3,000 RPM Jolt - injector rewire for NA2T

[JustinCase]

Crowbar, reading that thread the 2nd page gives a little information on what type of resistor to use...

To make sure i dont blow something up (exaggeration) what type of resistor should i use, and on which lead?

[JustinCase]

Small update:

This 3,000 rpm bump only started happening when i went turbo with 84T parts. Turbos have the 2 injectors cycles, NA's dont.

Out of curiousity i put my 89NA ecu into my car just now. I didn't go into boost and only drove in my neighborhood. However, i had no bump - as i suspected. However running an 89NA ecu with the turbo injectors probably isn't the best idea to do on a daily basis.

So, I guess one option would be to socket the 89NA ecu and get it tuned to my factory 84T injectors (or would loading a factory late-model turbo specrtum be good enough for NA2T stock setups?) OR would that still integrate the 3,000 rpm changeover? I have no idea what to do to remedy this.

Crowbar's advice to put a resistor between the CHTS has not been attempted yet, mainly because everyone was arguing about it and i really dont know what type of resistor or which lead to put it into. Any clearification would be good.

*This is my 100th Post!*

[Dan-TSS]

I think I am as frustrated now as you are, but for different reasons.

This issue of the 3000rpm bump isn't from the fact that the ecu is switching modes of injection IF your car has the injector service campaign wiring done.(you need to fully understand what happens when the re-wire is done and how the ecu switches modes..you'll understand if you read all through how this works...I believe this is why Crowbar got curious and asked about it. The FSM is your best friend for understand that feature that was incorporated, then disolved with the re-wire)
If you have reverted back to the oem production(pre-recall) wiring, then yes...there IS a Small chance that this can be included into the list of possible reasons.
**You have failed to update everyone as to your remedy for the base timing issues. If you still haven't resolved it, I'm going to leave this as my last response in an effort to help because I am 99.9% sure that your issues start with that.

[JustinCase]

I believe my timing light is busted...i have it set TDC perfectly and the dist is in the middle. It's driving great except for this 3k thing.

I understand how the wiring was redone, and why... Changing the injector order and such. However i don't know what you mean by it would only matter if i HAD pre-recall wiring...

I mean, i know i'm not an expert in any means...im just going by what i know and that is that this only happened after i went turbo. The only thing electrical changed, was the ECU, & injectors. I know i keep saying this, so there's no need to call me an idiot and tell me that i'm ignoring everyones statements.

2 - 1
4 - 3
6 - 5

Pre recall is 1-2-3 / 4-5-6
Post recall is 1-2-5 / 2-4-6

You said post-recall wiring eliminates the injector mode (or thats how i read your post)

As im sure you've read and know:

The ECU is not touched during the injector work. Because of the condition of most of the cars that come in to get worked on, Nissan opted to install a new injector sub harness. Before the service campaign, the ECU had two firing modes, simultaneous and group. Simultaneous Injection mode means that all injectors fire at the same time. This mode is when the engine is over 3000 rpms, injection pulse duration is more than 6.5ms, or cylinder head temperature is below 60oC or 140oF. Group or Batch Injection mode means that the six injectors are divided into two groups. The groups are cylinders 1, 2, 3, and 4, 5, 6. These groups are fired once each engine cycle 180o opposite of each other. After the service campaign, the ECU still has both of these firing modes. The only difference is the groups. The new groups are 1, 3, 5 and 2, 4, 6.

I'm not too sure i understand what you're trying to correct me on...There are 3 things that i know of to happen at 3k rpm. Injector from batch to simutaneous, det sensor stops, egr stops.

I don't really see how it can't be injector firing as an issue, it was corrected with a NA ecu that doesn't switch between modes....so...yeah...

[crowbar]

For those of you who would like to try this, just splice a 470-500 ohm resistor in series with the CHTS. Next, take a timing light and check the timing. Set timing to 25-28 degrees for a start.

Do the timing after the car has warmed up by the way.

[JustinCase]

Put the resistor on any lead? (+/-)

[crowbar]

Open up the circuit, either side, and insert the resistance into it in series.

[JustinCase]

I'll try that this weekend when i have some free time.

So, if this goes away after this CHTS thing...what does that mean. I don't wnat to run it in simutaneous mode 24/7....

I'm getting really tired of this issue...its so stupid.

[crowbar]

Its a troubleshooting method. If the problem, goes away, then you will have narrowed it down pretty much to the transition of bath mode to simultaneous mode.

Your car will run closed loop by the way. Especially on the highway. But open loop, you will be eating gas I bet. In any case, give it a shot.

My advise would be to get a later turbo ecu.

[JustinCase]

I've never had a good understand of open loop / closed loop. Why one is used at certain times vs the other, etc etc.

I've been thinking about going ECU fishing but the weathers been rough as of late. I may go to the junkyard after i go hunting this weekend.

[JustinCase]

The only other ECU i could use with my O2 sensor is from an 85...but i don't know if that will make any difference since they're pretty much the same ECU anyways.

To "rewire" the oxygen sensor for the late-model turbo O2 sensor, do you just cut and solder in the new plug, or does it go further into the harness to the ECU and replace the entire sensor wiring harness?

I wouldn't mind having an 86/87T ECU, or i could socket my 89NA ecu but that would be expensive and i'd need to run dropping resistors.

[crowbar]

You could use a bung adapter to move up to a smaller O2 sensor and then a later ecu.

[JustinCase]

How far back to i have to go when rewiring my NA harness for a Titania O2 Sensor. Just the plug, or the entire o2 harness?

[JustinCase]

anyone...