Fuel cut??

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Tobz
Posts: 3
Joined: Wed Jul 24, 2024 11:57 am
Car: 1997 Nissan Silvia Qs JDM

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Hey guys, been browsing for a few months throughout the forums online and finally dove in an made an account, I need some help. I'm not new to working on anything that runs on fuel, but this is stumping me only because I can't view a lot of sensor data on a computer, and that's my strong point working on diesels for a living, So here's the situation.

1997 JDM S14a with a sr20DE, 5 speed. Completely stock.
Concern- at WOT most noticeable in gears 3-5, at around 4000/4200 ish I hit a wall and the car will decelerate (while continuing to hold WOT), if I let off the pedal around 65% throttle it'll kick back in and rev perfectly fine all the way to 6k(I shift here because I don't feel the need to rev higher). I can watch some data through the Yashio Factory version 1 display I have, and if I keep throttle voltage at around 2.3V and climb through the RPMS it won't happen, only from 2.5-4.1v it seems like the ECU is commanding fuel cut.

This car has only 122000 KM on the odometer, extremely clean
New plugs/wires, cleaned up cap and rotor
Base timing set dead nuts at 15°
Idle set to 850
TPS voltage set to 0.47v(also measured with Scope and see no drop outs)
MAF has been cleaned and voltage readings not dropping out when this is happening.
Verified yesterday, 0 intake leaks.
Vehicle speed isn't capping out as I can let off throttle and increase.
I unplugged knock sensor no change
Unplugged VTC no change
Fuel filter looks brand new, but again it happens at a specific rpm/specific TPS position, so I really can't put money on it being something mechanically wrong like the fpr or filter as it has no sensors attached.

Im really curious if the timing of the cams is one tooth off possibly on the intake? And throwing cam sensor a faulting reading?

Idles really well, tho every once and a while it's gives a little shake, to me these 4-cylinder engines should be extremely smooth, so that's also another concern that could be related.

I want to have this engine running perfectly, before I decide to either do a +T or just save more and do an RB swap. Any help is greatly appreciated :mike


Tobz
Posts: 3
Joined: Wed Jul 24, 2024 11:57 am
Car: 1997 Nissan Silvia Qs JDM

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Soooooo tonight I went ahead and said **** it and pull the valve cover.....

Gents I was a tooth off on cam timing, re did the timing from the top, set the ex locator pin at 12 o'clock and counted 20 spaces in the chain links and put the intake indicator right there, set the distributor per fsm. Slight tweak to idle and timing for 15°. Thing runs so smooth and clean through entire RPM range accidently hit the limiter once because I was expecting it!

Hope this thread finds someone well who needed the info as I did.

No that I know I'm rock solid for a foundation for my +T time to start gathering parts 😎

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PapaSmurf2k3
Site Admin
Posts: 24100
Joined: Thu Nov 21, 2002 3:20 pm
Car: 2017 Corvette, 2018 Focus ST, 1993 240sx truck KA Turbo.
Location: Merrimack, NH

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Congrats!


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