HELP, turning but not starting...

[mike-evans]

My 172 wouldnt start last week, my immob does not dirarm sometimes,i know when that is the prob due to the red light flashing, this is something else! When it try to start, it wil turn over but not fire,took it to halfords,batt check showed 12.5 volts 51% start capacity, he told me that wil give me starting probs, but i aint sure as it is turning over fine! I manage to start it off a bump,never first time, but just now in work,it wouldnt start,2 of my mates pushed me,tried bumping and no joy,ran out of room to push,tried starting it and it started..strange! One thing i noticed was when i jump in and dont have the immob prob stopping it starting, then it wil start first time, if it wil not disarm the immob and i have to keep putting the key in the ignition and trying it until it wil disarm,then it wil turn but not fire,dont know if they are related? Anyone got any suggestion, can it be crank/cam sensors? Can i clean/check them myself?

 

[Sargara]

Get out the car. Lock it with the fob. Wait 30sec. Unlock with the fob. Start the ignition.

If you notice the imobiliser doesnt disarm try the above incase you interupted the sequence. Might help?

 

[mike-evans]

after just reading a couple of posts about probs where it is turning but not firing, then i believe theres a very good chance its the TDC senror. So I wil remove it,clean it and try that, how easy is it to do? Also if i get a new one, can i do it myself or does it have to fitted with a diagnostic machine etc? Any ideas how much the sensor is for my 02 172?

 

[Russ_16v]

easy to clean, 2 bolts to take it off mate

 

[mike-evans]

just removed it,wiped it and stil no joy.how else shal i clean it?

 

[Russ_16v]

some sort of contact cleaner mate

 

[Sargara]

^ WD40

 

[mike-evans]

removed the TDC sensor again and cleaned it with brake cleaner as oppose to just wiping it over on first removal, fitted it and it started on the third turn..dont know how long that wil last?! If the TDC sensor is not working properly wil it only cause problems when starting, or, wil it cause running probs, i.e cut out when driving?

 

[Russ_16v]

yup, if signal is lost to the tdc the car will cut out

 

[mike-evans]

phoned Renault for the TDC sensor, £24, and he said I need another piece, a connector/wire that goes with the sensor, also £24..how does that sound? How do I change the wire? When I cleaned it earlier, I just dis-connected the sensor from the wire, didnt go any further to remove the wire, so dont know how to change that piece...

 

[keg]

i have just payed £16 for a TDC sensor from PCS i have the same problem hopefully this has sorted it

 

[mike-evans]

after removing the TDC sensor and cleaning it with brake cleaner, it has been fine since, starting first time...until now! Again, its turning over (until after 5-10 turns then the batt dies, i know i need a new batt, starting capacity at 51%) but not firing, so I am going to replace the batt and get a new TDC sensor in there, when i rang renault they said i also need the wiring loom to go with the sensor! What i need to know is how to change that wiring loow? Im assuming its the wires/connector that i disconnect the TDC sensor from? Ive also read on here with 172s not starting to clean the TDC sensor (done that) and to check/clean 3 black relays and the white connector? Anyone got any info on that for me?