Rtek Forum Discuss the Rtek 2.0 and other Rtek ECU's

Why only +/- 15% Fuel adjustment on 2.0?

Old 06-05-06, 06:19 AM
  #51  
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The rtek reads the temp after the IC with stock sensors or u gotta have aftermarket one?
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Old 06-05-06, 08:01 PM
  #52  
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Cool. How much adjustment will the new version have, hopefully a lot so we can have close to a standalone setup?

Will this update require the ECU to be sent in or can it be updated through the serial port?

I realize there might be something still up with one of the sensors, but I can't get any good data logs until the AFC is not interfering with the ECU. I am also starting to think the AFM cant keep up with the added air flow of a T04 turbo. Maybe the ECU calculates Injector pw using the AFM and the boost sensor together and thats why it is not giving enough fuel at the PSI I am at (lower PSI same air flow as stock turbo).

I will try to hook up a FP gauge to check my FP. Dont know how it could be low though.

All the runs I logged the AFM temp was very close to the intake temp. Only about 3-5 degree difference C. I just looked at them again. The ambient temp for all my logs is around 85-90 degrees F. I dont know why but my logs on the PL Viewer graph as C not F. How do I change that?
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Old 06-05-06, 08:02 PM
  #53  
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stock sensor

BTW No one else is running a larger turbo with the Rtek to compare my logs with?
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Old 06-06-06, 01:21 AM
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Originally Posted by edomund
Cool. How much adjustment will the new version have, hopefully a lot so we can have close to a standalone setup?

Will this update require the ECU to be sent in or can it be updated through the serial port?
Doubled to +/-30% which should be more than enough for most applications.
Upgrade would require removing the old ROM and plugging in a new one. Its
socketed so will be easy to do.

Originally Posted by edomund
I realize there might be something still up with one of the sensors, but I can't get any good data logs until the AFC is not interfering with the ECU. I am also starting to think the AFM cant keep up with the added air flow of a T04 turbo. Maybe the ECU calculates Injector pw using the AFM and the boost sensor together and thats why it is not giving enough fuel at the PSI I am at (lower PSI same air flow as stock turbo).

I will try to hook up a FP gauge to check my FP. Dont know how it could be low though.
I'm not seeing the AFM maxing in your logs. If it was maxed, then you should
see a leaning of the AFR as rpm's (and airflow) rise. From your logs, I would
suspect something that affects fuel delivery linearly with airflow. ie; its always
x % lower fuel flow than expected. Low fuel pressure could do this or an
AFM that's been tampered with could also have this behaviour.

Originally Posted by edomund
All the runs I logged the AFM temp was very close to the intake temp. Only about 3-5 degree difference C. I just looked at them again. The ambient temp for all my logs is around 85-90 degrees F. I dont know why but my logs on the PL Viewer graph as C not F. How do I change that?
ah, that makes more sense. Mike, is the PL viewer configurable or does it
display in the units that the log was captured?

-Henrik
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Old 06-06-06, 08:35 AM
  #55  
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I captured them in F and they display on the PC in C thats what is weird. On the Palm they are F.

Why are you going to only do 30%?
Why limit the tuning capabilities?
If you are going to claim standalone capabilities then give us standalone capabilities.
Take the handcuffs off and let us tune.
Even if something is wrong with a sensor or low FP I was able to tune my car fine with the S-AFC.
Now this Rtek is merely a data logging tool for me, without the fuel adjustment I need and my data logging is also useless due to the need of the AFC.

You know for my situation 30% will not be enough.
At 15 PSI I have to run +40 on the AFC. With the 4X720cc setting it leans out 25% off the top which is great for my low map (low map AFR's are OK) but my boost map suffers. I dont want to have to set the ECU to 4X550cc just to get the boost map correct that defeats the purpose of having a Rtek in the 1st place. So I lose 25% fuel right away.

All my AFR's are ok under 2PSI-4PSI so thats not true my fuel flow is X lower than expected. Only under heavy boost my AFR is lean.

