Hello. Swapped my vq23de to a vq35de. vq35de ecu was immobilized, got the immobilizer bypassed. Car starts and runs, but the cel was on and the car was in limp mode. needs nissan consult 2 for diagnostics (regular obd2 readers don't work) so I downloadeded NDS2 and pulled 3 codes. I understand 2 of them are sensor codes, but I don't know what the other one is. Also, cleared the faults and cel is gone, but car is still in limp mode and every time I scan the car the codes appear even with no cel. Thanks. *Note: Engine came with a CVT trans but is now mounted to the vq23 4 speed auto and also, the wiring harness is from the vq23.

 

U1001 - you left a computer unplugged on the can Network - could be the cause of limp mode

P0031 - left a primary O2 sensor unplugged most likely if you didn't have this pre-swap - uhhhh I have to go run out to my 6th gen to see if this causes limp mode

That last code... Self explanatory.... Hell that may cause limp mode too let me play with my 6th gen brb


​​​​​​Edit: my 6th gen doesn't have the front primary plugged in due to the headers.
I unplugged my coolant temp sensor and it drove the same.

Your limp mode is caused by something unplugged on the can Network go-to the fsm (The fsm for the car you got the ECU from) it will list all the modules.

​​​​​Question.... Did you have this problem with your stock ECU?

 

Thanks so much for the help sir. everything is plugged in. I was checking the sensor readings using NDS2, and all important sensors were plugged in. My stock ecu was somehow running the vq35 great with no cel and full power (not FULL full bc it squirts out enough gas for the 2.3, not 3.5, but faster than the vq23). I can't get the fsm bc there is absolutely no info on the 3.5 2007 Presage van. You can try. I am really stuck now bc the guy that bypassed the immobilizer broke my stock ecu. He said he is gonna fix the car no matter what, but he is 100 miles away and in my country, that'll take you 5 hours with a running car, and about 9 hours with a car that takes LITERALLY 2 minutes to get to 50 (won't go over 50). So ANY help is highly appreciated. P.S. Towing is not an option.

 

U1001 is nothing. Don't worry about it. Replace/repair bank 1 sensor 1 O2 sensor. You don't need consult for anything. NDSII that you have is all you need to keep the car running.

 

Thanks for the response, highly appreciated. should the o2 sensor cause this bad of a limp (will not rev over 2k while in gear, will not shift over 2nd, have to use manual mode to get to 50mph, will not go over 50, shudders massively while trying to rev in neutral and runs great on the vq23 ecu). shouldn't the stock ecu also trigger the cel, let alone limp mode if o2 sensor was bad? The car should be painted within a week or 2 and I'll try replacing the o2 sensor, coolant temp sensor, checking all the connections and erasing the codes. Fingers crossed. And btw User1, unfortunately decided to paint it audi nardo grey, nobody around me has the skill to paint desert camo lol.

 

Page 175 in my 2003 EC FSM section:

SYSTEM DESCRIPTION
NFEC0826S01
Sensor Input Signal to ECM
ECM function
Actuator
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)
Engine speed
Heated
oxygen
sensor 1
heater control
Heated oxygen sensor 1 heaters
Engine coolant temperature sensor Engine coolant temperature
The ECM performs ON/OFF control of the heated oxygen sensor 1 heaters corresponding to the engine speed
and engine coolant temperature. The duty percent varies with engine coolant temperature when engine is
started.

Make sure coolant, cam and crank sensors are functioning properly. All sensors can be tested. Get any FSM for your engine.

 

Do you have data to support this? Methinks you're wrong.....


This is 100% wrong.

I just said none of these things are the problem in my initial post.

To be honest your best bet is to go with your stock ECU . Get another one and live your life. It's clear the presage has a few minor differences from your vehicle. I would say get a 04 maxima ECU but unless your have EGR then you will be in the same position you are now.

 

My bad.

I still have money on incorrect data from the triad of sensors (CKP, CPS, HOS1) that has him in limp mode. We'll see what he does.

