Technical MK2 1.2 8v Revs like crazy constantly.

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Technical MK2 1.2 8v Revs like crazy constantly.

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Just bought another MK2 to work on. However, the guy said that the RAC guy who recovered the vehicle from breakdown said the head gasket had gone. However, when you start the car, it really struggles. ones its going, the engine revs up to like 5000rpm as stays around that level (fluctuates a lot tho, but stays in the top end of the revs.) This it without touching the pedal. It doesn't lack power either - after towing the car home, i had to drive it up the driveway, and when i slowy released the clutch, it shot up the hill, so definatly no power problem.
It was pitch black when i got the car home, so i haven't had a real look, but surely it cant be the HG? With a blown HG it would struggle to run at all, never mind get to 5000rpm. So im thinking ICV? or could the TPS cause it? any other things that could cause it? Would i be better just replacing the entire throttle body?

Cheers :)
 
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had a better look after work. Inside the TB (under the butterfly) is a pool of dark brown oil, but the oil breather pipe is dry, suggesting oil got inside the TB through a leak in the HG between an oil gallery and a cylinder. Am i thinking along the right lines?
So if oil is leaking into a cylinder, would the oil be burning aswell, causing it to increase speed? After the cars been running, it absolutly stinks of fumes. There is also oil all over the outside of the gearbox end of the block.
 

D4nny8oy

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Yep, still here.
It's not unusual for the 8v (and 16v) inlet manifold to have oil laying inside, the breathers tend to cough it up from time to time. ;)

If the head gasket has gone, it's very common for the plastic inlet manifold to melt around its fixings until it leaves an air gap, causing leaks and a huge over-revving issue. If you look where the 12/13mm nuts hold the manifold on you'll probably see the plastic has melted and sunk around the metal inserts.

Only fix is a new inlet manifold (after fixing the head gasket!)

(y)
 
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Cheers, ill have a look tomorrow (y) doesn't sound like a nice job if it is tho :(

we'll have to see. keep the ideas/advice coming tho (y)
 
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well i took a look after work and it looks ok. but i didnt go as far as removing the tb/injectors etc to get a proper look as it was getting too dark, and i didnt want to have bits dismantled until i next get chance to work on it as im bound to loose something :eek:
 

D4nny8oy

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Yep, still here.
Why remove the throttle body and injectors? leave them on!

Just disconnect the wiring plugs, throttle cable, coolant/fuel hoses, unclip the wiring loom underneath (two simple clips, but one's a b***h sometimes:cry: ), then undo the 5 nuts and two bolts, all 13mm, and it's off.

Be careful if fitting a second-hand manifold as Fiat made some subtle tweaks to parts on the exterior after a set chassis date.

(y)
 
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Why remove the throttle body and injectors? leave them on!

Just disconnect the wiring plugs, throttle cable, coolant/fuel hoses, unclip the wiring loom underneath (two simple clips, but one's a b***h sometimes:cry: ), then undo the 5 nuts and two bolts, all 13mm, and it's off.

Be careful if fitting a second-hand manifold as Fiat made some subtle tweaks to parts on the exterior after a set chassis date.

(y)

Cheers mate, will have a look on tues if i get chance (y)
 
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well the intake manifold looks fine, which is a relief in someways, and not in others as i still have no clue what it is.

Maybe T or another fiat tech could tell me if the fault might show on a fiat diagnostic computer?
 

The Sultan

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early 188 putos have a problem with the ecu causing reving up witch can be solved with an update software on your ecu

if it is not this then I would say idle control valve

and before anyone says it idle control valve can rev to 5000
 
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Ill give fiat a ring to see if the update is applicable/already installed on this car (y) would an ICV fault show up on diagnostics? just thinking i might be able to save myself a whole load of hassle if i just get it diagnosed by fiat. haynes says the ICV is fully contained within the TB and cant be repaired, is this right? am I looking at another TB?
 

The Sultan

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Ill give fiat a ring to see if the update is applicable/already installed on this car (y) would an ICV fault show up on diagnostics? just thinking i might be able to save myself a whole load of hassle if i just get it diagnosed by fiat. haynes says the ICV is fully contained within the TB and cant be repaired, is this right? am I looking at another TB?

yes it may be contained

the fault wont show on diagnostics
but a good technitin will easilly diagnose it if it is faulty using the icv test on the examiner
 
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Cheers for that (y)

I was just thinking today- it must be a fault somewhere in the TB. Something in the TB has to be letting too much air in because theres no other way it could rev like that. even if something was causing petrol to be pumped through like mad, it would just run rich and splutter - i wouldnt have thought revs would be able to rise that high without more air.

So i came to the conclusion that even if there are other problems, the TB has to be at fault anyway so i should replace it with a known good one from a scrappies - probly gonna be the best approach.

Now the coolant is below minimum and there is oil marks down the gearbox end of the block, so HG may have gone aswell - could make sense... if the TB failed and over revved the engine, that could have blown the HG.

I have another possible theory aswell tho... if the HG has gone and its drinking oil, could the lambda be thinking the engine is running rich and open up the valve a little more?

Fun times ahead :D :(
 
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The Sultan

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replacing the throttle body from scap may be dogy as there are minor change from year to year

the oil leak will have nothing to do with head gasket but eating water will top up and keep an eye on it

you will need to order a new throttle body to manifold seal if you want to change it or you will fix one problem and cause another ie air leak causing once again over revving
 
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cool (y) Having thought about it, it could just be the rocker seal causing the oil marks... ill have to have another look. The coolant *may* have been low anyway (havent topped it up since i got it as its obviously been out of action,) so fingers crossed :)

I had a look on eper for the TB to manifold seal but it seems they come as a complete set of seals for the manifold. Are they not available seperatly?
 

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cool (y) Having thought about it, it could just be the rocker seal causing the oil marks... ill have to have another look. The coolant *may* have been low anyway (havent topped it up since i got it as its obviously been out of action,) so fingers crossed :)

I had a look on eper for the TB to manifold seal but it seems they come as a complete set of seals for the manifold. Are they not available seperatly?

probably not
 

The Sultan

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if you know anyone that's just bought a head set they will have one left over providing they did not separate the manifold and t/b

wouldn't have thought a seals set would be to expensive for your car normally aren't when i look on Eper
 
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Ive got 3 days in a row off work this wk so im gonna start tackling it tomorrow :)

I've already started to remove the inlet manifold, and after about 2hrs, its about half off :eek: Any tips or trick for how to remove the bottom two nuts? i got the drivers side one off using a ring spanner from the side, but the pass side one it being a PITA. I can only seem to reach it with a ring spanner between the two injectors. im doing like 1/6th of a turn at a time :( even worse, the studs coming out with it so ive got a fair bit to go yet! also the 13mm bolt below the coolant hose - any tips for getting to that one?

BTW, I had an OBD2 reader on it (cost naff all :) ) and it showed no errors, but as you said, the error probably wouldn't show anyway.

I've decided if im gonna do it, ill do it properly, so ill just buy a complete set of gaskets so i can dismantle it all and look for any signs of air leaks. If the manifold looks ok, ill buy another TB and cross my fingers (y)
 

The Sultan

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yes the centre bottom bolt is a pain but you can get it with a socket and extension from the back

as for one under the water pipe same again socket set

you can get them all with a decent spanner but it will take a wile
 
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it seems to have solved it *touches wood* I used a new full set of seals, got a known good TB from a scrapped car, tried to start and eventually she did! no more constant high revving, although it is running like a bag of balls at the mo, but im hoping thats just cos she aint been started in like 3 months. ill let her run for a while tomorrow, see if it clears up (y)
 
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