SR20DET falls on its face @ 5.5K rpms - Page 2 - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

JDMRIDDAZ · 07-24-2011, 08:31 AM

ur over looking something simple...i can feel it

fullthrottle · 07-24-2011, 08:56 AM

Try a different maf. I know it says you have a z32 but you seem to have gone through every other suggestion I had. Timing was my first answer and then fuel pump. So if it's not the maf it could be that the Ecu was tuned for a rev limiter at that rpm.

Silverbullet · 07-24-2011, 09:44 AM

I suffered from a similar issue a while back. Where the cut off seemed consistant to the RPM, but I noticed it was load dependant. The cut off point would be lower in a higher gear, amd the amount of throttle affected it also. For instance, at WOT in 2nd gear it may cut off at 6k rpm, and 3rd gear, it may cut out at 4.5k rpm, but at partial it may not cut out at all. Is yours like this also?

*StryfeS13* · 07-24-2011, 11:54 AM

Yes mine is similar to that. If I go half throttle, it will not do it. Sometimes it cuts at 5, sometimes at 5.5, sometimes at 6. Etc.

Kyle W. · 07-24-2011, 03:07 PM

Check your tps. I had the same thing happen to me.

GSXRJJordan · 07-24-2011, 03:56 PM

Quote:

Originally Posted by codyace

boost leak

My first thought too.

Quote:

Originally Posted by StryfeS13

- I tried retarding and advancing the timing, like 20 different times. Was never any better or worse, it made no difference.

This worries me. Check/set the base timing per the FSM. This was my second thought.

Quote:

Originally Posted by StryfeS13

Yes mine is similar to that. If I go half throttle, it will not do it. Sometimes it cuts at 5, sometimes at 5.5, sometimes at 6. Etc

If it's not rev-dependent (it'll rev to redline with less load) then it's load-dependent, and that makes me think fuel or MAF. If it were more or less rev-dependent, I'd think more about timing/CAS/wiring.

What engine management is he using? SAFC or ROM tune?

*StryfeS13* · 07-24-2011, 05:07 PM

Hey Jordan, thanks for stepping in.

- We checked for boost leaks, there are none.

- I set the timing back to FSM spec. It's at 15 BTDC @ 850 rpms.

- That is also what I was thinking. Because I can accelerate at 80 - 90% throttle and it wont do it. But the second i go WOT, it'll do it. The more boost I give it, the earlier it cuts. (for example, 14 PSI cuts at 4.5K) When it cuts, the AFR's don't go all crazy or anything, so I don't think it's fuel...

Maybe it is the MAF.

GSXRJJordan · 07-24-2011, 07:12 PM

Load dependent and not going lean = MAF or engine management. You never mentioned what you're using to tune it? I know you're not trying this all on a stock SR ECU...

*StryfeS13* · 07-24-2011, 07:19 PM

Yeah, definitely not stock ECU. It's an EFI Specialist ROM tune. We've talked to Khiem, he said it's all good.

jr_ss · 07-24-2011, 08:09 PM

Have good grounds on the chassis/motor/etc? Sounds more like electrical inference causing the issue... I dunno just thinking out loud here...

*StryfeS13* · 07-24-2011, 10:07 PM

Yeah we have good grounds. I'll check them just in case whenever the car is here again though. Probably tomorrow.

Still haven't tried a new maf yet either.

*StryfeS13* · 07-25-2011, 02:28 AM

Tried a different MAF. Nothing.

GSXRJJordan · 07-25-2011, 04:14 AM

Grounds are a great thing to start, but they tend to be more rev-dependent than load-dependent symptoms.

I'd start logging actual data, starting with MAF voltage. I'm guessing you're either max'n the MAF voltage or something's not getting enough power (voltage drop on an important component). Also what were your actual TPS readings at close/WOT, referenced to the TPS sensor ground?

fullthrottle · 07-25-2011, 08:04 AM

Is it possible that the injectors aren't the size you thought they were and are actually flooding the cylinders at full boost? Did you buy them new or used? It would suck to have to get the flow test but if they are say 740cc instead of 550s or whatever you have it might not be flooding until a certain boost/load. Exhaust smell like fuel at all? Do you have a wideband?

