06 LGT 5EAT Stalling and engine vibrations

So, I've been lurking here for awhile doing a lot of reading on this issue since it seems to come up from time to time for people. My car began having harsh engine vibrations and eventually started stalling early in the Fall. It only happened when the engine was cold though.. and once it was up to temp it ran normally without issue. I've been working with Andrewtech Automotive in MD to figure out the issue and have until now zip-tied all vacuum lines, cleaned the MAF, replaced the turbo inlet tube, swapped OEM TMIC for an AVO unit with TB hose, and this past weekend replaced those pesky o-rings under the intake manifold. Each of these things have helped as the inlet did have a small tear in it, and the IC and IM were in-fact leaking. The shaking is much less now than before but still noticeable. Cars never thrown a CEL on this.

 

Today was my second cold start since the o-rings were installed and it stalled out in traffic at a red-light while stopped. 15min later it was warmed up and again no problems. Not really sure where to go from here. Any thoughts?

 

Note: I went stage 2 this summer with UP/DP, EBCS, new fuel pump, and tune at EFI Logics.

Did you reset ECU and relearn idle after replacing the o-rings?

The battery was pulled while doing the o-rings so the ecu was reset. Didn't do the relearn idle procedure though (just googled that) but I'll give that a shot.

The battery was pulled while doing the o-rings so the ecu was reset. Didn't do the relearn idle procedure though (just googled that) but I'll give that a shot.

 

Try it. Would be the first logical and free thing to try.

Did you reset ECU and relearn idle after replacing the o-rings?

 

Gave it a shot last night. Took it out from a cold start this morning. No luck, same problem

Need LV and datalog.

Need LV and datalog.

 

As of now I don't own an AP. Its next on my list to get

How did you get tuned? Brought the car there, got tuned and just left?

 

Every person who has a modified car should either have an AP or a Tactrix cable+laptop.... you are doing yourself a HUGE disservice by not having these important tools on hand.

Yes, it was an open source tune

Buy a Tactrix cable, pull an LV and log.

LV? Didn't see that one in the common acronyms thread if you'd care to elaborate. I'll research some of the logging threads on here as well since I'm new to this.

 

And I know most people typically run PCs when doing this but I happen to have a Mac. Any software for us or would I have to go the AP route?

Learning View

 

Since you are OS tuned, your only choice is a Tactrix cable, or a Vagcom cable that uses the FT232BL chipset (RARE, hard to find). I believe people have been able to emulate Windows on their Mac and use the cable successfully.

 

You can not use an AP since you are tuned OS. If you do get an AP, you will lose your tune and have to be retuned on an AP.

OCVS replacment help these symptoms for me... As well as the rest of your list aside from going back to the stock TMIC.

 

Also FYI there is an updated gasket for the throttle body as well. Same construction and taller like the manifold gaskets.

OCVS replacment help these symptoms for me... As well as the rest of your list aside from going back to the stock TMIC.

 

Also FYI there is an updated gasket for the throttle body as well. Same construction and taller like the manifold gaskets.

 

Gotcha. I'll have to look into that. For you, did the problem get as bad as stalling too or just the vibrations?

I kept stalling in parking lots, stop and go traffic and driving condition with minimal throttle input. Would come out of the blue. Rough idle was part of it but I also was experementing (poorly) with other intake parts and such without a proper tune for them.... Go WFO and no stumble no hiccups.

 

Long storry short after replacing some of the experement parts with stock stumble and rough idle kept happening. This was the last item changed before the turbo swap and things the low end really smoothed out.

 

I have a feeling one was probably sticking and the other wasn't so it sent the ACVS into an imbalance... But thats all theory.

 

I personally feel these should be changed at the 105K maintance interval regardless of them being on the schedule or not.

Update: Car improved noticeably since o-ring replacement and given a few more weeks for the ECU to learn as well as replacing spark plugs and cleaning the OCV's. No stalling but still a bit of rough idle until the engine warms up.

 

I think at this point my tune is the problem. I had numerous air leak problems come to light post tune last summer including a leaky TMIC (since replaced with an AVO unit), and torn turbo inlet tube not to mention the IM o-rings. I think being tuned with these issues present and now correcting them has me running rich at the moment. A proper AP tune is on the horizon for me.

I'd look at cleaning or replacing the PCV. Also take a bit to pull the crossover vacuum manifold that connects the heads to the intake, clean the inside... Pull a rag fragment through with some carb cleaner to be sure there is no blockage.

 

As for the OCVS... replace them... Seriously. Solinoids fail to work over time.

 

As for the tune... If your tune was with the stock IC and now you have a AVO. Yes go get a retune after addressing the above.

I see what you mean with the solenoids. Maybe the LGT community should consider replacing them regular maintanence at this point.

 

And yes, the tune was done on a stock IC not the AVO unit

 

Is the "crossover vacuum manifold" the last part of the intake track before incoming air is routed into the intake manifold?

It's a hard ABS Tube that bridges the two heads together and intesects at the intake manifold. It's under the wire loom that crosses the intake manifold. IC has to come off. Three 10mm bolts out of the wire loom cover and some cursing it will come out. Take your time with it. Make sure it's clean.

 

How many miles are we talking about on your car?

Ok, I have a better idea of where you're talking now. 110K on the car.

Yeah with that many miles the OCVS are done... I fought the car for a while not replacing before I did... Once I did it's was sooooo much better. Plus making sure she breathes. PCV and such are essential for smooth operation.

Update: I took Kzr750r1's advice and did the OCVS replacements as well as a new tune sometime ago (this time on AP) at TurboXS in MD. All has been well since and the issues are gone.

Good to hear. Did you find any gunk in the crossover pipe? I finally had to replace the hoses from the head after my turbo swap, one cracked at the head bung.

No not especially on mine. My TB on the other hand did have a bit of buildup on it.

Good move looking at it. I had to clean mine as well. Didn't help the VF40 was starting to puke oil into the system. Have not torn down again after the G16 install. Considering doing it soon for other reasons. I need to replace a few more coolant hoses looking for a leak.