Little gas out of two of the four tailpipes | FerrariChat

Little gas out of two of the four tailpipes

Discussion in 'Mondial' started by jmcscotty, Jan 27, 2015.

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  1. jmcscotty

    jmcscotty Rookie

    Jan 27, 2015
    12
    My wife has a '86 Mondial 3.2 L with 30K miles. I run it once a month for 10 miles for exercise and had the coolant changed 3 months ago. Recently the "Slow Down" indicator came on even although I was driving slowly. Home in the garage acrid vapor rose out from the space between the exhaust system and the engine compartment from the direction of the exhaust system. The next day, on the theory that maybe something had crawled up one of the pipes and died, I started it up and immediately felt the exhaust gas blowing hard in the two exhausts on the passenger side but little gas from the two on the driver side. After 5 minutes I could hold the passenger-side pipes with my bare hands hands. The two pipes on the driver side got too hot to hold. I can only see four spark-plugs, the others are hidden from view. I can examine and maybe switch plugs for a start. A picture of the exhaust system shows that the two pipes on the passenger side combine onto one pipe which comes out of one end of what I presume is a muffler. Same on the driver side. Two pipes come from the engine, one into each side of the muffler. If it's not a dead snake or mouse, how can all 4 cylinders go bad (fuel injection, or electric or plugs) going to one side of the muffler? Does anyone have ideas? Thanks
     
  2. Bell Bloke

    Bell Bloke Formula 3

    Dec 6, 2012
    1,839
    UK
    Hi Scotty, it sounds like you have one bank out, the smell I suspect is the fuel that is not being burnt. You will need to get a spark tester and find out which side is dead or intermittant and trace it back. It could be a coil or a lead or a sensor etc, need a tester to find out which. Obviously don't drive the car like this otherwise you will damage the engine by bore washing the bores with fuel, Static running for short diagnostic periods is ok though.
    Ragards Bell.
     
  3. PV Dirk

    PV Dirk F1 Veteran

    Jul 26, 2009
    5,401
    Ahwatukee, AZ
    It is normal for more pressure to exit one side of the exhaust than the other, it is the internal design of the muffler. They all do basically the same. I don't know about your smell. In cold weather you will get much condensation before it comes to full warm so the exhaust could spit water if it's idling in a cold space and the exhaust system hasn't come to full heat.

    if the engine runs smooth and you have normal power you have not lost a bank. Significant loss of power. Could you have gotten a drop of oil on the exhaust to cause the smell. I don't really know what smell you had. In cold weather the car will run rich to compensate for the temp until up to full temperature.

    The slow down light is a catalytic converter over temperature light. They are more often faulty than they have an over temperature situation but it is possible you have an excess fuel delivery issue causing it to overheat. I would drive the car (if you have normal power) and if the slow down light comes on again get out of car and look under rear. The exhaust should be basically glowing.

    Did your slow down light blink steady before it came on? it has two stages. 1st stage is blinks steadily as a warning it has reached a temp threshold, then it will go steady when it reaches a very high temperature threshold. Again these fail with regularity and are often faulty readings.

    You could have an issue or everything could be normal.

    If you have a cabriolet there is a hatch behind the back seats that gets removed to access the forward bank of the engine and plugs. If you have a coupe you should be able to get to the plugs with work from engine bay.

    PS - Welcome to Ferrarichat !
     
  4. Meister

    Meister F1 Veteran
    Silver Subscribed

    Apr 27, 2001
    5,516
    Duluth, MN
    Full Name:
    The Meister
    unequal pressure from different sides of the exhaust is fairly normal.

    smoke after a short run would indicate oil previously dripping from cam covers down onto exhaust manifolds when the car sits idle.

    the slow down light does indicate overheated cats/exhaust. Strange smell could be the beginings of a nest...for whatever reason mice love exhausts.
     
  5. Bell Bloke

    Bell Bloke Formula 3

    Dec 6, 2012
    1,839
    UK
    Scotty, if your exhaust bank is as you said ''COLD'' on one side then you have no combustion and the smell is raw fuel.
    It's an old trick but when working on multi carb V12 or V8 Lamborghhini or Ferrari cars a quick down and dirty test I do for a bad running engine is to start from cold, run for 1 minute and then touch all of the exhaust manifolds. The cold ones provide a very quick goto for tuning issues and it saves absolutely loads of time. Try it and you will have the info you need for the next step.
    These old tricks get lost in the mists of time...
    Regards Bell.
     
