A similar thing happens on mine, albeit different ECU, the tuner suggested tit could be related to air intake sensor being heat soaked and out of range

 

If AIT sensor is out of range, as above mentioned, with proper configuration and Air Temp Failsafe ON, it should default to 77F on AEM Infinity for example. So check the failsafe as well.

 

yeah, we did talk about the heat soak on the engine causing the iat to read high, but... how is that connected to the slow crank?

also a reason why i believe that this isnt the problem is because: when i stall the engine while hot it wont start back up, even after 1 second. my IAT was reading about 70 degrees the other day when i stalled at a stop sign. hit the start button within 1 second so it wouldn't have had the time to heat soak.. obviously it didnt start...

 

No one is blaming your tune, they're just giving you recommendations on what you can check to cover all angles before tearing apart the actual hardware like starter, etc.

As mentioned above, sort out your slow crank. Rectifier was mentioned, battery, grounds, etc.

Good luck.

 

I've had identical issues with hot starts, though I've got a AEM v2. I've also got a trunk mount battery, brand new ACDelco Group 51 AGM Battery and 4ga wiring. I'm also fairly certain the started is original at 150,000 miles. I'm in North Texas so weather was in the mid-60s when i was driving.

I had @AP1Chief take a look at my tune and he said that AGMs can have issues with heat soak and delivering voltage to the front when installed in the trunk. Further, he said the AEMs are sensitive on voltage drop. We logged a few starts and saw voltage dropping as low as 9.5-10v if the fans were on and it had to crank a few times. He said the AEMs are sensitive to voltage at/below 10v and may not start. He adjusted the startup tables to add in more fuel and a bit more timing and it dramatically improved the percent-chance-to-start. I've had to actually go in myself and add a little more fuel as well and am still testing through whenever it's nice enough to drive outside.

I'm not saying the startup map is your problem, but I wouldn't rule it out so quickly. It may be a combination of things like type of battery, location, starter health, tune, etc.

 

Been having same issue when the car is hot.. after a 15 minute drive it barely cranks, typically will not start.. cold start is perfect every time.. 2007 with 65k miles. No mods other than a Takeda intake.. I've had battery checked (only a year old); volts are normal... Disconnected all grounds, cleaned and reattached... any other ideas?

 

So based on your description, "no other mods" means you're not forced induction (this thread location, typically also means a stand-alone ecu) and your battery is not relocated to the trunk. Could still be battery. Even if voltage is okay you're cold cranking amps could be super low so you should have it tested with something besides a voltmeter. Or get someone to watch the multimeter reading while you're trying to start it to see if volts or amps dips.

 

What's the voltage under load on the battery load tester? A voltage check a voltmeter is far different. Simple $19 battery tester is usually good enough for this regardless of brand name, they're so similar I expect they're all made in the same PRC factory.

Any voltage drop to below 9vDC (at the terminals) indicates a bad battery regardless of the voltage at rest.



Hope it's a simple solution.

-- Chuck

 

Ahh shit, I didn't notice what thread I was in; just noticed a similar issue to mine



Using this basic tester I get 12 + at the terminals while idling.. 12- at start. I'll have to get it checked at an auto parts store to get a more accurate reading.. I was having the issue with my last battery as well, Honda Genuine battery from the dealer. Had no issues for 5 years prior... It seems odd/bad luck if it were to be the battery... Thanks for the info!

 

Get the battery load tested.

1. 12v at the terminals when not under load is a very low battery (less than 50% charged). At rest you should see 12.7v DC, at idle you should see 13.7vDC at a minimum. There's not much voltage variation between full and dead. Use a meter with some scale.



2. Honda doesn't make batteries so there's nothing "genuine" about it but the label.

3. 5 year old battery can easily fail, even one less than a year.

-- Chuck