Hi.

These idle problems drives me nuts:bang: .
First the engine idles like scrap all the time (To low charging voltage)
Then the idle is low all the time followed by too high Co readings (Lambda probe)
Now it idles fine at cold start and during warm up, but when engine reaches working temp, the idle speed is below 500 rpm, but steady.
I read some where that the ECU uses coolant temp for setting idle speed during cold start and warm up, when the engine is warm it uses the RPM signal from the TOD sensor.
So in my case it could be a defective TOD sensor, or could it?
The RPM reading on the dashboard is OK, doesn't is use the same sensor?
How does a engine run without the TOD sensor? My guess it would have problems with ignition timing causing missfires.

Any advise would be great, i'm lost in this bad idle problem...

Tod?

Hi mate what engine?

mountainmachine said:

Hi mate what engine?

Click to expand...

1.6

Cool now we just need to find out what this TOD sensor is, even google doesnt know!

It's proberly a sensor we all know but abbreviated in Danish!

I reckon he means camshaft sensor.




Or crankshaft sensor:chin:

Sorry guys, i missspelled it, it's the TDC Sensor.
(The crankshaft position reference).
The engine is a 1,6 16V.
Michael

Unlikely to be crank sensor,more likely HT misfire or air flow problem/leak.Have you changed timing belt recently?

Hi T14086.
The timing belt was chaged last year by a Fiat garage.
But it has run OK a periode after the change.
Do you know if the TDC sensor is used for displaying the RMP on the dashboard?
If it's a HT problem or a airflow problem wouldn't it be present during cold start and warm up?

Michael

At start up the auto choke is on,does the engine light come on(has been on)?

Is there a misfire or just poor idle(motorised throttle fault probably/map sensor/air leak)

if its noisy while idleing it is possibly pinking which is an ignition problem. 2 possible causes are 1) problem with the octane level of the fuel and 2)if the engine is running hotter than usual.

Hi.

No, the engine symbol hasn't been on since the lambda probe was replaced a month ago.
The engine doesn't misfire...
Everything is normal except from this one problem.
The Fiat workshop manual (by Fiat) states the idle speed is set by the ECU using the TDC sensor when the engine is warm.
But it looks like it's the same sensor that the ECU uses to display RMP at the dashbord... So it seems like it's not the problem.
The ISCV motor was tested a few months ago, working fine.
I guess it's also the ISCV motor that raises the idle speed when the engine is cold, and that works OK.
Is there an easy way to determine if the engine is taking false air somewhere in the intake?

Michael

Migaard said:

Is there an easy way to determine if the engine is taking false air somewhere in the intake?

Click to expand...

that cant be happening, a vacuum leak would cause high idle.

have you tried cleaning out the throttle body?

when cold the iscv will bleed air in, allowing a decent idle rpm to be achieved, but once the coolant temp sensor tells the ecu that warm condition has occured, the iscv goes to normal position, which is then not allowing enough air in with butterfly valve in closed position. give the throttle body a good clean out, you'd be very surprised how often this is the cause of low idle rpm on fuel injected cars.