Fiat Coupe losing power when hot.

Hi everyone. I have asked this on the Fiat Coupe club forum but I didn't get any replies so I thought I might ask it here..

When cold My fiat Coupe drives normally, but when it gets up to temperature it looses quite a lot of power. It also seems to suffer more turbo lag, and will not hold the boost as well as when the engine is colder.

The car has a GTEC1 chip and PRV boost controller but the problem was still there whilst the car was standard.

I have changed the lambda sensor, cleaned the MAF, and checked the hoses for leaks.

The air filter element is new, and fuel economy still seems pretty reasonable, although the exhaust gets pretty black quickly.

The thermostat is also fairly new, and becasue the car now gets up to the correct temperature the problem is now worse.

I have no nasty noises, no smoke from the turbo and no warnig lights on the dash. Oil pressure is good.

Has anyone any ideas as to what my problems may be?

I am thinking Coolant temperature sensor, but the cooling fan still comes on at the correct temperature. Is it still possible it is stuffed?

Many thanks,
Simon.

head gasket leaking...???....i had a saab 9000 turbo with those very symptoms...i hope its not that bro, might be worth checking tho...

Originally Posted by biggbn

head gasket leaking...???....i had a saab 9000 turbo with those very symptoms...i hope its not that bro, might be worth checking tho...

I don't like the sound of that..

I will check it, but there are no other problems you would associate with a leaking HG, oil and water are still very seperate etc. It also doesn't overheat. And runs pretty well apart from the power loss.

I did read on FCCUK that headgasket failure is pretty rare on the coupe, and it generally happens after the car has overheated. So fingers crossed its ok, though I am sure it is.

Simon.

Exhaust manifold crack? I know they're quite prone to this, although I'm not sure the symptoms do actually match.

Originally Posted by bazza

Exhaust manifold crack? I know they're quite prone to this, although I'm not sure the symptoms do actually match.

It does actually have a small crack, and ticks when the engine is cold. I was told by the guy that did the cambelt that the crack wasn't too bad as it seals back up when the engine is hot, and wasn't likely to affect the performance.

I have ordered a new coolant temp sesnor, as I am not sure if the rad fan is controlled by a different sensor to the one the ECU monitors. At least then thats one possibility ticked off of the list.

I am still thinking I have a boost leak. I'll have to get the undertray off at the weeksnd and check all of the hoses.

check the intercooler end caps as I think they can split but would have though any sort of boost leak would manifest itself when cold also.

Originally Posted by symonh2000

It does actually have a small crack, and ticks when the engine is cold. I was told by the guy that did the cambelt that the crack wasn't too bad as it seals back up when the engine is hot, and wasn't likely to affect the performance.

Ay yes, I was getting it the wrong way round, thinking that the crack could widen when hot, hence only getting the symptoms then, but that's wrong.

Originally Posted by bazza

Ay yes, I was getting it the wrong way round, thinking that the crack could widen when hot, hence only getting the symptoms then, but that's wrong.

Thats ok.

I am still drawn to a small boost leak. I have been doing a bit more research.

Boost leaks can cause the car to run rich, as the air is being sucked through the MAF before being lost hence tricking the ECU into thinking that the engine is getting more air than it really is.

Running rich would explain for the hot power loss....

I was thinking an intercooler problem, why not get a cheapo exhaust mani for the car? To rule out the crack that is in the mani all ready. And if the intercooler is wrecked why not get an FMIC??

Hi. Have you checked that the turbo is revolving freely? The impeller on the exhaust side gets pretty hot, and relies on the oil circulation to help dissipate the heat. If the bearing has picked up and is dragging, it could tighten up as it heats up so causing boost loss. Might be worth investigating. Hope this might help, regards louis boy

Originally Posted by symonh2000

Thats ok.

I am still drawn to a small boost leak. I have been doing a bit more research.

Boost leaks can cause the car to run rich, as the air is being sucked through the MAF before being lost hence tricking the ECU into thinking that the engine is getting more air than it really is.

Running rich would explain for the hot power loss....

It also explains the black tailpipe.

I am planning to do some work on the car at the weeksnd. I have a new strut top mount for the drivers side and a new pair of lower arms. Whilst its in the air I will check all of the large and small boost hoses. Apparently splits can be very hard to find..
I don't think it will be anything too serious otherwise there would be noises, smoke, warning lights, and the car does drive pretty well otherwise...

Thanks Guys..

Hopefully you get it sorted man Great car you have.

Hey Si,

Hope the car's alright mate and it's nothing too bad,

Can't say I noticed anything like that when I had the car, but as you said you changed the thermostat so it could be making itself more known.

Good luck with it though bud,
Darren

I'm with Sandys and Damien - look at the intercooler side of things.

Hope it's an easy fix.

ditto..my sugestion was total worst case scenario.....heres hoing its something relatively simple bro, fantastic cars..keep on top of it....

Thanks guys.. I was driving it into work today in the rain and the car seems to perform a lot better.

If it is the intercooler I can probably get a good second hand one cheap. I don't want to go for a front mount though as they are expensive and side mount are not much better than the original apprently..

I think its probably one of the hoses though. I had the wheelarch liner out and had a look down from the top as well and the intercooler looks fine.

I am sure I'll get it sorted, if not I will sell it and buy a 156 V6 or a GTV.

Originally Posted by Darren156

Hey Si,

Hope the car's alright mate and it's nothing too bad,

Can't say I noticed anything like that when I had the car, but as you said you changed the thermostat so it could be making itself more known.

Good luck with it though bud,
Darren

Thanks Darren. When you had the car it wasn't running full boost as the original boost valve was stuck. Whatever I have done raising the boost to the correct level and changing the thermostat has highlighted the problem. Its an absolute rocket now when its going well though.

Don't worry we'll get it sorted at the weekend.

Yeah, good luck with it anyway mate.

Lisa's harrasing me to get a new car though at the mo so she can have the 156

Not sure what to get though... Maybe another 20VT?



Nah, been there, done that, maybe a TVR Chimaera, they've gone down in price a fair bit.

Originally Posted by Darren156

Yeah, good luck with it anyway mate.

Lisa's harrasing me to get a new car though at the mo so she can have the 156

Not sure what to get though... Maybe another 20VT?



Nah, been there, done that, maybe a TVR Chimaera, they've gone down in price a fair bit.

TVR's are great. My dad had a Chimaera 500, which he wrote off, and I had a Griffith 500.
They are mental cars, but not for the faint hearted. Maintenance isn't cheap and they don't crash very well.
My dad ran into a landrover in his fracturing his skull on the steering wheel and breaking 3 vertabra in his back. The police reckon the impact speed was around 25mph.
If he was in a car with an airbag he would probably have walked away.

He also got MRSA whilst in hospital which also didn't help.

Oh dear