Hi guys

I was wondering if you would be so kind to have a look at a couple of questions, as I am a bit desperate.

I am trying to fix my 1.2 8v 1996 punto and the problems are the following

- Temperature gauge won't go up to the 9 o'clock possition unless sitting in traffic and outside temperature is not too cold, when it's warmed up then traffic starts moving or I do motorway then the needle will go back down to maybe the 7 o'clock possition - I am suspecting open/faulty thermostat? heating works fine and I have already changed coolant, cleaned with radflush and bled everything. I am assuming that when the thermostat is working fine then the needle needs to be at 9 o'clock regardless temperature or driving conditions right? if that is the case then I think I will change the thermostat.

- Revving up spontaneously - when starting the car sometimes the red injector light is on or it will come on after a while - then it goes of - intermittently - then at a given point the car starts revving up between let's say 1500 and 3000 revs up and down, I have noticed that when the car is warmed up the revs will stay statically at 900 most of the time, but it sometimes revs up as well when warmed up not only when cold. When driving for a long time in the motorway then the light does not come on normally - only when backing off the throttle while going downhill. Strange but the car does not rev up when the red injector light is on and revs are steady at around 1.500. Sometimes it sorts itself up and revs stay at 800-900 mainly after a long trip with engine well warmed up.

- I tried plugging off the lambda sensor - but it revs up anyway - i suspected the lambda sensor might be faulty but I am unsure if unplugging the lambda should makea difference? Also when I passed the MOT all emissions parameters passed with flying colours.

- I am also suspecting the trottle body or sensors in it - apparently this is a commont fault?

- It can also be a vacuum leak but if that is the case - would I get the dreaded red light injector? which tubes should I check for leaks? I suspect not as if it was a leak then it would do it all the time but sometimes idle just works fine, so I suspect something electronic rather than a leak?

I have been offered a 60s lambda and throttle body - do you happen to know if they are the same as in the 75sx? I can also get the temperature sensor if I need it. they are both the 1.2 8v engine but I can't check if they are exactly the same as I don't have any photos of the one being offered.

I have also seen in the forum water temperature sensor - not sure if that will have to do with my gauge temperature not rising properly - I have seen that the sensor used for the gauge in the dashboard and the one in used by the ECU are different? if there are the same maybe that's what is creating trouble. How can I check? just by disconnecting the sensor?

Thanks guys for your help.

turbitoz said:

I am trying to fix my 1.2 8v 1996 punto and the problems are the following

- Temperature gauge won't go up to the 9 o'clock possition unless sitting in traffic and outside temperature is not too cold, when it's warmed up then traffic starts moving or I do motorway then the needle will go back down to maybe the 7 o'clock possition - I am suspecting open/faulty thermostat? heating works fine and I have already changed coolant, cleaned with radflush and bled everything. I am assuming that when the thermostat is working fine then the needle needs to be at 9 o'clock regardless temperature or driving conditions right? if that is the case then I think I will change the thermostat.

Click to expand...

Change the stat.

turbitoz said:

- Revving up spontaneously - when starting the car sometimes the red injector light is on or it will come on after a while - then it goes of - intermittently - then at a given point the car starts revving up between let's say 1500 and 3000 revs up and down, I have noticed that when the car is warmed up the revs will stay statically at 900 most of the time, but it sometimes revs up as well when warmed up not only when cold. When driving for a long time in the motorway then the light does not come on normally - only when backing off the throttle while going downhill. Strange but the car does not rev up when the red injector light is on and revs are steady at around 1.500. Sometimes it sorts itself up and revs stay at 800-900 mainly after a long trip with engine well warmed up.



- I am also suspecting the trottle body or sensors in it - apparently this is a commont fault?

- It can also be a vacuum leak but if that is the case - would I get the dreaded red light injector? which tubes should I check for leaks? I suspect not as if it was a leak then it would do it all the time but sometimes idle just works fine, so I suspect something electronic rather than a leak?

Click to expand...

Check all the hoses to the TB, including the breather hose. Disconnect both ends and blow through the long MAP hose. Yes, you can get the ECU light.

If all that fails, strip and clean the throttle body, especially the idle air control.

turbitoz said:

I have been offered a 60s lambda and throttle body - do you happen to know if they are the same as in the 75sx? I can also get the temperature sensor if I need it. they are both the 1.2 8v engine but I can't check if they are exactly the same as I don't have any photos of the one being offered.

Click to expand...

Some are the same, some are different -- I don't know which car you have or which is the doner!

turbitoz said:

I have also seen in the forum water temperature sensor - not sure if that will have to do with my gauge temperature not rising properly - I have seen that the sensor used for the gauge in the dashboard and the one in used by the ECU are different? if there are the same maybe that's what is creating trouble. How can I check? just by disconnecting the sensor?

Thanks guys for your help.

Click to expand...

They should be different. The one on the inlet manifold (usually blue) is the one the ECU uses.

