Murz' 1986 Arctic Silver GXL aka Silver

[ITSWILL]

I would not use a fuel cut defender. They just trick your ecu into thinking it is only making factory boost. Therefore it doesnt make any fueling or ignition corrections.

[murz]

It would be used only until a new ECU is installed. I'm well aware the stock S4 Turbo ECU cuts fuel to the rear rotor around 7PSI, having a free flowing exhaust, 7PSI should be pretty easy to hit, and i'm well aware as much of a precaution that is, it's also very easy to go lean with that. Also, having 720 secondaries, and a 255 walbro should provide more fuel up top anyways.

[ITSWILL]

It's not just the fuel that is the issue it's the ignition timing that is the bigger problem.

[murz]

Engine is assembled, now just to throw it in the car and get it running! I have a four day weekend to get it all done, hoping to have it running by Sunday!

People seem to have no problem running an RTek, or hell even the stock ECU with a FCD, and an exhaust without the timing needing to be changed. Of course, being able to adjust the timing needed for really tuning the car. Which is why I'll be going with an after market ECU once I get the car running and broken in, I'm going to break it in on the stock ECU before I start playing with the boost and tune.

[fidelity101]

I've always wanted to do Megasquirt, and might even still later down the road. Right now, MS is pretty intimidating and far from plug and play. I have a stock S4 ECU that's on the car now, and has ran just fine two years ago, I had a 1.7 RTEK unit too, but that never worked right, my guess is something was wrong with the board thinking about it now?

Since RTEK is gone, buying a used one can be pricey now, as compared to what they went for previous to the company announcing their discontinuation. Though, if I come across one of the later models for a good price i'd probably go for that.

This is why i'm partial to the adaptronic, it's plug and play, you tell it your car's basic parameters (AFR targets, timing, rev-limiter, overboost, Fuel inj size, etc.) and it sort of sets it self up with a base map. And further tuning it from there would be less daunting if the base map is good to go.

For now I'll use my stock ECU and come up with a decision, though if anyone is selling a Fuel Cut Defender, let me know.

When i tried your RTEK it always wanted to cycle the fuel pump relay and was not functioning very well at all. I think that one is junk

go standalone!!!

[murz]

yeah I had issues with it not wanting to start, I assumed it was due to other reasons, but then you told me you had issues too.

[murz]

Well, last night I got the car running, but not without issues. First issue, went to prime everything, then noticed a good fuel leak, one of the clamps wasn't tightened enough (the one just below the filter). Then the battery died after about 3 more starts, I was using the vert's battery which has been sitting on a trickle charger since September. I was able to get my FC's battery from Ishin (I lent him it to do some testing about two years ago).

Then the car just wouldn't start. I went through the throttle body settings, and tried to set it back to factory, or as well as I could (I had it all messed up from the previous engine.)

Then, it started, the car is so quiet, I watched the revs climb, but I expected it to be louder, so it was almost surreal. It smoked the neighborhood for about 2 minutes, then cleared up. I let it sit at 2k for a bit with my foot, then i let off the gas and tried to see if it would idle on its own. To my surprise, it did! It was idling at around 600rpm, so i bumped it up with the BAC valve's idle adjustment screw to around 800-900rpm. Checked for leaks again, then decided to take it for a spin.

The Exedy stage 1 HD clutch and the lightweight flywheel really help the car out down low, it's got pretty good low end, it's actually quite surprising. The turbo starts spooling pretty early, and you can hear it spooling by 1700 rpms it seems. The idle is a bit lumpy, and has a definite brap to it, though nothing compared to Jake's FC, but more lumpy than my FD's idle and previous engine setups. Coming to a stop, the dashpot is doing its job by settling the idle to around 1100rpm, then a few seconds later it slowly drops down to 800-900rpms (I had a problem with this before).

Right now the only problem is that it's difficult to start without using the fuel cut switch I have. From what I've read, this should be the case as my setup has the stock fuel pressure regulator, plus a walbro 255lph pump. This shouldn't be an issue once I change over to a parallel fuel system. I don't have a gauge, but from what people have seen, this setup usually runs at 55lbs of pressure! Stock, i believe is around 27lbs?

[FCwidman]

Congrats, Can't wait to finally get the 2 silver cars cruising woodward together!

[ITSWILL]

I never had an issue using a walbro and the stock regulator. It ran a slight bit rich but fired up immediately on the coldest day of the winter or hottest day of summer. might be worth figuring out what your fuel pressure actually is.

[murz]

I read up online about it, a lot of people on the club have had hot start issues with the walbro and stock regulator. My car starts up just fine cold, but hot, i have to crack the throttle plates just a bit for it to do anything. I've got an aftermarket regulator coming in soon, going to do a parallel setup. I noticed too if i let a little unmetered air in, it idles a bit better.

