Punto Rough Idling

magnumlady

Hiya all. I just recently bought a Used car from a trader. 1999 Fiat Punto 1.2cc 8valve. The trader offered 3 month warranty which we took up. When he dropped it off there was a smell of burning coolant in the car with the heater on. My husband and the trader surmised that the Heater Matrix/Rad inside the car might have a little leak so he told us to leave it back into him and first he was going to try some sealant (expensive trade stuff) to see if that would cure it and if not later on he would put a new heater matrix in.

Whilst it was in his workshop he reckoned that the head gasket looked like it had a leak so he changed that and skimmed the head and whilst it was there he thought he would change the Timing Belt as well.

He has since dropped the car back to us and said it was grand. The only problem is now we feel that before we left it in the car idled lovely and smooth and purred along - now we have got it back on Idling now it sounds so lumpy and there is a chugging sound out of the rear of the exhaust, the engine is considerably shaking and sitting inside the car with it idling now vibrates inside the car!

We phoned him up he is nice enough fella and said he would have a look at it but reckoned it was OK but now he is also more going on about giving our money back for the car if we are not happy with it. But I really liked the car when it was Idling and accelerating smoothly and I am figuring that it if it was just a simple job (like timing or mixture needs adjusting or something like that) then I would be a fool to take it back to him and get my money back if its a simple thing that could be put right.

Going on what I have said, what could have happened when it was in the workshop for this to happen, should we try and get it repaired (by him or another garage) or should we just take his offer up on the refund for the car. If it isn't a big job then it seems a shame to shoot ourselves in the foot and get a refund that could have been sorted simply. Does anyone have any clues to whats causing the rough idling? - We have looked at spark plugs and spark plug leads and they are all OK.

Thank you for any helpful advice fellow Boarders,

Val.

AMurphy

Does this engine have a distributor or not. EFI or CArb of some sort?.

Riven your rocking engine, Puffing exhaust, I suspect one of several items.

You have either a spark plug or injector that is not correct and the engine is mis-firing on one cylinder.
Or the valves are set very badly on one cylinder...
One injector was replaced wrongly and leaking air into the intake.
Valve timing is out a tooth on the belt... I assume this has an overhead camshaft - belt driven.
Check the head had been removed and replaced... easy, the edge of the headgasket (where visible) will look new, and the exhaust and intale manifold bolts & nuts will have signs of being disturbed.

Does this engine have balance shafts or not?.
if so, they could have been could be out of synch and if so the engine will rock, even when running well.

Interceptor

AMurphy wrote:

Valve timing is out a tooth on the belt... I assume this has an overhead camshaft - belt driven.

These engines are notorious for blowing head gaskets and if the head was removed and a belt fitted there is a strong possibility that AMurphy is right. I have rebuilt several of these engines and despite clear timing marks on both pulleys it is still possible to get it wrong by a tooth. I would take his offer of a refund and find another Punto - there are lots of them around and you will get a better one. If you are in any doubt, get out is my motto.

A second opinion from another mechanic would be the other option - if it is just a tooth skip on the belt it is easily fixed and it won't have done damage but the head gasket may not have been done properly and you are losing compression or getting interference as the compresson leaks from one cylinder to another between the bores.

My car (same engine) started running on three cylinders one evening after I hit a pothole - turns out the shock knocked the plug out of the ECU, so your problem could be anything...

I'd drop it back to the seller and if he can't fix it to your satisfaction, walk away.

'cptr

AMurphy

Another possibility, is whomever put it back together turned over the engine without the belt in place and hit a valve, jut a tip is enough to cause them to leak and given teh "bad cylinder & "Puffing" exhaust condition.
Quick Compression test will tell.

And loose wires are always a possibility after major engine surgery.

I had a 6sp 1.6L Punto rental once, went well overall

magnumlady

AMurphy wrote:

Does this engine have a distributor or not. EFI or CArb of some sort?.

Riven your rocking engine, Puffing exhaust, I suspect one of several items.

You have either a spark plug or injector that is not correct and the engine is mis-firing on one cylinder.
Or the valves are set very badly on one cylinder...
One injector was replaced wrongly and leaking air into the intake.
Valve timing is out a tooth on the belt... I assume this has an overhead camshaft - belt driven.
Check the head had been removed and replaced... easy, the edge of the headgasket (where visible) will look new, and the exhaust and intale manifold bolts & nuts will have signs of being disturbed.

