S13 Sr only starts when jumped or bumped

[Bay_area831]

I'll start off by saying I'm very knowledgeable about this motor and car. Been reading, researching and diagnosing for months and as a last resort here I am.
Car fires right up when I put a jump pack on it. As soon as I kill it and fire it back up just cranks and cranks. New battery, coilpacks, ignitor, spark plugs, cas, alternator, starter,
Injectors all read 12.0v checked and re checked grounds.
I'm stumped
If anyone has had a similar issue I'd love you know what you did to fix it.
Much appreciated

[s13 @ fullboost]

You probably have a voltage drop from the battery to the starter.

[Bay_area831]

Starter cranks totally fine. Just cranks a little faster when jumped. But I'll check into it for sure thank you for the tip.

[s13 @ fullboost]

Starter cranks totally fine. Just cranks a little faster when jumped. But I'll check into it for sure thank you for the tip.

Have you tried putting a fresh battery in? Its also possible under load the voltage is just dropping. (bad cell) Also jump it & while its running disconnect the battery completely. If it stays running alternator is good or if you have a multi-meter just check voltage at the alternator while running.

[S14rebuild]

Sounds like bad battery , or crappy connection( bad battery terminals/battery cable

[gaz_moose]

engine earth strap? try a jump lead between engine and chassis

[jedi03]

another thread I was reading suggested instead of junction block, use the starter as the splitter...my fc started doing this after I sold it...sr swapped

[s13 @ fullboost]

Any updates on this? Did you get it resolved ?

[Bay_area831]

After splitting my head trying everything. I swapped ecu. I should have mentioned before that I am running AEM v2. Swapped with a stock one and it fires right up. Swap back and just cranks. I'm now searching AEM forums as most people here don't have that much in depth experience with tuning. My tuner who is very highly regarded. After he tuned it it started fine but this problem has progressively gotten to this point. I'm gonna run 2 batteries is parallel until I can find a permanent solution

[inopsey]

have you verified your timing is correct?

[Bay_area831]

Not down to the degree with a timing light. But as far as cam timing, yes. That was my first thought. Even double checked it to no avail.

[brndck]

when its cranking but not starting, have you checked for spark / fuel injectors with a noid light ?

[Bay_area831]

I do not own that tool but ive just manually checked for spark and since it does run I know the injectors are working. Also checked and they all have 12.0 volts

[s13 @ fullboost]

Sounds like a driver burned out inside the AEM

[Bay_area831]

Full boost. Have you heard of something similar to this situation. It is just so odd it would run so good and start with was when jumped. I was hoping it was some stupid setting in the AEM

[s13 @ fullboost]

Full boost. Have you heard of something similar to this situation. It is just so odd it would run so good and start with was when jumped. I was hoping it was some stupid setting in the AEM

To be completely honest no I have not. Can you take the jumper off and it stays running?