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Car Forum / Fiat Cars / July 2005Mk1 Punto timing problem?
Hi everyone! Our 1999 MY Mk1 Punto Sporting is feeling a little sick. It doesn't seem to have the same "go" as it used to and at idle, it's very lumpy with the RPM gauge occasionally jumping up. At speed, I can hear "rushing" noise which I have previously discounted as road noise, but it seems to be related to the throttle operation, along with a high pitched whining. The whine is not gearbox related and can be best heard just on throttle or when the clutch has been dropped, like when stopping at traffic lights. It had a service not so long ago (albeit a poor service by a mechanic who we will not be using again), which amounted to an oil change and new spark plugs. I have checked plug tightness and lead connection - they're okay. I have connected a vac meter to check the idle pressure - that's okay, too. My thoughts are that the timing is off. I don't have the tools or the know-how to check that. Am I on the right lines? Is timing on the Punto of that vintage something that any garage can check, or is it likely to be some arcane procedure that is best entrusted to a FIAT specialist with a computer to plug onto the car? Any advice? TIA. Paul > Hi everyone! Our 1999 MY Mk1 Punto Sporting is feeling a little sick. It > doesn't seem to have the same "go" as it used to and at idle, it's very [quoted text clipped - 10 lines] > will not be using again), which amounted to an oil change and new spark > plugs. <snip> Did he put the right plugs in ? Graham >> It had a service not so long ago (albeit a poor service by a mechanic who >> we [quoted text clipped - 4 lines] > > Did he put the right plugs in ? That's a good point. Is there a recommended 'performance' plug of should I just ensure that the one stated in the owner's manual is used? Paul > At speed, I can hear > "rushing" noise which I have previously discounted as road noise, but it > seems to be related to the throttle operation, along with a high pitched > whining. The whine is not gearbox related and can be best heard just on > throttle or when the clutch has been dropped, like when stopping at traffic > lights. Checked the brake servo? The round cannister shaped thing that the master cylinder bolts onto. It has a manifold vacuum connection, and a diaphragm. There is a hose connection going into it. A meter indicating a low pressure doesn't rule out an air leak. At light and trailing throttle, and when stationary, there is a near vacuum in the manifold, any air leak produces a rushing noise. > Hi everyone! Our 1999 MY Mk1 Punto Sporting is feeling a little sick. It > doesn't seem to have the same "go" as it used to and at idle, it's very [quoted text clipped - 23 lines] > > Paul Sounds like you may have air intake leak somewhere between the base of the carb/SPI and the engine manifold face of the engine block. I would check 1) The vacuum anvance tubes coming from the carb/SPI unit. If a carb. model then there could be a collection of these tubes going to water temperature sensor air switches. (on my uno SX I disconnected all of these and just left the feed to the vacuum advance unit. 2) If you have an 'economy guage' tihs is almost certainly vacuum driven so check for leaks/spilts in this hose (goes to back of instrument cluster) 3) Check the brake servo unit vaccum hose from inlet manifold to servo unit. 4) Check the brake servo unit has not developed a diaphram or other leak. Easy to do. a) with engine off pump the brake pedal unti it goes hard. you may hear a hissing of air. this is ok. b) press the brake pedal firmly and start the engine. the pedal should sink under your foot with the vacuum astistance. release pedal. c) with engine running press the brake pedal firmly and keep the pressure on. hold the pedal pressure for 30 seconds. the pedal should not creep or sink under yoor foot towards the floor. release pedal. d) turn off engine AND DO NOT touch the brake pedal. leave for 30 minutes+. then press the brake pedal down. you should hear air rushing and the pedal should feel normal. release and repeat. same should happen again. release and repeat again. on each cycle the pedal will sink less and become more firm. after 'n' cycles the pedal will be very firm as all the vacuum will have been relealed from the servo unit. Some servo systems will hold the vaccum for serveral days, even weeks. others may struggle to hold the vacuum for and hour or more. I would repeat step d when you park up one evening and then see if the vacuum is there in the morning. oh yes, most servo units require a minimum of 3 pedal stroke to expel the full vacumm before the pedal goes hard. 5 or 6 strokes is common. Nick ///// .
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