Saxo 1.1 hfx failing mot

1. Villu Newbie Joined: Sep 2014 Posts: 2

   #1 13th September 2014, 22:38

   Hello saxperience´rs!!!
   
   I have bought my second saxo. First one was a 1.5 diesel.
   
   This one is with cng equipment fitted. It had head gasget blown, wich I changed. Also the valve stem seals.
   
   Now its failing mot With rev CO: 0.71% and idle CO: 0.66%
   rev HC:246ppm and idle HC: 134ppm
   
   I have check with OBD interface. All sensors seems working; manifold pressure, throttle, water temp. lambdas are both changed. Only intake air temp is around 35c (celsius) real would be 18c
   
   Can it be coil pack? spark plugs are changed.
   
   Or is it an air leak somewhere? I tried spraying quick start around inlet manifold, no change of rev´s.
   Im wondering where is one of the vacuum pipe is going. to fuel pressure regulator or crankcase ventilation (if it has any)?
   
   also i checked injectors, I put acetone trhoug all these. Idont know what the pattern should be, but they didnt spray, instead 3 straight lines come out of them. I pressurised with air comp. maybe my pressure was too high.
   
   but here I am with my new saxo
2. user_20080 Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.

   #2 13th September 2014, 22:58

   Catalytic converter?
3. tiger1983 Regular Poster Joined: Aug 2014 Posts: 279

   #3 14th September 2014, 00:31

   I second the cat, I'm sure those are similar readings to what mine failed on, changed the cat and passed with no problems.
4. oxass Infrequent Poster Joined: Sep 2014 Posts: 215

   #4 14th September 2014, 00:40

   Visualy inspect the cats internals for damage including silicone poisoning if you have access to a laser thermometer take a reading at the inlet of the cat and the outlet of the cat when the car is fully warmed up.
   The readings should be over 450° or higher with the outlet of the cat being hotter than the inlet.
5. Villu Newbie Joined: Sep 2014 Posts: 2

   #5 14th September 2014, 06:21

   Actually I marked these readings wrong, the opposite way, Readings where higher on idle
   
   With idle CO: 0.71% and 2000rev/min CO: 0.66%
   With idle HC:246ppm and 2000rev/min HC: 134ppm
   
   
   yeah the garage diagnosed also the cat and they want 600 eur for changeing the whole exhaust. Job and parts. Diagnose cost 78eur. This is f...ng expensive to go to garage here.
   
   Maybe its really the cat.
   
   I thought this motor should run leaner, and man on MOT test sayd that, it doesent burn all the fuel its getting.
6. oxass Infrequent Poster Joined: Sep 2014 Posts: 215

   #6 14th September 2014, 07:31

   If the vacum hose is missing from the fuel pressure regulator the fuel rail will be unregulated and the pressure can reach 100 psi that would explain the higher readings at the lower idle speed.
7. oxass Infrequent Poster Joined: Sep 2014 Posts: 215

   #7 14th September 2014, 08:02

   Quote:

   Originally Posted by oxass If the vacum hose is missing from the fuel pressure regulator the fuel rail will be unregulated and the pressure can reach 100 psi that would explain the higher readings at the lower idle speed.

   If your car has one fuel line to the fuel rail the fpr is located by the fuel tank.
   If the fpr is on the fuel rail and the vacum pipe is absent this will be a problem.