• Welcome to the Contour Enthusiasts Group, the best resource for the Ford Contour and Mercury Mystique.

    You can register to join the community.

Vacuum leak on turbo car

T

TUFTOUR

Hard-core CEG'er
Joined
Dec 6, 2002
Messages
2,908
Location
Harrisburg, PA
1999 SVT with NPG's turbo kit for those who don't know the car. My wife and I went to a shop this morning to have new tires mounted, ran fine. After tires were done, car would start, but would stall as soon as you gave it gas. Since I was at work and she stayed at the shop while they mounted the tires, I left work to determine what happened. So here's actual symptoms: car starts fine, will idle normally and can rev with no problems...however, within a minute or so, vacuum starts dropping like crazy, car leans out, then it stalls. I have a vacuum/boost gauge and wide band, so can see and hear what's happening. I've been messing with this for last several hours...no obvious leaks underneath the car or in engine bay. Just to be sure, replaced fuel filter and cleaned MAF sensor...same problem. Luckily, the shop is full-service and can do a smoke test, so it will remain there until probably Monday or Tuesday when they can do it. I figure a leak that big should be obvious, but can't find anything...any suggestions?
 
If it was a vacuum leak that bad you should be able to hear it. In my experience when a boost hose comes off by the front bumper you won't be able to hear it. If there is a boost leak there will be a problem with the MAF signal and it will cause everything you are experiencing.
 
I checked at the waste gate and everything in the engine bay related to boost, but may have missed something. I'm now wondering if it's O2 sensors since happens only as engine is warming. From what I've read, in open loop, everything is based upon MAF function...once O2 sensors heat up, goes to closed loop and then stoic is maintained based upon O2 readings. And I agree, I vacuum leak that big would have been heard, but couldn't find anything...and would consistently idle and rev normally on start-up if engine was cool.
 
If you think it's the O2 sensor warmup, start with a cold engine, pull the O2 sensor heater fuses in the under hood fuse box and see if the behavior changes, the sensors will still warm up, but more slowly without the heaters.

A quick way to find intake leaks is with a spray can of starting fluid (ether), you spray it at potential leaks and the engine idle should change when you spray at a leaking spot.

Do you have a blowoff or recirculating blowoff valve? Maybe that's leaking?
 
I'm using a blowoff valve...I checked that and everything is tight. I even used a tissue where it opens to check for any airflow and nothing. We used brake cleaner on areas that might be leaking (or looked to be leaking) and still nothing...no change in idle and it didn't suck the fluid in.
 
You must log in or register to reply here.
Back
Top