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Who understands Cobb datalogs and can tell me what my car is doing?


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I got my car running again, upon the engines reinstallation, I replaced the old catted up-pipe with a Cobb Catless up-pipe.

 

Before I flashed the ECU to stage 1, I was getting a pending P0171 code. That means I'm running too lean, from what I understand, and that was that. High idle seems to take a while, but I have no idea if this has anything to do with it.

 

After flashing my stage 1 map, I ran a datalog and got 2 pending codes: the P0171 and a P0030.

 

Looking at my datalog, nothing looks amiss. My boost looks to taper down a bit early, but other than that everything looks okay.

 

How do I fix this problem?

 

Attached file is my accessport datalog, maybe you guys can tell me what exactly is going on.

 

 

Thanks!

 

 

Also, reading around I've read that completely removing the EGT sensor is a good idea to prevent the sensor's stick from breaking off and killing the turbo. Is there any truth to this?

Datalog1.thumb.png.77b535977af2edf3f7a797d3291a9c01.png

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So you replaced the UP with a cat-less. What did you do with the EGT probe that used to go in the stock UP?? That is the question. If you have a random EGT probe hanging around, not good. If you just unplugged it from the harness, not good. If you just clipped the wires, not good. But in the 3rd instance you can just do the 2.2K ohm resistor mod and be done with it.

 

But since you have an AP... you can tune it out via software rather than a resistor too.

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Ok, I'll stop at RadioShack and see if I can get one.

 

Would this have anything to Do with idling? Last night I went to start the car up. Once it started it kind of seemed like it was searching for idle.. The tach went up slowly from about 700 rpm up to roughly 1200 and slowly went back down to normal 750 rpm. I revved the engine a little and noticed that when I let off the throttle the car started to struggle to stay running and went down to 500 rpm.

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Got the resistors and put them in. No codes, but the car STILL stalls almost every time I come to a stop or have to put the clutch the whole way in and let the car drop to idle.

 

What the hell is going on with this stupid thing?

 

 

Just to further my own and everyone else's confusion, threw a P1153 again hard acceleration, but now it doesn't stall when I go down to idle. However, my gas mileage SUCKS.

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The idle is just the car relearning the idle. Takes a short bit of driving to settle in.

 

The code, maybe your sensor is bad. Would explain the gas mileage. Regarding your log:

1) Don't post screenshots of your logs please. Post the log itself in CSV format.

2) You're logging the wrong thing. Log the AF sensor. I want to see what it's reading. No need to do a pull for the log, but you can if you want.

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iNVAR: Okay, I'll look into replacing that wonderful $200 part. But regarding my log:

1) I tried, but couldn't post it in the csv format. The site's attachment program wouldn't let me.

2) Will do. I'm going away for the weekend so I won't be able to log it immediately, but as soon as I get back home I'll run a log on it and make sure it logs the AF sensor. I just went with what AP had on it from the factory. Should I be logging A/F Sensor 1 Current or Ratio?

 

Gex: How much cheaper is the Bosch unit?

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I'm actually not certain anymore.... I've never seen someone's AFR off that far before in boost, and you are reading 20+ in boost which is unheard of.

 

On the other hand, you are also reading -8 degrees of feedback knock too, which is exactly what would happen if you actually went that lean.

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It seems these datalogs are useless and confusing. I'll run a couple more not half @$$ed ones after work is done. These were 2nd gear pulls and I think one was on a hill. I should've taken the extra few minutes and went down the road to run a 3rd gear pull like Cobb says to.

 

 

That said, would cylinder roughness be a good way to narrow down what injector is bad? Could it even be a vacuum leak, or would that alter my boost pressure reading?

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Your front o2 is a narrow band. It really only reads accurately in closed loop ( ie, light throttle, idle, cruise. NOT in wot), which is the only time it gives feedback to the ecu. In open loop, the ecu pretty much guesses how much it needs to adj it's trims based on the learned trims in closed loop.

 

I'd get an external afr gauge like aem wideband to monitor open throttle.

 

It's best to do 3rd and 4th pull logs. 2nd is too quick to retrieve any useful information from the ecu. Run a boost leak post turbo and a vac leak test pre turbo to clarify a sealed system.

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Okay, I did a few cruise runs and an idle/cooldown run. I hope some of these help clear things up. I noticed in datalog #13 that the A/F ratio stayed locked up at 20.4 no matter how much I pressed or depressed the throttle, and it was under low load. I was watching my AP while cruising later and saw it do it again, and no matter how much more gas I gave it, or how less and anywhere in between it stayed locked at 20.4. I'm starting to think that my O2 sensor is bad?

datalog11.csv

datalog10.csv

datalog12.csv

datalog13.csv

datalog14.csv

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Would you like to donate the $100? I'm not only trying to figure out what's wrong with my car, I'm trying to learn how to diagnose some of this stuff. Furthermore I'm not going to toss $100 away based on a hunch. I don't appreciate you getting irritated at me for asking questions.
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