Misfire/stalling issues

[Dose Pipe Sutututu]

The stock one will outperform any aftermarket standard position exhaust manifold.

If you don't believe me, do a back to back test (same turbo, same boost, same timing) and you'll be super surprised.

[Chris_Guthrie]

That's good to hear I'll stick with the stock I hear they are good for 500hp and I'm only shooting for 350-400 once I can get this thing sorted and get to actually building it. 

[Murray_Calavera]

44 minutes ago, Chris_Guthrie said:

I hear they are good for 500hp

You'd need to weld on an external gate to achieve that number though. I can't remember seeing anyone make 500hp at the wheels with the stock manifold / internally gated turbo.

[joshuaho96]

On 4/24/2024 at 2:40 PM, Chris_Guthrie said:

Well considering I have the exact same problem with that as the original one I don't think that the ignitor is the problem. I would imagine that this being such an uncommon problem the possibility of getting a new ignitor that is bad in the same way as the old one has to be very slim. I'll definitely pull everything apart this weekend and check the turbo out. Got quite a bit of things to check out Saturday like fuel pressure and the pcv so I'll report back once I do that. 

Thanks everyone for all the replies this is all really helpful

 

Easiest way to know is to break out the multimeter and measure it when cold, then measure all the resistances again once it gets hot enough to misfire. Both the original ignitor and the J Replace version. Factory service manual will have the spec for the terminal measurements.

Edited April 28 by joshuaho96

[Chris_Guthrie]

Latest update, reinstalled the evap canister. No change. Disconnected the fpr vacuum hose, no change. 

Hooked up the fuel pressure tester. 42psi when primed, consistent with what I've been seeing online. When running, drops to 34psi. Ideas on this? 

Also, when I did my fuel pump rewire, I tested hot before tapping. I attempted at first to just unplug my relay to relieve fuel pressure and the pump still primed and ran. Thought that was strange. Unplugged the connector in the trunk by the fuel hat and was able to relieve fuel pressure that way. Starting to wonder if I jacked something up with my wiring because shouldn't be priming without the relay hooked up. 

[Chris_Guthrie]

Fuel pressure increases to about 48 when blipping the throttle while running

[GTSBoy]

44 minutes ago, Chris_Guthrie said:

drops to 34psi. Ideas on this?

Is correct. Manifold vacuum at idle is about the difference.

[Chris_Guthrie]

Just got back from a quick test and I'm really thinking that maybe the fuel line is sucking air in. I noticed when I removed the fuel pressure tester the hose on the fuel filter was easily spin-able. When it was twisting I noticed a slight change in the engine rhythm. Took it out to see and did fine again without boost and for the most part did fine in boost until I got a big hiccup about half throttle going up a hill. Going to investigate that further when I get more time. Probably just replace the fuel filter and the hose and see if there is any changes. Was able to go about 10m away today with the car feeling fine, actually felt a little stronger im guessing thats the splitfire coils (still an intermittent  misfire at idle).

18 minutes ago, GTSBoy said:

Is correct. Manifold vacuum at idle is about the difference

That's good to know at least. Guess I can rule out the pump. Also thinking could be bad fuel though I filled up my bike (11' R1) at the same place  the other day with the same 93 octane and got a crazy misfire that I never had on that before too. 

[joshuaho96]

On 5/1/2024 at 5:04 PM, Chris_Guthrie said:

Just got back from a quick test and I'm really thinking that maybe the fuel line is sucking air in. I noticed when I removed the fuel pressure tester the hose on the fuel filter was easily spin-able. When it was twisting I noticed a slight change in the engine rhythm. Took it out to see and did fine again without boost and for the most part did fine in boost until I got a big hiccup about half throttle going up a hill. Going to investigate that further when I get more time. Probably just replace the fuel filter and the hose and see if there is any changes. Was able to go about 10m away today with the car feeling fine, actually felt a little stronger im guessing thats the splitfire coils (still an intermittent  misfire at idle).

That's good to know at least. Guess I can rule out the pump. Also thinking could be bad fuel though I filled up my bike (11' R1) at the same place  the other day with the same 93 octane and got a crazy misfire that I never had on that before too. 

If your working theory is that air is getting into the fuel hose and those air bubbles are causing lean-outs it would run horribly at first or most likely no-start until the air is purged.

Also, if your fuel hose isn't sealing too well more likely it will manifest as a fuel leak, not air leaking into the system. I would be suspect of the gas station potentially having dirt intrusion in their underground tanks if you think it's the fuel filter causing a fuel pressure drop that causes lean-out. Fuel pressure has to be measured under load or you have to take a delta measurement at different points in the circuit if the idea of getting the car to a dyno or running a hose all the way from under the hood into the cabin and having one person check fuel pressure while the other drives is unpleasant.

[Chris_Guthrie]

On 5/3/2024 at 12:24 AM, joshuaho96 said:

I would be suspect of the gas station potentially having dirt intrusion in their underground tanks if you think it's the fuel filter causing a fuel pressure drop that causes lean-out

I'm thinking this but when I checked the fuel tank the fuel strainer under the pump was as clean as new. I do have a new fuel filter I'm going to replace that hose and filter just to be safe because maybe something did get through the strainer but I'm also going to attempt at some point next weekend to get the remaining fuel out and fill it up with some high quality fuel. 

[Dose Pipe Sutututu]

You need the fuel pressure gauge reading when the car is running and on boost.

Revving it stationary doesn't tell you much.

Get a wideband O2 installed, or borrow a portable one.

Will show very valuable data.

[Chris_Guthrie]

On 5/4/2024 at 9:04 PM, Dose Pipe Sutututu said:

Will show very valuable data.

Both of those things are on my to do but not quite in a position to do that just yet until I can at least get it running back to stock. Going to work on getting the exhaust manifold gasket and studs replaced first, an obvious need it now. Then I'll try out the new maf and see hownthat does. After that I'm thinking cas if I'm still having the same issues. Still need to run the fuel out and refuel I'll change the fuel filter tomorrow along with cleaning the iacv with carb cleaner. If all else fails I'm going to get a serial port and see if I can get some sort of data on what the ecu is seeing when the issue is happening but really hoping one of the methods above work out first. After I get a good base I'm going link but have to save for that so it'll be a while for that based on my tuners suggestions. Definitely need the exhaust leak fixed first though car has always fallen flat after about 4-4500 rpm since I've had it and suspecting that's the issue. Then I can move forward with the rest. 

[GTSBoy]

5 hours ago, Chris_Guthrie said:

car has always fallen flat after about 4-4500 rpm since I've had it and suspecting that's the issue

Won't be.

[Dose Pipe Sutututu]

All the above effort, time, swapping out parts in the dark (i.e. no O2 data).

You're literally running in the dark.

[czeno]

On 5/2/2024 at 12:04 PM, Chris_Guthrie said:

Also thinking could be bad fuel though I filled up my bike (11' R1) at the same place  the other day with the same 93 octane and got a crazy misfire that I never had on that before too. 

Have you explored this possibility further? I've been quietly watching this story unfold, early on I thought seems like bad fuel.