Contour Enthusiasts Group Archives Forums General Troubleshooting Need advise - loosing brake boost, rough idling

I have seen lot of information here and I am totally confused - where do I start
It has been really cold for the last couple of weeks and that is when the problems began:

• Car starts at really high rpm (3,000) then rpm drops and car dies (IAC is one year old)
  
  
• If I force it to warm up by pressing the gas to keep it from stalling for 3-4min (rpm @2,000) it eventially misfires and CEL flashes, but it stops flashing once I restart the car
  
  
• Once driving, I am constantly loosing brake boost . To get it back, I have to shift into Neutral, rev the engine (over 3000 rpm) then press the brakes again and the boost is back.
  
  
• On the highway, (at 2000-2500 rpm), sometimes the car hesitates while going at a constant speed
  
  
• Idiling is rough and at low rpms, and I always have to shift to Neutral to avoid stalling at traffic lights.
  

I have read many threads that suggest: vacuum leak, fuel pump, fuel filter, clogged injectors and many others.
Can someone help me, where do I start and what would be the least expensive things to do and in what order?

I'd start with the vacuum leak. Check all of the vacuum lines around the brake booster. I've had a couple with broken or slit pcv line. It is located under the IAC valve area and tends to rub against a bracket. listen for a hissing sound as the car is idling.

I second that. I bet the hose to the brake booster is either cracked or not seated properly.

What Stazi said..

On top of your UIM are two plastic lines. I think 1 runs to the brake booster. Check those two first. That sure sounds like a cracked line.

Good luck!

Agree, look for intake leaks first but then look for leaking intake manifold gaskets, (spray carb cleaner around the gaskets and see if the idle increases......) Are you throwing any codes? Any lean condition PO171,PO174 without obvious vacuum leaks would make this almost a certainty...

You need a significant leak to cause the symptoms you describe which you may even hear if it was a split or disconnected hose etc.

I had similar symptoms.

Cheers, William

Just pulled the codes: P0171,174,1151,1131 (all showing lean) and 0300 (I guess from the misfire during warming-up)

Sprayed around the vacuum hoses, but found nothing. The idle changed when I sprayed on the UIM posts (where the bolts go through).. I guess that points to the UIM gasket, am I correct?

Looks like leaking gaskets unfortunately as this seems endemic with this engine. Spray on the edge of the upper intake manifold gasket. The RH side when standing infront of the car is easiest to see and to spray on to make sure.

The job is not hard - just tedious - especially the cleaning of the manifold. Lots of info on this site about it. Just be careful and use gloves if you use a Xylene based solvent as it is bad stuff. I got some Felpro gaskets PArt #MS 95726 which seem better than the Ford OEM gaskets at half the price....

Suggest that once you have the upper manifold off that you also do the lowwer one as the gaskets are the same construction. Clean the butterfly valve and the throttle body as well when you have everything apart and make sure you clean the EGR passeges on the UIM.

With everything off it is a good idea to do the plug wires and plugs as well as the PCV valve as they will be very accessable instead of a PITA... I also replaced the EGR valve when I had everything off as the large nut from the exhaust pipe is almost impossible to get off without the UIM off and this part seems to also cause trouble according to experiences from foks here.

Good luck.

Cheers, William