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boosted 2.0 fuel cut? boost problem?

4K views 21 replies 10 participants last post by  Projectb15 
#1 ·
hey all, ive got a couple questions about my 2.0 boosted sentra. To start off ive gota electronic boost controller which is not tuned right, so everytime i step on it and give it full throttle from 5-6 rpm it will backfire almost and not have the same power it did at 4k... is it loosing boost or is it loosing fuel possibly??? Its like when the turbo spools up and peaks at 4.5k then it just stops accelerating as hard and almost sounds bad for the engine like its not running right. Shouldn't i be able to go into the higher rpms with no problem? My brothers srt-4 powers through the gears no problem. What can i do about this? anyone have ne knowledge on greddy electronic boost controllers? or had any same experiences? i wanna have torque all the way through the gear, right when it starts accelerating hard all the power drops. :(
Cheers, Alex
 
#4 · (Edited)
It does pop and backfire some, but it does feel like a brick wall, could this be i need to tune it better with the electronic controll? or is it definately i need to upgrade my fuel pump?

i will have to take my car out and mess with it some more. But i do not have a tune on this car, and i just put in a stage 2 clutch. WOuld a tune fix this problem? and where would i go to tune it? Thanks for the reply, this site is really the only place to find info about my car lol.

I forgot to mention that when at idle rpms in the car will die down to as low as 400rpm and then jump back up, does this support the fuel pump theory or something else, because when i turn on the fan or turn the wheel at an idle it does the same thing. i would expect the rpms to raise if anything
 
#5 ·
okay so i printed some intructions on how to tune it with the electronic controll, and in the process of WOT i noticed a smell coming from the engine, it was the heat wrap catching on smoke/fire!!!!! where can i buy good but cheap wraps, and shields for the exhaust side of my turbo? The exhaust (downpipe)? is rubbing against a black tube that is wraped but they started smoking. :eek:
 
#8 ·
So after some looking around, i found the cars long lost owner, and found out about it somemore since i was not given any paper work on the car i had to do the diggin myself. < http://www.b15sentra.net/forums/showthread.php?t=157673 > It has a JWT B14 ECU (Jim wolf) The work was done my Genesis Racing Development, Would my best bet be GRD? Im pretty sure my turbo timing is off which is causing the poping at high rpm, and im running rich or lean cause of my AFC isn't tuned properly.

I am loacted close by Gurnee mills shopping area, and six flags 60046. wud anyone recomment 1 6 racing? or is anyone in the area that can tune this for me?
 
#11 ·
OP, reading your post hurts my head. Could you try and post in proper English and grammar?

You need to get yourself a wideband o2 gauge, and a boost gauge. Only then can you begin to diagnose your issue. Do you even know what your boost controller is set to?

I'll agree with JP. The most logical answer is a boost leak. If that doesn't happen, then I would start checking spark plug gap, and perhaps go a step colder on the plugs. You should also check the terminals on the spark plug wires for corrosion.

If you don't have a boost gauge you could potentially be running out of fuel. This is why you need a proper data logger to monitor a/f ratio, knock, maf readings, boost, and injector duty cycle.

I'll never understand why people install something on their cars they know nothing about. That's a recipe for destroyed ring lands.
 
#12 · (Edited)
In a way you are correct.
I pretty much assisted in building this car in it's different states. He doesn't need a wide band because like he said he is running a JWT ecu that is already programmed for his setup. The SAFC in his car was not tuned as of when he got the car back from the shop. If he has since messed with it then that could be an issue. Plugs were gaped properly when it was handed over to him, and I am pretty sure he is running 7's so he is fine. The car has a boost gauge, but his issue is that he is running the digital boost controller that is not very user friendly. A boost gauge does nothing to tell you what your fuel cycle is.

I don't have anytime this weekend to help you out, but maybe next tuesday I could. I live in Schaumburg so if you were able to drive to my place I can give it a once over.

The OP didn't install anything on this car he bought the car as is.
 
#14 ·
Tuning your "electronic boost controller"?

Turbo timing?


You have a fuel issue. Your tune is ****. That is all.
GO GET YOUR **** TUNED BY A REPUTABLE PERSON

Please, PLEASE don't post your "assumptions" without knowing wtf you are talking about. It makes you look stoopid.
 
#16 ·
If I were you, I wouldn't look into fuel issues just yet. It has an upgraded Walbro fuel pump. If you just need a working car, this isn't the car for you.

I've learned that the hard way. I will never buy a modded car, or mod a working car, unless I am prepared to deal with it (need time, space, money, and a troubleshooting mindset) from now on.

Now for the helpful troubleshooting part of my post:

My last dealing with this car was the IC itself was punctured, which introduced an open circuit for the air. After that was replaced, I was still having issues pointing to air leak, but didn't have the time or the money to bring it to a shop to do a leak test.

There were two leak points I've fixed - the IC (replaced), injector o-ring (found by spraying engine cleaner). The shops charge too much to get it tested each and every time, plus parts, so I sold the car - just can't afford it. If I had the time, money, and workspace, I would have loved to continue troubleshooting the car.

