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Old 10-03-2015, 10:51 AM   #1
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Default Stuttering between 3k and 4k rpm

hi everyone.
ive got a mspnp gen 1 on my 1989 eunos roadster which is now turbocharged.
the car is mapped at 205hp at 10psi and its great when im in boost.

so heres my problem, the car seems to run lean (around 17-18afr) at partial throttle when the engine is between 3000 and 4000rpm.

Ive changed the cas sensor at the rear, i have ngk bkr7e rate plugs gapped to 1.1mm and installed toyota cops.
but the problem is still there.
i have a innovate MTX-L wideband hooked up correctly. just bought a new set of ngk plugs thinking it could fix this.
Its had this problem before it was mapped therefore for a while i was thinking the map needs tweeking i told the company that it tends to misfire and he told me that he thinks it could be the pressure regulator being faulty as its not designed to have boost pushed into it.

has anyone got any clue whats wrong with the car?
im not that good with laptops and software, i tend to leave it to the professionals
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Old 10-03-2015, 11:18 AM   #2
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So, it clears up above 4000?
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Old 10-04-2015, 03:02 AM   #3
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Sounds like the "professionals" didn't tune your car very well. How does your VE table look?
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Old 10-04-2015, 09:52 AM   #4
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once it goes past 4k its fine. ive just found out if i just rev the car and hold it between 3-4k it will run lumpy.
The guy thats mapped it has done many mx5's, evo's, subarus and even the new r35 GTRs
hes mapped my mates 580hp celica and that is perfect, he seemed to know his stuff when he was mapping it too.
the VE table looks normal pretty smooth
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Old 10-05-2015, 01:51 PM   #5
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Record a data log of the event while accelerating and post it here.
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Old 10-05-2015, 01:52 PM   #6
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Quote:
the car seems to run lean (around 17-18afr) at partial throttle when the engine is between 3000 and 4000rpm.
solution: Add fuel so the car doesn't run lean, partial throttle, when the engine is between 3000 and 4000rpm.
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Old 10-05-2015, 03:09 PM   #7
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Quote:
Originally Posted by Braineack View Post
solution: Add fuel so the car doesn't run lean, partial throttle, when the engine is between 3000 and 4000rpm.
I missed that when I came back to this thread.

Doesn't everybody autotune anymore? How could you have lean spots?
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Old 10-05-2015, 05:16 PM   #8
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i did use autotune before but it just made the a/f ratios all over the place! hmmmm ill give it a go but im definately gonna create a backup file incase i mess things up!
im just thinking if the car would be running lean maybe the fuel pressure reg has gone faulty after pushing boost into it?
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Old 10-05-2015, 05:39 PM   #9
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Autotune changes your VE table to match the target AFRs that YOU tell it to achieve. If it makes your AFRs all over the place, then maybe that's because your AFR table is all over the place?
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Old 10-05-2015, 05:42 PM   #10
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Quote:
Originally Posted by Itty View Post
Autotune changes your VE table to match the target AFRs that YOU tell it to achieve. If it makes your AFRs all over the place, then maybe that's because your AFR table is all over the place?
One time I walked into a Library and said I wanted to buy a tire.
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Old 10-05-2015, 06:20 PM   #11
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Old 10-05-2015, 06:25 PM   #12
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I remember that early megasquirt (MS1 and MS2) needed to have an extra capacitor added for the CAS over/above the typical install directions or otherwise there was a miss at lower RPM. Not sure if that applies to the mspnp1?
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Old 10-05-2015, 07:25 PM   #13
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thats just ms1 hi-res code.
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