[Mike Diaz]

Looks like I may have worked out a deal for getting someone to produce the kits for me. I will update with further updates to this matter.

I am also going to attempt to use a missing link for my setup off of a Sabb.
You will find out how this goes as well.

Lata Fellas,
Kyle

You know I'm ready. Bring the noise!

 

[BUZZARD]

Looks like I may have worked out a deal for getting someone to produce the kits for me. I will update with further updates to this matter.

I am also going to attempt to use a missing link for my setup off of a Sabb.
You will find out how this goes as well.

Lata Fellas,
Kyle

Duty cycle valve in the fuel return line ??

Chris

 

[sr79labrat]

Duty cycle valve in the fuel return line ??

Chris

How would I do that? What would its effects be on my car?
Thanks for the help!
Kyle

 

[Mikey851]

How would I do that? What would its effects be on my car?
Thanks for the help!
Kyle

Sounds like it is a way to have complete and constant control over fuel pressure?? I don't know.

Is that also the same thing as a Lambda valve Buzzard?

 

[william_s]

any new updates?

 

[BUZZARD]

Sounds like it is a way to have complete and constant control over fuel pressure?? I don't know.

Is that also the same thing as a Lambda valve Buzzard?

Yes.

Labrat you said you were waiting for a part of a SAAB. I just wondered if it was a lambda valve.

Chris

 

[sr79labrat]

Yes.

Labrat you said you were waiting for a part of a SAAB. I just wondered if it was a lambda valve.

Chris

It is a PCV valve, and all I do is throw it in line between the manifold and MAP sensor. It is supposedly a ball and spring deal. I tried that this weekend with the corrections put back in the SAFC and I am still getting a CEL. What a pain in the ass! I may just buy that AEM setup if you can do the plug adapter. Let me know what you think about this- I am about out of ideas...
Thanks, Kyle

 

[Mikey851]

Kyle did you ever check all of your voltages? You may just have a bad MAP sensor or a bad connection to the ECU.....etc. etc. I think you should verify everything first before you go and spend alot of money.

How about the voltages from the ESM? Is it correctly clipping the voltage when it needs to? Just curious. I guess I'm asking because Beav has told you that a checkvalve setup wouldn't be your best bet as the MAP sensor can take up to 10 psi. So if you're using the ESM, the checkvalve wouldn't be necessary.

 

[swift]

yo guys i sent kyle a pm about the whole map sensor thing after a friend of mine with a turboed rx7 showed me the stock map sensor and check valve. We later printed out the legends and went to my car. I came to two conclusions which i wont go into right now but have found some interesting info. I believe kyle just needs to take a deep breathe and look over the wiring and do what Mikey has suggested. Some info:

NSXs:
The Comptech system has a great reputation because its engine management (actually fuel management) is so simple. Most folks probably only run at boost for brief moments (stop light GPs), so for the most part the Comptech is running just like stock with all the bells and whistles associated with the great stock ECU. Can't beat that! At boost, the Comptech simply fakes out the Map Sensor and manipulates fuel pressure, one parameter the stock ECU doesn't monitor as it's constantly self-checking itself. And low and behold it works, up to a point. That point being when the owner wants to start upping the boost. That's when the limitations (and problems) associated with the Comptech start. But for 90% of Comptech owners, the stock setup is fine and they are happy.
Then there are piggyback systems that take engine management to the next level. Problem is that the Honda ECU is a smart bastard and will soon begin to "make adjustments" on it's own based on its original programming. Pretty soon you end up just scratching your head and chasing your tail. I'm sure there are ways around this as well, but it's a learning experience, which is why some systems need more development time then others.

--------------------------------------------------------------------------------

Compech says the clamp should be set at 2.92 volts, this can be tested with the car key in the on position with out the engine running. There are two ports on the box for probes, and another where you can adjust it with a small screwdriver.

I have a 92 NSX w/ CTech "Hi Boost" kit. Per CTech's instructions vacuum hose 3 and 4 are reversed in their kit. With this done, does the MAP sensor see FULL boost?

^^intriguing..

A lot of people run check valves off of their MAP line. This vents boost to the map (no check engine) and keeps from vacuum leaks in atmospheric -situations, but I dont see how this will do anything to change loop style.

Well, it seems to me that zero vacuum is where you get the full 3v from the MAP sensor to the ECU, and zero vacuum is interpreted as high load and/or WOT. So if you bleed off the vacuum on the line to the sensor then it sends the full 3v and I presume (but don't know) that's enough for the ECU to stop closed loop activity. Perhaps it must also sense a certain physical throttle position (I believe there are two sensors for that) or other parameters, I'm not sure, but simply inducing a well placed vacuum leak should cover the MAP requirement. Admittedly a small valve that closes off the line ahead of the sensor is more elegant, but you'd need it to also vent the sensor side to keep from trapping vacuum in that part of the line. However, such a tiny leak shouldn't be a problem since it would only be left open between runs.



