Laggy SOB

6speedsd · Apr 1, 2014

Just as the title states.... The truck has gotten laggy as hell lately. Most noticeably the past couple days. Start off from a stop, and boost builds slow. Mash on it and it'll come on up. Say I go 50% pedal, it'll jump up to about 20psi, then as the rpms are still climbing before a shift, you can watch it start to drop slowly. Cruising around about 45mph, in OD with TQ locked and start up a decent hill, it'll climb to maybe 10psi. That much of a load on it shouldn't it build more than 10? a few mths back I had about 8k on the trailer, cruise set on 70, hit a long hill and when it kicked in to maintain speed, psi jumped up to 23-24, then dropped back to maybe 15. Also noticed on the same trip on level ground the turbo would randomly spool to 20ish, then drop back to normal with no change in throttle or load. Had the stock file loaded when that happened. Everyday driving with Eric's AggStreet, 70 mph on level ground I'm seeing 3-5psi. But like I said, starting off from a stop, it comes up slow. Truck is an 05 if it matters.

Bad thing is that I won't get a chance to fool with it before the weekend. Part of me thinks the turbo is sticking and needs a good cleaning, but that random surge in psi makes me think otherwise. I'd like to explore all options before I take the time to pull the turbo. Other than cleaning the EBP sensor and tube, what else could I check?

What are normal MAP readings? Or would that not even be causing an issue?
Is there a way to test the VGT solenoid?
What else am I forgetting? Been a long day and the brain isn't functioning correctly at the moment.

On a somewhat side note....
Will a laggy/slow to build boost truck throw off the shifting much? Mainly timing and cause harsh shifts?

jdeeg4276 · Apr 1, 2014

Before you get antzy and tear shuffff up. Get a computer on it. Watch your engine and peramators.

Call me if you need help. What your defining sounds like a ipr.

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6speedsd · Apr 1, 2014

Why IPR? Seems to me that would cause other drivability issues. Other than being laggy, this thing starts and run perfect. But I will watch everything this weekend.

Are 05 turbos really as crappy as I've heard in the past? I've never gotten this thing to build over about 24psi, no matter how hard I've driven it. They few times I've gotten it that high, it wouldn't hold it.

Harley Strokin' · Apr 1, 2014

If you have a way to monitor vgt % see if it varies up and down w/ no throttle change, had a truck doing the same thing and it ended up being a bad vgt solenoid.

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6speedsd · Apr 1, 2014

Pretty sure I can monitor that with AE. I'll check it out and see.

Gary · Apr 2, 2014

Does it have any codes? Then I think the first thing I would look at is EBP and MAP. Check the EBP, KOEO and KOER, and see what your PID's are. Check the EBP tube. Then if that's good I'd look at the turbo, I've had them that you could work back and forth with the scanner but they were still sticking, so if everything else looks good and I still have a problem then I pull the turbo and clean it up.
And yes if it's running badly it will effect the way the trans shifts. So first fix the running problem and the trans issue should go away.

6speedsd · Apr 2, 2014

No codes at all. First thing I checked.

What are specs for EBP KOEO and KOER? I know EBP and MAP should both read pressure KOEO, but what are specs on both?

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6speedsd · Apr 2, 2014

Read something that stated MAP, BARO and EBP should all read 14.7ish psi KOEO. Does EBP read atmospheric pressure without the truck running like the other two?

ghohouston · Apr 3, 2014

6speedsd · Apr 3, 2014

I'm off work today because of rain, so when I get the kiddos down for naps I'll run outside and see what the numbers show with KOEO if nothing else. Maybe I'll get lucky and one of the sensors will be off or something. I don't have a problem pulling the turbo to clean, but I'd rather eliminate everything else before I take that route.

No opinions on the effectiveness of the 05 turbos? Like I said, I've heard they don't like building much boost.

6speedsd · Apr 3, 2014

Ok, got some numbers. Ya'll tell me if something looks off.

KOEO...
Baro 14.46
MAP 14.46
EBP 14.8

Curious why EBP reads higher, but it's less than the .5psi spec.

MAP voltage 1.29

KOER...
Baro 14.46
MAP 14.68
EBP 18.7

VGT duty cycle....

When I first started the truck (cold engine), it was at like 82ish%, but as I let it idle, it started dropping. After maybe 10 mins of idling, it was down to 67.2%. Didn't really fluctuate much...up or down maybe 1-2%

ICP and IPR are just about perfect at startup and idle.

Something I did notice, CMP/CKP sync kept changing from yes to no. Not sure why they don't want to sync up.

Fuel PW was at like 1100uSec at idle as well.

What do ya'll think? I'm not seeing anything out of the norm that would cause it to build boost slow. Only thing I'm not certain about is where VGT duty cycle should be reading at idle. I did put the truck in gear, mashed the brake and brought the rpms up to about 1200. EBP climbed when I did up to like 27psi I think. Boost gauge only came up to 3psi when I did that.

6speedsd · Apr 3, 2014

I'm still not sold on sticking vanes. Seems like I'd get some smoke on takeoff if they were, or the code for low boost (can't remember the exact number for it). But then again, if you mash on it, boost will come up... just won't hold over 22psi. Only place I haven't checked for leaks is the uppipe. Need to do that.

6speedsd · Apr 4, 2014

No one at all? Really?

Anyways, try this one on...

Returned the truck back to stock this afternoon for my ride home. Figured what the hell....I've changed a few sensors... lets see how my shifting problem is now. To my surprise, no more lagginess. Truck builds boost off the line as normal, cruising down the highway at 65 I'm seeing anywhere from 7-10lbs (with Eric's AggStreet file I was seeing 5 at most). Hit a hill, and it jumps to 15 and holds like nothing was ever wrong. Get on it and it climbs fast and hard to 24ish psi, and actually holds it unlike before. This makes no sense to me at all. Why would it be so laggy with a tune loaded, yet run fine without it? I also have Matt's SRL... rarely run it because they truck hates it apparently...terrible shifting....anyways, loaded it the other day and same issue. Laggy as hell until you mash on it. I guess this weekend I'll at least pull the EBP and clean it and the tube if nothing else.

Thoughts?

6speedsd · Apr 6, 2014

Think I figured out the boost problem.

She was just a bit on the nasty side. Turned the unison ring by hand and you could feel it hanging up. Got it all cleaned and back in the truck an went for a short ride to make sure all was working right. Immediate boost off the line, no more lag, made one pretty hard run and got it to build to 25psi and held there...I've never gotten 25 out of it before.

Still don't understand why it was only laggy tuned, but whatever. It's working right now.

Like to never got the halves separated. Tore up a good rubber mallet beating on it before it finally broke loose. I don't think it has ever been apart.

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