Edit. Just saw that you said your a/f ratio is good.

fullthrottle · 07-25-2011, 08:11 AM

Squeeze the intake and see if it's soft. It could be collapsing when the turbo starts to pull hard. Make sure the metal coil inside of it is spread out evenly through the whole intake pipe. If that's good double and triple check your couplers for cuts. Like around where it goes through the body of the car. Turbos build boost a lot faster than a compressor and can expand the couplers causing leaks that aren't apparent when testing for a boost leak. What psi did you bring the system to when doing your boost leak test? Make sure you test it at a lot higher psi than you plan to run. I test at 25psi to run 16psi.

Sileighty_85 · 07-25-2011, 08:12 AM

What brand plugs and Heat Range are you running?

*StryfeS13* · 07-25-2011, 01:40 PM

Quote:

Originally Posted by GSXRJJordan

Grounds are a great thing to start, but they tend to be more rev-dependent than load-dependent symptoms.

I'd start logging actual data, starting with MAF voltage. I'm guessing you're either max'n the MAF voltage or something's not getting enough power (voltage drop on an important component). Also what were your actual TPS readings at close/WOT, referenced to the TPS sensor ground?

The TPS voltage was .045 at closed, and like 4 something at WOT.

Quote:

Originally Posted by fullthrottle

Squeeze the intake and see if it's soft. It could be collapsing when the turbo starts to pull hard. Make sure the metal coil inside of it is spread out evenly through the whole intake pipe. If that's good double and triple check your couplers for cuts. Like around where it goes through the body of the car. Turbos build boost a lot faster than a compressor and can expand the couplers causing leaks that aren't apparent when testing for a boost leak. What psi did you bring the system to when doing your boost leak test? Make sure you test it at a lot higher psi than you plan to run. I test at 25psi to run 16psi.

I'll try that today.
I tested it at around 20 PSI. I'm sure the car will never see more than 16 lbs.

Quote:

Originally Posted by Sileighty_85

What brand plugs and Heat Range are you running?

NGK BKR7EIX gapped at .025. Have also tried .028, .022, .030, .032

I'm trying to convince him to switch to copper plugs.

codyace · 07-25-2011, 02:04 PM

Quote:

Originally Posted by StryfeS13

NGK BKR7EIX gapped at .025. Have also tried .028, .022, .030, .032

I'm trying to convince him to switch to copper plugs.

Material isn't going to make any difference in this circumstance, just on the longevity of the plugs.

Do you have a way to log the values as you drive through the ECU or your consult port?

*StryfeS13* · 07-25-2011, 03:10 PM

No, unfortunately I don't..

*StryfeS13* · 07-25-2011, 07:57 PM

Figured it out....intake was collapsing.

Thanks for all the help dudes!

ultimateirving · 07-25-2011, 08:14 PM

Quote:

Originally Posted by StryfeS13

Figured it out....intake was collapsing.

Thanks for all the help dudes!

haha, make note of that shit. hard to diagnose for sure! what did u upgrade to, post a pic plz. ima gonna be upping my boost soon and wanna make sure this dont happen to me. (E85 conversion in progress)

codyace · 07-25-2011, 10:52 PM

Quote:

Originally Posted by ultimateirving

haha, make note of that shit. hard to diagnose for sure! what did u upgrade to, post a pic plz. ima gonna be upping my boost soon and wanna make sure this dont happen to me. (E85 conversion in progress)

Run a proper intkae tube and couplers

*StryfeS13* · 07-25-2011, 11:36 PM

The intake that was on the car actually had NO spring inside of it.

We got a new intake and all problems have been resolved.

GSXRJJordan · 07-26-2011, 12:19 AM

Quote:

Originally Posted by StryfeS13

The intake that was on the car actually had NO spring inside of it.

We got a new intake and all problems have been resolved.

Fairly common problem, and I think it was brought up earlier in the thread! Glad you got it figured out

codyace · 07-26-2011, 06:58 AM

Quote:

Originally Posted by StryfeS13

The intake that was on the car actually had NO spring inside of it.

We got a new intake and all problems have been resolved.

Yea those stock ones collapse so easily!

A friend of mine had an instance of his car actually sucking the plastic cone inside the intake filter into the intake, essentially closing off the the intake...it would do some wacky stuff until he sorted it out.

bc. · 07-26-2011, 07:37 PM

Quote:

Originally Posted by StryfeS13

Figured it out....intake was collapsing.

Thanks for all the help dudes!

Lol, what?

