Technical Erratic Revving

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Technical Erratic Revving

fedupwithfiat

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Feb 2, 2004
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London, United Kingdom.
I have a Fiat Punto (1995) that has had something wrong with it since day one. It has just come back from an independent garage where it had four valves replaced because the timing belt slipped. When I drove away from from the garage (after having paid nearly £400 pounds) I noticed that the ECM light was permanently on. I went back to the garage but was bluntly told that it is not their problem since their remit was to get my car running again. After much argument I have reached the conclusion that they are not going to do anything about it unless I pay them some more money. Well, after two days of the light permanently staying on I have learned why it should be checked out as soon as possible. There is now a problem with erratic revving as soon as the engine is switched on. There is so much erratic revving that I can’t even drive the thing because it just doesn’t stop. Before I go back to a garage I would like to have some suggestions so that I can go back to them prepared and not like the wet, nodding, idiot I usually am. It may help you to know that the water pump was recently changed and that I have also noticed a leaking (drip-drip more than free flowing) from the front of the car. This mostly occurs when then engine is switched on and the leaking liquid is light blue in colour and smells like anti-freeze. If anyone could shed some light on the problem I would be very grateful.
 
check the basics,coolant leak check the hoses arn't loose but i would take it back to the garage,for the idleing again basics check that the air truncking isn't loose and all leads,connections etc are clean and good before you look at technical reasons

The Fiat Cinquecento
Fun While It Runs
 
I have tried to have a look and it seeems that if you pull out one of the two electrical plugs that are attached to the right side of the engine and restart the car then the revving stops. Unfortunately I can't trace the wire to its origin as a few cm's after it leaves the engine it joins another set of wires sheathed in a rubber hose. The only thing I can say about the wire is that where it plugs into the engine the socket is angled at 45 degrees. Does anyone know whjat this is?

Sanj
 
Fedupwithfiat welcome to fiatcentral. If you have the 8v engine don't give that garage anymore money. If the timing belt on a punto 8v engine slips or brakes there is no way your valves will get bent, the punto 8v engine is designed so that even if the piston is at top dead center and the valves fully open there is still a gap between piston and valves.

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Dave,

Thanks for your reply but the garage never mentioned anything about that and have already claimed to replace four of the valves which they say had bent. From what you say they must have been lying. This together with the new problem that has arrived makes me wonder if their isn't some foul play involved on their part. Anyone know what to do, is their anywhere you would recommend to get the car checked out?

Sanj
 
Hi,

Tell the garage you think that the work was done incorrectly and that you are having the car inspected as a result of advice from the Office of Fair Trading. Should the results of the inspection show that unnecessary work was carried out, then you will take the matter further.

As the light was not on before you took the car in, they are responsible for repairing it whatever they say. Did you pay with a credit card, if so ask the credit card company to hold the payment while you sort it out. You can say that the work was not carried out as agreed and they should hold off on the payment.

£400 to replace four valves seems a hell of a lot to me.

Poggy
 
I'm not so sure that a timing belt breaking absolutely cannot cause damage to an 8v engine. After hearing this claim for the first time I did some checking and although it seems as though the usual problems with bending after piston-valve contact aren't an issue there remains a chance the pistons can bottom out with enough force to cause vertical damage to the block.

However it does seem highly unlikely, and more likely that you've been ripped off, but I'd be careful before saying anything libelous. As others said get it checked by someone with clout and if you've been ripped off demand your £400 and any other costs incurred back. If the work really did need doing, £400 is about right though.

That dripping problem sounds like a classic case of coolant system hose. Look for crystaline deposits on the hoses to check for leak, or more likely it's leaking from where it connects.

Spirito di Punto | M-reg 55SX, black, 5dr. Clear repeaters. Remote locking fitted, no light confirmation yet though - need relay fitted
 
yep, the 1.2 8v is a 'safe' engine.
it basically means that the valves and piston don't overlap, that is to say they cannot physically come in contact and bend as a result.
 
[:0] Thanx for posting guys, but I have to say that most of what I have read has made me less than comfortable (since it suggests I've just thrown away £380).

Are there any circumstances under which the vavles would bend. I ask becuase I had a couple of people look at it, albeit without taking apart the engine it, and they seem to think that the work has been done.



Sanj
 
Oh, and before I get too carried away with sloving the mystery of whether or not I got fleeced, does anyone have any suggestions regarding my initial enquiry, i.e. the erratic revving.

Sanj
 
I am sure the revving problem is the ECU temp sender either breaking down, or having a faulty connection. This makes the ECU get no reading at all or one which is excessivley high. So the ECU leans off the mixture, (as is should for a v.hot engine). Then the lambda sensor picking up the weakened exhaust gases cause the idle stepper motor to increase the revs top stop it stalling. But the ECU weakens it off again as it thinks it is too hot. Hey presto it revs like mad at idle, normaly between 2000-2500. To overcome this check the sender. It is sited at the rear of the thermostat housing on the block. If you need a new one £25 from fiat. You need to state if it has a blue or black connector on the sensor itself. To check remove the connector and have a look. To make sure b4 buying, get a freindly garage to check your emmissions when it revs. If the lambda reading is too high, the mixture is then too weak, and that is DEFINITLEY your snag.
Hope this helps Cheers Rob.
 
Cheers Rob

I've taken off the the sensor (on the side of the engine and should be getting a replacment soon). But, i noticed that the water leak I mentioned has got worse. It is located at the left side of the radiator. Could this have anything to do with the problem? The degree of the leak has become quite severe. Topped up water saturday, bottle empty by monday!!

Sanj
 
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