Couple SR Problems - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

azreark1 · 07-05-2015, 07:08 PM

So first problem is that i'm getting good fuel pressure but it's running on the lean side (14-15 at idle) and 13 at WOT with misfire (will be checking plug gap). Has good acceleration with an easy gas pedal but at WOT it bogs and misfires. I'm thinking the injectors might be bad, what do you think?...motor has FMIC, and T28 turbo but stock otherwise.

Next problem is the gear ratio...so my speedometer is telling me i'm doing 80 when i'm only doing 70, and it stays roughly around the same 10mph difference through the whole range. At 80mph indicated, the car is sitting at 3500rpm, it sounds a little high and has really good acceleration so i'm thinking that the gear ratio's were changed or it has the wrong speedo gear in the tranny? Any way to confirm this without tearing the rear end or tranny apart? What are your highway speeds and rpms?

jr_ss · 07-05-2015, 07:32 PM

Rotate drive shaft by hand. Count how many turns it takes to get your wheel to rotate 360 degrees. That's a pretty good indication of what your FD is.

Stop going WOT until you figure out the lean issue. You're only going to break something. What boost pressure are you at?

azreark1 · 07-05-2015, 07:50 PM

Yeah I'm not going WOT a lot, just rebuilt my motor, but ran it WOT a few times to see the readings on the UEGO. I currently don't have a boost gauge, but it has stock internal wastegate so unless it's broke, it's 7-8psi.

azreark1 · 07-05-2015, 09:09 PM

But now that I think of it, with all the rest of the crap I've found wrong while fixing up this car, wouldn't surprise me if the wastegate was jerry rigged to up the boost

azreark1 · 07-10-2015, 04:43 PM

Out of curiosity, what function does the cushion ring spacer do in the injector cap do? Needless to say i want to say it actually might be bad injectors, the pic shows how they came out of the car, with two of them missing the cushion rings.

Kis4Kouki · 07-10-2015, 08:53 PM

do you have a walboro or other aftermarket pump to support the fuel system. and a boost gauge would be a good investment.

azreark1 · 07-15-2015, 08:58 PM

okay i've checked everything i can think of...i replaced injectors, re-wired the fuel pump, double and triple checked for boost leaks, disconnected wastegate, it still does the same thing...any other idea's? Only thing i can think of now is it's blowing the spark out but they are gaped at .028", and color looks okay on the plugs. Could the plugs be going bad? And the coils look good, can't see any cracks that are obvious...

07-05-2015, 07:08 PM	#1
azreark1 Leaky Injector Join Date: Feb 2015 Location: San Antonio, Tx Age: 36 Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	Couple SR Problems So first problem is that i'm getting good fuel pressure but it's running on the lean side (14-15 at idle) and 13 at WOT with misfire (will be checking plug gap). Has good acceleration with an easy gas pedal but at WOT it bogs and misfires. I'm thinking the injectors might be bad, what do you think?...motor has FMIC, and T28 turbo but stock otherwise. Next problem is the gear ratio...so my speedometer is telling me i'm doing 80 when i'm only doing 70, and it stays roughly around the same 10mph difference through the whole range. At 80mph indicated, the car is sitting at 3500rpm, it sounds a little high and has really good acceleration so i'm thinking that the gear ratio's were changed or it has the wrong speedo gear in the tranny? Any way to confirm this without tearing the rear end or tranny apart? What are your highway speeds and rpms?

07-05-2015, 07:32 PM	#2
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,052 Trader Rating: (34) Feedback Score: 34 reviews	Rotate drive shaft by hand. Count how many turns it takes to get your wheel to rotate 360 degrees. That's a pretty good indication of what your FD is. Stop going WOT until you figure out the lean issue. You're only going to break something. What boost pressure are you at? __________________ My SR20VET

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07-05-2015, 07:50 PM	#3
azreark1 Leaky Injector Join Date: Feb 2015 Location: San Antonio, Tx Age: 36 Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	Yeah I'm not going WOT a lot, just rebuilt my motor, but ran it WOT a few times to see the readings on the UEGO. I currently don't have a boost gauge, but it has stock internal wastegate so unless it's broke, it's 7-8psi.

07-05-2015, 09:09 PM	#4
azreark1 Leaky Injector Join Date: Feb 2015 Location: San Antonio, Tx Age: 36 Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	But now that I think of it, with all the rest of the crap I've found wrong while fixing up this car, wouldn't surprise me if the wastegate was jerry rigged to up the boost

07-10-2015, 08:53 PM	#6
Kis4Kouki Leaky Injector Join Date: Feb 2015 Location: High Point, NC Posts: 111 Trader Rating: (3) Feedback Score: 3 reviews	do you have a walboro or other aftermarket pump to support the fuel system. and a boost gauge would be a good investment.

07-15-2015, 08:58 PM	#7
azreark1 Leaky Injector Join Date: Feb 2015 Location: San Antonio, Tx Age: 36 Posts: 71 Trader Rating: (0) Feedback Score: 0 reviews	okay i've checked everything i can think of...i replaced injectors, re-wired the fuel pump, double and triple checked for boost leaks, disconnected wastegate, it still does the same thing...any other idea's? Only thing i can think of now is it's blowing the spark out but they are gaped at .028", and color looks okay on the plugs. Could the plugs be going bad? And the coils look good, can't see any cracks that are obvious...