Riddle me this Batman, what causes a car not to start when hot and has no CEL?

Can you add some of the factory tunes back to your Accessport and putter around on the “Economy” map? Don’t drive aggressively, just drive for the sake of seeing if it’s a tuning thing.

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I'm not puttering anywhere until this car can idle for more than 10 minutes lol.

Well might as well throw in the towel and not even try then, right?!

Well might as well throw in the towel and not even try then, right?!

After having to tow the car 2 times back to back and sit on the side of the road for over an hour i'm not so cavalier to drive on the street. I didn't say I wouldn't try another tune, I'm just not driving on the road with no inspection until I know I can get it home! Last time the cops came and sat with me until the tow truck arrived because it was dark and I was in the middle of a busy road. Luckily they didn't run the plates or check my inspection otherwise they would have towed my car to the impound. So yea driving on the street, no inspection, with a car that frequently dies.... not a good idea. If I leave it somewhere after it dies, its very likely it won't be there when I get back!

Are you towing with your own truck? Might not be a bad idea to drive down the street a *very* short distance (like a quarter mile max) so a tow is easier. If not towing yourself, then I get it.

If you need the economy and other OTS maps, I believe you can restore them on the V3 version of the Accessport within the built-in OS. If older then you might need to download them, I'm not sure.

Any luck with the cloned ECU?

Nope, have to call AAA, then wait for an hour or 2 for a tow truck company. I only get 5 a year and I wasted 2 already, was about a mile or 2 from my house.

Installing the ecu in the morning.

So I tried the gas cap, double checked for vacuum and exhaust leaks, resetting the ecu and trying the econ base map. All a no go, but while I was removing the cap i put on the intake for smoke test, tension was put on the maf wiring and I got a code for maf high voltage CEL, can't remember code number. P0013 maybe?

Next I will install the new maf connecter pigtail I have and see what happens.

I never understood this open closed loop thing people are talking about when it comes to tuning. Could it be the car will only run in one of the loops, either closed or open? Something is making it go to the other loop and it stops working? Does an ecu even work like that, where given enough time it will revert from one loop to the other?

I never understood this open closed loop thing people are talking about when it comes to tuning. Could it be the car will only run in one of the loops, either closed or open? Something is making it go to the other loop and it stops working? Does an ecu even work like that, where given enough time it will revert from one loop to the other?

Closed loop is when your cars uses sensors (MAF, oxygen, etc) to meet stoich for the a/f ratio. Once your car meets specific criteria (time, coolant temp, no codes, etc) it goes to closed loop for economy and emissions; it happens fairly quickly when warming up.

Open loop is when your car just uses pre-set tables for air and fueling (no sensors-besides MAF). This happens at/just after startup and under load or quick throttle changes. Essentially, any time your target afr is under 14, you'll go to open loop. There are many different places in tuning where you can change how your car enters open loop.

So could it be my open or closed loop is no good? Does a cold start and warm start have different loops? Seems it died the 3 times on the road when I did a quick throttle response, normally I would ease into the power versus just stomping on the peddle.

The issue seems consistent, warms up for a specific amount of time, then stops working until a cools to a certain point. Like it warms up switches loops and wont start again until it goes back to the loop it uses when cold.

So could it be my open or closed loop is no good? Does a cold start and warm start have different loops? Seems it died the 3 times on the road when I did a quick throttle response, normally I would ease into the power versus just stomping on the peddle.

 

The issue seems consistent, warms up for a specific amount of time, then stops working until a cools to a certain point. Like it warms up switches loops and wont start again until it goes back to the loop it uses when cold.

One thing you can try if you haven't yet is to start the car with the maf unplugged and see it the result is the same. It won't go to closed loop this way.

Nothing's changed hardware and tunewise, but I have replaced a bunch of parts with the same parts since trying to track down this issue. I sent this log to the tuner earlier today, and they are looking at it. Wondering if the tune was done on bad data/faulty parts, and now that they are fixed its causing issues. I will see what the tuner says hopefully by Monday.

So, just to confirm, same injectors before and after the rebuild correct?

Installed the new ecu, and setup my ap on it. Also spliced in a new maf connector, this one is a lot firmer, took a lot of strength just to get it to click on.

Going to wait until the afternoon before I start, way to early on a Sunday morning to start with all the noise.

How can you wait lol.....it's after 9! Send it.

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happened again. But I got a misfire on all 4 cylinders this time. What do I log to see if its on open or closed loop? Or is there some way to tell?

datalog5.csv

Wondering why the fuel pump goes to 100 right at the end before it shuts off.

I'm almost positive you have a moderately large vacuum leak. Once the car warms up in your log, you're still 2-4 psi high in terms of manifold pressure. I'm seeing -6 psig, whereas you should be in the -8 to -10 psig range given your baro and IAT readings. Not to mention the high fuel trims.

I suppose it could be a damaged MAP sensor, but I don't see how that would impact CL fueling to the extent you're seeing. You are definitely in CL fueling, BTW. Fuel trims being active is a dead giveaway, as no fueling corrections occur in OL since fuel delivery is based on MAF reading only in that regime.

The above may or may not be the entirety of your problem, but it's glaringly obvious that it's at least one of your issues so I'd address it.

