Engine freeze on start up

[NA_Vogue]

Im having an unusual problem when starting my vehicle. The car starts just fine but sometimes right when it starts, instead of the rpm jumping up 1000 rpm or so, it freezes and gets "stuck" for a split second at 500 rpm and then works its way up to 1000 rpm. Throughout the entire incident the engine sounds like its cranking normally overall. Could this be indicating a serious problem?

[jveik]

is it carbureted?

[curtis73]

How about year, make, model, engine... also a little better description might help. A "frozen" engine implies that it stops. 500 RPMs implies that its running. Help us out with a bit more in depth explanation.

[2.2 Straight six]

it could be a number of things, maybe it's running lean at the beginning so the idle is low and as more fuel gets to the engine it raises.

on my mum's audi there are two different idle points, when you first start the car it injects more fuel to help it turn over, after sitting for about a minute the idle drops as less fuel is injected, because the engine's then running fine.

its possible, if you have a similar system to the audi, that it's doing this the wrong way round.

if it's carburated then maybe the fuel system need to be cleaned out, if there's a blockage somewhere which is causing a drop in fuel pressure after that point, but at the engine runs it becomes fine.

[2.2 Straight six]

his prifile says he has a 1996 240sx, i believe that has a CA24DET.

[NA_Vogue]

Nope, a KA24DE. And yes, 240sx. The engine pretty much starts like normal, its just that the rpm just kinda hangs there at about 500 rpm for a slipt second right after its done cranking and the engine starts.

[2.2 Straight six]

yea, we only got the 1.8 SXs over here. im not so good outside the newer engines.

[NA_Vogue]

Well I pulled up the shop manual for my car and did some digging. For P0325 I measured the resistance of the knock sensor and it came out over limit when it should be 500 to 620 K ohms, so thats gotta go. Along the way I noticed one of the spark plug wire had a small gray spot like a bird took a crap on it (suspecting arcing). Measured the resistance and it was higher then it should be but consistant with the rest of the wires since they're really old. Took the cap and rotor off and saw the inserts were so worn that now I'm afraid to drive my car. Putting these things together, I think the miss fire could have been caused by bad secondary ignition parts. This also makes me wonder if there was a chance of arcing somewhere in the secondary ignition system, could it be possible that my ignition coil could have shorted or developed a track?