Hi all.
Was driving around at night, when a focus decided it was fast, and I took chase :P. Anyways 1/2 way through second gear, my engine did what I thought was 5 hard fuel cuts.... So I stopped and pulled over to check everything.

I should have known that it wasnt fuel cut, becuase 1, I have a ported s4 wastegate, and 2 I have a Fuel cut defencer (or how ever its spelled).

The car was still running and I heard a loose vac line, and I was right, the vac line that comes right off the UIM nipple by the BAC was just laying there....!

For me, that line goes to, boost gauge, pressure sensor, and the BOV! So it couldnt have been fuel cut also because the pressure sensor wasnt seeing any pressures.

My question is.... ... well I have two questions. With the pressure sensor vac line disconnected it was seeing 0 pressure, meaning it wasnt adding any extra fuel to make up for the boost correct? And second what should I do other than check the compression to make sure everything is ok? It seems to still pull hard and idles fine and what not. I need to find a replacement s4 NA engine asap! args I go through more engines than underwear! I just got put this NA-T engine in, I'm glad it was strong enough to survive 5 predets, but I don't know if it is injured in any way.....

Let me know if you have any ideas.
Thanks
~Tweak

 

you didnt hurt the engine the hose just blew off simple as that.

thats how a typical boost leak goes. your car was just surging.

 

pressure sensor mostly pulls some timing under boost, so without it working right you have an increased risk of detonation. fuel is mostly controlled by AFM signal

 

noooo it was at 6000 / 6500 rpm ..haha
(remember I took chase after the focus)

 

Ok, well hmm.... Since I'm running a S4 NA turbo, I'm guessing that it really does need to have the timing retarded when it needs to.....

I hope everything is fine... I guess we will see.

 

hmmmm do s4 turbo's have limp mode if the vac line falls off the pressure sensor?

 

If the hose falls off the sensor just sees atmospheric pressure, the ECU has no idea the hose fell off.

 

Damn, you must have a long 2nd gear.

S4's don't have limp mode. We're not smart enough for that.

 

How does it run now and whats the compression?

 

well my cars been through a ton of pre det, and i hate to say it. even a few that should have sent a rotor through the housing, but since it was a rebuild ( a very good one) the compressions is still at 125 front and 130 rear. my guess is maybe you are as lucky as i was and nothings wrong.