Spawne32

iTrader: (3)

So heres the run down. Supercharged 95 integra, b18b1. Stock JRSC kit, methanol injection, RMF narrow header, 2.5" exhaust system, warm air intake, mild hand ported head, running on 93 premium gas, tuned on ectune.

Start the car, cold start, no problems, idles smooth and great AFR. Driving it around town in hot weather, no problem. Start sitting in traffic, car will gradually start to lean out in the 15's AFR...sometimes higher depending on how long i sit. Punch the gas real hard and the AFR will drop some. IAT and ECT remain normal and unchanged while this occurs. Car also starts to develop a misfire (unrelated to lean running) while this occurs.

Second scenario, driving around town on a hot day for a while, stop to grab a drink at wawa or something, get back in car 5 minutes later, start it up, very rough idle (misfire) and running super lean, 15.5 or so, again, punch the gas real hard, problem goes away, especially while moving.

I have replaced or checked/repaired the following....

-fuel pump upgraded to a walbro 255
- swapped FPR's with known good one
- new alternator (old one was a tad bit on the weak side, new one is great, verified voltage via datalog)
-new battery, interstate megatron
-upgraded ground wires 2awg
- new fuel filter
- double checked tuning for any fuel retarding in hot weather
- new plugs, wires, dizzy cap
- reflowed solder on main relay for possible dry joints

Now it gets really really hot under the hood on a day like today (96 degrees), so hot that the hood prop will burn my hand, but i have been unable to associate the problem with anything other then the fact that it only occurs after something gets heatsoaked.

I threw out a really weird suggestion that it was possible that the fuel in the rail was boiling over, or "vapor locking". One thing i have been able to notice out of all of this is that when it runs lean like this, the fuel pressure is down to about 39psi, compared to 43.5 at idle on a cold start. Also, after sitting, the fuel pressure will drop randomly and rapidly depending on the day, sometimes ive seen it drop to 30psi after 10 minutes, on a hot day like today i saw it drop to 20psi and hold there. Immediately i assumed a leak, but there is none, and i have primed the fuel system when cold, and it will hold pressure for about 10 hours if it stays cold and primed.

Only real thing i was able to measure was the fact that the fuel rail external temp was about 165 degrees after coming home from some long driving. But i am damn near completely stumped as to what this issue is, and i have exhausted all "reasonable" solutions.

fcluddington

remember the hotter the air the more space it takes up. Sounds like your fuel and ign. tables are good for you use the iat correction and retard timing the hotter it gets. and for the hard starting their should be a fuel trim for starting only. whenever i have a starting issue i usually add fuel and a little timing. In your case maybe you need to adjust the pump prime time. at 200 degrees your 10psi could only have the air energy as 7 psi would.
When you were stating the fuel psi dropping this is at idle cold engine vs hot engine.

Also when you punch it. it's getting meth injected to cool things down?

Spawne32

iTrader: (3)

The car doesnt reach temps above 165 degrees now for IAT, so thats not an issue, and it is tuned for hot IAT temps. The fuel pump prime time was increased to 3 seconds instead of two, and the fuel psi starts dropping when it starts heatsoaking under the hood for a long time. You dont have to get the methanol injection to spray to get it to go back to normal from punching it, the methanol just helps, its done it regardless of whether it turns on though.

fcluddington

Problem 1. is it possible the wideband gets less accurate do to the heat. I have seen heat shields made for O2 sensors. What is your ect when you have this problem. try turning car off and back on when you notice your WB starting to read funny or are you really going lean.
problem 2. what is your ect and iat after car sits getting heat soaked while you getting a fix. anyway does your fan stay running during the 5 min. what are the temps when it doesnt want to start.ect iat and do u have egt

Spawne32

iTrader: (3)

1) yes, it is possible, but the wideband does not control the way the car runs, it merely provides feedback for datalogging, the car runs on open loop tuning

2) ECT stays solid between 190-200 degrees on a 90 degree day depending on sitting or moving, i have a heavy duty double row radiator, and two gigantic cooling fans attached to it that provide more then enough airflow, it never exceeds 200 degrees. The IAT's never exceed 165-170 (which is normal for a supercharged car and what it was tuned at ). Fan doesnt stay running after the car is off because ectune doesnt have programming for that, no EGT gauge as there was no need for it, at WOT the methanol drops the EGT's a couple hundred degrees.

Spawne32

iTrader: (3)

and like i said, if it was just a matter of it running lean, the car runs fine all the way up to 15.5 AFR at idle, but whenever the problem occurs, it develops the misfire, and it will misfire anywhere from 14.5 afr to 15.5 afr, it doesnt matter. So whatever it is i know it is related to heat soak, and i know that it drops the fuel pressure, and causes a mis. Only thing i can put my finger on that would cause something like that is a problem with either boiling gas, or air in the fuel rail or some kind of vapor lock problem. Which is so far out there i question my own beliefs on that. All i can say about trying to prove it correct is that the fuel rail is so hot after this happens, that it will burn your skin.

fcluddington

You are on pump gas also? you can always look up the boiling point of the different fuels.try different fuels like racing fuels their are several kinds take ur pic. The next time you know this is going to happen be ready with dry ice or even bagged ice, and some cans of freeze it. (basically nitrogen in a can , but spray down the entire rail only and lay the bags on your fuel filter, lines, ex. if you think it will melt plastic dump the ice all over your fuel rail or use the cans of freeze it. I think you need to see if you can get your fuel temp really cold and drive car and if their is still a miss then start looking into fixing a miss only when the car is heat soaked. are u sure your miss isnt really pre ignition or detonation? high temps cause both.
I knew you were in open loop just using wide band to monitor, and Neptune doesnt have any way of keeping fan running either but in 30 min you could wire up a seperate on off switch that works in conjuction with ecu on fan control.
I am a member of the getting rid of blast furnace temps under hood club. really I cant stand losing power due to heat. You could also have carbon build up creating a hot spot that would give you a miss. GL

DRAGLS

Try logging short term and long term fuel trims while engine is cool and then after it reaches operating temp.

Spawne32

iTrader: (3)

im gona make sure the gas tank is venting properly today, and pull all the fuel system between the filter and the injectors