Problem... ECU or Boost?

[SpeedBeaver]

Problem... A/F related or Boost?

Ok I'll begin by the beginning, this morning it was quite cold outside (living in Canada so I have crappy weather right now). I noticed a low idle when I was stopping on red lights (600 rpm) but I tought that it was because of the weather and nothing more.

Then I took the highway and went back to my place. During the travel, I had to do a quick passing and I noticed that my engine bogged for a second.. I was like WTF was that? Then I went back to the right lane and tried again but I watched my cluster that time. So quick acceleration, let go of the gas pedal then pressed the clutch pedal to the floor. Then I saw it: The rpm went from over 3000 to ZERO and the engine stalled. The whole cluster lighted up like a freaking Christmas tree. Check engine, brake light, battery light, etc.. Then I had to restart the engine while still roling (cuz that time it didn't restarted by itself). So I spent the rest of the road doing heel-n-toes while braking so the damm engine won't stall.

I tried it again on an empty road to try to find more details so here it goes:
-over 3000 rpm to zero (stalls)
-under 3000 rpm to 500 (near stalling)

I'm on my winter setup now: all stock except for CustomMSP's SMIC wich was too much work to remove for winter. I was running 9psi last summer so maybe my BPV is just done for. So it looks like a BPV issue but then again, the low idle could be due to the ECU not injecting enough gas.

I'm thinking of trying to reset the ECU and go for a test run but checking the BPV and vaccum/boost lines at -15 Celcius is just not possible.

So I'm asking for your toughts about all this. Any advice?

 

[Fudgie]

sounds like a vacuum/boost leak to me. Find somewhere warm and do a visual under the hood.

 

[BlkZoomZoom]

Sounds like a hose popped off.

 

[funktownp5]

Sounds like a hose popped off.

Yeah look for one of the IC pipes loose, one proly popped off.

 

[SpeedBeaver]

Ok thanks, I'll try to figure it out tomorrow. Now it's even colder

 

[Brian MP5T]

what was the A/F doing when you let off?

 

[SpeedBeaver]

what was the A/F doing when you let off?

Hard to say with a narrowband But I'll try to check that tomorrow.

 

[Brian MP5T]

Hard to say with a narrowband But I'll try to check that tomorrow.

Sometimes the Stock ECU Boggs and you will see it run a bit lean under acceleration. If it's that, Reset the ECU...

 

[SpeedBeaver]

Sometimes the Stock ECU Boggs and you will see it run a bit lean under acceleration. If it's that, Reset the ECU...

I'll try resetting the ECU and I'll check the hoses and BPV for leaks.

 

[Cusson]

Ok thanks, I'll try to figure it out tomorrow. Now it's even colder

It's so funny to live in Quebec !!! It was -25 Celcius with the wind near Montreal... (stoned)

 

[SpeedBeaver]

It's so funny to live in Quebec !!! It was -25 Celcius with the wind near Montreal... (stoned)

Tell me about it... now I'm starting to regret not taking the indoor parking for an extra 50$/month with my new appartment(wedge)

 

[SpeedBeaver]

UPDATE!!

I went for a ride after resetting the ECU. - No difference, it's still having the same behaviour.

what was the A/F doing when you let off?

I noticed two things while paying more attention (and by doing this at night):
-1st the A/F goes rich as hell while the engine chokes.
-2nd all the electrical systems (dash lights, heater, headlights, etc) are dimming down.

As for the hoses I checked them the best it is possible to with a flashlight and a bone-freezing wind.(ugh)

So two things remain: boost leak or maybe an alternator problem? I already got my alternator changed because it was doing a weird sound while driving.

Any new opinions about these observations?

 

[Chilledboost]

mine did the same thing. check the charge air cooler lines. they tend to get loose at the throttle body. also check the maf sensor. sometimes dirt manages to get its way inside.

UPDATE!!

I went for a ride after resetting the ECU. - No difference, it's still having the same behaviour.



I noticed two things while paying more attention (and by doing this at night):
-1st the A/F goes rich as hell while the engine chokes.
-2nd all the electrical systems (dash lights, heater, headlights, etc) are dimming down.

As for the hoses I checked them the best it is possible to with a flashlight and a bone-freezing wind.(ugh)

So two things remain: boost leak or maybe an alternator problem? I already got my alternator changed because it was doing a weird sound while driving.

Any new opinions about these observations?

 

[SpeedBeaver]

Contacted my dealer and they're gonna check my car tomorrow since I can't do it myself with the weather outside (Tightening up pipes at -20C could be a bad idea).

 

[SpeedBeaver]

Hum, seems the problem was not in the list above.

My primary O2 sensor on the exhaust mainfold was defective

 

[SpeedBeaver]

Now that's weird... I still don't have my car back: seems the TB needed to be changed too.

Just wondering: could the oem bpv have damaged the TB at 9psi last summer?

 

[BlkZoomZoom]

So you needed an o2 sensor, t.b. (probably for the IAC)?

Interesting. Still say its a vacuum/boost leak.

 

[SpeedBeaver]

So you needed an o2 sensor, t.b. (probably for the IAC)?

Interesting. Still say its a vacuum/boost leak.

I checked my boost gauge while testing it: it's holding steady at 7psi without dropping. The only leak possible would be at the oem bpv when I let off the throttle, but I could be wrong...

 

[igdrasil]

you can still boost 7psi with leaks, but the turbo would be spinning faster.

Check the MAF and check for leaks

 

[SpeedBeaver]

Dealer just called back:
-MAF is fine
-New throttle body
-EGR was tested ok
-New BPV

Still the problem is persisting. The dealer asked me if I've been modding it (except for the gauges right now my car is stock - winter setup).

I'm tinking about leaks too but the problems only appeared lately and my gauges have been in place since a year so I'm very doubtful about leaks for the boost gauge... What else could leak?