Hey there,

I've got a 1991 NA with a GT2560r, 2.5 inch exhaust with high flow CAT & muffler, Poly-engine & diff mounts, and a Gen 2 MSPNP. Just installed the turbo and have been doing the tuning myself since my last turbo kit; which was an IHI Bell engineering kit from back in the day.

However, started setting up this tune & have been hitting a persistent issue. Currently I've got the boost at ~10.5 - 11 psi, but during a pull I seem to get what seems to feel like a fuel cut to an extent. Max duty cycle was 75%, so I do not think it is the injectors; which btw are 420cc injectors. There is a chance that maybe it is the fuel pump, which is stock; but I have a DW165 at home I might finally put in. AFR's are good and have got that down pat I think; highest is 12.3 around 3200 rpm which is ~5.12 psi. Timing is safe, I think the most I have is 15.1 degrees at the 7000 & Up range. I read somewhere that it may be the ecu losing sync with the engine in certain areas, so it could be that the ground near the turbo isn't as good as it could be. The bump seems to be around 5500-6500 in second mostly.

Any ideas are appreciated, I'll post some pics from TS if you are wondering about a certain one. Thanks, John

 

 

Here's a few pics. Still trying to sort everything out.

 

Like curly said, can't tell you much without the actual msq tune attached, and a log of the issue. If you suspect it's sync loss, take a composite log. Your spark map is really really bad. Take a look for maps around this site, there should not be a huge sharp jump at 100kpa. Without actually finding a good spark map right now, all I'll say is it's pretty typical to have around 28-30 degrees at 100kpa (like you have), but then taper around 1-1.5 degree of timing per psi of boost. Don't take that as a suggested spark map, just saying that you shouldn't go from 30 to 15 in one cell, it should be more like 30, 27, 23, etc. If you open the 3d tuning map, there should be no sharp peaks.

 

I think I attached my tune and log that I did together. I do not come on the forums that often

 

Your RPM trace is pretty terrible, have you done basic maintenance to the ignition system? What spark plugs and what gap are you running? I think you're just experiencing misfires.

 

I am running the FAB9 COP kit with their Denso spark plugs, and I want to say that they are gapped to ~0.28-0.32 . Is there a gap you would recommend?

 

Should the dwell be constant?

 

Wait... attachments in this forum actually work now?

Now that I've got a real log, I can see it's definitely not a fuel cut, and going by the AFR trace, not some other part of the fuel system running out, either. I'm thinking this is likely to be spark blowout. Check with FAB9 to see if their coils can take more dwell, and try a tighter spark plug gap.

 

Those pencil coils actually seem to like less dwell, like 1-2ms. Does it work better when cold? The modules like to heat soak as well. But start with the easy step, smash the plugs on your nice new COP setup to within .010" of it's life and see what happens.

 

Hey there,
Haven't had a chance to do much since I last talked. I just got some new spark plugs because I am just trying to eliminate variables. NGK Bkr7e, and planning to gap them to 0.028. that is all I have been able to do recently. I do have the composite log you guys suggested, but I do not understand the data. Would you guys walk me through what I am looking at?

 

Hi did you ever work this out?

I am having a similar issue at around 3500 rpm when the boost ramps in rapidly. I added a COP setup to mitigate the "spark blowout", but my issue still remains. I do believe it to be ecu/tune related bc when I disable the ebc everything runs smoothly. Could the ebc be using a bunch current right in that spot and cause sync issues? I will pull a composite log and data log once I try the new plugs.

 

lol at your spark map.

you're retarded 16° of timing at ~2.5psi.

1° of retard per psi is still conservative imho.



also those coils are sad if they need such a small gap. The shitty Toyota cops can run 20psi at .040" gap.

 

Hey guys,
Sorry I haven't come back to this thread in a while, I was able to figure out the issue thanks to you guys. For me, the issue was the spark plug gap. I put the gap to btwn 0.022 - 0.025, and that seemed to fix the issue. I guess I thought that spark gap wouldn't have been the problem since I only changed the turbo and am making roughly the same amount of power; but I guess that is what I get for not going for simplest solution first. Thank you for your help and advice

 

lol i was just about to post the same thing i did a few months ago. your spark map is **** that got shat on.