If you accelerate about mid level and keep it there does the car's rpms spin up quickly then grab at 4500 rpms all the time?

Just curious because I don't know what's happening with letting off the gas pedal as you're referring to. If you're off the gas pedal how is it that the power would kick in (and accelerate?) if you're off the gas?

I looked up the Mustang dyno and it seems to be a rolling dyno. I don't know anything about dyno's but if that drum rolls freely I'm still wondering if there is enough resistance to experience the same as on the street.

 

Haven't had time to check the data yet. To check your clutch, put it in 6th around 1000-1500 RPM and go WOT. If RPM increases and you aren't increasing vehicle speed, your clutch is slipping. If it just slowly accelerates, clutch is ok.

I know I'm probably not who you're talking about but I registered in 2008 then finally bought a G35 8 years later. I've always liked them.

 

Looked at the 3rd gear pull and I'm not seeing much so far but I'm leaning towards injectors still. Was it doing this before you swapped them in?

Can you swap OEM ones in and OEM MAF back in and put in the stock flash?

Have you done a compression test?

Edit:
Looking at the 4th gear pull. You say that the car even in 4th gear doesn't really pull until 4500 RPM? RPM seems to move linearly but the only thing that smooths out around that point is injector pulse width. It's not fluctuating a lot before but it might be worth looking into. Both banks appear the same so I don't think the problem is isolated to one set of injectors/wiring/etc or the other. I still say swap back to stock and make sure it's tuned for stock injectors.

 

This problem was identified about 3 months ago, not sure how long its been sleeping in the background, other than that, car just always wants to stall coming out of first it seems(feels like not enough gas, especially when the tank gets below half full, noticeable decrease in performance)

Compression test was good 176 around except 5th cylinder had 170

The car will only wake up if I tap the gas pedal while coasting (tap is: releasing foot entirely from gas pedal while coasting in gear, lightly tapping the gas pedal, release ,repeat until 4500rpm, then that magic wake up occurs) other than that, nothing happens at 4500 rpm when driving any other way.

 

Definitely strange.

Since your car runs OK on the dyno but not on the street we probably need to think of the different variables between the two.

Since Larimer has been assisting you with the numbers would you be able to record the same on the dyno?

What are variables between dyno and street runs?
Like I mentioned before is the resistance to the drive wheels there?
Is air forced into the engine during dyno runs?
Anything else?

 

I agree, and I will reach out to ECS to see if they can send me the more recent dyno runs where we saw consistent runs of 280rwhp without Knock 156 top speed smooth shifting..

the main variables I see between street and road would be the coolant temp sensor, fuel regulation, knock, front wheel speed sensors, vehicle speed sensor,abs module, brake booster/vacuum leaks, and clutch.

I am pretty confident at this point, between the P0303 code I saw with misfire, the car behaving differently on full tank versus less than half, and every electrical sensor/air hose/fuel delivery component replaced EXCEPT the fuel dampener(regulator) on the fuel rail, the injectors, and the injector harness. I believe swapping the dampener, injectors, and harness should produce the power that this car sees on the dyno to the pavement.

Ordering those three soon unless anyone has objections..

 

Just tried this, car accelerated very slowly , needle didnt move on rpm tach , so we should be good here

 

Did you try this yet?

 

No I haven't fully, but I did swap the 3rd cylinder injector with the OEM injector again, and it ticks much slower than the rest whether it's the 370z or the OEM injector on that cylinder.

This is why I feel that one of the following needs replacement:
the injector harness -not replaced yet
the fuel regulator on rail -not replaced yet
the current set of 370z injectors -swapped with OEM twice, no difference made

I would like to replace the entire in tank fuel assembly or the small fuel regulator attached to it(if possible), as I've swapped the OEM fuel pump with the 255lph Walbro with no differences made already.

 

just received this wonderful news in regards to the original dyno logs(extreme sarcasm, as I live in Albany, NY ~3 hours away) see below

"ECS Sales
To 'David Sheldon'
Today at 1:32 PM

Hey Dave,



If you’d like to stop by we can give you a printout of your dyno graph if that’s what you are looking for. I’m afraid I cannot send any of that electronically.