You don't want to deal with too many things at once, or you won't know what caused what to happen, etc. First, lets work on the intake side - make sure there is no air or vac leaks. Get it pressure tested.

It's been a while since I had the car, so while I did a compression test, what was good then may not be good now, so go check that.

If that all checks out, make sure the fuel pump is still good - just because it's been upgraded doesn't mean that it isn't failing NOW. Make sure fuel filter isn't clogged while you're in there. I had a fuel pressure gauge installed for this purpose. Unless the previous owner removed it, it should still be visible under the hood by the brake fluid tank.

Get as much documentation as you can about the car (service manual), the boost controller, and the SAFC. We will be looking into electronics and wiring issues here. I'd blank out the SAFC for now (make it just a pass-thru device just for monitoring ONLY). As JP said, the boost controller isn't very user friendly, and while I found out their cryptic way of tuning, relaying that info to the shop owner was futile. I don't remember how it all works now - it's been a while, so please don't contact me regarding the specifics of tuning with that boost controller. Sorry.

Re-check wiring on the ECU. I think it's mostly correct except for one or two wires that JP figured out after I sold my car. You may need to send it back to JWT to get it tested - make sure all modules are still functioning as JWT intended. I heard somewhere that someone fixed a check engine light this way (a code specifically for EVAP or something like that) on this very car. Perhaps with all this tinkering, something got shorted and fried that part of the module again.

The transmission was good when I had it. The only issue I had was the spring popped out on the shifter. It was kinda hard going into 1st, but other than that, I loved it. The stiff clutch I got used to - I loved the low biting point. I have no advice to give on it.



In my experience, it is not wise to try to tune the car until you checked out everything. Everytime I did troubleshooting, I'd find a problem, and I would think "that fixed it", and took it to tuning. Of course it doesn't work out, and I had to spend more time troubleshooting. In the mean time, the shop earned their money for me taking the car in just to ATTEMPT to tune.


So Cliff notes:
I'd focus on plugging up the air leaks, making sure there's no leak, then continue looking into the fuel delivery system. If all is good, check wiring and the ECU itself (send it to JWT for testing). Hell, you can even remove the SAFC to have one less thing in the mix. I'd even go a little further and check for exhaust leaks before I finally take it in for tuning.


If you don't want to go through all that trouble, you can try dropping it off a performance shop and say "I just bought this, I dunno what's wrong with it, check it out, and get it running" and see what happens.
 
#17 ·
I would first be sure that you got a genuine Wally pump. A lot of fakes are going around these days, and the only way to tell is by looking down the pump. If you see metal gears inside it, you're good. Plastic = you're ****ed. That would explain things.

You should also get a data logger that shows your injector duty cycle, air flow readings.

Don't run a highly modified car without logging equipment, that's asking for it.
 
#18 ·
k. here is where i step in....lolz. Turbo guy.

Installing an aftermarket fuel pump will not solve the issue. Your FPR (Fuel Pressure Regulator), FMU (Fuel Management Unit), and ECM are designed for a certain PSI of fuel delivered in your vehicle under normal and driven hard circumstances.

Turbochargers pull in more fuel than n/a, So, yes! you are getting fuel cuts. For an easy fix for small psi on that turbo, would be a FCD (Fuel Cut Defender) (HKS and Blitz offer 1) or you can Home Depot it, just google it and it works for under 8psi.

To make your new turbocharged sentra run smooth and up to 7psi with no hiccups, your gonna need Fuel Pump, Fuel lines, Adjustable Press. Regulator, injectors (WRX ones should work), and Fuel management unit. THats for fuel. You would probably wanna get a set of NGK step cold plugs to prevent any ignition detonation.
 
#21 ·
"Hi, my name is ______. I really don't know what I'm talking about, but will give you advise anyways. Please ignore what knowledgeble people are saying and follow my extremely accurate advise I found in a cracker jack box." :rolleyes: lol

Based on the OP statements so far, I would say forget about trying any tuning or moderate wrenching yourself. If JP can help you out, awesome! Otherwise, I'd look into a reputable shop for assistance. It's going to cost some money, but so would blowing your motor by screwing around with the tune blindly ;)
 
#22 ·
wow, way to brush a cold shoulder on someone who knows about Turbocharged automobiles.

Jp, understand where your coming from, but if any turbo vehicle gets fuel cuts, obviously something wrong with the ECU, chipped or not chipped/reflashed. Not a big fan of Reflash, cheap EMS IMO.

MSD injectors? wow, i know that they are good for ignition products, but wouldnt trust their fuel anyday. Only companies that are known for fuel injector upgrades are HKS, RC engineering and are reliable.

If he is having fuel cuts, it has to do with the MAF sensor, My turbo MazdaSpeed protege needed one from HKS, it just hooks up to your maf with a 1.5v additive on it. Not to mention the fact that his car isnt balanced right on a/f mixture, which will lead to either bogging or burning lean.

So, cheapest fix, run less pounds per square inch of boost on your sentra. Or talk to some people on here who have their sentra turbo'd. Last resort, talk to Jim Wolf Technology and tell them that they need a ECM reflash for turbo'd sentras, ahem non Sunny's, lol.
 
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