Technical Engine dies when clutching after driving downhill.

[FryNOR]

Hello.

I have a strange problem with my 2001 Punto 1.2 8V, whenever i have been driving downhill for a while using the engine for braking the engine shuts off when i press the clutch pedal.

This only happens when going downhill and there are no error codes after this happens, otherwise the car runs good but it can be a bit of a kangaroo when driving slow in first and second gear.

There is one thing i have noticed and that is the temperature gauge drops a lot when going downhill, this happens even thou the ambient temperature is 38-40°. I have a new thermostat and temperature sensor but they have not been fitted yet.

The parts i have changed so far is:

- Coils.
- Spark plugs.
- Spark plug cables.
- Air filter.
- Crank sensor.
- Cam sensor.
- MAF sensor.
- Throttle position sensor.
- Idle air control valve. (the old one came out in a thousand pieces, will buy a new throttle body next time).
- O2 sensors. (the only parts that came up with error codes).

I know that throwing parts at the car like this is not a smart economical move but i really like to work on this small gem, my daily is a 43 year old Land Cruiser that almost never go wrong but when it does everything is so heavy.

I will appreciate any suggestions you might have.

 

[bugsymike]

Hello.

I have a strange problem with my 2001 Punto 1.2 8V, whenever i have been driving downhill for a while using the engine for braking the engine shuts off when i press the clutch pedal.

This only happens when going downhill and there are no error codes after this happens, otherwise the car runs good but it can be a bit of a kangaroo when driving slow in first and second gear.

There is one thing i have noticed and that is the temperature gauge drops a lot when going downhill, this happens even thou the ambient temperature is 38-40°. I have a new thermostat and temperature sensor but they have not been fitted yet.

The parts i have changed so far is:

- Coils.
- Spark plugs.
- Spark plug cables.
- Air filter.
- Crank sensor.
- Cam sensor.
- MAF sensor.
- Throttle position sensor.
- Idle air control valve. (the old one came out in a thousand pieces, will buy a new throttle body next time).
- O2 sensors. (the only parts that came up with error codes).

I know that throwing parts at the car like this is not a smart economical move but i really like to work on this small gem, my daily is a 43 year old Land Cruiser that almost never go wrong but when it does everything is so heavy.

I will appreciate any suggestions you might have.

1. When engine idling in neutral does the revs drop when you dip the clutch, if so it can be crankshaft thrust bearings, so hopefully not.
2.When engine idling in neutral does the revs drop when you press the brake pedal, if so it can be a vacuum leak, possibly brake servo.
3. This is unlikely on your age of vehicle, but recently I had the same issue you describe and it was the clutch pedal position sensor on a 2014 vehicle with stop/start so I doubt if anything like that is fitted on yours.
4. If thermostat is stuck open and engine temp drops a lot it could be affecting the fuel/air ratio. So new thermostat may help.
5. Very unlikely, but a friend years ago had a performance carb icing up. Unless you have no air filter or intake has been modified.

 

[FryNOR]

1. When engine idling in neutral does the revs drop when you dip the clutch, if so it can be crankshaft thrust bearings, so hopefully not.
2.When engine idling in neutral does the revs drop when you press the brake pedal, if so it can be a vacuum leak, possibly brake servo.
3. This is unlikely on your age of vehicle, but recently I had the same issue you describe and it was the clutch pedal position sensor on a 2014 vehicle with stop/start so I doubt if anything like that is fitted on yours.
4. If thermostat is stuck open and engine temp drops a lot it could be affecting the fuel/air ratio. So new thermostat may help.
5. Very unlikely, but a friend years ago had a performance carb icing up. Unless you have no air filter or intake has been modified.

1. Revs don't drop when pressing the clutch, it idles very smoothly.
2. I have to check if the revs drop when pressing the brake pedal, but i am pretty sure that's not the case.
3. I am not sure but i don't think that this model have a clutch sensor.

4. I am going to change both the thermostat and the temp sensor, the thermostat that is on it now looks pretty new but car owners here have a tendency to take out the thermostat if the engine is running hot. This is caused by the fact that they don't bother to use proper coolant, someone might have jammed the thermostat open or ripped it out of the housing.

5. No icing here since it's the Canary Islands.

One thing that crossed my mind is if it could be because of blow-by from the engine, failing fuel pump or vacuum related. This only happens when going downhill for a couple of kilometers, if i drive a shorter distance downhill the revs drop a lot but the engine manages to compensate.

 

[ZaphodB]

Is this fuel injection?

Most modern cars will shut injection off on in gear over-run (i.e. going downhill in gear with no acc input).

Too early for stop start isn't it?

 

[FryNOR]

Is this fuel injection?

Most modern cars will shut injection off on in gear over-run (i.e. going downhill in gear with no acc input).

Too early for stop start isn't it?