Am I the only one running a larger turbo and at 15-16 PSI? The Rtek only can map out up to 14PSI stock turbo how can it be expected to handle 15-16 PSI from a T04 without a lot of adjustment room? If someone else is and they are not having any of these problems then OK, but so far it looks that way. I am still not sure there is something wring with my setup. All my readings look OK.

Please give me the freedom to tune my car as I need. Is it harder to just make the fuel map infinitely adjustable like the timing. I dont understand the thinking on limiting the fuel map. If I blow up my car or max out my injectors thats my fault.

I really like the Rtek and want to endorse it and show you can tune a high HP setup without going standalone around the local Northern California RX7 club guys, but until I can setup my car it's hard
ed
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Old 06-07-06, 01:21 AM
  #56  
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Under WOT and with the secondaries on, the stock system targets an
AFR in the mid 11's. When the Rtek is configured for the installed injector
sizes, it will maintain that same target AFR provided that the AFM is not
maxed.

The +/-x% allows you to fine tune the curve. At +/-15% you can adjust
the target AFR in the range of about 9.7 to 13.2, with +/-30% this would
allow a range of about 8.0 to 15.0. The 15% may be a little skinny, but
the 30% will certainly cover all useful AFR's.

Using an external device to compensate for some other problem (low
FP, bad sensor, etc.) is just not good practice and is not what the
Rtek is designed for. If the root cause is not understood, then how
can you be sure what to expect next time the car is started?

Your setup seems to be unusually lean and not just a bit lean, but way
lean. Contrast this with hughes's results where he's considering leaning
the AFR with the Rtek and mine where I see mid 11's without any
corrections.

Originally Posted by edomund
All my AFR's are ok under 2PSI-4PSI so thats not true my fuel flow is X lower than expected. Only under heavy boost my AFR is lean.
This is new and important information as this could then be caused by fuel
filters, low voltage to the fuel pump and/or vac leaks between the AFM and
turbo.

I'de like to start from the beginning again with your setup, so let's take this
offline from here, email me at henrik at pocketlogger.com. I'll be able to
respond quicker via email as well. Any pertinent information can be posted
back here.
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Old 06-07-06, 10:55 AM
  #57  
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yeah please do post back, this is the most informative thread ive found about rtek yet.
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Old 07-08-06, 04:08 PM
  #58  
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Ok, I must be completely lost on the math here regarding the logic behind taking off 25% automatically by selecting the higher injector size. let's just keep it simple and look at the 1.7 ECU. If a person gets a 550/720 setup for injectors and purchases the 1.7 ECU, then the ECU will take off automatically 25% duty for the 720cc. Stock duty cycle is 58-63% so it would take the 720 to a mere 35-40% duty cycle therefore making the 720cc upgrade less effective than the stock 550 at 58-63%. Adding 15% to that on the 2.0 ECU makes total fuel injected more than stock but only by a tiny %. One might as well keep the stock injectors and get a SAFC to take the duty cycle to 80%. This is why I must be missing something - IT DOESN'T MAKE SENSE.

Also, if the duty cycle cap is only increased by 5% then one would figure the max duty cycle attainable is only around 63%-68%.

Last, with the injector set-up options 550/550 550/720 or 720/720 you will either be too lean up top or too rich on bottom. This might not be the case if you were able to add the other combo 720/550. I would think most people would have the issue of keeping the bottom lean enough and the top rich enough.

Please help me understand this because if what i'm thinking is true, the 1.7 upgrade barely adds any extra fuel (not enough fuel flow to justify changing out the tops to 720cc when you could just add more duty cycle to the stockers).
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Old 07-08-06, 07:22 PM
  #59  
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Because if you don't take 25% off the 720's you're going to be getting way too much fuel in when the secondaries come on because they flow more than 550s at the same duty cycle.
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Old 07-08-06, 07:25 PM
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If a person gets a 550/720 setup for injectors and purchases the 1.7 ECU, then the ECU will take off automatically 25% duty for the 720cc.
Yup.

Stock duty cycle is 58-63%
This is not true. Stock is upwards of 85%, ~90% with the increased capacity.

