Technical Injector Light - Help Needed?

[Ben20vTurbo]

I have been the proud owner of my 20v Turbo for 16 months and have enjoyed every minute of it with it flying thru MOT and not 1 problem until now...

When i start the engine all dash lights go out as normal apart from occasionally when the injector light has stayed and there is a large noticable loss of injector power If the engine s turned off and restarted immediately the light goes off and it drives fine...

However, very recently the light has started to come on after the engine has been running for a while - 5mins - 45mins...... Again there is a loss of injector power, Turbo still works so not a total loss of power if on motorway.
If the Engine is switched off at any time and restarted hot/cold the injector light goes out and won't come on for 5mins - 45mins.
Even if the engine is turned off and on quickly at lights etc the injector light always goes out.. and the car will immediately drive fine for a while

Does anyone haveany ideas as to what the problem could be...
Injector gone?
Sensors?
ECU?

:worship:

I ideally don't wanna be going to a Fiat garage for lot's of expensive diagnostic tests?

Thanks for reading.

Ben

 

[Rustbucket]

You got an old Meta alarm with 3 control boxes? 2 in Footwells and 1 under dash? They've been known to cause a load of problems. Not the highest quality units ever made and often wired in dockside by drunken Orangutangs.

The Meta immobiliser box in the footwell was faulty..in this car it sometimes worked and sometimes didn't. Part of its security is to shut down the power to the ECU, hence no injector light on startup--no start or sometimes the code light flashed when the engine was running..sometimes neither.

Sorted by an auto electrician removing the alarm unit and just leaving the original code box..owner then had a modern alarm fitted, no more trouble.

 

[NigelO]

Its very unlikley to be the alarm - any alarm intervention with the ECU is either nil or complete (ie it works or it doesn't - there's no inbetween)

The injector light AND poor performance is going to be a sensor of some kind, causing the ECU to fail to "limp" mode

There are all dozens of possible causes and your only solution is to get the car hooked up to a code reader

If you're anywhere near Stafford or Coventry, I'll do it for the price of a beer, but there are several independents that will do it for around £25, which is about a third of what it will cost you at a main dealer

Without a code reader, you're just guessing, and you'll end up spending more replacing stuff that didn't need replacing, unless you're spectacularly lucky and guess it right first time.

 

[Rustbucket]

Its very unlikley to be the alarm - any alarm intervention with the ECU is either nil or complete (ie it works or it doesn't - there's no inbetween)

Not so, I've seen intermittant units, particularly if they have the extra chip immobiliser fitted into the steering column. They also don't like getting damp..so control boxes under the mats if damp produce various interesting faults when wet, dry out and then work perfectly for a while.

However I bow to the superior wisdom of the fundamental oriface of coupe law...

 

[rallycinq]

Guessing is the expensive way of doing it. Most local autosparks will have an Examiner clone that will not only read the codes, but then be able to ping the individual sensors.

Everytime you switch the ignition off you are rebooting the operating system, so if the sensor that is causing the fault is not active at that point the light won't come on.

The lack of power you notice is probably the management system going into limp home (safe) mode. If the management is seeing a reading it doesn't understand from a sensor it will revert to a standard map where it know the values are right and make sure your engine can't get to the higher revs where incorrect fuelling can have disasterous effects.

Cheers

SPD

 

[Bro_Coupe20VT]

First thing to do that is simple, free and will source the root of a very common problem with coupes, is to have the engine running while the engine light is on and it is running rough, then one by one remove and replace the sparkplug leads. If the engine runs rough but has no change to the engine tickover while a sparkplug lead is disconnected then this is the source of your problem and reduces the possible reasons down to that faulty injector. The engine should get slightly worse while running if an injector that is working correctly is removed from play so ultimately you are looking for a no change in its tick over while it is running rough.

 

[hmallett]

Not necessarily. The Coupe 20VT has one coilpack per cylinder, so disconnecting the coilpack and no change in engine running could indicate a coilpack fault rather than an injector fault.

 

[Bro_Coupe20VT]

Apparently a faulty coil pack does not set the engine light on. I don't have first hand experience on this but one of the most knowledgeable guys on the coupe told me this. That was why I didn't mention it.
Either way it will still reduce the possible problems down to at most 2 instead of multiple sensors (MAF, thermo's etc......) and other problems.