Yes it's fuel injection and it's too old for any of that fancy stop start, the engine fires right up again if i let out the clutch while it's still moving just like when push starting a car.

 

[ZaphodB]

Yes it's fuel injection and it's too old for any of that fancy stop start, the engine fires right up again if i let out the clutch while it's still moving just like when push starting a car.

So it's unlikely to have a clutch pedal switch (or sensor as you describe it)

 

[FryNOR]

So it's unlikely to have a clutch pedal switch (or sensor as you describe it)

I doubt it has a pedal switch, it's a very simple car and the technology reminds of something from the late 80's early 90's.

 

[GrandePunto PL]

8V = valve clearance ("lash", adjustable with shims) and cam lobes lift (camshaft wears out a bit).

 

[bugsymike]

Re the Canary Islands bit and temperature for icing up, the issue wasn't caused by local temp outside but the principle that is similar to drawing air into your mouth through a mint polo making your mouth cool if you know what I mean.
Look up carb "icing" to see what I mean.
Another point when engine cuts out is there any smoke from exhaust such as caused by worn engine, I have seen cars going down hill on the"over run" then a plume of exhaust smoke as they accelerate away caused by oil fumes drawn into the intake making the car run bad.

 

[Mike1alike]

Did you clean the Throttle body when you put the new TPS and IACV in? Did you manage to place the IACV correctly? It has the oring that sits in that little designated spot (there are multiple layers, different sizes inside TB) and is very easy to catch it and misplace it. If it sits in it's place, the IACV will sit a little bit outside TB and no air passes beside it. If it goes all the way in, means the oring does not sit in its place and air will pass beside it.
This is it fitted correctly and incorrectly



You can test if there is vacuum leak. Engine running, air filter box off, cover the TB opening using your palm. If the engine cuts off, no leaks. If it's stiil running, just RPM drop, leaks.

Definitely put the new thermostat as soon as possible. The one that's on now is either missing, either stucked open.
You should clean the injectors. There are very good solutions for this, fuel additives. I used this one, it's not expensive and efficient

After that, do a Phonic wheel reset using MultiEcuScan.

 

[FryNOR]

Did you clean the Throttle body when you put the new TPS and IACV in? Did you manage to place the IACV correctly? It has the oring that sits in that little designated spot (there are multiple layers, different sizes inside TB) and is very easy to catch it and misplace it. If it sits in it's place, the IACV will sit a little bit outside TB and no air passes beside it. If it goes all the way in, means the oring does not sit in its place and air will pass beside it.
This is it fitted correctly and incorrectly

View attachment 471395View attachment 471396

You can test if there is vacuum leak. Engine running, air filter box off, cover the TB opening using your palm. If the engine cuts off, no leaks. If it's stiil running, just RPM drop, leaks.

Definitely put the new thermostat as soon as possible. The one that's on now is either missing, either stucked open.
You should clean the injectors. There are very good solutions for this, fuel additives. I used this one, it's not expensive and efficient
View attachment 471397
After that, do a Phonic wheel reset using MultiEcuScan.

The TB was pretty clean but i still gave it a clean with carb cleaner, i am pretty sure that the TPS and IACV is mounted correctly since there is no difference between before and after. But i will check if there are any vacuum leaks and change the thermostat and temperature sensor.

Also the TB gasket looked good and i could feel that the TB was pushing on it, might change it anyways but i can't find it online anywhere. Because of my location i buy parts from Autodoc and i am trying to find a new TB that comes with screws and gasket.

This is just a thought but is it possible that a vacuum leak can occur because of temperature expanding/shrinking materials?.

 

[bugsymike]

This is just a thought but is it possible that a vacuum leak can occur because of temperature expanding/shrinking materials?.

Less likely I would have thought, but you never know.
As they say "Every day is a school day"

 

[Mike1alike]

This is just a thought but is it possible that a vacuum leak can occur because of temperature expanding/shrinking materials?

Yours is not a problem of vacuum leak, I mentioned it because you said you replaced the IACV and TPS and if not fitting those correctly, with their orings closing the space, results in small vacuum leaks that does a little difference in how the engine is running, it goes like about 100 RPM higher on idle. That wouldn't cause the problem that you're having. On vacuum leak the RPM is always higher and if the leak is bigger the engine would revv by itself to 2500~3000 RPM then come down to idle value, repeatedly.
Yours is lack of fuel. Try what I said above, cleaning the injectors with fuel additive plus Phonic wheel reset afterwards. That should fix it.

 

[Mike1alike]

Also the TB gasket looked good and i could feel that the TB was pushing on it, might change it anyways but i can't find it online anywhere.

Yeah, you cannot find that gasket alone. I think your TB is the same as on all Punto mk2 (codes 46781326, 71718959, 71787554, 71788061, 77363298). You would find the gasket for that in a set with screws and TPS with this code 71738921 Ricambi Originali, but you already got the TPS. You can find it also in a set with all intake manifold gaskets, code Elring 728670 or 71716684.

