Nick De Ath

Hi gents, I'm new to the forum so please forgive me if I'm covering old ground.

Got a problem with my daughters Fiesta, 1.4 DOHC Duratec.

Engine will rev to about 1500 all the warning lights come on and after a short while engine cuts out. Looking the other day and when I re-started it , it would only rev to 800 then drop and cut out Both faults occur intermittently.

Put code reader on it and got P0113- IAT sensor 1 High Input.

Question is will replacing the IAT sensor cure the fault or is something else causing the high input.

Thanks for any help and replies.

Regards Nick.

oldford

The problem with these codes is that they specify the condition the ecu triggers on.
It does not have to be the sensor. It could be a wiring fault of even a loose connector.

Does this car have an airmass meter of a map-sensor?
With a map-sensor the IAT is very important for calculating the fuel amount.

Nick De Ath

Thanks for your reply.

OK so having studied books and pictures I think I can fairly safely say this has got a map-sensor on it.(I'm not fully familiar with all modern bits-I prefer old simple cars).
Does this help to confirm that it is the sensor at fault?

Regards Nick.

oldford

No. It only confirms that this entire circuit is important and could cause it.
It still can be the sensor, the wiring or the ecu.
Can you locate the Intake Air sensor? Remove the plug and measure with ignition on.
One of the pins in the connector should have 5.0 volts on it. The other should have 0 ohms to ground.
Then measure resistance of the sensor. Depending on temperature expect something in the range 0.5K to 3.5K.

oldford

According to my supplier of parts the intake air temperature sensor is combined with the mapsensor. The sensor is plugged into the intake manifold.
I think this is the sensor: http://www.rinis-automotive.com/product.php?xProd=463

Nick De Ath

Thanks for that info. It gives me something to check rather than just put a sensor in and hope it does the job. The picture in your link looks the same as the pictures I have been looking at.
Just a thought after reading your post, you mention 2 pins, 1 with voltage on it and the other to earth. I notice in the picture that the plug has 4 pins, I'll put a meter on the pins and see what I get.
1 bit I have read says that inlet air temp and density information is provided by a "temperature and manifold absolute pressure (TMAP) sensor".
Is this a dual unit providing 2 lots of information to the PCM?
It looks like a Ford dealer is the only place to get one over here, none of the motor factors seem to stock them.

Thanks again, I'll have a look on saturday and see what I can find.

oldford

I first assumed a standalone IAT sensor. This is a combined unit.
The 4 pins should have 2 * 5 volt feed. 1 feed stays 5 volt for the map-sensor.
The other 5 volt pin will/should drop when connected - this is the IAT signal.
One pin has the map-sensor signal, and the remaining pin is ground.

Nick De Ath

Thank you my friend, I think I should be able to get to grips with that in the morning. I'll let you know what happens.

Regards Nick.

Nick De Ath

Mmmmmmmmmmmmmmm?
OK, checked the voltages, sensor pins marked 1234 on the plug. Pins 2 and 3 have 5v, pin 4 to gnd, pin 1 I assume for the map sensor signal.

Fitted new sensor.

Started the engine, revving problem still present. Checked fault codes P0113 still present. Erased fault codes.

Re-start engine and turn off again. reconnect fault reader P0113 and engine revving at 1500 still present.

Because engine rev fault didn't appear to have connection to sensor I removed the throttle body and stripped it to see if anything was stuck, all appeared OK, re-assemble and refit.

Engine management light now on- Disconnect battery and reconnect- engine light now off.

Re connect fault reader and erase faults, turn off ignition. Restart engine- NO FAULT CODES. But engine still revving at 1500/1600.

Turn engine off, remove fault reader. Start engine run for a while and turn off. Connect fault reader- no codes engine still revving.
Repeated this 3 or 4 times still no codes, engine still revving.

Any suggestions welcome, or in another way HELP!

Frustrated Nick

Nick De Ath

FOUND IT!!

A friend of a friend came and had a listen and thought it could be sucking air. He held his hand over the inlet to the throttle body and instead of cutting out the engine kept running.

This morning I set to getting the inlet manifold off to check for leaks. Didn't get as far as taking the whole thing off. After disconnecting a few plugs and pipes I took off the crankcase breather pipe- which had a 40mm split in it.

Did a temporary bodge, put it back on and hey presto everything working fine. Ticking over at about 800/900 when hot. Off to the Ford dealer tomorrow for a new hose.

Thank you for your information oldford, the sensor wasn't causing the engine to over rev but it was faulty.

Regards Nick