ECS Performance

1000 Old County Cir.

Unit 115 Windsor Locks, CT 06096

Phone: (860) 758 7644

Fax: (860) 758 7646

www.eastcoastswappers.com



PRIVILEGE AND CONFIDENTIALITY NOTICE
The information contained in this electronic mail message is proprietary and
confidential under applicable law, and is intended only for the use of the
individual or entity named above. If the recipient of this message is not
the above-named recipient, you are hereby notified that any dissemination,
copy or disclosure of this communication is prohibited. If you have received
this communication in error, please immediately purge it without making any
copy or distribution."

 

This would have been good information up front. I don't think the harness is bad, both banks were reading pretty much the same so stop throwing parts at it without diagnosing. Please, it's making this really difficult to figure out with shotgunning parts all over the place.

Rent a fuel pressure gauge from the auto parts store (just deposit and get it back when you return, free essentially) and see what it is at the rail at idle. Sounds like your higher flowing fuel pump could be overrunning the stock regulator possibly since it appeared to look very rich before the stall (in the data I looked at the other day).

Edit: Have you seen this? Did you do the fuel pump install or somebody else?
http://www.christurnbull.com/project...-g35-fx35-etc/

http://host.cj-motorsports.com/pdf/3...uel%20Pump.pdf

 

Larimer, I can understand your frustration but please understand the sequence of events in reference to your last paragraph. The OEM fuel pump had the same EXACT "engine wake up" at 4500 RPM symptom that is also occuring with the higher flowing walbro.

I haven't thrown a part at this car since the fuel pump was installed. In fact, my bank account has been thanking me since creating this thread....so not sure about the shotgunning statement....but I do appreciate the help, I'm just not trying to go backwards here, as this has been 2 years of driving this vehicle in a dormant state, and it's getting to that point for me where I am willing to replace parts that are logical at this point through testing.....

I have an overwhelming response saying that the fuel pressure regulator, injectors, or harness driving the injectors is bad at this point. So to me throwing money at any of the three wouldnt be shotgunning...but I haven't made a decision yet, as I'm optimistic to all suggestion

The advance auto near my house has a fuel pressure tester I can rent, but I believe the consensus would be to see the pressure as the vehicle drives, and I'm not sure how to rig the tester to allow for that ...

Edit: I did not drill a hole in the small regulator attached to the fuel pump assembly in the gas tank. That portion was not included on the DIY I followed. I installed the Walbro pump twice(O-ring ballooned the first time)

Also, Larimer, have you ever heard of faulty injector O-rings(top or bottom) creating symptoms similar to this? jw as this was brought up by a friend recently as a possibility, but I'm up in the air on that one..

 

Here is a picture of the run we did in May 2016, the only difference between this and the run completed in July 2016(most recent) is about ~10whp being achieved by welding the mid sleeve/rear clamps on the Stillen exhaust(which is supplied to you with the cheap clamps that allow air to manipulate the back pressure)

 

It's frustrating since there's so many things going on with this and some of the things you're saying aren't completely clear, and I don't know the full timeline of mods and when the problem started, etc. Sorry, not trying to be a jerk about it.

Check the pressure at idle first because it's easy at least and might tell you if the regulator is bad. None of this makes any sense why it would be fine on the dyno and not on the street, though.

 

Okay, I will check the fuel pressure at idle asap. I heard that if gas is coming out of your tailpipe(which it is) that your fuel pressure regulator is bad. However, i've already replaced the regulator on the passenger side, but not the one on the rail. Just so we are all on the same page.

I wish I could give you a run down of each component replaced, and when, but ultimately, we are at a place now, where every sensor on the car is brand new, and every air hose on the car is brand new.

Now I'm moving towards fuel...with only the fuel pressure regulator on rail, injectors, harness, and small regulator that I didn't drill a hole in or replace attached to the fuel tank assembly as possible culprits for fuel...