tried installing stock air box in and didn't notice a change in the fuel trims.

I can feel the clicking and it's not loud also I have a p0171 about to throw at the check engine light. Uploaded a pdf of the freeze frame.

[TheMechanic]

Check the Turbo clamp. Manufacturers used to much glue on the gaskets and the bolt got glue on them. Need to remove the bolt, clean it and retorque. Here is what a bad one looks like
3271117.jpg
here is a proper torqued one.
3272387.jpg

One more thing. You say you tested for intake leaks. Did you use a smoke machine? Did that smoke machine go into a decent pressure. A good 10 psi will often result in leaks that didn't show with a normal old school style smoke machine but does with the new high pressure testers.

[Xnitro67]

I've torqued that down to spec 115 in lbs from workshop manual I don't have current pic but here's what it looked like while doing a leak test

[TheMechanic]

If that is shop air pressure than might not be to bad. If that is 10 to 20 psi or so. Well not so much.
Here is a test you can do that will help with exhaust dilution issues. Take a socket that will fit into the exhaust pipe with easy effort. Put the square drive side in first. Use a vise grip to hold the socket in. It increases the pressure inside the exhaust and instead of pulling fresh air in through the leaks it pushes exhaust out. You will see fuel trims come back into like or go slightly neg. If this is the result you need to work harder at the exhaust leaks. Use your smoke tester around suspect areas to see if the exhaust leak "blows" the smoke away.

[Xnitro67]

It's just a shop vac on blow. Not sure where you mean put a socket in with a vise grip into the pipe, unless you mean that bolt that tightens the vband clamp.

[sbarisic]

I think you're on the right track with the purge valve. Try what is suggested in this video.

[Xnitro67]

only thing is that the fixkit i have to remove some hoses but still same idea. its just odd that fuel trims only jump up in drive but ill get another purge and see what happens

[Xnitro67]

so heres whats weird before turning started the o2 waveforms looks just fine with normal trims so maybe the exhaust leak isnt there? uploaded that log but didnt have the right sensors being watched but still not sure what changed after this and look at that log and the earlier one the o2s are different. also starting to think this new o2 went bad already

[Xnitro67]

i got a log here but waveforms look fine but you can see while im in drive/idle trims go up but when i go into park it drops and evens out so it begs the question what is it?

[TheMechanic]

It's just a shop vac on blow. Not sure where you mean put a socket in with a vise grip into the pipe, unless you mean that bolt that tightens the vband clamp.

I am talking about putting a restriction in the exhaust at the tailpipe at the back of the vehicle. You can even use your foot. Works good at finding exhaust leaks.