Kim Jong Illest

I think I have a fuel issue because I have checked all the coils wires, and plugs - everything seems good.


last week when I got off the highway and wanted to redline in 3rd to clean out the engine I got stuck at 8k RPM and got a flashing CEL (gas tank 2/5ths full) - p0302 so I babied it back to my place ordered new plugs and wires thinking it was time for a tune up anyways because I could not replicate the problem later at night. next day on the way back from work (pretty hot day) the car started cutting fuel while I was in 3.5 -4k rpm in 5th (gas tank 1/4 full) so I pushed the clutch in and rolled into a parking lot. I let it idle for a bit - it was coughing a lot and really rough when finally it just died (STFT went to +25 before it did). I let it sit for 3 min until the fans turned off and managed to start it up again without trouble - again idled really rough and died again 30 secs later. I let it chill for 3 hours while I went to the gym and came back to it, started her up - still running rough but I got it to the gas station - filled up and went home.


I've been troubleshooting it all weekend and the ignition is fine, all the spark plugs are firing so it must be the fuel pump but the thing that's leaving me scratching my head is that - the fuel pump assembly got replaced 6000 miles ago to the one in this link . After I tested the ignition I warmed it up and took it for some pulls around the neighborhood and the power it was putting out was great, didn't cut the fuel at all but after I drive it around for 1.5 hours it starts cutting the fuel supply.


Idle STFT cold is +3 and after driving around for a bit it's +7, cutting fuel and not seeing any codes.


Any suggestions on how I can test this?


Car has 94000 KM on engine
Catless
MS CAI
D585 coil kit
coolant temps never above 210
91 gas premixed

Loki

iTrader: (1)

If it only does this after warming up, that sounds like a heat problem. So either the fuel pump is overheating or something in the line is heating up and expanding. The reviews for that particular pump are terrible, sounds like a mix of poor assembly and people not understanding s1/s2 differences. How did you install it?

Kim Jong Illest

I'm the last review in that amazon link.
It's a S1 pump designed like the S2 and I did have to cut 1/4 inch off the nipple at the bottom.

it came to me assembled backwards lol which really set me back a day when installing it I couldn't wrap my head around how it didn't fit. It worked like a charm and my butt dyno thought it was better than stock I'm 95% sure it's still working?



Could it be the fuel pump resistor? https://www.rx8club.com/series-i-tro...roblem-164926/
Can I test it somehow before I throw money at it?

Kim Jong Illest

I replaced the spark plugs, car idles great, LTFT was +2.3 at idle when I took it out for some pulls tonight -- and it pulled amazingly for the first little bit. I was redlining without problems even at coolant temps of 208F.



Took it out on the highway and tried to redline in 3rd, but it would not let me past 8.5k rpm before flashing CEL (P0302 same as the first time before I changed the plugs) and I began getting power loss in all gears, but less noticeable in 1st and 2nd but definitely performance got worse, center console was considerably hotter (I am catless).


I'd be worried that the engine is on it's way out but I have absolutely no starting trouble cold or hot. Even when I was getting power loss I pulled over turned her off and started back up without issues. I also don't get this power loss at full operating temps when the car hasn't been driven longer than 30 mins.



Should have read the manual for my multimeter because it did not have a milliohm test range for continuity, but I got continuity on the smallest range my mm had. Guess I will have to go out and buy one tomorrow.







Other than the fuel pump and the resistor - is there anything else that can heat up to trigger a misfire? at the risk of sounding stupid - in the second rotor specifically. Can a dirty SSV do that? I do hear a clicking from the engine bay near the alternator.



I had a spare ACDelco D585 coil (never used) that I swapped into the the rotor 2 leading coil in the off chance that my old coil was failing at high RPM.

04Green

iTrader: (1)

I would offer it is still fuel related. The very high STFT indicates it is doing all it can to shove more fuel in to combat a lean condition. I am not sure if it goes any higher. So, either the fuel is not getting where it needs to go (rear housing) or a lot of extra air is getting in only when the engine is warm.

1/4 tank or 2/5 tank is still not a lot. I would fill it to just over half, maybe 3/4, and test again. This will assure that the pump and all the pieces are submerged. If the problem goes away, or is noticeably changed, fuel pump. And, the reason you did not fill it is because you now hope that the fuel level is below the opening for the pump.

The other option is a pretty good sized vacuum leak. I am having a hard time thinking this is it because at high RPM the throttle body is a huge hole letting air in and a leak that would impact that would have to be huge. ( I would also check the accordion tube for cracks, just do it, do not ask).

SSV has a sensor to see if it works. It will throw a code. I cannot recall if the VDI is for an intake path, or just for a tuned length. If it sticks, I am not sure if it would take things that lean. I am also not sure it would impact performance much, just cost you some power.

Fuel filter is not temp sensitive. Injectors and wires not likely temp sensitive.

Regarding high STFT. This is based on o2 sensor reading. A misfire is just that, the fuel and air go out the exhaust. This air has oxygen. If the o2 sensor sees the oxygen, it will drive a higher trim to make the oxygen get used up. So, it is possible that a bad ignition will look like low fuel. Also, if way rich, will look lean, due to the misfire. Or, you do not say how old the o2 sensor is. If engine is 94 Km, how many miles are on the car? And, what year?

Does this help?

04Green

iTrader: (1)

And, for giggles and grins, clean the MAF. Less likely to be an issue, but cheap, and should do it anyway.

Kim Jong Illest

Honestly I am really starting to suspect the fuel pump as well. Maybe I installed it incorrectly.

Could I have a clogged secondary injector in the rear housing?


When it first shut off on me on the highway I returned later that night and filled it up 4/5ths - but it was cold to begin with.



I wish I thought of this earlier today when I was testing it because I could have just topped the tank off with some cold gas to see if the situation is remedied. Now I am afraid to even redline it. I guess I would have to get it sufficiently hot to check the fuel pressure with a guage anyways...


The rear housing only misfire is strange though...


I have a long metal pipe (MS CAI) and I have tried spraying brake cleaner on it and around the engine bay while it's running to look for RPM bumps on my ODB2. Did not see anything. I could clean my filter though I am long overdue for it but I doubt it would be a heat sensitive part.


2007 Manual GT 94k KM on body and engine. I have had it since 50k KM
The idle is currently pristine with the new plugs.



Absolutely! I bought this car knowing it would be prone to problems and looked at it like an opportunity to learn. I don't know much but am learning a lot - really surprised by the variety of different problems this car has.