Stock duty cycle is 58-63% so it would take the 720 to a mere 35-40% duty cycle therefore making the 720cc upgrade less effective than the stock 550 at 58-63%.
How does it become less effective? The 720s inject 25% more fuel for the same pulse width.
550s at 75% flows about the same as 720s at 25% less D/C of 50%.

If 85% was the max D/C stock, then 85%- 25% (with the 1.7) = 60%. So at 60% DC with 720s, you are injecting the same amount of fuel as maxed out 550s, but you still have another 30% more duty cycle (and therefore fuel) available.

This might not be the case if you were able to add the other combo 720/550
I believe this was already mentioned in this thread.
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Old 07-10-06, 01:37 PM
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Originally Posted by DarkKnightFC
Because if you don't take 25% off the 720's you're going to be getting way too much fuel in when the secondaries come on because they flow more than 550s at the same duty cycle.
Yes, I know this, thank you. What I was trying to note here was that the 25% didn't make too much sence seeing is how you can't correct it back cause you're only allowed +15%. You would still be down 10%.

Turbo2ltr, I reviewed the thread again and I didn't see anything mentioning that you could select the injector configuration to 720(bottom) & 550(top). If it was I simply missed it. It didn't seem like edmundo had been able to choose that selection yet. So, you're saying you CAN choose 720(bottom) & 550(top)? That is very good then if you can cause I would see that as solving the issue of getting the bottom injectors lean enough and the top rich enough.

Turbo2ltr, Rotary Performance, on their injector calculator, points out the stock duty cycle to be 58-63%. I have heard this argument before but I don't know who to believe. I guess I just need to test it myself seeing as how professionals even disagree. Don't take that as a wise remark, that's just what I've observed.

Turbo2ltr, basically what I was pointing out on the whole 1.7 thing was that the 25% reduction limits the 720cc to near 550cc levels. Yes, it's still more but not by much. For the 2.0 chip having that 30% extra D/C doesn't do any good if you can't tap into it cause of the 15% limit. The proposed 30% would be much better though. I guess I was just saying the same thing Edmundo was saying.

I'm looking at this as a prospective buyer. I have a 550/720cc set up and am looking to put the 720s at the bottom and purchase 8xx-1000cc up top. From what Edmundo is pointing out, I forsee myself having his same problems. If you're right about the duty cycle being more than 63% then that would be a major difference. Also, if I could do a 720/550 chip configuration then that would help also. That, combined with the ability to select the 720(bottom) 550 (top) would probably solve any issues. Not trying poke at your product, just want to clarify what I'm looking to purchase.
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Old 07-10-06, 02:31 PM
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Ok, that second to last sentance I posted didn't make sense. I ment to say that the 720(bottom) 550(top) chip configuration coupled with the proposed 30% adjustability would probably resolve any issues. Ok, I'm done now. Sorry 'bout that.
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Old 07-12-06, 01:02 AM
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These are good questions, hopefully this will help clarify.

First, having decoded the stock ECU fuel algorithm I can say for a fact that
the 58-63% "cap" is a myth. The stock ECU will drive the injectors to
about 80% duty cycle depending on rpm/load/air temp and a couple
of other factors. If you look at some of the logs posted from people with
2.0's, you'll see injector duty cycles well over 58-63%. The 1.7 and 2.0
raise the cap to ~85%.

The way it works is as follows:
The ECU has a target AFR for each rpm/load combination; based on current
load/rpm/etc. and injector size, the ECU will compute a squirt time for the
injectors to track the target AFR. The 1.7 and 2.0 adjust the ECUs computation
of squirt time to accomodate other injector sizes and still maintain the stock
AFR target.

The cap is applied after this computation and is independant of injector
configuration. In other words, if the ECU computes a squirt time that would
be above ~85%, the cap will limit this to ~85%. The 1.7 and 2.0 have had
the ECU code modified such that it will (with sufficient airflow) drive the injectors
to 85% under all injector combinations.

