[RESOLVED] Thats a first: turbo spooled but no go and lurch

[AlphaAssault]

I was driving home today, and dropped down to about 15mph or so in 3rd gear. I left it in 3rd, and started accelerating. I got up to about 3k rpms and pushed hard (didnt floor it) on the accelerator, and i hear the turbo spooling but Im not accelerating hardly at all. I go to let off the pedal and put it into neutral, and the engine lurches once pretty violently, then drops back down to idle like nothing happened. I put it back into gear, and everything is back to normal, more or less. I didnt gun it the rest of the way home, but I did push it so the turbo would kick in, just to see if it was still working; and it would spool up and begin to kick in normally. WTF happened that one time? It lurches then its all good again?

Ive owned the car several weeks, and this is the first time this has happened, and ive floored it more than once. Yesterday I took out the old radiator, which had developed a leek where it sat, and replaced it with a new metal one. The only other change I made was I reconnected the BOV to the intake, because when I bought it the BOV vented into the atmosphere. SO, does anyone care to enlighten me on what just happened?

 

[booostedGSX]

Is the car stock, or do you have bigger injectors and pump/etc.?

 

[AlphaAssault]

95% stock. The only aftermarket items seems to be a boost controller, which I havnt touched, the BOV, and the radiator I dropped in yesterday. Also, the MAS has been hacked, and all that honeycomb stuff has been removed.

 

[SethA]

I would get an aftermarket boost gage asap if you don't have one and do a boost leak test. You might have accidentally caused one during the radiator install. The intermittent thing is sort of weird but It would be good to do a test anyway to rule that out.

Seth

 

[pitbull419]

If your spooling with no go, its more than likely a boost leak in the intercooler piping. check all your clamps again.

 

[booostedGSX]

Like pitbull said, probably a boost leak in the IC piping. Does the BOV vent to the atmosphere?

 

[AlphaAssault]

Like pitbull said, probably a boost leak in the IC piping. Does the BOV vent to the atmosphere?

It used to. I rerouted it back to the intake when I swapped out the radiator tho. NOW its venting correctly.

 

[99gst_racer]

Have you tested for boost leaks yet?

(I feel like bruce, asking this question)

 

[AlphaAssault]

Nope, I dont know how to perform a boost leak check, and I think I need an aftermarket boost gauge, which I dont have.

 

[Twistaye]

They have manuals to show you how to build one for like $15. I had the same problem a few times when driving, . Finally did a boost leak test, sure enough coming off my puny little stock sidemount the clamp has come loose and it was leaking. And I also found a few more leaks. After all was said and done the car was like new again ! It only cost like $15 to make my own, went to home depot and got everything I needed. Search vfaq or here on DSM Tuners, can find it in both places. Good luck to ya

 

[Twistaye]

Here's a link how to make a boost leak tester and it explains how to use it.
2G Turbo DSM Boost Leaks -How to test and fix

Hope all goes well, it sure helped me out a bunch

 

[AlphaAssault]

Ok, I replicated what happened last night. Today, I went out to see if it would do it again. Heres what I did:

1st gear, gunned it from a roll, no discernible issues there. turbo spooled, satisfying kick, etc...

2nd gear, hard on the accel. turbo starts to spool, then lurches at around 4k rpms, I pull it out of gear and into neutral, everything returns to normal.

I turn around and make my way home, not letting the turbo spool.

I only get the lurch and power loss when I am pushing it. If i had to describe what it felt like, it feels as if it wants to go into turbo, then something gives and the engine loses all the power. Turbo was still spooling. It is odd that it didnt happen in first though. First gear ran fine, as far as I could tell, it was second gear where something decides to give. Other than when I am pushing it, the car drives fine. Does this display symptoms of a boost leak, or is it a transmission problem??? God I hope its not the tranny.

EDIT: The clamp that tightens the hose onto the BOV is completely gone, though the hose seems to be fairly snug on the BOV. would this cause the symptoms I described? If so, why didnt it lurch in 1st?

 

[99gst_racer]

Nope, I dont know how to perform a boost leak check, and I think I need an aftermarket boost gauge, which I dont have.

Vfaq is your friend. ------> http://www.vfaq.com/mods/ICtester.html

Yes, definitely pick up a nice, accurate boost gauge for your car.

 

[AlphaAssault]

Ok, the hose clamp at the BOV wasnt the problem. I reconnected everything, and went for a test drive. Again, I heard the boost spool up, but I wasnt feeling the power of the boost. I pulled it into neutral before the engine had a chance to lurch like it did yesterday. Next, which was should i turn the knob on the MBC to get the boost down a bit? Im thinking I should turn it clockwise. I dont have a boost gauge, so Im shooting in the dark here.

 

[MrBoxx]

If you have a TurboXS boost controller, turn the screw clockwise to decrease boost, counter-clockwise to increase boost. MOST other boost controllers are the other way around: clockwise to increase boost, etc.

Before you even touch the boost controller, you need to get an accurate boost gauge. And you need one to do a boost leak test anyway, so that would be the first thing on your list.

 

[bpestilence]

Sounds like phantom knock. Turbo spooling but no power = timing retarded.

 

[AlphaAssault]

Sounds like phantom knock. Turbo spooling but no power = timing retarded.

What causes phantom knock, and how do I fix it? Would rerouting the BOV back into the intake instead of the atmosphere cause this?

 

[AlphaAssault]

Problem solved: there was a MASSIVE boost leak at the intercooler piping right as it goes by the air can. Also, i lowered the boost just a hair to compensate for the slight increase because im venting correctly now. it made a HUGE difference. Thanks for all the suggestions.

 

[booostedGSX]

Good job figuring it out.

 

[SethA]

I am glad you found the problem. Make sure you get a boost gauge asap. Running a boost controller without a gauge is flirting with disaster.

Seth