 

[Mike1alike]

And of course, if need be, you can always use sealant on the used gasket. I did that couple of weeks ago, then replaced the TPS and discovered that I had a new gasket remained from the Elring 728670 set. It is plain round, but fits perfect.
Sealant on the old gasket I used Renzosil by Victor Reinz, put a round line on top of gasket, mostly on the outside edge, let it sit about 15 mins, placed the TB directly in its place (using the screws), let it sit for about 1 hour then tightened the screws. Let it rest overnight and started the engine the next day. It did a perfect job, had no vacuum leak, tested it by covering the TB opening with my palm and the engine would cut off.

 

[Mike1alike]

replaced the IACV and TPS and if not fitting those correctly, with their orings closing the space, results in small vacuum leaks that does a little difference in how the engine is running, it goes like about 100 RPM higher on idle.

Actually, I take that back. That doesn't happen.

Yes, you can wrongfully fit the IACV or TPS oring and then there is a little vacuum leak. And that can make the engine not cut off if you cover the TB mouth testing for vacuum leak. But overall, it doesn't affect the engine's workrate or RPM idle. Because the leak is so small that ECU can adapt and will maintain desired intake manifold pressure by opening fewer steps the step-motor on idle.

@FryNOR, any progress?

 

[FryNOR]

Actually, I take that back. That doesn't happen.

Yes, you can wrongfully fit the IACV or TPS oring and then there is a little vacuum leak. And that can make the engine not cut off if you cover the TB mouth testing for vacuum leak. But overall, it doesn't affect the engine's workrate or RPM idle. Because the leak is so small that ECU can adapt and will maintain desired intake manifold pressure by opening fewer steps the step-motor on idle.

@FryNOR, any progress?

Sorry for the late reply but i think that i have found the culprit, today i changed the temperature sensor and the thermostat.
I present you with a Spanish special, the thermostat-less thermostat.

Before i changed the thermostat and sensor i flushed the cooling system two times with TPS Radiator Flush, after i changed the parts i vent for a long ride downhill and there was not even a hint that the engine would shut down. The temperature gauge stayed right in the middle the whole trip, it also seems like the kangarooing at low RPM vent away.

One thing i have noticed is that the radiator cap is leaking and the radiator is not in great shape so i have ordered a new radiator and cap, i struggled a bit to find the right radiator since my car has AC and the description of the radiators on AutoDoc is lacking to say the least. So i ordered a radiator from Ridex even thou i know that the quality might be garbage, it was only 70€ including a cap and shipping so it might be worth a shot.

Oh and i have checked for vacuum leaks and i could not find any.

Now it is time for a cold one and a tap on the back.

 

[bugsymike]

Now it is time for a cold one and a tap on the back.

Must be in the air, I have just opened a tin McEwans and topped it up with Navy rum, I have recurring pain from hip to knee and to add the pleasures of the day asked Insurance broker to change cover to a different van, there was 4 months left on policy and they wanted to charge me £155 for the remainder on a basic van, I pointed out another company would insure it for £273 for twelve months, they wouldn't budge so I cancelled the policy and they decided with cancellation fees etc. I would get nothing back. This is a company I have insured several vehicles with over several years and a clean license and they wonder why insurers have a bad name. Loyalty means nothing to them.

 

[ZaphodB]

Must be in the air, I have just opened a tin McEwans and topped it up with Navy rum.

 

[FryNOR]

Must be in the air, I have just opened a tin McEwans and topped it up with Navy rum, I have recurring pain from hip to knee and to add the pleasures of the day asked Insurance broker to change cover to a different van, there was 4 months left on policy and they wanted to charge me £155 for the remainder on a basic van, I pointed out another company would insure it for £273 for twelve months, they wouldn't budge so I cancelled the policy and they decided with cancellation fees etc. I would get nothing back. This is a company I have insured several vehicles with over several years and a clean license and they wonder why insurers have a bad name. Loyalty means nothing to them.

I watch a lot car related stuff from the UK on YouTube and i must say that the way your insurance system work is pretty strange and it seems complicated.

Back in Norway where i am from it is the car that is insured and not the driver, the price of the policy depends mostly on the car and the age of the owner, there are some conditions that can make the insurance more expensive like horsepower and statistics like if that certain model of car is often in accidents.

If someone under the age of 23 is to insure a car it is more expensive but if they don't have any incidents they get that extra money back when they turn 23, they also get a 10% price reduction for every year without incidents.

It is pretty much the same here in Spain except for the bonus part, sadly the insurance companies have a tendency to turn up the price every year at renewal even if you have never been in an accident. But if you are on the case and talk to the company the will often adjust the price back down.

Good luck with your insurance and health, i am going to chug down a good amount of beer and watch All The Gear.