-Henrik
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Old 07-18-06, 12:08 PM
  #64  
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a BNR stage 3 like Edomund has with 4 720cc injectors would be maxing out their duty cycle as that turbo and intercooler is easily capable of 375R+WHP, since i can't see the logs maybe you can review them and see how high the injector duty cycle is climbing.

i also agree, there should have been more freedom in fuel trim. since we are talking about airflow but not really focusing on pressures... yes the airflow theoretically should compensate correctly but changing the turbo will yield a completely different map, a map that with your adjustability will not support but instead was pointed out that it was a fault with his car somewhere. the combination of the AFC and the 2.0 was not a good setup either since it basically tricks the ECU into thinking it is under a completely different load situation.

having more freedom with fuel trims may have saved this engine but without more testing we will never know.

death occurred around the peak torque range(~5k RPMS) meaning it was likely timing related as well as a lean condition at that point in the map.

Last edited by RotaryEvolution; 07-18-06 at 12:13 PM.
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Old 07-18-06, 12:36 PM
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You can see the logs by downloading the log viewer from our website. It's free.

We have already looked at the D/C and it's is only ~ 50% with +15% which makes no sense at all. We didn't immediately blame the car, we looked at all the logs he had given us, compared it to what we know about how the ECU decides fueling as well as compared it to logs we've collected during testing. We then felt the evidence was pointing towards an external issue keeping the D/C abnormally low.

...a map that with your adjustability will not support
Please show me the log that has the Rtek 2.0 running on this turbo with the injector D/C maxed out and the car still running lean. This was not the case with Edmund. If it was, I would totally agree with you, but it wasn't.

How much boost was being run?
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Old 07-18-06, 03:08 PM
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if im calculating correctly, with +/- 30% correction, it lets you compensate for 4888 cc's of injectors

100% stock fuel map
- 25% auto injector preset correction
- 30% user correction
=
45% available correction

Stock is 550cc x 4 = 2200 cc total, so with 45% correction, you could theoretically correct for 4880 cc's of injectors (2200/.45). Which would be adequate available correction for say, 1600cc secondaires with 720cc primaries. (720+720+1600+1600 = 4640)

With the current +/- 15% correction limit, you are limited to a total of 3667 cc's of injectors, which can only support for example 720cc primaries and 1000cc secondaries.

This is not taking fuel pressure into account at all.

If i am thinking correctly above, +/- 30% corrections seem plenty unless you plan on running HUGE injectors all around, which is unlikely, since the rtek cannot adjust for boost above 14 psi anyway...

Last edited by gxl90rx7; 07-18-06 at 03:22 PM.
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Old 07-19-06, 02:22 AM
  #67  
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Originally Posted by Karack
a BNR stage 3 like Edomund has with 4 720cc injectors would be maxing out their duty cycle as that turbo and intercooler is easily capable of 375R+WHP, since i can't see the logs maybe you can review them and see how high the injector duty cycle is climbing.

i also agree, there should have been more freedom in fuel trim. since we are talking about airflow but not really focusing on pressures... yes the airflow theoretically should compensate correctly but changing the turbo will yield a completely different map, a map that with your adjustability will not support but instead was pointed out that it was a fault with his car somewhere. the combination of the AFC and the 2.0 was not a good setup either since it basically tricks the ECU into thinking it is under a completely different load situation.

having more freedom with fuel trims may have saved this engine but without more testing we will never know.

death occurred around the peak torque range(~5k RPMS) meaning it was likely timing related as well as a lean condition at that point in the map.
I'm not sure what you mean by focusing on airflow vs pressure. For fuel, its almost all about air mass entering the engine. The AFM is before the turbo and provided that its readings are not being clipped it will measure the increased airflow accordingly. This is the only real benefit of running with an AFM; it will "see" changes to the VE of the engine. Under boost, more than 30% throttle (WOT as far as the ECU is concerned on an S4) and RPM above the secondary staging point the ECU will target an AFR in the 11's. So, if the AFM reading is not clipping, with a 0% correction on the Rtek you should still see 11's with increased airflow. A +15% correction would allow adjustment into the low 10's. Edomund's logs were at 7ish psi and at even at that level he needed about +50% externally to get to stock'ish AFR's, yet his logs show no clipping on AFM reading (they were around what I see on my TII at 10psi) or maxing of duty-cycles (they topped out in the mid 70%'s). The cause was not found.

-Henrik
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