Can you take a picture of this happening and post it on here? It would bring this thread full-circle...

codyace · 07-26-2011, 10:56 PM

Quote:

Originally Posted by bc.

Lol, what?

Can you take a picture of this happening and post it on here? It would bring this thread full-circle...

Imagine the intake tube to the turbo sucking the rubber accordian junk (or crappy coupler) shut....

91s13shawn · 07-28-2011, 02:15 PM

no i dont have one

Tearlessj · 07-28-2011, 02:21 PM

I was just about to come in here and post that.

Funny story, I was a instructor at one of the events and everytime I drove this guys car it would do that. When he drove it didn't do it. We figured out it was his intake and I was flooring his car all the way and he wasnt. Go figure.

fullthrottle · 07-29-2011, 06:47 AM

What do I win for figuring it out?

07-24-2011, 08:31 AM	#31
JDMRIDDAZ Zilvia Junkie Join Date: Sep 2007 Location: ｆォリダ Age: 44 Posts: 440 Trader Rating: (3) Feedback Score: 3 reviews	ur over looking something simple...i can feel it __________________ シチサｎ w/ka20det:in progress シチサｎw/sr20det:stolen

07-24-2011, 07:12 PM	#38
GSXRJJordan Post Whore! Join Date: May 2006 Location: << 626 >> Posts: 9,135 Trader Rating: (19) Rides Gallery: GSXRJJordan Feedback Score: 19 reviews	Load dependent and not going lean = MAF or engine management. You never mentioned what you're using to tune it? I know you're not trying this all on a stock SR ECU... __________________ Jordan Innovations has a new web site! www.JordanInnovations.com -- All your favorite FD Pro Drifters love it, trust me -- www.JordanInnovations.com

07-24-2011, 08:09 PM	#40
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,056 Trader Rating: (34) Feedback Score: 34 reviews	Have good grounds on the chassis/motor/etc? Sounds more like electrical inference causing the issue... I dunno just thinking out loud here... __________________ My SR20VET

07-25-2011, 04:14 AM	#43
GSXRJJordan Post Whore! Join Date: May 2006 Location: << 626 >> Posts: 9,135 Trader Rating: (19) Rides Gallery: GSXRJJordan Feedback Score: 19 reviews	Grounds are a great thing to start, but they tend to be more rev-dependent than load-dependent symptoms. I'd start logging actual data, starting with MAF voltage. I'm guessing you're either max'n the MAF voltage or something's not getting enough power (voltage drop on an important component). Also what were your actual TPS readings at close/WOT, referenced to the TPS sensor ground? __________________ Jordan Innovations has a new web site! www.JordanInnovations.com -- All your favorite FD Pro Drifters love it, trust me -- www.JordanInnovations.com

07-25-2011, 08:12 AM	#46
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	What brand plugs and Heat Range are you running? __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

07-24-2011, 08:56 AM	#32
fullthrottle Zilvia Addict Join Date: Apr 2009 Location: Saint Louis, MO Age: 34 Posts: 661 Trader Rating: (13) Feedback Score: 13 reviews	Try a different maf. I know it says you have a z32 but you seem to have gone through every other suggestion I had. Timing was my first answer and then fuel pump. So if it's not the maf it could be that the Ecu was tuned for a rev limiter at that rpm.

07-24-2011, 11:54 AM	#34
StryfeS13 It's Always Broken. Join Date: Feb 2010 Location: Fresno, CA Posts: 1,363 Trader Rating: (14) Feedback Score: 14 reviews	Yes mine is similar to that. If I go half throttle, it will not do it. Sometimes it cuts at 5, sometimes at 5.5, sometimes at 6. Etc.

07-24-2011, 03:07 PM	#35
Kyle W. Join Date: Jul 2011 Location: Sacramento CA Age: 29 Posts: 38 Trader Rating: (0) Feedback Score: 0 reviews	Check your tps. I had the same thing happen to me.

07-24-2011, 05:07 PM	#37
StryfeS13 It's Always Broken. Join Date: Feb 2010 Location: Fresno, CA Posts: 1,363 Trader Rating: (14) Feedback Score: 14 reviews	Hey Jordan, thanks for stepping in. - We checked for boost leaks, there are none. - I set the timing back to FSM spec. It's at 15 BTDC @ 850 rpms. - That is also what I was thinking. Because I can accelerate at 80 - 90% throttle and it wont do it. But the second i go WOT, it'll do it. The more boost I give it, the earlier it cuts. (for example, 14 PSI cuts at 4.5K) When it cuts, the AFR's don't go all crazy or anything, so I don't think it's fuel... Maybe it is the MAF.

