briggs33

I posted here because SC300s and supra are basically the same car and members of this forum are usually more helpful regarding NA-T issues.

I have a 1995 mkiv na 5 spd with somewhere around 200k miles(odometer doesnt work). I did the tt ecu mod with a turbo install 2 years ago along with 550cc rx7 injectors a walbro pump and is300 coil/igniter setup according to this writeup. Also i have an safc and wideband for tuning
https://www.clublexus.com/forums/sc-4...t-ecu-mod.html (Great mod for anyone who wants to go NA-T BTW. All the info you need and very knowledgeable support.)

The car has ran perfectly for the past 2 years with no issues whatsoever after the initial setup was complete. In the past month I did an AC fix for the jdm ecu to get my AC to work. The fix worked and i drove my car without issue for a week before one day when i went out for lunch turned it off for an hour or and the car wouldn't start and acted like it was flooded(backfiring and semi starting before sputtering out). I did the deflood procedure and eventually got it to start and run fine for another couple days thinking it was just a fluke thing, something that had happened to me once a few months after doing my turbo install and was no big deal. Outside temperature seems to have no affect on the issue.

Now it seems that every morning or night the car has a very hard time starting when it sits for a while, it does it sometimes while still hot but less frequently. Everytime i have to go through the deflood procedure to get it started so my first thought was that it was flooded.

I went down a list of things to change and here is what i have gotten so far.

1.)I found oil on number 6 cylinder spark plug and found that valve cover gasket had been leaking, changed that.
2.)one coil was missing the little spring inside, bought a new one. 2 more are on the way but those look fine.
3.) changed plugs
4.) base timing was retarded at about 5 degrees, adjusted it up to 10-9, then 8-7 after a few days. I've checked it daily and seen no change.
5.) changed oil to a heavier weight after valve cover gasket leak.
6.) replaced fuel filter.
7.) switched back to stock 330cc injectors thinking one of the 550s could be leaking. AFRs are more stable with 330s as the 550s seemed to dip rich a bit randomly but other than that, and a fear of boost with the 330s there is no change.

The car runs and drives completely fine after i get it started so it really seems like just a flooding issue to me, but i could be missing something. I have a brand new walbro pump in my car that i've had for a while, and am thinking of installing that to eliminate the fuel pump. Other than that all i can think of is the fuel pressure regulator but i really want a way to test the stock one before buying another.

I appreciate any help that is offered to get this frustrating issue figured out.

briggs33

So i had an idea that maybe the EFI wire was being stretched to thin, i had it feeding the AC relay and my SAFC, so i cut the wire going to the AC relay just as a low risk low probability fix since i had just done that fix a little over a month ago. The car has now started up twice in a row after sitting cold over night and again 5 hours later. Im not convinced the issue is resolved as the car has started several times in a row before and then gone back to hard starting just when i start to ease up in my uncertainty.

Does you guys think that drawing too much power from the EFI would cause an issue like this, and if so why would it only be an intermittent thing and not all the time?

briggs33

Still doing it after all. Nobody has any ideas?

t2d2

iTrader: (8)

I had a few instances where the car refused to start. Between repairing the ECU and bypassing the fuel pump ECU, the problem has never returned. I think everything else I had tried while chasing a long-crank start-up issue, such as a new FPR, came prior to that resolution.