Hopefully Kyle will be able to get her going strong.

 

[Mikey851]

Swift you copied and pasted that stuff right? That's pretty much the just of it, but I wanted to make a few corrections to the last paragraph so no one will be confused.

Checkvalves placed along the vacuum line to the MAP sensor actually bleed off pressure which is over atmospheric (boost). It is essentially the same thing as the Comptech ESM in that even while under boost it simulates a WOT condition and no more. In other words the checkvalves keep boost in the manifold from reaching the MAP sensor, so that the highest the MAP sensor will read will be around 3V and it will not throw a CEL. And, of course since it's a checkvalve it will not allow air to leak in while the engine is under vacuum. I just wanted to clarify that because that final paragraph states that the checkvalves control vacuum in some way or the other, when all they do is bleed off excess pressure (because we all know that 14.7 psi is percieved by us as 0 vacuum and 0 psi of pressure).

Edit: That paragraph is also incorrect when it says that if you were to pinch off the vacuum line going to the MAP, that the sensor would send WOT signal voltage, when in fact it would throw a code. Reason being is that even while at WOT there is a small amount of vacuum, hence the fact that the correct signal for a Honda MAP sensor at WOT is 2.94V and no where above it. The power going in to the MAP is 5V, so theoretically if there is absolutely no vacuum there whatsoever, it will send a signal of 4.5V or so, which of course is out of the ECU's range.

 

[Kenso]

Edit: That paragraph is also incorrect when it says that if you were to pinch off the vacuum line going to the MAP, that the sensor would send WOT signal voltage, when in fact it would throw a code. Reason being is that even while at WOT there is a small amount of vacuum, hence the fact that the correct signal for a Honda MAP sensor at WOT is 2.94V and no where above it. The power going in to the MAP is 5V, so theoretically if there is absolutely no vacuum there whatsoever, it will send a signal of 4.5V or so, which of course is out of the ECU's range.

Actually if the MAP sensor sees zero vacuum it doesn't set a code. The voltage won't cross over the threshold of allowable input to the ECU unless the sensor is subjected to positive pressure. I've encountered several cars over the years with disconnected or damaged MAP sensor vacuum signal lines. The ECU interprets zero vacuum as WOT and dumps fuel, even if the car is at idle with no throttle opening input.

 

[Mikey851]

Really? Hmmm, i've seen MAP sensors throw codes without the vacuum line on it. Maybe the sensor had a different problem then. I guess you can't judge everything by experience.

I guess I was also thinking about it wrong. Of course you know that the engine doens't ever produce absolute 0 vacuum even at WOT. There is always a little bit. So I guess I was looking at it as, if the MAP sees absolute zero or ABOVE then it would set a code. But, like I said I had a different experience with it. Thanks for telling me though, next time i'll know that the lack of vacuum may not be the problem.

 

[sr79labrat]

map sensor

--------------------------------------------------------------------------------

kyle,

Myself and a friend with a boosted RX7 were talking and bored in class so we printed the voltage specs and diagrams of the legend map sensor. We then walked out to his car. His is called a boost-map sensor but is the same(three wires running to same spots on ECU etc) except he has a check valve right before it in the vacuum line. HE is very smart and we were theorizing why you are having problems with the check engine light. I said that i thought you tried the check valve to no avail. We concluded two things so far:
1) the less vacuum you have the higher the voltage. At 3 volts you are at 0 vacuum however you are boosting and without check valve it is raising the value past 3 volts causing check engine light
2)Now this is the part you wont like. Everything you have done is right and the map sensor is fine except that there are tables/graphs in the ECU. It uses and compares the %throttle with the %of vacuum and knows based off of one what the other should be. So if you are at 45% throttle but your vacuum is to low(voltage at map to high) then it throws a code because it thinks there is a vacuum leak.

The last one makes a lot of sense since Beav was saying he found tables he did not know what they were there for. If you could please fill me in on what you have tried i will continue to try and help you. My friend is going to look up the specs on his map sensor and I may have him purchase it and the check valve and send it to you free of charge if the values(voltages will work).

I am also going to search around about the piggy back unit that used to be used on the NSX while they ran stock ECUs and see if i find anything out.

later
BEN
__________________________________
Ben, this makes sence to me, and I have been thinking that because the ESM or checkvalve is messing with only one setting we are confusing the ECU. I am sure all reading are supposed to be relative to other readings at all times. If one is off the it throws the CEL. I think this is what Beav meant by using larger injectors because the reading between those and the adjust MAP sensor reading will be closer to what the ECU is looking at for ideal performance conditions with AF ratios and sensors matching up closer to that point. I think the AEM is going to be on my list of things to do this summer.