  6. Wade

    Wade Three Time F1 World Champ
    Owner

    Mar 31, 2006
    32,793
    East Central, FL
    Full Name:
    Wade O.
    Or use a noncontact IR thermometer. I have one of these; bought it on sale at Northern Tool.

    www.vibratronics.com/files/miniTemp.pdf
     
  7. Rapalyea

    Rapalyea Formula 3

    Jun 18, 2013
    1,511
    Georgia Mountains US
    Full Name:
    David Rapalyea alias
    That is not very much exercise time. Do you let it warm up at idle? That is a bad idea because it permits fuel to condense. After warm up do you ever rev to 5,000 rpms at full throttle? If not that also a bad idea. Does your oil temperature ever go above 140? It should if you are giving the car good exercise.

    Speaking for myself here is what I would do. Start the car and let it run 10 seconds for oil flow. Then warm it up in first or second between 2,500 and 3,000 rpm. If the slow down light does not go on then run it in second at full throttle to at least 5,000 rpms.

    Repeat as necessary. I believe you have carbon build up and a clogged cat that is absorbing excess condensed fuel. Then warms up, releases the fuel and it gets hot. But thats just me. Your results might vary....
     
  8. Rapalyea

    Rapalyea Formula 3

    Jun 18, 2013
    1,511
    Georgia Mountains US
    Full Name:
    David Rapalyea alias
    Here is an easy way to test for a cylindar bank down. Use full throttle and if the car accelerates like a Honda Civic? That happened to me once. I did not get 'slow down' or gas smell. I did not need to slow down because the car would not go fast to begin with.

    I jiggled all the wires in ignition modules assuming one of them was bad anyway and was about to [and may still buy a module for spare] However. It never happened again. The car runs like scalded hound and thats how I run it much of the time. Full throttle each day every day for 9,000 miles now total 53,000miles. Although I pretend to have a 6500 rpm red line.

    The car did not love me till I gave it some respect.
     
  9. Bell Bloke

    Bell Bloke Formula 3

    Dec 6, 2012
    1,839
    UK
    Full throttle with a bank out?.....sorry not good idea, raw unburnt fuel will wash all the protective oil off your bores and cause wear, it's called bore washing.
    Sorry but that's not a good way to make a judgement here.
    Regards Bell.
     
  10. Rapalyea

    Rapalyea Formula 3

    Jun 18, 2013
    1,511
    Georgia Mountains US
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    David Rapalyea alias
    Perhaps I was saved by the 8oz two cycl oil I always add to the gas. Plus, without any combustion pressure the bore wash would not be under much stress. Back in the old days, before our VERY hard silica blocks in these cars, engines would routinely spit our all sorts of gassy crud.

    Besides, my car is a control example. It ran that way for many miles at light throttle. It was only going uphill I noticed the VW esq power curve. Then applied full throttle. Did not need to do that for more then a few seconds to realize the problem. In any event, oil pressure is always adding lubricant. But I take your point.
     
  11. Bell Bloke

    Bell Bloke Formula 3

    Dec 6, 2012
    1,839
    UK
    Any news? You can also buy a strobe light with a lead clip, that's a very quick easy way to see if you have a spark.
     
  12. Rapalyea

    Rapalyea Formula 3

    Jun 18, 2013
    1,511
    Georgia Mountains US
    Full Name:
    David Rapalyea alias
    You can also just unplug the connector wire that hangs down from each ignition module. My mechanic played a trick on me and unplugged the rear one and when driving away I just drove back, opened the engine hatch and noticed it hanging there.

    Plugged it in and just drove home.
     
