Jump to content
LegacyGT.com

Need help reading a datalog for possible OCV diag


Recommended Posts

My 05 LGT 5EAT is having problems with low end power and responsiveness. Everything I see says it's probably the OCVs. I did a datalog sitting in the garage. It's a long log. Could someone look at it and see if it is in fact a bad OCV? The car almost died towards the end of the log.

 

I think the most telling thing that it probably is an OCV is that the car runs great above about 2600 RPM. When I hit 2600 or so, it's like a switch is turned on and the car takes off. Below that, it's a dog right now, after the weather has gotten a little warmer.

 

Thanks for your help!

 

http://1drv.ms/1k7nBf1

The log is too big, so it's on a OneDrive share.

Link to comment
Share on other sites

Yeah looks like one of them may be bad. They should be in sync at all times, maybe a couple of degrees off sometimes. But one of them at one point is way off compared to the other one. So time to investigate the left one.

ocv.png.c7ff4128c6475473ce25750552485a9c.png

Link to comment
Share on other sites

Thanks for the help!

 

I replaced the driver's side OCV, and I think I have two issues going on here....the car runs a little bit better, but the rough idle / low end power still persists. I have been logging, and it appears that the two OCVs are now in sync, so that's better. The car ran great on the way to get gas immediately after the replacement. I turned it off, realized the gas station pump was broken, started it back up to move then the car almost died again. It seems to be worse if the car is warm, gets shut off, then I start it back up, but not always. I have very little power below about 2600 RPM, then it takes right off above there. When the car died the other night, I noticed one of the coolant lines leaking from the top of secondary tank behind the air cleaner box - a stainless screw type hose clamp fixed that issue.

 

Right now, I've got some mass airflow sensor cleaner coming, and am thinking about using that to also spray around and look for a vacuum leak under the hood. Other than that, I guess I'm at a loss.

 

I'll log again. Does anyone think I should log any additional sensors at all? Any other blatant ideas I'm missing? Thanks for everyone's help!

 

Also, FWIW, the "blue tee" looked good.

Link to comment
Share on other sites

I will definitely do an LV for this. I assume that's something RomRaider does? I'm fully stock right now.

 

I just had a chance to blow into the system, and can hear some air coming from the intercooler area on the turbo side. I can't tell if it's where the turbo and I/C meet, or if it's the intercooler itself. I pulled the intercooler to check the "blue tee", so maybe I need to replace the gasket where those two meet. I think it's probably the intercooler, because it seemed like the air was coming from where the plastic and metal meet. Also, there is some oil that is seeping from the area as well. It's not a ton of air...the system still holds some pressure after I stop blowing, but I definitely feel it. Is this normal, or is any air leak from an I/C bad?

 

Here's a pic of some of the oil residue on the intercooler:

 

redir?resid=AE0DBEBFCDE32DA3!65860&authkey=!AMm40lX20ZzL_5Y&v=3&ithint=photo%2c.jpg

 

or https://onedrive.live.com/redir?resid=AE0DBEBFCDE32DA3!65860&authkey=!AMm40lX20ZzL_5Y&v=3&ithint=photo%2c.jpg if you can't see it there.

Link to comment
Share on other sites

Ok, with the help of some soapy water, I can definitely see it's the intercooler. Bubbles formed all over where the black plastic meets the metal.

 

I'm afraid I ruined it by washing my car....did soap do this? ;-)

 

So, should I stop here and not try anything else until I get a new I/C? Is this pretty much a moot point to troubleshoot more?

Link to comment
Share on other sites

Hey OP, good job on doing your troubleshooting.

 

Your LV looks OK as your iam still shows a 1.0, and timing has not been pulled anywhere (0s everywhere in the table). Your AF trims should be between +/-5%. You can see the first one is borderline (idle state), which may indicate a vacuum leak. This probably supports what you've discovered with your IC.

 

It is OK to find a thin film of oil on that side of the IC, but not a puddle.

 

You can always (what we call over here) bulletproof your IC. It may be an easy fix. Here is the link.

