Just wondering if anybody has any idea what could be causing an intermittent starting problem on my ageing (1994) Renault 21. 1995cc multipoint injection with CAT.
SEEMS to be only when warm/hot. Engine turns over fine, fuel pump starts then stops as normal. The problem is a complete lack of spark from the "coil".
So far, if I leave it a while and come back to it, it starts fine.
Please help!
Thanks, Marie
Check out the primary ignition pick up- its probably a crank angle sensor located above the flywheel on this engine- they characteristically fail when hot..
Tim..
Thanks Tim, that was my initial thought but then I got to wondering why the engine ran fine (assuming it starts). If there was a hot fault with the TDC sensor, would I not expect to get at least a mis-fire as the engine reached its operating temperature?
Usually no. The heat soak after the engine has stopped results in a higher temperature, and the sensors usually fail open circuit, so its a case of a proper spark or no spark at all.
As amplitute is related to engine speed, a faulty sensor will often allow the engine to keep running as the higher voltage (aroound 10v at idle, upto
100v at 6000rpm) jumps the break in the windings, but at cranking speed the voltage induced isnt enough to do this so you get no output.A quick check is to induce a non start situation then spray the sensor with a cooling spray (brake cleaner willdo) If the engine will immediately start - you have found the problem
Tim..
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