jwahaus

I'm looking for tuning advice from those with experience at such things. I've done a bit of reading on the net but still lack many of the fundamentals needed to feel like I know what I'm doing. My setup is a supercharged 3.4L Tacoma. Currently I don't have any gauges but I do have the OBDII interface so I can read what the ECU is saying.

My setup currently is un-tuned. I do have the TRD 7th injector with the piggyback controller but as far as I know there is no way to adjust this setup. So I'm looking for suggestions for an inexpensive tunable setup (control computer and necessary gauges).

I've read that an EGT or PyroMeter is the best way to tune. There seems to be a lack of information on exactly what temperature is optimal. Also, I've read that an A/F gauge is good for tuning but others say that they are not accurate. I'm guessing the Oxygen sensor reading is as good as an A/F gage but maybe I'm wrong there.

I would like to be able to make small adjustment and evaluate the changes during normal driving. I know a dyno is the best way to tune but I'm wondering if it can't be done via small changes and normal driving while observing the changes on the OBDII.

jwahaus

Here is a graph of the OBDII readings during a moderately frisk acceleration.
You can see from the chart that the ECU is cutting fuel after about 1750
RPM's. This seems to be causing a lean-out and thus poor acceleration.
The O2 reading (bank 1) is typically pretty constant during such a run so
I'm thinking the Fuel Trim is responding to the O2 sensor keeping it constant.
Perhaps the O2 sensor is just not accurate enough, especially on a boosted
engine, and fooling the ECU into cutting fuel and killing performance and
causing ping?

jwahaus

Also, any advice on which parameters to log from the OBDII would be helpful. The
interface is too slow to log everything with enough resolution so I have to pick 3
or 4 parameters at a time.

Did I pick the right ones to determine fuel curve adjustments? Sometimes I log
engine load, and speed would be helpful to actually determine the acceleration rate.

For now I'm just trying to get moderately quick acceleration under control which is
about 1/3 to 2/3 throttle. At less than 1/3 throttle the current fuel map seems to
be very good and I have excellent acceleration for normal everyday driving. At
WOT, depending on the phase of the moon, I either get kick ass acceleration or
(most of the time lately) intermittent surges of good to not so good acceleration.

The factory ECU just does not seem to be able to give consistantly good WOT
acceleration. It's like it is always hunting and does not know when it hits the
sweet spot.

jwahaus

Here is another graph showing more brisk acceleration, around 2/3 throttle.
Notice again the ECU cutting fuel (I assume that's what fuel trim means)
as it gets into the high RPM's. This run had pinging and poor (for the amount
of throttle) acceleration.

TRDOLMAN

My friend, unfortunately you can't tune a TRD 7th injector setup by itself. No "outsider" has the key to unlock the TRD 7th ECU. The best way I have found to tune it is with the URD additional injector controller (AIC). Install that device so you can dial in the flow from the injector. After installing the AIC you will still need a wide band unit to tune it properly. Once tuned the 7th injector setup works great. Too bad TRD didn't set it up so you could tune it for your truck out of the box without having to invest in another controller.
Dave

Duffdog

another way to tune your setup is with a safc. Although im not sure how much you would gain using that device. I have one, but I also have 370cc injectors and a bunch of other junk including an o2 bypass circuit I designed myself. I was just wondering what you hoped to gain by "tuning" the trd system? It seems like its designed to give you x amount of horsepower and there is nothing you can do to alter its performance. I wouldnt go screwing around with that device unless there is something wrong with it....is there?

T

jwahaus

I've been considering the URD AIC and it's on my short list of things to
buy but there is something that bothers me about using this setup. I'm
thinking it would be better to control the main 6 injectors rather than
the 1 additional injector mounted on the SC. You can see from the
graphs I posted that the ECU is cutting fuel at mid to high RPM's. So
ideally I want to be able ot keep the ECU from doing this. If I add
more fuel using the 7th injector then the ECU is going to see this via
the O2 sensor reading and try and cut fuel even more. I'm assuming
that the bank 1 O2 sensor is the primary determing factor for the ECU's
short term fuel trim setting. Anyone know if this is a correct assumption?

