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400hp b15
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171 Posts
Discussion Starter · #1 ·
well its been about three weeks now ive brought about evey piece of diagnostic equipment home from work and out of my tool box spent countless hours trying to find a fix. I have a 2001 nissan sentra se with a u12 bluebird
sr20det im having issues with car heres the list of probs im having

1. backfires in the intake
2. low vacuum between 6-10 in/hg does not bounce or fluctuate rapidly
3. severe hesitation when partial throttling
4. will not idle very seldom it will idle but lopes heavily bounces from 800-500 rpms tried idle adjust but no help
5. my head hurts

my current set-up consists of
1. B14 jwt ecu tuned for 72lbs injectors and z32 maf
2. msd 72lbs injectors dropping resistors wired into injector signal wiring
3. 300zx maf
4. jim wolf technology msd fuel rail
5. aeromotive 13109 FPR
6. all -6 steel braid fuel line
7. walbro 255lph fuel pump
8. borg warner T4 turbo 96 a/r turbine 4inch outlet 70 a/r compressor 4inch inlet and 2.5 pressure outlet
9. tial 46mm wastegate
10. spoolin performance log mani
11. 4inch downpipe reducing to 3inch from mid of the car back
12. billet throttle body spacer
13. turbo smart veeport bov
14. built bottom end stock blue bird head

what i have done so far as to diagnosing vehicle

1. compression is 155-156 across all 4
2. leak down test is roughly 10% per cylinder
3. running compression in the 90s but across all 4
so this indicating that internals are still sealing well
4. tps sensor is at .45 volts at close and around 4 volts WOT
5. new oxygen sensor seams to be switching as normal
6. R and R the dizzy cap to inspect the points in the cap for the most part looks good
7. regapped ngk bk6re plugs to 32 thousands
8. verified cam timing and ignition timing at 15 degrees at idle as per jwt
9. checked continuity of all sensors necessary all signal,ground and power wiring ohmed out below 3 ohms
10. verified that that no vacuum leaks present
11. regrounded maf to block
12. boost leak test with both pressure and evap smoke machine
13. drank beer

well at this point i dont now what else to look for im stumped i talked to ben a jwt but as always no help they are like talking to walls there and always assume that there programming is fine but im starting to doubt this so and input from u guy would be greatly appreciated i have a number if youd rather shoot me sum info over the phone my numis 443-683-2955 or just post ur thoughts

thanks
stefano
 

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Banned
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609 Posts
i dont know if u have access to stock stuff. might want to try stock injectors and ecu and maf and see if it still does it. Im guessin u used an obd1 harness? since i know the b15 harness wont work on that motor. check to make sure ur getting a reading from all ur sensors. also make sure all ur injectors are actually firing.
 

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2001 B15Ve+T
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632 Posts
can u get ur hands on a nother ecu, and swap it out, i been reading about jwt ecu and alot of ppl having trouble with them. and can u data log with the ecu? and see what is happening.
 

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400hp b15
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171 Posts
Discussion Starter · #5 ·
i dont know if u have access to stock stuff. might want to try stock injectors and ecu and maf and see if it still does it. Im guessin u used an obd1 harness? since i know the b15 harness wont work on that motor. check to make sure ur getting a reading from all ur sensors. also make sure all ur injectors are actually firing.
yes you can use the b15 harness that what im using i have spliced in the b14 harness connector also i have been running a 370cc 3bar stock maf program from jwt for about two years prior to this no problems then and yes every thing through the scan to is reading i have a SNAP-ON scan tool and im throwing only the egr fault whicj jim wolf claims does not affect drivability
 

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400hp b15
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171 Posts
Discussion Starter · #6 ·
can u get ur hands on a nother ecu, and swap it out, i been reading about jwt ecu and alot of ppl having trouble with them. and can u data log with the ecu? and see what is happening.
yeah ive been reading about this that people are have problems with there 72lbs programs so im def starting to suspect the problem is with the tune
 

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2001 B15Ve+T
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632 Posts
ur best bet it, do u have the stock stuff or get ur hands on some parts to just swtich over and see how everything work, then u know its the ecu. or just call jwt up and give them an large amount of **** but in a nice tone... then see what they can do, i recommend ordering a calum or nistune

good luck
 

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400hp b15
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171 Posts
Discussion Starter · #9 ·
and before i had this program i had the 370 stock maf jwt comp and it ran completely fine
 

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Registered
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898 Posts
problem is your using a b15...
 

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boost monkey
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325 Posts
like others have said, try using stock stuff. I spent the longest time trying to trouble shoot a problem, and it ended up being the JWT ecu w/ the 72lb program. Popped a stock de ecu in with emanage and the car idled fine.
 

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Se-riousr
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176 Posts
i see that u have the gap on the plugs at 32 bring it down. check the way u have the spacer it sound like a vaccum and make sure the idle air hose is on good it goes under the throttle.
 

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200SX SE-R T3/T4 SLEEPER!
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130 Posts
B15, DET, T4 Turbo.. I WANNA SEE, PLEEEAAASE! :D You should post some pics! If I see what it looks like I can better find the problem ;)
 

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CAR SLÜT
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1,622 Posts
Its sounds like its running lean at idle, I think ECU is the culprit unless you want to crank some more fuel pressure into it at idle and see if that improves things
 

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400hp b15
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171 Posts
Discussion Starter · #16 ·
Its sounds like its running lean at idle, I think ECU is the culprit unless you want to crank some more fuel pressure into it at idle and see if that improves things
yes this is exactly what im thinking as well its is running very lean at idle
i tried to bump up the fuel pressure but that didnt really help much until it was around 60 psi at idle which is crazy pressure at idle lol
 

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CAR SLÜT
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1,622 Posts
At which point I would say the ECU is programmed for the wrong closed loop idle mixture ;)
 

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400hp b15
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171 Posts
Discussion Starter · #18 ·
ok so this tune is definitely running to lean it idle now i know that you cant be exact on a tuned for every car because there all different so what if i were to use a e-manage or and safc to correct the fueling to a much finer tune would this work or does the b14 ecu fight it ?
 

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Done.
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3,923 Posts
First and foremost, you have vacuum leaks. Get a pressure tester and find them. They will make you pull your hair out until you're bald, if you don't fix them all first. The tune will ALWAYS be off with vacuum/boost leaks.

Secondly, an SAFC is highly recommended on top of the JWT ECU, to help with fine tuning. JWT generally overinflates their tunes to have a larger buffer area, to keep a user from blowing his motor and blaming them for it.
 

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Done.
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3,923 Posts
Oh yeah, and go down to a BKR7E. 6E is too hot a plug with your setup. Get 7's and gap them to around .026"~.028".
 
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