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i have a strange problem... 700 88

Heya all (again!),

I started my car today, and out of pure curitosity, i pulled the hose the goes from the "oil trap" (i think it's the pcv valve, the hayes manual calls it an oil trap...), and i had just started the car for the first time in the day, outside temp was about 26 degres celcius. I pulled the hose out from the air intake duct, and noticed that a constant smoke (not really thick, but thick enough to see) coming from it, is that normal? I covered the hose with my thumb, and i could feel any pressure at all...is this normal?!

Also, something else strange happend today...my tacho looks like at idle, that it is showing around about 500rpm....so after driving the car around, everything seemed normal, so i pulled out the engine analyser, and set it to "tacho" mode. What did i get? About 770 rpm, and a strange phenonomen... After about 5 seconds, i went "wah?!". at what seems to be semi-regular intervals, the "idle" jumps from 770 to 1100rpm, then goes back to normal, then about 2 seconds later, it does it again, then won't do it again for another 5 or so....when i say 5 or so, sometimes it doesn't happen at all....(for about 30 seconds). When the "tacho" (the "tacho" being the engine analyser, the cars dash tacho jumps randomly on the odd occasion also), jumps, the engine nearly seems to go lower in idle by about 50rpm or something, for a split second then everythings normal again.....i have recently replaced the dist. cap, rotor button and spark plugs and coil lead, but it was still doing this before i replaced them. (believe me, they NEEDED replacing!!! Try 200,000 on the origional dist cap, rotor, and coil lead!!). The only thing i can think of that would cause this random sparking (the "tacho" was running off an inductive pickup on cyl. 1), would be a seriously confused hall sensor (or a possible stuffed one!), or a screwy computer......the only other engine problem i have noticed is a bit of black smoke at WOT after about 5g rpm. I have only gone that high 3 times, but it seems to be pretty consistent.

Oh, just today, while idling i noticed that there seems to be strange "sucking through a straw" type noise in between cyl. 2 and 3, on the intake side somewhere, is this normal? I couldn't pin point it, but am going to try....

Sorry, am i boring now?!

One last thing before i go, does anyone know of a red paint that volvo used on 740's, which has an extremely fine metallic type thing in it? My description of the colour isn't quite fire-engine red, but more of a "burnt orange" metallic with a fire-engine red base......sound wierd? I think it is! If anyone knows what colour this is, could they please let me know?! (and if there is another similar colour from another paint range!)

Thanks all, i'll keep you updated!








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    Re: i have a strange problem... 700 88

    If the tach jumps but the engine speed does not, and you are sure the tach is working right, you are getting primary pulses you should not have. The tach reads the number of +- switches the coil is seeing. Definitly an ignition problem, and I would say 3 chances in 4 it is your hall effect switch. Other possibilitys would be ignition power amplifier or ignition control unit, or probably about 3,000 other things.

    A little smoke out the breather is normal. That is what condenses and plugs them.

    A dash tach that is inaccurate at idle is normal. If they are within 10% at low speed that is pretty good.









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    Re: i have a strange problem... 700 89

    If you get hold of a manual of dulux automotive paints I am sure you will be able to find the colour.

    I was at a cabinet maker the other day and he had a book of dulux paints. It seems for those glossy cabinets the guys use automotive paint. I took the opportunity to look up mine, blau somethign or other, because my car is blue metallic.

    the reason why i suggest the dulux book is that it appeared to list every car sold in Oz since dot.

    good luck

    Alex








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    Re: i have a strange problem... 700 88

    This is just wild theorizing...That sucking noise you hear near the intake may be a vacuum leak in the flame trap area. (Oil trap, PCV system, whatever you want to call it.) Check closely for any loose hoses. A significant vacuum leak may be causing the idle control motor to "hunt" giving you an unstable idle speed.

    With the miles you have on that car, it would probably be a good idea to clean the flame trap, throttle body, and idle control motor. Also see what is causing the sucking sound. It could be a leaking hose or gasket at the throttle body or intake manifold.

    Do the free or cheap stuff first.







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