Yes, I agree. Lack of tunability with the TRD setup is very unfortunate.
Especially since it typically needs to be tuned to get the best performance.

What I would like to get instead of (or perhaps in addition to) a controller
for the 7th injector is a programmable piggback computer that can control
the 6 main injectors. I can perhaps do this by modifying the O2 signal
but I'm not sure this is the best way to accomplish this.

jwahaus

Can you elaborate on that, what is a SAFC and what type of control does
it give you?


Why are you bypassing the O2 sensor? Are you simply providing a dummy
signal or are you modifying the signal in real time to effect the ECU?

Um.... more power, smoother mid throttle responce, longer engine life ...
This seems like a strange question to ask.

TRDOLMAN

The reason the ECU is cutting fuel is because the 7th is kicking in and providing more fuel lowering the AFR's below the 14.7 the ECU likes to see.
All I can relate to you is my experiencs with the 7th. Most 7th setups, including mine, run very rich at WOT. So much so that many people are reporting their cats becoming clogged. My AFR with the stock pump and 7th was 10.5. I put the 190 pump on and my AFR's went to 9.5 (which let me know that I was right on the edge with the stock pump). I put on the AIC to be able to lean the 7th out. My AFR's now are 12.1 to 12.5. With the AIC you can tune your open loop and also a lot of your closed loop as well. Brian Trager from URD tuned my truck with the R4 software that comes with the AIC and a LM1 wideband. The truck runs very smooth, even smother than when it was NA.

Bottom line is the ECU does a good job of controlling the other 6 injectors. If you tune the 7th properly with the AIC, your truck will run great without hurting your cats and it will make more power as shown on my dyno run sheet in the webshots link in my sig. That run was made with no cats and a 2" pulley but it still shows how much power can be had with a properly tuned 7th. I am rather new to tuning and modding computer controlled engines and am learning new things every day. I don't have all the answers. All I have is what I have learned so far and what advice I have been given. I do know this--my truck seems to like what mods have been done so far.
If you had a chance to drive my truck, you would do the same things I did with the 7th setup.

Dave

jwahaus

It is strange, perhaps it is the weather, but today my rig was running near perfect.
It was about 45 deg and 60% humidity today, I don't know if the weather has any
effect but sometimes my rig runs perfect and other days I notice ping and less than
optimal acceleration. I wish I could FREEZE what the ECU is doing and keep it from
changing anything but as you know, the modern ECU's are constantly "adjusting"
themselves. I do seem to notice that some gas is better than other gas, I always
run 93 octane but BP gas seems to be consistantly better than the other brands I
frequently buy.

When I have trouble with ping it is always under a load in 2nd or higher gear at
mid RPM's. Today I was trying to make her ping but I just couldn't do it, I kept
getting smooth hard ping free acceleration. I didn't have the OBDII connected to
see if any engine parameters we acting differently. I sure do wish I could always
get her to run this well.

jwahaus

What does the wide band unit tell you that the standard O2 sensor does
not? Is it just more accurate or is there some other data it gives you?

Also, what about a pyrometer? Some tuners have stated that a pyrometer
is really all you need to tune. Anyone using a pyrometer? If so what is
the optimal temp you should be looking for? (I would expect if varies
with different engines)

midiwall

A wide band sensor is good 'cause it doesn't sway anywhere near as much when you're watching it in closed loop with a A/FR meter.

Tuning via A/FR is a bit two-sided though. Open Loop tuning lives for A/FR meters, but closed loop is kinda' useless. But then, then only thing you can really do in closed loop is to help the ECU not have to fight to get LTFT to 0.0. You can't actually set up the engine to run rich or lean.



EGT is the key way to know if you're running dangerously lean. As the mixture leans out, the EGT will start to climb. If you use a fast acting probe, then you'll actually see the spike.

Something else is that EGT is valid no matter what the ECU loop state. That means you can watch for lean-outs midrange.


