Fuel Cut at WOT, VVT Swap MS3
#1
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I have swapped a 2001 VVT engine into my 93 based on the method in the mega thread. I have it running well except for one problem. The car will cut fuel if I go above ~90% throttle. It doesn't seem to matter what RPM, gear, accel enrichment (including 0 enrichment) or anything else I can think of. It is not just going lean it is completely cutting fuel as evidence by 0 pulse width when it happens. I have attached my tune and log file. The picture is of an instance where it happened 4 times in a row with me trying to be gentle with the throttle.
1993 VVT swapped
2001 gutted intake manifold
2001 tps
2001 injectors
MSlabs ms3
LC2 wideband
1993 VVT swapped
2001 gutted intake manifold
2001 tps
2001 injectors
MSlabs ms3
LC2 wideband
![](https://image.ibb.co/bXWurn/Fuel_cut_out.png)
#5
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No need to feel dumb, that is definitely a weird one. Full fuel cuts are always an ECU-induced limiter, so I just ran through all of those, starting with overboost protection, then AFR protection, then the rev limits page. Noticed you had pretty aggressive CLT limits, but it wasn't RPM dependent. A second look and I noticed the TPS bypass. It's set that way to prevent you from hammering on the car when it's cold. I would leave it like that and back down the CLT protections so you can go WOT at or above 160*F.
#6
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No need to feel dumb, that is definitely a weird one. Full fuel cuts are always an ECU-induced limiter, so I just ran through all of those, starting with overboost protection, then AFR protection, then the rev limits page. Noticed you had pretty aggressive CLT limits, but it wasn't RPM dependent. A second look and I noticed the TPS bypass. It's set that way to prevent you from hammering on the car when it's cold. I would leave it like that and back down the CLT protections so you can go WOT at or above 160*F.
My understanding is that boost when cold is not as big a problem as high RPM when cold.
Thoughts?
#7
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My mind was thinking that it has to be some ECU safety measure but I had forgot about the rev limiter/throttle bypass. I'm actually considering turning it off. This is an autocross only car so I shouldn't have an issue with not having it warmed up (this is also the reason I am conservative with my low temp limits). I guess 160F is considered the safe temp for rev limiter action. Ill probably keep it dialed back a little until 180F.
#8
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The original application is to have non-bypass induce a CLT based rev limit, preventing high revs on cold oil. However, in an emergency, above 90% TPS, that is ignored and the Rev Limit set higher. That enables you to potentially sacrifice a bearing while saving the rest of the car from a collision.
My understanding is that boost when cold is not as big a problem as high RPM when cold.
Thoughts?
My understanding is that boost when cold is not as big a problem as high RPM when cold.
Thoughts?
I would worry about turbo bearings at low oil temps but that may be unfounded as I am just surmising.
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