 

I'm more inclined to this theory. As for evidence, the vq23 ecu would cause the engine to surge massively while over 80mph and accelerating. And you could tell it was running lean. The sensors are working as the vq23 ecu wouldn't trigger cel and would run the engine pretty smooth. I will let you know in about 2 weeks as to what the ecu guy says. Thanks guys.

 

​​​​​​
Any error in CKP or CPS will cause an immediate shutdown or idle only.

As i stated above I just drove my 6th gen with the ho2s1 and coolant temp sensor unplugged with no limp mode.

I have however disabled vehicles with u1001/u1000 or put them in limp mode simply by leaving non important modules unplugged.
(Most recently a seat module in a g35 &#129396
​​

 

You should have the 5 wire wideband readings to back you up. NDSII can read these and determine a Lean condition.

Did you use your old injectors or the ones with the 3.5?
​​​

​​​​​

 

the vq35 ones. Didn't touch the engine (yet). didn't have the obd2 interface back when the vq23 ecu was good, so couldn't get the afr. If the guy fixes the vq23 ecu, will let you know.

 

Gotcha. So he just needs the proper ECU?

 

Correct, that u1001 is what's causing the limp mode, I don't think I could easily get a presage fsm and the OPs fsm to determine what's not on the network and why that ECU is going into limp mode.
​​​​​​
​​​​​​It could be something simple or something complicated.

 

I got the fsm and the can comm list for both cars. ill upload both so you can see. Please give me some advice. I am truly very grateful brother.

 

Here is the presage can comm circuit list with the red dots representing the parts my oem vq23 can comm circuit is missing.

 

Here is my original car's can comm circuit list with the red dots representing what is not on the presage 3.5. I highly suspect this is a cruise control or tcu related code.

 

On a side note, my car's platform code is J31, the presage is on the exact same platform and has the chassis code U31. My car has the 4 speed auto, the presage has a cvt. The interesting part is, the L31 altima also shares the same platform and has a vq35de, but also uses the same 4 speed auto trans as my car. So in theory, shouldn't the L31 3.5 altima ecu work with my current set up as it is the same?

 

Does your car have EGR?

And I think you confirmed you can't swap a CVT car to an auto trans (something I've always pondered in the past).... Without swapping the ECU

However I still think you can swap between 4at and 5at (again I'm guessing, I have not really researched this because I really had no interest, it was just a passing idea).

There's only ONE ECU, that I think you can use that I'd say is your best bet to work (if you have EGR).

That's an 04 Maxima 4AT.

All of the 4speed Altimas (TO MY KNOWLEDGE, not 100% confirmed yet) are older style computers (gray 1 plug boxes aka basically 5.5gen maximas).
-05/06 3.5 Altimas are all 5AT.
-02/03 I know for a fact are all gray box ecu's (1 plug).
-04 is questionable but highly likely a gray box based on what I've read.

But the 04 Maxima had the option to be 4at and I know and have confirmed it is a black box (two plug) ECU, however these vehicles have EGR's (unlike 02-04 Altimas), which require some sort of input on the EGR circuit to NOT be put into limp mode.

If you don't have EGR then I'd gamble on a 350z Auto ECU.

 

Yep 100% true. Minus the se-r, they all have the older ecu, but the se-r is a 5at. I'll check for egr when i get the car back and it looks like i'm getting an 04 maxima ecu. thank you so much man. true lifesaver.

 

Hate to nit pick.... But I'm bored....

All US 2005/2006 3.5 Altimas have a black two plug ECU.
All US 05/06 3.5 Altimas are 5 speed auto / 5 Speed Manual or 6 Speed Manual.

And since I just looked this up...
02-04 US 3.5 Altimas are all one plug gray ECUs.
(If you see an 04 Altima black box 2 plug ECU it's a 2.5... via FSM and part #s, it will have the code T1 (or some combo of T and a number) on the sticker).

#bored

 

looked up L31 3.5 altima 4 a/t ecu on ebay. that's what I could conclude.

 

They stopped making FWD 4AT 3.5L vehicles in the US in 04 (Maxima, Altima, I35 - Only the Maxima has the ECU you can use).