Hoping for some help with engine problem.

2016 1.2l KA car starts and goes into limp mode after about 10 secs if left to idle, however if you rev the car immediatly on start it will run fine until you let revs drop below 1500 revs, Codes show Throttle position sensor circuit B.

Changed the following:

Throttle pedal

Throttle body

maf sensor

Took the car for a 20 mile drive and it drives perfect as long as i keep the revs above 1500 as soon as the revs drop below this car goe back into limp mode and management light on ?

Any help gladly accepted.

Do you have Forscan or even a basic OBD reader that's capable of live data?

Watching graphs of pedal position and throttle body position should show which of those is causing the problem.

I think it's going to a loose connection or damaged wire to one of them.

Worst case scenario would be a fault inside the PCM but definitely start with wiring tests. 

Got Autel which shows Live data  but unsure how to read data.I agreei think its wiring issue but where the hell do you start.

11 hours ago, vanduara37 said:

Got Autel which shows Live data  but unsure how to read data.I agreei think its wiring issue but where the hell do you start.

You start with live data readings to reduce the amount of wiring that can be at fault...  As your problem always occurs stationary at idle, that will show either the pedal readings or the TB TPS readings to be out of spec at idle.

Once we know whether it's the pedal or TB we can then select just the wiring between that part and the PCM for testing with a multimeter.  If you don't have access to live data, you'll have to test wiring for both parts, potentially doubling your testing time.

Apologies for lack of response but really appreciate the replies.

I won,t get another look at the car till this weekend and get the live data info needed then hopefully get a solution from the forum members.

Below are some live data readings, 1. Error code 2. Engine at 3000rpm 3. Engine at idle 4.Engine in limp mode 1500rpm.

Any suggestions based on these or do i need to collect more live data.

Thanks.

 

 

 

 

 

I would prefer a graph to watch the voltage change smoothly but that is still useful data.

It looks like both pedal sensor voltages are the same each time.  Which would suggest that the pedal sensors are working OK so more likely to be the throttle body TPS at fault.  If you can find separate throttle body readings on the live data, they would help confirm it.

You will need a wiring pin-out to test the TB effectively.  I've quickly pulled this one from Google which looks the same as the Ka TB but may not be 100% correct - the Fiat 500 forum may have one as these are rebadged Fiat 500's.

A&B can be ignored.  I would test for a constant 5 volts on the reference pin (E) first.  Assuming that's fine, I'd then want to test resistance from pin F right along the length of that wire to it's corresponding pin on the engine ECU plug.  (Both ECU and TB must be unplugged for this test).  Any wiring damage or loose connections should show up as extra resistance while will put the reading out of spec time it gets back to the PCM.

20 hours ago, TomsFocus said:

I would prefer a graph to watch the voltage change smoothly but that is still useful data.

It looks like both pedal sensor voltages are the same each time.  Which would suggest that the pedal sensors are working OK so more likely to be the throttle body TPS at fault.  If you can find separate throttle body readings on the live data, they would help confirm it.

You will need a wiring pin-out to test the TB effectively.  I've quickly pulled this one from Google which looks the same as the Ka TB but may not be 100% correct - the Fiat 500 forum may have one as these are rebadged Fiat 500's.

A&B can be ignored.  I would test for a constant 5 volts on the reference pin (E) first.  Assuming that's fine, I'd then want to test resistance from pin F right along the length of that wire to it's corresponding pin on the engine ECU plug.  (Both ECU and TB must be unplugged for this test).  Any wiring damage or loose connections should show up as extra resistance while will put the reading out of spec time it gets back to the PCM.

Thanks, unfortunately the plug layout does not match the one i have.

A- Grey/blue

B- Blue/yellow

C- Black/white, which is getting 5v feed.

D- Purple/white

E- Purple/red

F- Black/orange

Have tried google but cannot seem to find any info about a connector with this layout.

Stumped yet again.

I don't have access to any wiring diagrams for the Ka unfortunately.  You'll need a pin-out for the engine ECU as well.

As above, the Fiat 500 forum might be able to help.  Alternatively if you know any techs that have access to Autodata, ask them to check.

PS - Don't worry about colour too much, wire colours can change throughout the years so best to use the pin numbers from the plugs. 

I have the Ford schematics for a KA Plus_EHZA 2016 if this of any help.

11 hours ago, unofix said:

I have the Ford schematics for a KA Plus_EHZA 2016 if this of any help.

Thanks but I think the Ka+ is based on the Fiesta, not the same as the 'Fiat 500' Ka.

Unfortunately still no success with this, all readings from throttle body to pcm wires showing normal.

One thing i found , periodically the code reader throws up "map sensor fault" even though it has been replaced?

Quick update on this issue. 
Car been to Auto Electric specialist and all electrics tested ok. 
Done a smoke test and found leaking at inlet manifold, removed manifold and the plastic has melted round bottom 2 flange nuts. Have ordered a replacement manifold. 
What I noticed yesterday when running “live data” was the absolute load value was in the red. The range status 0-100 % at idle , this car was showing 285% at idle. Would this be caused by the leaking manifold ?