Besides that, one of the rear brake pads disintegrated and locked up on me last night, going to do brakes and rotors all around.

[toplessFC3Sman]

My experience with the Walbro 255 and OEM regulator was that basically, the pump was completely maxing out the OEM regulator. There was no variation in fuel pressure with boost, it was just constantly at around 50 - 55 psi. This is definitely undesirable since not only is it working the pump harder, but the whole point of regulating the fuel pressure down as the MAP drops is to get more "range" out of the injectors and allow them to act more consistently.

The ECU knows nothing about the fuel pressure, it just assumes a certain amount of fuel injected for a certain duration of injector pulse - which for our purposes is basically true as long as the FPR is doing its job and keeping a constant difference in pressure across the injector (we're going to ignore injector needle dynamics, effects of pressure waves in the fuel rail, etc here since these are all secondary effects). Basically, for a 1ms injection time, if the pressure difference is 25 psi (so MAP when cruising is 10 psi and fuel pressure is 35, or MAP at idle is 3 psi and fuel pressure is 28 psi), the amount of fuel injected is the same. Therefore, if the walbro pushes fuel pressure up to an almost constant 55 psi, the differences at WOT in boost are going to be fairly small since the fuel pressure would have ordinarily been 48ish PSI for a MAP of 23 PSI (~8 psi boost above atmospheric), but the differences at idle and very low throttle openings are going to be large, meaning that you're getting a lot more fuel under these conditions than the ECU thinks its delivering. Since starting, idle, and low-throttle at low engine speeds are the most sensitive places for a rotary to run due to high amounts of EGR making combustion less stable (especially a ported rotary), you're going to notice more instability, hunting, and un-evenness here. Adding extra un-metered air that the ECU doesn't know about and thus doesn't correct for will help since it will balance out the extra fuel that the ECU doesn't know its injecting, making things more stable.

Basically, this is a long-winded way of saying "get your FPR working and the problem will fix itself".

[murz]

Thanks for the detailed explanation Pete! I'm surprised the car even idled at all really, i'm certain a new fuel setup will correct it. The current idle is pretty rough (it sounds good though!), but as the car warms up, it does smooth out a bit. In fact, after testing the car out last night, I noticed on cold start, it idles at ~750rpm, but once reaching operating temperature it idles at 900rpm decently smoother. This was another hint that it's just way too rich. 

I've got a turbo smart FPR and the necessary connectors, and lines en route!

The new setup will look like this.

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I've also ordered an adaptronic, as well as a sensor to read fuel pressure, a fast acting air temperature sensor, and an integrated wideband.

[murz]

-New Fuel Pressure Regulator installed.
In order to set this up, I needed to convert to a parallel fuel system, which required AN lines and several fittings. It was actually super easy, considering the S4 fuel rails have removable end pieces. However I totally messed up, when I went to test the fuel system (key on, plus opening the MAF flapper door) fuel shot out everywhere. Apparently you need the male to male fittings with the O-ring on one side. Initially the fuel pressure was set to 15PSI, so the car would start, then die. It now idles at 31PSI (stock is supposed to be 29PSI). It starts up like it should now, even hot starts are a breeze! No need to use the fuel cut switch I have, that can now be hidden for security purposes. Also, I installed a boost gauge too.

-New Oil cooler installed.
The old oil cooler sprung a tiny leak at the upper inlet, the new one needed to be re-tapped pretty bad, I was about to send it back in, but I was able to make it work and keep a lot of aluminum shavings out of it. While this was done, its first oil change was performed, considering it needed it from break in already.

-Rear brakes replaced and bled.
Apparently not good enough though, as I took the car out for a spin last night, the fronts aren't doing as much work as they should be. So time to re-bleed again.

-Things I noticed and need work still.
The alternator spacer was placed in the wrong spot, so the alternator pulley was severely misaligned, somehow I did not notice this. Getting a coolant leak from the water pump filler neck area, seems to be either the cap itself or the plastic neck where the cap screws onto.

I got into boost for the first time yesterday, while staying under 3.5k it definitely moves. Also, has wayyyyyy more low end than the FD does (considering the FD is running non-sequential). Guessing the small turbo, small intake piping, 10lb flywheel all play a part into that. It's a lot of fun, I can't wait to drive it some more, too bad I won't have time to bleed the brakes until next week.

The Adaptronic ECU came in as well, before that goes on, it needs to be broken in a bit more.

[murz]

Replaced the coolant cap, now it seems the water pump is starting to leak from the leak hole. I can never catch a break on this car it sure seems. Anyways, here is a video of it running. You are not allowed to view links. Register or Login

[~Groll69~]

So glad to see you have it up and running.