1997 polo 1.0 litre some power lost

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sav1
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1997 polo 1.0 litre some power lost

Post by sav1 »

my car has lost some power ,some times its alright then some times not ,it starts alright ,but when in higher gears it seems flat ,some poeple have told me it could be the maf or the temperature sender on the right side of the block next to the water pump ,whats the must common problems for this lack of power ,thanks for your time
Tahrey1043
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Re: 1997 polo 1.0 litre some power lost

Post by Tahrey1043 »

Could be a number of things..... need more info!
It's a right problem in a car that's only got 45-50hp and quite a heavy body though.

Is it at a particular point or area in the rev band? Any particular conditions that bring it on - climate, time of day, cold/hot engine, etc? Is the engine racing but you're not going much faster? Running lumpy or with extra vibration? Using lots of fuel and making a petrolly smell, but quite smooth?

The above questions can relate to:
Knackered ignition leads (had that a couple times) - create a poor spark that robs the engine of what little low-end torque it normally has, although it runs just fine past about 2500~3000rpm. Can be exacerbated by wet conditions, and borderline leads that are fine in the dry can exhibit it when it's damp or raining (or on a dewy morning before the condensation has been cooked off)

Knackered spark plugs can do similar, and also lead to completely "missing" cylinders (as can broken* fuel injectors on an MPi). Misfiring is usually easy to clock though, particularly on a 3- or 4-pot - there's a hell of a lot of vibration and at idle/low rpms the engine has a fairly rythmical sound to it rather than an even purr. Plus you'll be out a fair whack of power and torque - the usable net amount that the cylinder normally puts out AND the amount that's normally sapped just to keep the piston, valves and air-fuel mix moving at the chosen RPM (which the others now have to make up), so slightly more than 25 or 33%. (When I once took out two cylinders on purpose to see what the effect would be like, the car could hardly move)
* or in the case of a Punto of similar vintage I once had use of, injectors the ECU thinks are faulty, so it then shuts down the fuel and spark to the whole cylinder. Even when they're actually fine and it's just a typically italian firmware bug.

Changes with engine temperature could well be the temperature sensor. If the ECU is being told the engine's cold when it's not, for example, it could overfuel (the injection equivalent of pulling out the choke), with all the classic symptoms of being a bit stinky, not revving well, etc, and chowing down on petrol (i hope i'm getting this bit right - might be confused between injection / carb ;). Though it will do so without making a fuss, it'll just seem like it's in a very low state of tune. Your catalyser won't like it, mind. Faulty MAF can cause similar symptoms as the ECU then thinks a different amount of petrol is going in than the true amount (and also "Lambda" / exhaust oxygen sensor, which is a secondary monitor to all this - if the exhaust gases are in the right proportion then it can be assumed that all is fine upfront. If not, then the erroneous signal can also send things off).
BTW: A little bit of overfuel can actually boost power a little, when you run on full-throttle open circuit it actually does this - but only slightly, in order to use up every last scrap of available oxygen for power generation and to hell with emissions or economy. Drastically too much fuel is a problem though, and can interfere with the spark plugs etc.

More dangerous is if things are assumed the other way, by the same kind of faults. If the engine is set to run too lean, then it could either feel normal or slightly down on power, without the smell etc, but will overheat the combustion chambers (extra fuel has a cooling effect, excess oxygen the reverse) that can melt pistons, particularly if you push hard. A faulty or underspec injector (difficult for a 1L, but it may be blocked!) can create the same symptoms by not being able to supply enough fuel to meet the demands of RPM and throttle setting. Ask the G40 guys about it...

If the engine's revving away when you're in high gear but the car isn't gathering speed, and the RPMs seem no longer so well connected to the road speed, but it's fine across the rev range in lower gears, then your clutch is either worn out or badly adjusted and you're getting clutch slip. It's not as terminal as the others, but having it changed is a day in the garage and a couple hundred quid, so try to adjust it as soon as you can so that it doesn't burn out. Until you can do that, shift down when you feel it happening, or if going too fast to do that safely, ease off and take the speed hit.
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dub6n2
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Re: 1997 polo 1.0 litre some power lost

Post by dub6n2 »

use vag-com if available. If it detects a miss-fire most probably it is a high tension lead, always if the spark plugs are in good condition. I had a problem when revving above 3000k it started loosing power. used vag-com and it detected a miss-fire in one of the cylinders. it saves a lot of money :wink:
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polo_mad
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Re: 1997 polo 1.0 litre some power lost

Post by polo_mad »

h sounds gd
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