306 HDi - No throttle response and stuck on 1300 rpm... Have I cooked my ECU?

[tdhalsall]

Hi all,

I've recently been trouble shooting an issue with my 2000 306 hdi 90. The problem has been a slight but very noticeable hesitation/miss on acceleration through about 1700-2100rpm. It's especially bad at 2000rpm.

I've been looking into a few things - most notably the EGR, the TPS and the MAF.

Today things got a whole lot worse.. I was trying to test the MAF by back probing the plug and reading the voltage output of the sense wire when I accidentally shorted something. The engine was running at the time and it immediately jumped from idle to 1300rpm and stayed there. I turned the ignition off and re started the engine and it went straight back to 1300rpm. I tried to rev it and the throttle did absolutely nothing. It's not reading inputs from the TPS! I plugged the MAF back in and the rpm dropped slightly but only by about 50rpm.

I plugged my OBD reader in and got the following codes:
P0560 - System Voltage
P0190 - Fuel rail pressure sensor circuit bank 1
P0220 - Throttle/Pedal position sensor switch 'B' circuit
P0120 -Throttle/Pedal position sensor switch 'A' circuit

I reset the codes and switched off and on again. Only P0220 and P0120 returned.

I had a look at the live data from the reader and this is what I saw (note the MAF was unplugged at this point)

Interesting to note the intake air temp was reading 215deg no matter if the MAF was connected or not. Also with the MAF connected the airflow was something crazy like 300gp/s.

I also noticed that the interior clock along with the (after market) stereo had reset themselves like they do if you disconnect the battery.

I checked every fuse on the car (that I know of - are there any other than the engine bay box and the drivers footwell box?) and everything looked fine.

Does anyone have any ideas? Have I cooked my ECU??

Any help is much appreciated.

 

[dmccurtayne]

My sons 306 hdi had exactly the same codes I put throttle sensor on it and it’s been fine for 2 years it’s the same as a 406 hdi and V6 c5 early style let me know if you want more info get a second hand one they are very expensive


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Fix it right the first time

 

[tdhalsall]

My sons 306 hdi had exactly the same codes I put throttle sensor on it and it’s been fine for 2 years it’s the same as a 406 hdi and V6 c5 early style let me know if you want more info get a second hand one they are very expensive

Thanks mate. A new TPS will be worth a try. I bet your son didn't short circuit a wire off the MAF though.!

Looks like I can get a new TPS off ebay for less than $100 so I might give that a go. Someone on a UK forum is suggesting I open the ECU and look for a burned/broken track. He said he had the exact same symptoms once after the pressure regulator wires shorted on the alternator.. he opened his ECU and repaired the track.

 

[tdhalsall]

Update: I ended up opening the ECU to check for visible damage. I couldn't see anything obvious after having a really good look at both sides of the board.

Anyone got any other suggestions other than a new TPS?