In my truck right now, I'm running boost and a removeable install of an A/FR. I just ordered a custom dual gauge from Westach that will let me see A/FR and EGT in one 2 1/4" meter. Those will then go into a 2-bay pod with the boost. I thought about running FP (Fuel Pressure) as well, but I'm confident that I can derive if I'm getting enough fuel into the engine by watching EGT.


Have you found "Gadget's" site? It's generally considered the starting point for a lot of questions like this:

Supercharger info:
http://www.gadgetonline.com/Super.htm

Fuel delivery:
http://www.gadgetonline.com/fuel.htm

Gauge info:
http://www.gadgetonline.com/gauges.htm

jwahaus

The bank-1 O2 sensor reading is very stable. The bank-2 O2 sensor seems
to fluctuate quite a bit. I'm not sure why though.


Well, I'm thinking that if you can modify the O2 sensor(s) reading then
you can indirectly control the closed loop A/F ratio. Something that
can add/subtract voltage based on RPM and or engine load should do
the trick.

What is purpose of the LTFT (long term fuel trim)?


Thanks for the links, they are helpful.

jwahaus

I'm trying to get by with just an OBDII reader and a loptop.

The trouble spot I would like to address is the famous "low RMP high load ping"
problem. On my rig this seems to be between 2500-3500 RPM at 50%
throttle in 2nd or 3rd gear.

I can see on the OBDII/Laptop that the pinging starts at the same time the
ECU begins cutting the STFT. When the STFT is around 8 or 9% the engine
is running great, once it hits 2500 RPM the ECU starts gradually cutting
the STFT back to 2% and sometimes all the way back to -4%. The fuel
trim cutback coresponds directly to hesitation and pinging. Now if I look
at the O2 sensor reading it stays flat at ~3.25 volts the entire time. So
the ECU is doing a great job at keeping the O2 reading flat.

I've been searching for something inexpensive that can modify the O2 reading
in order to adjust the A/F in closed loop. My theory is that if I can keep the
STFT at around 8% the problem will go away.

I've looked at the Split Second ARC1/ARC2 which may work but it seems
that as soon as the O2 sensor sees the added fuel it will cut the fuel trim
even more to compensate. I'm not sure how much ability the MAF sensor
has to over-ride the O2 sensor in closed loop?

Also, the Split Second FTC1 looks like it would work but I think it is a bit
overkill for what I need. It is also failrly expensive.

Is there anything out there that will modify the O2 sensor relative to RPM
and load?

jwahaus

Another note:

Some have suggested that the STFT is being cut back because the 7th injector
is kicking-in causing a rich condition. I'm not so sure about this because I was
under the impression that the 7th only kick's in at high RPM?

Perhaps the additional injector controller will work since I could then add fuel via
the 7th Injector to compensate for the ECU cutting fuel at the trouble spot.
BUT!!! the O2 sensor is going to see the extra fuel and cut back the fuel trim
even more. I would prefer not to be fighting the ECU but rather controlling it
(via the O2 reading)

midiwall

Hi;

I've never heard of anyone trying to cheat the O2 sensor, but I don't know if it makes sense to do so.

In closed loop, the ECU is using the O2 sensor to get the engine to run at an AF/R of 14.7:1. If you cheat the O2 reading, then the ECU will just try to compensate for it and push it back to 14.7:1. If it gets to a point where it can't adjust anymore, and the O2 reading says it's still lean/rich (either way) then it'll throw a code.

This is why tuning is done via the airflow signal. You want to "lie" to the ECU on the front end - but even then, the ECU will still try to tune for Stoichiometric conditions (14.7:1) while in closed loop.

If you're pinging, then you need to adjust the timing. That's going to take something like the FTC1 or SMT. But neither of those have been seen to work _with_ the 7th injector piggyback. Dropping a piggyback on top of a piggyback isn't a real good idea.

