Hello,

I've had a problem with a persistent hesitation under load for quite some time in my 2006 Panda 1.2 Dynamic. I've done everything I can to try to troubleshoot the problem including replacing the following parts with new original equipment items:

Both coil packs
HT leads
Spark plugs
ECU (yes, I replaced the ECU)

The car runs perfectly otherwise and has new correct grade oil, genuine oil filter, air filter. The MIL lamp is off and there are no trouble codes.

I have checked for inlet manifold leaks.

There is no sign of head gasket trouble.

I have removed the injectors and had them cleaned and tested.

Today I checked the resistance of the throttle position sensor and found that it increases steadily as expected and then at about 3/4 throttle starts to drop again. Measuring resistance between the two outer pins I get the following readings:

Throttle closed (idle): 1760 ohms
Throttle 3/4 open: 2700 ohms (that's about the maximum reading)
Throttle fully open: 2250 ohms

Assuming the TPS is a normal potentiometer, it appears to be faulty. My questions are:

1. Does anyone have the correct resistance readings / specifications for this unit?
2. Is this likely to be the cause of the hesitation problem?
3. Can the TPS be replaced separately or am I looking at a new throttle body?

Thanks in advance for any advice you can offer

need special tools too remove the pot so maybe best to get throttle body from scrapyard/ebay? (same as mk2 punto I think?)

Thanks for that.

I see Shop4Parts have the throttle bodies very cheap at the moment.

Today I hooked the car up to FiatECUScan and monitored the reported Throttle Angle in the live data view. It changed smoothly between 0.2 degrees and 82.4 degrees (pedal to the metal) with no sign of it going up and down again. I rechecked with DVM on the connector socket and the resistance went up and then down again like before, so I'm a little baffled. I am now beginning to think the TPS is OK after all and that the TPS is maybe not a conventional analogue potentiometer (could it be a hall sensor?)

Back to the drawing board I guess!

Have you checked the MAF? When I had this problem on the Corsa it was that.

not got one

There is no MAF (that part would only be fitted to the diesel version) but there is a MAP sensor. I don't really know how to test it. With live data reading it indicates atmospheric pressure with ignition on and engine not running then reads various levels of vacuum with the engine running depending on engine speed (and presumably engine load).

lamlash said:

There is no MAF (that part would only be fitted to the diesel version) but there is a MAP sensor. I don't really know how to test it.

Click to expand...

I know, said that in post #5 anyway test MAP with voltmeter or by subsitution as cheap on ebay. You can always take to dealer to monitor the parameters of the MAP if your not sure what readings you should be getting.

T14086 said:

I know, said that in post #5 anyway test MAP with voltmeter or by subsitution as cheap on ebay. You can always take to dealer to monitor the parameters of the MAP if your not sure what readings you should be getting.

Click to expand...

Thanks for that. I think its time for my local Fiat dealer to have another look. They want £70 to plug in the Fiat examiner which I think is a bit steep but I'm running out of options now. I doubt the MAP is the problem but something must be causing the problem!

£70 to plug in examiner!

No.....you are paying for an hour so you should be getting a hours diagnostic from a trained technician. If its just to plug in & read errors then take it to local garage for £20-25!

I'll ask the main dealer what exactly I get for £70 - I haven't had good experiences with them in the past so they are a last resort. My local garage charged £45 just to plug in their code reader which turned out to be no more useful than my laptop/OBD cable and free software. They basically just said no fault found!

This evening I removed the MAP sensor and tested it with a vacuum pump. I only have a crude analog dial gauge on the vacuum pump and had to convert the units and adjust for today's atmospheric pressure but the ECU reading of manifold pressure (as viewed with live data feature of my scan software) compares pretty well with my gauge so I think the MAP is good:

ECU..........Gauge (all units mbar)
992..........1003
840..........870
699..........736
577..........603
449..........470
285..........337
221..........270