  13. jmcscotty

    jmcscotty Rookie

    Jan 27, 2015
    12
    Thanks everybody. I bought a spark plug signal tester and tested all 8 cylinders. 5,6,7,8 were firing fine based on the flashing from the indicator. 1,2,3,4 gave no signal. I switched plugs 4 and 5( it may have been 8 because I cannot read the number stamped on the engine for 5 through 8). It fired fine so there is nothing wrong with number 4 plug and I guess neither with 1,2,3. Therefore probably cylinders 1,2,3,4 are not getting a signal from their electrical ignition of which there are two, each marked Accensione Elletronica (AE). An orange line goes from each AE ( a cylinder about 1 1/2 inches diam and 3 inches ling) to a 4 inch diameter device with a rubber cover on the end of the engine block. Out of that device (is this the distributor?) 4 orange leads go to 4 spark plugs. So is the problem in the AE or in the device (distributor?). What is my next step?
     
  14. gsfent

    gsfent Formula 3

    Nov 16, 2009
    1,096
    PB County, Florida
    Full Name:
    Jerry
    Not sure what it looks like on the 3.2, but can you swap the boxes? If you can, and one is bad, the non firing cylinders will switch to the other bank.

    Regards,
    Jerry
     
  15. MvT

    MvT F1 Rookie

    May 25, 2013
    4,248
    The Netherlands - NH
    Full Name:
    Tijn
    Yup, you can swam them.
     
  16. davehelms

    davehelms F1 Rookie

    Jan 3, 2004
    4,629
    Full Name:
    Dave Helms

    Unplug the single plug wire going to the coil assy, from the 'dist cap' on the affected bank.
    Prop the wire where it is held secure 1/4" outside of the coil, close enough where a spark can still make the jump to the coil terminal inside.
    Start the car and observe if a spark is present from the coil to the wire... Dont touch the wire or the coil with the car running or it will light up your life. The same test coud be done with your tester on that wire but the neon bulb can give false results if it is too near another wire

    Spark present is likely a burned through ign rotor under the cap, No spark will be a connection issue or a failed component. Report the results before taking anything else apart
     
  17. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    3,628
    Canada
    Sounds like a coil failure, can swap each of the two to confirm. The check for a failed rotor is certainly worth doing first. Caps rotors and wires are expensive so do not get replaced as often as in regular cars. The coils do fail, but one can replace the coil module on top of each coil for less cost than three whole coil.
     
  18. Bell Bloke

    Bell Bloke Formula 3

    Dec 6, 2012
    1,839
    UK
    Just a little caution here, if you want to test a coil by watching a spark go to earth, better that you do it with a spark plug attached to the end of the lead, that way if you accidentally dead short it (highly likely) you won't blow up your lovely expensive coils or worse a pack.
    Better still get a spark tester.
    Regards Bell :)
     
  19. jmcscotty

    jmcscotty Rookie

    Jan 27, 2015
    12
    Thanks for suggestions. I switched the coils. Cylinder 5 now with coil from 1,2,3,4 continued to fire (plug tester flashing) as it did before switching coils. Cylinder 4 (and I presume 1,2,3) continued not to fire as before. So both coils operated cylinder 5 plug, so both coils are good. Cylinders 1,2,3,4 remain not firing. So the problem then must be in the distributor for 1,2,3,4. I pulled off the rubber cover and it is held on engine with four 8mm bolts, two on top easily accessible the others very difficult. I tried pulling gently on the orange HT wires coming from the distributor base (hoping they were push fits), these being in the way of the lower bolts but no result. Am I correct in assuming they are not push fits? I even unbolted coolant tank and moved it a little to improve access slightly. Still cannot get wrench to these bolts. Removing coolant hoses may help. Any suggestions?.
     
  20. jmcscotty

    jmcscotty Rookie

    Jan 27, 2015
    12
    Update. I removed the distributor cap for cylinders 1,2,3,4 which are not getting a spark. Cylinders 5,6,7,8 all spark Both coils are good (I switched them) and all plugs are good (I switched 4 and 5 and cylinder 5 sparked. There appeared to be metal "filings" coating the distributor cap. Maybe I will clean it and reassemble.
     
  21. jmcscotty

    jmcscotty Rookie

    Jan 27, 2015
    12
    I have in-line plug tester. Is it OK to connect plug tester to bottom of coil and hold other end of tester close to or against ground? This is to test whether I am getting a signal out of coil on dead bank side of car which has no sparks on cylinders 1,2,3,4. JMcScotty
     

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