07-24-2011, 07:19 PM	#39
StryfeS13 It's Always Broken. Join Date: Feb 2010 Location: Fresno, CA Posts: 1,363 Trader Rating: (14) Feedback Score: 14 reviews	Yeah, definitely not stock ECU. It's an EFI Specialist ROM tune. We've talked to Khiem, he said it's all good.

07-24-2011, 10:07 PM	#41
StryfeS13 It's Always Broken. Join Date: Feb 2010 Location: Fresno, CA Posts: 1,363 Trader Rating: (14) Feedback Score: 14 reviews	Yeah we have good grounds. I'll check them just in case whenever the car is here again though. Probably tomorrow. Still haven't tried a new maf yet either.

07-25-2011, 02:28 AM	#42
StryfeS13 It's Always Broken. Join Date: Feb 2010 Location: Fresno, CA Posts: 1,363 Trader Rating: (14) Feedback Score: 14 reviews	Tried a different MAF. Nothing.

07-25-2011, 08:04 AM	#44
fullthrottle Zilvia Addict Join Date: Apr 2009 Location: Saint Louis, MO Age: 34 Posts: 661 Trader Rating: (13) Feedback Score: 13 reviews	Is it possible that the injectors aren't the size you thought they were and are actually flooding the cylinders at full boost? Did you buy them new or used? It would suck to have to get the flow test but if they are say 740cc instead of 550s or whatever you have it might not be flooding until a certain boost/load. Exhaust smell like fuel at all? Do you have a wideband? Edit. Just saw that you said your a/f ratio is good.

07-25-2011, 08:11 AM	#45
fullthrottle Zilvia Addict Join Date: Apr 2009 Location: Saint Louis, MO Age: 34 Posts: 661 Trader Rating: (13) Feedback Score: 13 reviews	Squeeze the intake and see if it's soft. It could be collapsing when the turbo starts to pull hard. Make sure the metal coil inside of it is spread out evenly through the whole intake pipe. If that's good double and triple check your couplers for cuts. Like around where it goes through the body of the car. Turbos build boost a lot faster than a compressor and can expand the couplers causing leaks that aren't apparent when testing for a boost leak. What psi did you bring the system to when doing your boost leak test? Make sure you test it at a lot higher psi than you plan to run. I test at 25psi to run 16psi.

07-25-2011, 03:10 PM	#49
StryfeS13 It's Always Broken. Join Date: Feb 2010 Location: Fresno, CA Posts: 1,363 Trader Rating: (14) Feedback Score: 14 reviews	No, unfortunately I don't..

07-25-2011, 07:57 PM	#50
StryfeS13 It's Always Broken. Join Date: Feb 2010 Location: Fresno, CA Posts: 1,363 Trader Rating: (14) Feedback Score: 14 reviews	Figured it out....intake was collapsing. Thanks for all the help dudes!

07-25-2011, 11:36 PM	#53
StryfeS13 It's Always Broken. Join Date: Feb 2010 Location: Fresno, CA Posts: 1,363 Trader Rating: (14) Feedback Score: 14 reviews	The intake that was on the car actually had NO spring inside of it. We got a new intake and all problems have been resolved.

07-28-2011, 02:15 PM	#58
91s13shawn Join Date: Mar 2010 Location: Bradenton, FL Age: 30 Posts: 19 Trader Rating: (0) Feedback Score: 0 reviews	no i dont have one

07-28-2011, 02:21 PM	#59
Tearlessj Nissanaholic! Join Date: Feb 2007 Location: Memphis Age: 29 Posts: 1,907 Trader Rating: (6) Feedback Score: 6 reviews	I was just about to come in here and post that. Funny story, I was a instructor at one of the events and everytime I drove this guys car it would do that. When he drove it didn't do it. We figured out it was his intake and I was flooring his car all the way and he wasnt. Go figure. __________________ Nagasaki Motors Friends help you move. Real friends help you move bodies.

07-29-2011, 06:47 AM	#60
fullthrottle Zilvia Addict Join Date: Apr 2009 Location: Saint Louis, MO Age: 34 Posts: 661 Trader Rating: (13) Feedback Score: 13 reviews	What do I win for figuring it out?

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