Thanks for the replies - The tubes come with a clamp at each end if I undo them do I need to put new clamps? or can I just plug them back in

Also the breather tube - is this the back one that goes to the side fo the filter box?

Original car is 75sx 1996 donor is same age but 60s does this makes sense? both are 1.2

turbitoz said:

The tubes come with a clamp at each end if I undo them do I need to put new clamps? or can I just plug them back in

Click to expand...

Depends on the type of clamps -- if they're the factory ones, they're one use only without a special tool.

turbitoz said:

Also the breather tube - is this the back one that goes to the side fo the filter box?

Click to expand...

Yep.

turbitoz said:

Original car is 75sx 1996 donor is same age but 60s does this makes sense? both are 1.2

Click to expand...

Yes. Yours is MPI (4 injectors), the 60 is SPI. Some of the sensors will be the same, but the throttle body is very different.

Check also that the throttle cable isn't sticking, has plenty of slack, and that the rubber nipple thing on the TB end of the cable isn't interfering with anything (it can safely be cut off).

What about the Mk1 75sx and the Mk2 75sx?

Sorry to be a pain but I can't find many 75sx throttle bodies available on the internet for the Mk1 and maybe there are more available for the Mk2

I've never seen a Mk2 75. My best guess is that it'll have a plastic inletmanifold, so, while you may be able to swap the whole mani, I doubt that the TB is a straight swap.

I'd clean what you have -- they're pretty reliable and the tests for most of the sensors are out there. The poundshop carb cleaner works a treat (or try Netto).

OK you have convinced me - I will do some cleaning lol

I Have here with me the Haynes manual - to do the cleaning - do I need to take it out? I would need then to drain the cooling system?

Also - which are the sensors I need to clean?

The Inlet valve and the TPS - where can I find the sensors tests?

Thanks for all your help man !

if it's like the 16v with the throttle body on the back, right-side of the engine as you look at it, mounted to a plastic inlet manifold, you can't replace either the ICV or TPS - it needs a new throttle body or, if ur lucky, a damn good clean. It's bolted on with 3 T30 torx bolts (be VERY careful when tightening them, I rounded mine). The bolts can be replaced with 35mm long M6 bolts if you do kill them You'll find it takes a good can of carb cleaner to really clean out the ICV (the top one) and even then, it still may rev about - it's even worse if you stick a 1600 body on

pic attached of body i'm talking about (so we're all singing from same sheet!). bottom is std 1.2, top is brava/bravo/marea 1.6.

Other thing to look at is the possibility of a blown HG. Compression test.

Hi

It seems the problem is a manifold intake temperature sensor

If I disconnect it when the idle is wildly revving then the idle goes steady, plug it again and idle starts jumping or stays steady but high.

I have a new sensor and in case someone wants to test it with a multimeter then impedance is 3Kohm when the sensor is at room temperature, then if you dip the tip in near to boiling water the impedance drops really quick and stays at around 300 Ohms.

When I checked the faulty one it was giving wild readings, sometimes it was fine and had the 300 Ohm when hot, but then it started jumping to 1K or 2K when the car was still hot, then went into open circuit and things like that.

I will change the sensor when I get a minute but I am almost 100% sure I have fixed the problem.

I have also cleaned the whole intake while I was at it - it was full of junk I could not believe how dirty it was - not sure if there is any way to put a filter or something in the breather pipe, that was also full of gunk.

Thanks guys !

Putting a filter in the breather pipe is likely to cause problems, rather than resolve them.

You could consider an oil catch tank, but it's real overkill. Probably the first time yours has ever been cleaned!

Hi there - I have some news - it's fixed !!


First I changed the cold engine sensor - the one with the blue connector in the intake manifold (mine was black but replacement was blue) - that made a huge difference - straightway the idle was more stable then it dropped quickly to 900 as soon as the car was warm.

Next I changed the thermostat (finally yeah) and although the temperature does not go past the 8 oclock mark (yes you were right on this one) then the temperature now does not drop to the 7 oclock mark (despite the very cold day we have today here 1 degree C) and it does not fluctuate as it did before - sitting on traffic it stays at 8 and doing motorway it stays at 8 - then if you leave it for a while standing it will go just below 8 oclock and the fan will start working.

All in all the car is fixed and I am a happy camper now!

Thanks for your help guys !!

hi guys, im very new to this and i still can't actually work out how to post a thread yet i don't know if im juts being stupid! anyways as were on this conversation i was wondering if anybody could help me aswell? i have similiar problems to the poster but mine is a 03 fiat punto mk2. my tempreture gague quickly rises up to half way which i know is normal, but it continues to rise up to the three quarter and to just under to the red but it never travels into the red and overheats and the red warning light does not appear. but if i turn my heating on fully the temperature drops back down to half way. any ideas what is causing this? i also have revving problems what i slow down to a junction, as soon as i take mt foot off the accelerator and onto the clutch and brake the car continues to rev up and down between 1 and a half and 2 thousand revs!i have had the throttle body changed but this hasnt fixed the problem!any ideas please!