 

Tell Barmanbean I sent you :).

Link to comment
Share on other sites

Thanks for the insight, xt2005bonbon. I don't have time right now to read all 33 pages, but do you think bulletproofing will help fix the leak? Should I try something easier like JBWeld (someone else said that on there), or should I just drop $300 on a new I/C? I'm not planning on keeping the car more than a year or so and it has 189k on it now.

 

I really appreciate all your help here!

Link to comment
Share on other sites

No worries. I am not sure which method is best really for your situation. You could always point BMB to this thread or PM him. He is VERY active on this forum so he'll reply to you in no time.

In my case, I've installed his kit on one of my cars and it is holding up pretty good. But then again, I did it before I saw any kind of air leaks.

 

Remember that there's always the member classified forum where you may be able to find used and in good condition stock IC at a good price.

Link to comment
Share on other sites

If you need a replacement intercooler and want one that is bulletproofed I have what you need in the garage. Can install a kit for you send the whole thing ready to bolt on.

 

So it's a used OEM TMIC that's bulletproofed? How much?

Link to comment
Share on other sites

Also, for a quick fix until you get a new I/C or the BMB kit, you can clamp the tabs back down onto the plastic and JB Weld the tabs. It's a bandaid for a while.
My wife's balls are delicious.
Link to comment
Share on other sites

I suspect my OCV are bad as well. Which parameters should I datalog with my AP to get a reading from them?

 

I'm no pro at this, but here's what I logged:

 

Time (msec) Accelerator Pedal Angle (%) Coolant Temperature (F) Engine Speed (rpm) Exhaust Gas Temperature (F) Intake Air Temperature (F) Intake OCV Current Left (mA) Intake OCV Current Right (mA) Intake VVT Advance Angle Right (degrees) Intake VVT Advance Angle Left (degrees) Intake OCV Duty Right (%) Intake OCV Duty Left (%) Manifold Absolute Pressure (psi) Mass Airflow (g/s) Vehicle Speed (mph) Roughness Monitor Cylinder #4 (misfire count) Roughness Monitor Cylinder #3 (misfire count) Roughness Monitor Cylinder #2 (misfire count) Roughness Monitor Cylinder #1 (misfire count) Requested Torque* (raw ecu value) Rear O2 Sensor (V)

 

The ones bolded are supposed to be within about 3 degrees or so of eachother. If you look at my previous post, you can see that mine were WAAAAY out - like 35 degrees apart at times. I think the new OCV has fixed that. Sorry for the terrible formatting - I at least wanted to get back quickly.

Link to comment
Share on other sites

Well, I've got some news. I was going to hop on the highway this afternoon, so I thought I would do another LV. As soon as I started the car (I didn't reset the ECU before I started it), it nearly died. The ratios on the LV are much different. Is this still consistent with a bad intercooler, or does it seem like there's something else going on too?

1325682556_LearningView_SS_4-9-201430153PM.jpg.4dc9afc351bccc4f03a531fdf75e3e24.jpg

LearningView_4-9-2014 3 01 49 PM.csv

Link to comment
Share on other sites

Well, now it looks like the first two AF trims are pegged at -15% (I believe it cannot go more than that). It's pulling fuel, so your engine is running really rich.

I am neither tuner no real mechanic. But I'd redo the quick vac test I told you earlier and see if it got worse. Somehow, you forgot to reconnect a vacuum line maybe :confused:.

 

Also, you should check the 'enable DTC reader' at the bottom of the LV. It will check for stored CEL codes or pending ones.

Link to comment
Share on other sites

Does anyone know if I can JB Weld the I/C while it's on the car? I'm thinking I'd like to seal it up for a couple of days so I can see if this is the last of my problems, or if I have more. I'm still deciding whether I will buy a "bulletproofed" TMIC for about $190 or so, or a new OEM from the dealer for about $315.

 

I haven't used JB Weld before. I'm a little worried some could creep in and go down to the turbo. The leak doesn't feel very big though. Has anyone done this?

 

Thanks!

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.



×
×
  • Create New...

Important Information

Terms of Use