Potential problem with '04.5 ECU's and F/I systems....
 

I am speaking with only PARTIAL KNOWLEDGE here, but I do wish to put out a word of caution before someone plunks down serious cash for any kind of F/I system on a 2004.5 or later 350Z. This has to do with the change in the ECU to make the car ULEV compliant. These cars feature wideband oxygen sensors that finely regulate the air:fuel ratio. I do not know what the "spec" air:fuel ratios are that are programmed into the ECU for various conditions, but I do know that if you run more than 12.5% rich or lean, as measured by the pre-cat sensors you will trigger a Service Engine light. The implication for this is that you will fail an OBD based emissions test. I do know that the ECU will try to correct off the post-cat sensor information if the pre-cat info is out of spec, but that will only work in the case of a stock engine. With a piggyback computer engine management system deliberately programmed to run rich to go along with safe boosting, this whole feedback loop may be ineffective leading to the SES light remaining illuminated.

If anyone has any other information with regards to actual FI systems being successfully run without an SES light on a 2004.5 or later Z, please post. Please also post what air:fuel ratios you are using that are NOT triggering the SES light. I would love to also know what "spec" air:fuel ratios are programmed into the stock ECU on these ULEV vehicles.

I wonder if it always runs in Open loop or something. That would cause it to lean out under boosted opperation.

All I know is that with my HKS F-CON that came pre-programmed with the HKS SC kit, the diagnostics showed the air:fuel ratio on both pre-cat sensors to be 20% richer than the stock "spec" setting. The correctable range for the stock ECU is +/- 12.5%. More than this will trigger an SES. The problem is that neither I nor the Nissan Master Tech who looked at my car had any info on what that actual "spec" A/F is supposed to be for any driving condition. I have contacted HKS and they are looking into it. All their R&D was done on a 2003 model and so the ULEV engine management was not an issue. To their knowledge, I am actually the first person to install the kit on a ULEV spec 350Z.

i'm not sure what you mean by "2004.5"...but i have an 04 w/ greddy tt, no problems w/ ses light

Depends on your build date whether you have a vehicle that is ULEV/ULEV 2 compliant or not. I'm not sure of the actual date, but almost for sure if your car was actually built in 2004.

Im sorry, but did I read this correctly? The 04 models come stock with a wideband sensor? If this is true, thats pretty cool (Im under the assumption that you can actually get a real # reading from the stock sensor).

O2.
 

Pretty much any ULEV2 vehicle will run WB O2 sensors at least pre-CAT. The attempt is to operate in closed loop mode under as many conditions as possible. A ULEV1 system will pop out of closed loop operation immediately under rapid acceleration.

Re: O2.
 

Any way to tell whether you car is ULEV 1 or ULEV 2? Apparently, there was no problem with the readings on my post-cat non-wideband oxygen sensors.

Re: Potential problem with '04.5 ECU's and F/I systems....
 

Actually all the post cat sensors do is monitor cat efficiency. On just about every OBDII vehicle I have tested follow the same general pattern. When there is enough degradation to where the waveform is >(around, depending on manufacturer)75% of the primary sensors reading it triggers a code 420 or 430. Correct call on the wideband sensor application on later model Z though. But before people run off and hook up a shiny new meter to the output of the 'wideband' sensor, check it with a DSO. you might be suprised as to what the voltage does ;)

Technosquare is currently tuning an 04 ECU for F/I for the Turbonetics kit and will be using my 04 ECU to create their re-flash for the 04 model so I'm sure he may take care of this.

Re: Re: O2.
 

THere is an emission ID sticker under your hood , passenger side. At least that wer it is on my G? It should state either ULEV or ULEV2 there.

Re: Re: Potential problem with '04.5 ECU's and F/I systems....
 

Okay....so what does the voltage do??? Also, what, then, is the implication of this for FI systems, that, by necessity, need to run richer to prevent detonation?

Do you think it is reasonable that the HKS system run this rich or do you think there is something else wrong? Could a SMALL leak after the MAF, but before the SC unit (this is how the HKS system is configured) cause this. Thanks!!

Yeah, I think I can confirm the bad news here. Kenji actually flew into Charlotte, NC to diagnose a problem with a 2004.5 ECU. A local shop here installed the TT kit on the Z, and the thing ran like crap. Limp mode, poor idle..just everything went wrong that you could image. Kenji sorta got the car running, but the ECU keeps reverting back to some other program, and the car continues to run like crap. I understand the owner of the car is going to uninstall the kit...too much trouble.

The wideband O2's on the new 2004's and 2005's are really throwing a wrench into F/I possiblities with the Z.

gq.....can you tell us which kit?

Oh sorry...it was the Greddy TT kit.

If the car runs even slightly too rich...the ECU freaks out...for lack of a better term.

That is what is happening with me, only I am not entering into any kind of limp mode. Infact, car runs fine, just the SES and bad mileage....around 14-15mpg, although I would imagine FI would hurt mileage somewhat anyway.

Bummer......I'd hate to have to pull my kit. Anyway, I'm really not going to be doing much driving over the winter months, so I'll take time to see if it can be worked out. If not....such is life!!!

I am definitely notifying HKS, however. I am actually the first person anywhere to put the HKS kit onto a 2004.5 car.

Re: Re: Re: O2.
 

Here is the code for the emissions control type in question:

2TWC(2)/2HO2S/2AFS/SFI

conforms to Tier 2/Bin 5 regulations LEV2


Yep!!!! I got it!!!!!

12.5%?
 

Now on the '12.5%' number, was it LTFT or STFT? or both? What code(s)s set? any freeze frame data to indicate when the fault occurred? Might want to get a few more details on exactly what is occuring with your vehicle. I think that +or- 12.5 is an pretty narrow parameter for an ECU to operate. Generally 25-30% is where I see OEM's allow their trims to wander before setting a SES light. Then again, if a FI kit is trying to fix something with fuel instead of timing, it could be a bit richer than you think...

Re: 12.5%?
 

Here is the info from my print outs:


1. The +/- 12.5% is what is shown by a shaded area on the bar graph for the "A/F ALPHA-B1" and "A/F ALPHA-B2" readings, with the center of the of the shaded region being 100%.

2. My actual measurements on the above mentioned bar graphs were consistently at 75% at 688rpm, 1688rpm, and 2675rpm.

3. At 2675rpm, the A/F sensor B1 and B2 read 0.040V

4. At 2675rpm, the HO2S2 for B1 and B2 read 0.99V & 0.98 V respectively

5. At 3025 rpm, the A/F ALPHA B1 read 74% and for B2 read 75%

6. DTC's were P1271 & P1281

7.System Data:
Fuel Sys B1 and B2.......Mode 4
CAL/LD VALUE = 41%
COOLANT TEMP = 167 deg F
L-FUEL TRM-B1 = 100%
L-FUEL TRM-B2 = 100%
S-FUEL TRM-B1 = 75%
S-FUEL TRM-B2 = 75%
ENGINE SPEED = 2125 rpm

Re: Re: 12.5%?
 

Bump......can anyone make sense of these #'s