Gadget's selling his own controller for the 7th injector, and from what I know, this may be the way to go:

http://www.urdusa.com/Merchant2/merc...Store_Code=URD

Please write him or Brian and confirm though... info@urdusa.com


In short... I don't think that fakinig out the O2 signal is going to help. You need to get more control over the engine timing.

side thought... You're running premium fuel, right?


edit:

I may be a bit sideways in thinking that the O2 sensor isn't the place to be looking at.

One of the configurations of the FTC1 box that Gadget sells has an O2 intercept in it. To quote from this description:So, what it does is confuses the ECU into open loop so that you can have control over fuel during what's actually closed loop. Interesting.

BUT, that's only for pre-1999 trucks, so it's not going to help you.

btw, I've learned why your O2 reading is so nice and smooth... You have a wideband O2 sensor in it as stock equipment. nice.

TRDOLMAN

I think you are trying to make this a lot harder than you should. I think if you try to mess with the O2 your asking for problems. If you get the AIC and tune it properly your truck will run great. When you tune the AIC, you will be tuning part of the closed loop as well. My map starts at 0 psi and I don't go into full open loop until almost 7 psi (I'm running a 2.2 pulley) so you can do actually quite a bit of tuning in the mid to higher ranges. Why make it so hard? Get the AIC ($250.00) then tune it with your scan tool and a wide band. You are done!

Dave

jwahaus

Exactly, that's why I want to use this signal. If I add or subtract a voltage
offset to this signal the ECU will compensate by adjusting the fuel mixture
to get the signal back to "normal". So escentially I'll be able to control
the closed loop A/F mixture directly with this signal.

This is why I believe that using the MAF would be inferior. The O2 sensor is
going to see the extra fuel you're adding and cause the ECU counter by
leaning. Perhaps the O2 sensor is not typically used for A/F adjustment
is because most O2 sensors are not stable enough. Mine seems to be.

I believe the 7th injector piggyback already retards the timing. Too bad it
is not programable though.

He is a reseler of Split Second devices. Perhaps he makes the wiring
harnesses?

How will the AIC effect the timing? I though it only controls the 7th injector.

Yes, always 93. I've come to realize that not all premium fuels are equal.
I've now been systematically using different brands since I noticed that
the pinging I'm having seems to come and go. The last 2 tanks have been
Shell 93 and the truck is running consistantly better now. I wonder if
some stations are cheating and selling me low octane fuel at a premium
price. My truck seems to certainly be able to tell the difference.


I'm not really looking to force open loop but I can see where this would
be useful.

I do think that the FTC1 box would do what I need, and even the URD
upgrade kit with larger injectors and fuel pump would be VERY nice but
it is outside of my budjet for now.

It's possible I could use the Split Second ARC1 and connect it to the O2
sensor instead of the MAF since does basically what I'm describing above
(adding or subtracting a voltage offset to the signal) but the problem I
see is that it would need to only do this under certain load conditions and
RPM range. Perhaps I just need to save up until I can afford the FTC1.

jwahaus

Can you be more specific here. What type of problem do you expect I'll run into? Perhaps I'm overlooking something.

You make is sound so easy! Did you disconnect the TRD injector controller
or leave it connected? I believe it also retards timing so I'm thinking it may
be better to leave it in place when going this route.

One side note though: My truck has a wideband and it shows a very consistant 3.25 Volts even during the RPM range that is problematic. As I
stated in the previous post, however, it may just be the occasional tank
of poor quality gas that is really the problem.

TRDOLMAN

It is easy! Leave the Trd controller connected. All you do is unplug the TRD connector from the injector, install the AIC as per instructions, and plug the AIC connector to the injector. Then use your scan tool and the R4 Split Second software supplied with the AIC to set your fuel trims to as close to 0-0 as you can in the closed loop portion. After your closed loop trims are set then use a wideband unit to set the open loop portion to around 12.1 to 12.5 AFR. Simple and easy without having to alter signals. The TRD unit does control timing. Timing has not been an issue on my truck. As I have said before, my truck is making 270 RWHP and 324 ft.lbs. of torque with this setup and I couldn't ask for it to run better. It runs smoother than when it was N/A.

Dave