I'd boost leak test the car (again if you've done so already). I'm not sure if you just have a pressure setup or a proper smoke tester, but the former can be a little tricky when it comes to finding certain leaks.

As for the FPDC spike at the end of your log, we'd need to dig into the control logic for the FPCM - I vaguely recall some discussions on the Romraider forums on the topic.

EDIT: Saw the discussion earlier in this thread on the topic of vacuum leaks. You sound confident you don't have one, but I'm at a loss to explain the high manifold pressure otherwise.

Hmm.... this spark plug doesn't look to bad. Still going to replace spark plugs and coil packs and send injectors to get tested and cleaned. Is there a way to test these things?

Which plugs do you guys use, I only use NGK, either the NGK 7913 SILFR6A or NGK 93893 LFR6AIX?

I'm almost positive you have a moderately large vacuum leak. Once the car warms up in your log, you're still 2-4 psi high in terms of manifold pressure. I'm seeing -6 psig, whereas you should be in the -8 to -10 psig range given your baro and IAT readings. Not to mention the high fuel trims.

 

I suppose it could be a damaged MAP sensor, but I don't see how that would impact CL fueling to the extent you're seeing. You are definitely in CL fueling, BTW. Fuel trims being active is a dead giveaway, as no fueling corrections occur in OL since fuel delivery is based on MAF reading only in that regime.

 

The above may or may not be the entirety of your problem, but it's glaringly obvious that it's at least one of your issues so I'd address it.

 

I'd boost leak test the car (again if you've done so already). I'm not sure if you just have a pressure setup or a proper smoke tester, but the former can be a little tricky when it comes to finding certain leaks.

 

As for the FPDC spike at the end of your log, we'd need to dig into the control logic for the FPCM - I vaguely recall some discussions on the Romraider forums on the topic.

 

EDIT: Saw the discussion earlier in this thread on the topic of vacuum leaks. You sound confident you don't have one, but I'm at a loss to explain the high manifold pressure otherwise.

I have checked everything and sprayed starter fluid while it was running, but didn't notice any changes. Will keep looking.

Hmm. I do have stage 3 cams! Bigger cams should have direct effect on the vacuum. I think its either higher or lower than, looks like lower from what you are saying. Bigger cams changes everything from what I know, so stock values are iffy. Bigger cams eat more air and therefore need more fuel. Theres nothing efficient about racing cams.

Maf doesn't make a difference plugged in or not. Not sure when I get it to start but when it dies, ive tried unplugging the maf, it was the 1st thing I did on the side of the road lol.

Don't think its a leak, if it is its very small. I just plugged the intake and shot air in the system and its holding the pressure. And thats like 100+ psi. It can hold that and I can't see any smoke or hear any noticeable leaks other than the evap purge valve going off.

Maybe I need MORE fuel pressure....

I'll try unplugging the maf before I start it next and see what happens! Doesn't make a difference after it dies, lets see what it does prior.

You will lose engine vacuum with "racing" cams or anything with larger lobes, increased lobe separation, duration etc. Race cars run a vacuum canister to aid in having enough vacuum to operate other bits such as power brakes, etc. Was this discussed with your tuner and accounted for tune wise?? I don't believe it is your problem but it may rear its head at some point. I am still thinking electrical something.

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You will lose engine vacuum with "racing" cams or anything with larger lobes, increased lobe separation, duration etc. Race cars run a vacuum canister to aid in having enough vacuum to operate other bits such as power brakes, etc. Was this discussed with your tuner and accounted for tune wise?? I don't believe it is your problem but it may rear its head at some point. I am still thinking electrical something.

 

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How can i test for spark from the coil packs? I need to be in the car and at the coil pack at the same time..... gotta find someone to come help this week. Could be spark, easiest way to test is to just unplug the coil pack and test it while I crank the motor.

Electrical would be more random I think, this is very consistent. Car won't start if timing is off, maybe crank or cam position sensor, but those give cels right? Electrical problems I thought were easy on these cars because everything electrical throws a cel.

What would stop working properly without enough vacuum? Brake Booster, FPR, Evap Purge Valve, Recirculating Valve, PCV and the 3 port Boost Control Solenoid.....hmmmm

Tuner never mentioned anything about vacuum being an issue. The cams are tuneable, just a pita apparently.

It sounds like it'll run when in Open Loop (cold and not paying attention to sensors), but once you warm up enough to go closed loop with sensor readings, someone isn't playing nice and the ECU thinks it needs to shutdown to save the engine.

Or it's a sensor that just dies when hot and it's just around the time of Open -> Closed loop transition.

Sensors to test that may I think may cause the issue:

- Cam Shaft Sensor

- Engine Coolant Sensor

- Crank Sensor

I've seen a few stories of one of those sensors working fine when cold, but crap out at operating temp and the engine shuts off to be safe.

Camshaft Position Sensors:

https://www.subaruoutback.org/threads/wont-start-when-warm.36648/

https://uk.subaruownersclub.com/forums/topic/16301-warm-and-hot-engine-re-start-failure/

Coolant temp sensor (under the intake on the crossover coolant line) is brought up many times as well.

Did you mention you had codes at one point?

P0117 or P0118 - ECT

P0340 or P0341 - Cam Sensor

P0335 or P0336 - Crank Sensor