Calparts

I've put an LS2 from a 2006 GTO into a Miata. It runs great, but it never starts on the first attempt. It just cranks and cranks. It always starts right up on the 2nd, or subsequent attempts. It doesn't matter if it's hot or cold, recently started/run or not. Fuel pressure is fine. Injectors/coils have power. We've even tried giving them direct power from the battery. VATS have been tuned out. No OBD codes are being thrown. Yet something is preventing it from initially starting. I feel that it's a computer related issue, like something isn't wired correctly. Any ideas?

Thanks,
Jon

MY_2K_Z

iTrader: (1)

Check and make sure the cam position sensor a&c wires armt reversed. I had this issue. Swapped wires and bam, first bump every time.

Calparts

The cam sensor pigtail was never cut from the harness, so it has to be in the correct location. It could be that the sensor is bad, or perhaps the crank sensor, but I'm hoping that's not it.

Thanks,
Jon

98CayenneT/A

Have you tried not cranking it over, just cycle the fuel pump a few times then try and start it.

subeone

iTrader: (5)

what cam sprocket are you running.

Calparts

Yes. We've turned the ignition on and can hear the pump run. We've run it until it stops, because the computer stops it after a few seconds, and then tried starting. No change.

Calparts

I believe it's stock, but can't be 100% certain because it was from a wreck that I bought at auction. It only had 39k original miles though and was very well maintained.

Calparts

How about a bad cam or crank sensor?
Or, someone suggested that the VATS may not have been completely programmed out. Can they be only partially programmed out? Mine were programmed out, supposedly.

subeone

iTrader: (5)

what harness, pcm, cam sprocket are you running?

are you using a 58x to 24x conversion module

it would help to post the file.

thanks

Calparts

E40. Stock 24x as far as I can tell from the crank sensor color.
I think it's all stock, so no conversion module.
I don't have the tune file. Tuner has that.

LOWZ71GA

I have a 02 6.0 that wouldn't start on first but always in second, turned out to be fuel pump

Calparts

I got the tune file from the tuner. Can I send it to you?

subeone

iTrader: (5)

yea go ahead and pm it to me

Calparts

PM sent

dw456post

Do you have your fuel system setup like the stock GTO--no return? Does your fuel pump have a residual pressure valve?
The prime on the stock setup is 2 seconds. If you do not have a residual valve, set the prime to about 6 seconds, turn the key to the on position, count to 3 and then start it. I don't have a valve in mine and I have to do this. If I just turn the key to start it, it just cranks. Even tho the regulator says it has 58# immediately, I guess the fuel rails are not full pressure. Regulator is before the fuel rails on mine. Maybe this will work?

Calparts

Yes, the fuel system is the same a the GTO. With key on, the pump primes and shuts off as expected. Pressure at the rail does not drop. We don't think it's a fuel issue, of course it still could be. It's too consistent. It simply never starts on the first try even if the engine is shut off and immediately restarted, meaning fuel has to be in the rails and injectors. It's a mystery. Still researching...

MontecarloDrag

iTrader: (3)

No starts on first try are commonly caused by not enough fuel on startup.
If you fuel system is OK and you already checked fuel pressure at startup, filter, pump and everything checks good, then modify the tune and give it more fuel to the cranking VE and/or cranking fuel tables.
Start with small increments of 5-10% and test.

Calparts

Thanks. That's a good idea. I'll double check everything again, and then increase the fuel.

Another interesting point about the failed first starts is that there is no firing. It's not even trying. Whether it cranks for a second or 20, it never attempts to fire. No stuttering. It's just cranks and cranks. Then on second attempt it fires immediately. We tested for current at the coils/injectors and they seem to have it. Maybe we need to run that check gain. So I feel that it's something computer or sensor related. Anyway, we'll keep trying every idea that is suggested. Thanks!

Skyguy

I am having the same exact problem on my LS3. Have you had any luck?

Tramminc

I had that problem with my LS3, I ended up putting a check valve on the fuel pressure hose close to the tank and replaced the regulator to hold the pressure in the line. Now when I turn the key without starting it the pressure still reads 60 psi. Sometimes the fuel pump valve or regulator leaks and drives us nuts.