Need help: Ignition issue ?

[Newlogics]

Hi.

It just started yesterday, out of the blue.

When I gave it some throttle, it started shaking, kinda like when your tire is blown, only steering didn't pull either way, and I feel serious power loss.

I checked all wheels, tie rods and all steering components, and it's all fine. Then I connected a logger, and tried to see if it would reflect anything, and it doesn't show anything out of the ordinary when it happens. (No knock, timing is fine)

It happens around 3K rpm, when my turbo just starts building boost, but can happen earlier if there is more load, like going uphill.
What I found out, is that when it happens, my EGTs start to rise fast, which is what made me think that somehow one or more cylinders stop igniting, and raw fuel burning in the manifold heats up EGT probe.

I haven't had a chance to dig into the problem yet, I'm planning to do that tonight, but I I could get some help on where to start, it would save me lots of time.

Thank you.

 

[AwdEi]

When your EGTs rise, you are running leaner. Running rich will make your EGTs lower, so the injectors may be firing completely.

What are your o2's? Our cars (1gs) should be around .86-.87 volts. Just for future reference, 2gs should be .92 volts. This should tell you if you're running rich or lean. (Lower voltage is lean.)

 

[Newlogics]

Originally posted by AwdEi
When your EGTs rise, you are running leaner. Running rich will make your EGTs lower, so the injectors may be firing completely.

What are your o2's? Our cars (1gs) should be around .86-.87 volts. Just for future reference, 2gs should be .92 volts. This should tell you if you're running rich or lean. (Lower voltage is lean.)

I'm afraid it's little more complicated then that.

First of all, keep in mind that it just started out of the blue, no changes to SAFC were made. (It's a 1G)

O2 voltage is fine, and I'm not running too reach or too lean. What seems to happen, is that somehow ignition to one or more cylinders gets cut off, and all the unburnt fuel is traveling into the manifold, igniting there and therefore heating up the EGT probe. So it's bit more then hot = lean cool = rich situation.

To add more mystery, I inspected al plugs, and there were perfect. Didn't have time to get to coil, but they didn't seem to be the problem. Pressurized my intake - 100% air tight. Took the car for a drive, BOV seemed way too stiff (I didn't adjust it) and barely blowing off.
THis time it let me build about 10psi before jerking. I drove for another hour and it went away completely.

I'm stunned.

 

[Newlogics]

Doesn't look like I'm getting a lot of input on this.
If you guys need more info, please let me know, I'll post it all. Although probelm went a way, I'm not happy with loose evil gnome lurking under my hood. I'd really like some opinions.

Again, this doesn't seem like your typical 'missfire' issue. It's not irratic. It feels like 1 or 2 cylinders just cut out completely as soon as boost hits.