Maxima.org experts step-in, I've got a good one for you guys help me figure out.

Quick vehicle specs:
-’96 GXE 5-speed, VQ35DE, Z33 manifold, JWT ECU w/ nitrous controller
-JWT ECU has been used for about 4 years, without a problem

Symptoms:
-Idles fine, but at 1200 rpm (nominal is 650 ac off, 900 ac on)
-Rev-limited to exactly 3,000 rpm
-Throttle limited to about 20%, any more and appears to hit limiter, revives after exactly 500 rpm drop. (i.e., I doing 20mph in 2nd gear (2000 rpm), give it half-throttle, engine appears to hit a wall, comes back to life at 15mph (1500 rpm)
-Check Engine Light ON
-Cannot Check codes manually (no response to screw driver actions)
-Cannot Check codes with OBD-II scanner (no comm.)
-Fans High Speed ON all the time
-Appears to be running really lean (40 mph = 1300ºF on EGT)
-Fuel Pressure gauge reads nominal fuel pressures (34 idle, 48 WOT)
-No pinging and obvious lack of power

What I've done:
-MAF Sensor has been swapped and that is not it
-Disconnected the battery overnight to erase all memory and learning parameters
-Checked harness on ECU, but appears fine
-Swapped Crank Sensor


Anyone even seen or experienced these symptoms? Some help would be GREATLY appreciated.





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Swap in the stock ECU and watch your problems go away.

 

Sounds like a MAF, but you already checked that..

 

I don't have a stock ECU readily available, but looks like I'll have to find one and try that. Any other ideas?

 

When you say 'MAF throttle' what exactly do you mean by that? You switched MAF sensors? Is the one that you switched with good?

 

Typo, I am sleepy, meant Mass Air Flow Meter. Yes, the one that I switched is of another maxima, and it does work fine on that vehicle.

MAF Sensor only causes a rpm limit, not throttle position limit right?

 

Re adjust the TPS. But it sounds worse than the TPS IMO.

 

What exactly are you saying here.

No matter how wide the throttle is open, it wont go past x,xxx RPM. Unless you have TBW, then throttle position cannot be limited...only by your foot.



meximax----->You need more data.

 

That would be ECM-failsafe mode.
- revs limited to 3K.
- fans on all the time
- DTC codes not accessible

In a nutshell, your ecu is toast.

 

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Looks like JWT jacked you

 

The engine is limited by two mutually exclusive situations.

1. Rev-limited (3,000 rpm)

If I press the accelerator pedal a bit, engine rpm will climb and hit a 3,000 rev limiter. With the accelerator pedal still pressed, rpm will drop to 2500 rpm, engine will come to life and rpm starts climbing again to 3,000. The cycle continues until I let go.


2. TPS LIMITED: Any rpm under 3,000

If I press the accelerator pedal more than about 20%, my engine will hit a limiter, and will fall 500 rpm (REGARDLESS OF RPM).

For example, if I hold the rpm steady at 1500 rpm, then stomp it (WOT), the engine will do a quasi-stall, drop 500 rpm, then come back to life at 1,000.

So, yes, throttle position is limited too, and no, I don’t have TBW.

 

No your throttle plate is fully open. The ecu is just not giving you the fuel to mix with all that air. Hence your high EGTs.

 

Thank you very much. The operational constrains imposed by a failed ECU closely resemble my current symptoms. Seems like I have my answer.

No, JWT did not jack me. This is the first that I have seen any problems with my ECU. By your rational, I guess Nissan jacked all of us because I am sure we all have seen a problem within 4 years of purchase. I am sure that problem is the ECU and not JWT's work.

Embarrassing supercharged mustangs and C6s with my JWT ECU w/ nitrous controller on my VQ35 does not constitute being jacked. I've never had a problem with JWT or his customer service. I have nothing but good things to say about them.

I am sorry that your experiences with JWT left you a sour taste.

 

Um no, that is wrong. JWT mods the insides of the ECU so that is not "by my rational"

But you like your ECU so I hope you have good luck with it.

 

From the error desciption given in the FSM, it appears that the cpu chip may be the source of your problems. It may be a socketed chip that you could replace from a donor ecu, IDK.

Possibly JWT would give you a deal to transfer your existing daughterboard into another ecu.

 

there was tsb for the 95/96 ecu's.

 

I agree with eng92...probably the chip went bad or the N20 daughter board came loose.

Pull the cover and see if you see any burnt chips or the daughter board connections broke.