Does this engine have balance shafts or not?.
if so, they could have been could be out of synch and if so the engine will rock, even when running well.

Thanks for the advice. My husband says the engine only has one injector its a single point injection engine. And he said that he has took out all the plugs and checked them. Strangely enough he found 3 plugs had the correct colouring (grey Brown Deposits) but when he took out Cylinder number 3 spark plug it was black and sooty only on that plug like it was wrong mixture setting but only one plug was like that - strange?

he looked at edge of gasket and could not tell if it was new or not, and there was no gasket sealant showing there (maybe it didn't need any sealant?)

He saw plainly that the exhaust manifold gasket had been replaced with a brand new gasket but it looked like the old gasket has been used for the inlet manifold gasket.

Thanks again for your help.

magnumlady

Interceptor wrote:

These engines are notorious for blowing head gaskets and if the head was removed and a belt fitted there is a strong possibility that AMurphy is right. I have rebuilt several of these engines and despite clear timing marks on both pulleys it is still possible to get it wrong by a tooth. I would take his offer of a refund and find another Punto - there are lots of them around and you will get a better one. If you are in any doubt, get out is my motto.

A second opinion from another mechanic would be the other option - if it is just a tooth skip on the belt it is easily fixed and it won't have done damage but the head gasket may not have been done properly and you are losing compression or getting interference as the compresson leaks from one cylinder to another between the bores.

My car (same engine) started running on three cylinders one evening after I hit a pothole - turns out the shock knocked the plug out of the ECU, so your problem could be anything...

I'd drop it back to the seller and if he can't fix it to your satisfaction, walk away.

'cptr

Thanks For the suggestions. Do you have to adjust timing when you fit a new belt? maybe they fitted the belt but didn't put it on a machine to adjust the timing? - Do you have to get a Fiat main dealer to adjust timing and mixture on the Punto's or should any garage have the necessary machine to do it do you reckon?

You say about taking the offer of a refund but it has been so hard to find 98/99 Mk1 Punto's down here where I live believe it or not I have been looking for ages. Up in Dublin there seems to be an awful lot more Mk1 Puntos for sale.

Most dealers down here will not sell any used cars under the year 2000 or sometimes 2002 because they say they dont want the hassle of them ones coming back or providing warranty for them! - I don't like the shape and the interior of the Mk2 punto's (2000 on) at all I liked the shape of the Mk1 much better.

The guy we bought off goes around these main dealers and buys all these traded in under year 2000 cars at trade prices and then sells them on.

Is it expensive to get a compression test done on the engine in a garage and again does it have to be Fiat dealer that does it or will any garage do it? - would it be a thing that could be done on the pot as well?

Thanks,

Val.

Interceptor

A compression test should be cheap/free - it is an easy test to do.

The timing is set from the crankcase position sensor to the ECU which optimises the fuel and spark via the ignition packs so it doesn't need setting.

The mixture is controlled by the ECU too and unless your lambda sensor, map sensor or cat convertor are shagged I wouldn't worry about this - either way the engine management light will come on on the dash.

The timing belt can be checked if you take the drivers side wheel off, wheel arch liner out and cambelt cover off. Pull out the four plugs and turn the engine until the white mark on the belt coincides with the notch on the camshaft pulley - then check that the other white mark coincides with the bottom edge of the crankcase - where it is mated to the sump. I'd nearly check to see if there really is a new belt there first too, just in case your sales guy is messing you about.

'cptr

magnumlady

Interceptor wrote:

A compression test should be cheap/free - it is an easy test to do.

The timing is set from the crankcase position sensor to the ECU which optimises the fuel and spark via the ignition packs so it doesn't need setting.

The mixture is controlled by the ECU too and unless your lambda sensor, map sensor or cat convertor are shagged I wouldn't worry about this - either way the engine management light will come on on the dash.

The timing belt can be checked if you take the drivers side wheel off, wheel arch liner out and cambelt cover off. Pull out the four plugs and turn the engine until the white mark on the belt coincides with the notch on the camshaft pulley - then check that the other white mark coincides with the bottom edge of the crankcase - where it is mated to the sump. I'd nearly check to see if there really is a new belt there first too, just in case your sales guy is messing you about.

