Vac Leak or Tune

[Davepurp]

Calling all Data Log Gurus

For the longest time I thought my care had issues with cold weather: rough stumble on idle, occasional stall idle, occasional Rev hang, but when the weather rose above 45 or all symptoms were gone. So I thought it would just be a slight tweat in the tune. Now that the temps have been up above 50 degrees for a while the symptoms are now almost consent and Im thinking it cant be tune must be vac leak somewhere that possible got worse.

Is there a way to read datalog for possible vaccum leak?

I know my Fuel Trims are a little all over the place during the idle when it is running rough, but during regular or WOT Trims level out where they should be from what I can tell.

I plan on going through all my lines to double check connections but didnt want to go crazy looking for a leak that may not exist

And boost levels on my vacuum gauge are now about 9 or so psi which is not much less than the 10 psi I saw last summer but still down ( I have changed the Mak pipe in, boss intake in, and recently a Red Race Valve so my Boost has fluctuated for a while now but always seems to be around 9-10 psi)

Thanks for the help as always

Idle With Stall

Rough Idle

Recent Highway Pull

Recent Highway Pull 2

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[markmurfie]

Bad MAF sensor

 

[ProChargerTECH]

Im sure Matt can dial you in if needed.

 

[Davepurp]

Bad MAF sensor

Seems easy enough to try

Might aswell try it when I pull the bumper to check for leaks

Thanks for the tip

Im sure Matt can dial you in if needed.

Matt has been a great help so far, but I hate to bother him with little stuff like this when I dont have to especially if its a physical issue.

What do you think about the MAF gone bad? Seems a bit early with only 6800 miles but symptoms make sense

 

[Dominant1]

i had the same issue i data logged it sent it in to my tuner. Got a revision and its gone, car is spot on every start up!

 

[wildcatgoal]

Check EVAP.

 

[bobc775]

I'm sure you don't have a vacuum leak but have a bad tune. It will cost you money but get a Lund tune.

 

[3beeps]

If you think the issue can be found in your logs, you should definitely send them to Matt. Who would be better at looking at logs? lol

 

[Davepurp]

I swapped out my Mass Air Flow Sensor over the weekend just to see what would happen and the Idle is now rock solid, took the car for a quick spin as well and there is a distinct difference in feel and power.

I took a a logs of both Idle and the Drive but couldnt get them loaded on my work computer so Ill pop them up later on tonight and share them with Matt see what he thinks


Thanks [MENTION=16352]markmurfie[/MENTION] for the suggestion!

 

[Davepurp]

I'm sure you don't have a vacuum leak but have a bad tune. It will cost you money but get a Lund tune.

No disrespect to Lund or PBD they both do great work, but when it comes to Coyotes and Prochargers I know [MENTION=20966]diablomatt[/MENTION] is the man to go to. Not only have I chosen many of my mods based off his own personal car and research but he has helped with tunes on my car since I had a cat back exhaust and Cold Air.

If you think the issue can be found in your logs, you should definitely send them to Matt. Who would be better at looking at logs? lol

Haha yes I would agree the tuner is probably the best go to when it comes to logs, but I had a strong feeling it wasnt tune related since it went from running great one day to running not so great the next without any changes to tune or fuel. So instead of bothering Matt again I thought id tap into the forums for other opinions

 

[superman07]

Mark, if you don't mind what was the data pattern in the log that suggested MAF?

 

[markmurfie]

intake air temp at -40.

6.7lb/min airflow at idle. 74lb/min air flow at 3500RPM.

After my post I realized this was probably logged with a diablo sport product and have been told the values can not be what they seem, so I very well could have been wrong.

 

[Davepurp]

New Logs with Replacement Mass Air

Part #1

Part #2

Part #3

 

[diablomatt]

New Logs with Replacement Mass Air

Part #1

Part #2

Part #3

hey dave. let me take a look at these in a bit :cheers:

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