Engine Diag. HELP. - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Fmcmaste · 09-14-2014, 11:51 PM

Hi, I just signed up because I need help diagnosing my sr20 because it has me stumped.

Okay, to start here are the details. I have a 1995 s14 ob1 that i just got done swapping a blacktop s13 sr20det into. I bought the motor from a friend that knew nothing about it. Once I pulled it apart to rebuild it I could see the rotating assembly had been balanced but seemed to be stock internals otherwise. The valve springs and cams are possibly aftermarket as well, but was unable to find any kind of marks discerning make/lobe or anything helpful so I guess we can assume stock for the time being. There's an aftermarket bottom mount exhaust manifold bolted to a garrett GT2871R thats hooked up to a full 3" Apexi N1 exhaust. I have a godspeed front mount intercooler with a TIAL bov set on the cold side of the tubing. Plenum is stock with what seems to be a stock sr throttle body, the injectors are a light purple so again I'm assuming they're the stock 370cc's along with a z32 maf. finally I have it wired in with a wiring specialties harness connected to a stock sr ecu as well as running a walbro 255. I also have and Apexi power fc that is not hooked up yet but but was acting the exact same way when I tried hooking it up

Now for the issue. When I go to start the car it sounds like its really fighting itself. It wont turn on smoothly you have to gas it to keep it running while hearing back firing, stuttering, sputtering only clearing up at around 1500 to 2000+ rpm. At which point after struggling to start and keep it running it will calm down and set into a smooth idle around 8-900rpm with around 15-20psi vacuum. Sometimes it will hold until messed with other times it will slowly tapper off and die unless you persist in gassing it. Now I set timing to a T from what I have read from the manual I have. I have checked all the grounds, I'm getting fuel air spark I'm just stumped at the moment and any insight or help would be hugely appreciated thanks for your time and sorry about the drawn out post if there's any pertinent info that I left out please let me know and I'll tell you what I know.

510n · 09-15-2014, 09:54 AM

A stock SR ECU won't work with a z32 maf. You can either get a stock SR maf or hook up your Power FC and tune it for your z32 maf.

Vegass13 · 09-15-2014, 06:59 PM

check the timing if you havent already

Fmcmaste · 09-15-2014, 09:42 PM

Have timing set as well as I can possibly get it going off of the FSM. At the moment have a SR maf on order to see if with the maf I can get the stock ecu to idle and run smoothly. Thank you for your responses I'll let you know if anything changes.

09-14-2014, 11:51 PM	#1
Fmcmaste Join Date: Sep 2014 Location: Tempe Posts: 2 Trader Rating: (0) Feedback Score: 0 reviews	Engine Diag. HELP. Hi, I just signed up because I need help diagnosing my sr20 because it has me stumped. Okay, to start here are the details. I have a 1995 s14 ob1 that i just got done swapping a blacktop s13 sr20det into. I bought the motor from a friend that knew nothing about it. Once I pulled it apart to rebuild it I could see the rotating assembly had been balanced but seemed to be stock internals otherwise. The valve springs and cams are possibly aftermarket as well, but was unable to find any kind of marks discerning make/lobe or anything helpful so I guess we can assume stock for the time being. There's an aftermarket bottom mount exhaust manifold bolted to a garrett GT2871R thats hooked up to a full 3" Apexi N1 exhaust. I have a godspeed front mount intercooler with a TIAL bov set on the cold side of the tubing. Plenum is stock with what seems to be a stock sr throttle body, the injectors are a light purple so again I'm assuming they're the stock 370cc's along with a z32 maf. finally I have it wired in with a wiring specialties harness connected to a stock sr ecu as well as running a walbro 255. I also have and Apexi power fc that is not hooked up yet but but was acting the exact same way when I tried hooking it up Now for the issue. When I go to start the car it sounds like its really fighting itself. It wont turn on smoothly you have to gas it to keep it running while hearing back firing, stuttering, sputtering only clearing up at around 1500 to 2000+ rpm. At which point after struggling to start and keep it running it will calm down and set into a smooth idle around 8-900rpm with around 15-20psi vacuum. Sometimes it will hold until messed with other times it will slowly tapper off and die unless you persist in gassing it. Now I set timing to a T from what I have read from the manual I have. I have checked all the grounds, I'm getting fuel air spark I'm just stumped at the moment and any insight or help would be hugely appreciated thanks for your time and sorry about the drawn out post if there's any pertinent info that I left out please let me know and I'll tell you what I know.

09-15-2014, 09:54 AM	#2
510n Leaky Injector Join Date: Nov 2009 Location: Loma Linda Age: 38 Posts: 64 Trader Rating: (11) Feedback Score: 11 reviews	A stock SR ECU won't work with a z32 maf. You can either get a stock SR maf or hook up your Power FC and tune it for your z32 maf.

09-15-2014, 06:59 PM	#3
Vegass13 Zilvia Member Join Date: Jan 2014 Location: Las Vegas Posts: 159 Trader Rating: (3) Feedback Score: 3 reviews	check the timing if you havent already

09-15-2014, 09:42 PM	#4
Fmcmaste Join Date: Sep 2014 Location: Tempe Posts: 2 Trader Rating: (0) Feedback Score: 0 reviews	Have timing set as well as I can possibly get it going off of the FSM. At the moment have a SR maf on order to see if with the maf I can get the stock ecu to idle and run smoothly. Thank you for your responses I'll let you know if anything changes.