'cptr

Thanks we will check all that tomorrow (Sunday) weather permitting!

Cheers.

magnumlady

Thanks for the replies. Today (Sunday) my Hubby took the Throttle body off the Inlet Manifold and the top and bottom gaskets looked a bit ropey so he had a tube of instant gasket and put some of that on them and after putting it all back and restarting it seems to idle a lot smoother now, maybe some air was getting in he reckoned.

Gonna test it over the next few days but hopefully that might have fixed it.

Thanks.

Val.

The OP

magnumlady wrote:

Punto

Aaaah - that's explains the problem.

magnumlady

The OP wrote:

Aaaah - that's explains the problem.

Yeah, I suppose hubby will be 'Fixing it again tomorrow' - and the next day, and the next day after that.......

Seriously though they do get a slating for reliability but I have come across a few people and read reviews who have had a Punto over the years and apart from the head gasket problem has found them to be not too bad. - I suppose you get good ones and bad ones like most cars. Parts are easy enough to come across I suppose which is a good thing.


Val.

AMurphy

magnumlady wrote:

Thanks for the replies. Today (Sunday) my Hubby took the Throttle body off the Inlet Manifold and the top and bottom gaskets looked a bit ropey so he had a tube of instant gasket and put some of that on them and after putting it all back and restarting it seems to idle a lot smoother now, maybe some air was getting in he reckoned.

Gonna test it over the next few days but hopefully that might have fixed it.

Thanks.

Val.

Hmmm, strage indeed. You say it is single point Throttle Body Injection (TBI), which tends to behave like a carburettor, all cylinders get pretty much the same mix, yet one plug has fouling... Are the plugs all the same and if so are they correct. Fouling does point towards a rich mix, (or an unburned one), replace that single plug see what happens or clean and switch that plug to another cylinder and see what happens, does the fouling stay with the plug or the cylinder?. if the plug, I'd suspect a defective plug, if the cylinder, may be a defective lead, or distributor cap (assuming it has a rotor and cap, ignition setup).

You removed this TBI assy and put gasket adhesive on whatever gasket there was. True a gasket if disturbed and reused, would leak. However, if it leaked, why does one cyl foul... cause fouling means rich, and leaking air means lean.... so does not compute, even though you report improvement.

Also, if your car has an O2 sensor in the exhaust, usually found in the CAT or between the engine and the CAT AND this gasket adhesive was not certified as "SENSOR SAFE", its bye-bye sensors, the Silocone in the generic gasket adhesive WILL kill off O2 sensors very quickly, if not immediately.

What sort of air flow measuring sensor does this vehicle have. it is either, MAF, MAP or none, ie it is internal to the TBI assy.

There is no additional sealant necessary on a Head Gasket,ask for your money back if there is.
If he can tell the inlet gasket was changed, use the same technique to check the head gasket.... and /or check the head bolts are new or were disturbed. Any collected oil, dust and gunk between the head and block should have been cleaned off.

Compression testing, simple. My garden tiller was not firing up as expected, I did the new plug bit, new carb diaphram, fresh fuel. Finally did a compression test. 30PSI. Problem found.... New engine required. You're looking for >120PSI and within 5psi in all cylinders.

Lex Luthor

My wife had a 97 Punto 1.2 8 Valve and twice the coils packed in causing it to run on 2 cylinders rather than 4 and displayed rough idling, but the ignition light on the dash showed up on both occasions.

There are 2 coils on these cars, one for 2 spark plugs each. I hope its as simple as this as they could be changed in 5 min and cost about €80 each. Its just a matter of trial & error to find the faulty one.

eth0_

The OP wrote:

Aaaah - that's explains the problem.

Post reported.

I really think mods should start banning people for unconstructive, slagging posts such as this one.

lomb

U need a compression tester as a murphy rightly says. u can buy them for small money from halfords. inset into each spark plug hole in turn and measure maximal compression.

also as he pointed out the silicone will kill the o2 sensor in the exaust system and this is another 100 euros in addition to contributing to a rough run due to running on defaults.

The OP

eth0_ wrote:

Post reported.

I really think mods should start banning people for unconstructive, slagging posts such as this one.

Post reported for being Off Topic.

mike65

Banned.

Mike.