BTW I have tried a check valve, multiple check valves and the Comptec ESM. I also have tried them together. Some days I wish I just put the work into making it a LS6 RWD 6spd. I did try messing with the voltage and there seemed to be no difference in the CEL activity. I feel SOL! I may just drive the car if AF ratios are ok. I am not out of options yet, but we will see...

Thanks for all of your guys help and support!
Kyle

 

[Mikey851]

Kyle, I know I've asked you already man, but have you tested with a voltmeter to see if you MAP is good and that your ESM is working properly? You absolutely have to do that or you'll never figure this out.

I'm definately not trying to be rude in anyway guys because you are close to grasping the idea but just a little off. I'm sorry if I come across as a know it all I just think it will be easier if you can get how this is working, and I've had experience with these same problems so I am just trying to share my knowledge and experience.

There is no problem with confusing the ECU if the setup is working properly. The ONLY thing that the ESM and the checkvalves work to do is to simulate an NA environment (to the MAP sensor) on a boosted car. This will keep the ECU from throwing a CEL. You are not and cannot tune anything with the ESM or checkvalves, they merely allow you to effectively use your piggyback.

Kyle, what Beav meant by using bigger injectors is this: Right now when your MAP voltage is at 2.94V or WOT your injectors are working at full potential.

(This is based on the belief that the fuel system cannot flow enough fuel) You will not be able to fine tune fuel adjustments for the boosted setup because if you're at partial throttle (tuning for acceleration with the SAFC) any voltage sent to the ECU lower than WOT will result in too little fuel, yet you don't want to send WOT voltage at all times as it will result in a crappy tune as well as bad gas mileage and terrible idling.

Honda anticipated a certain amount of fuel being injected at a certain load with their knowledge of fuel injector flow. If you enlarge the fuel injectors the amount of fuel at the same WOT voltage will now be higher. This will now allow you to tune within the limitations of the SAFC and still keep from throwing a CEL.

I don't know what else to say. I am frustrated for you Kyle because I know you've worked so hard on this project. For your low boost setup the way that the SAFC and the ESM can work together is not really any more difficult than what it appears to be, even with our smart ECUs.

I guess if I had one sentence to sum it up it would be this: With the setup working properly, your ECU WILL be operating within all of it's parameters. If your fuel system is lacking for the boost you are using, then you must increase fuel flow unknowingly to the ECU (aka bigger injectors, more fuel pressure etc.) Good luck Kyle.

 

[sr79labrat]

Yea, I know that I need to test the readings out. You are coming across clear. I am just pressed for time. A lousy excuse but it is true. Do we know what the readings are or what they should be reading? That would really help out. I actually think I am pretty bad with electrical problems. Usually I can get it right after some time.
What are your thoughts about the readings?
Thanks for your patience with me!
Kyle

 

[Mikey851]

Ahh man, it's not about having patience, I just know how frustrating it must be for you. I can understand being pressed for time, I'm busy everyday and hardly have time for anything. The only reason I can post so much is that I work on a computer.

About the readings, I will have to look up the wire colors again later tonight. I'll get back to you on that one. I know what you should see but there's no point in posting all of that up until I can say which reading should be on each wire to test.

Main thing: Just don't give up. You admitted you don't have much time, so I suggest not making any rash decisions or conclusions until you can sit down and test everything and make sure it's all setup right.

 

[beav]

Mikey is right about what I was getting at before. If you get bigger injectors like 6 turbo DSM blue or black top 450 injectors then since I believe our injectors are 240s take out about 35% -%40 fuel using the vafc and you will not see anymore check engine lights. Then just send your ecu to me and I will rescale your timing map to correspond correctly and safely. And get it tuned on the dyno or street with a wideband. This should work okay right now.

There was still some speculation above about how the map sensor works and the corresponding voltages. I have it all sorted out and you can view the voltage scale accross the map in my newest version of BeavEdit.
http://other.ditcorp.com/legend/BeavEdit.zip
If you open the stock rom and then click the "Rom Configuration" tab and change the "Map Headers" option to voltage it will show the corresponding voltage accross the headers, flip back to the stock honda map sensor and you can see the corresponding vaccuum for each header to compare. The stock range the ecu will accept is .705 volts at 23in/Hg of vaccuum to 2.97 volts at 1.3psi. At about three volts it will throw a cel. It even shows how other map sensors like 2 and 3 bar map sensors would fit into out ecu stock range and even allow boost, although it clips into the low vaccum side a good bit.
The bottom line is to get your setup to work as is with a fmu you need to either mechanically or electronically keep the ecu from seeing boost. You either do this electronically by keeping the map sensor from going over 3 volts like the EMS is supposed to do. Or pneumatically stop positive pressure from getting to the ecu. If you want to give up on the EMS then you will need to use check valves. To set up check valves you need at least 3-4 fish tank check valvles and a vaccuum tee for each one. In the vaccuum line going to the map sensor you put a tee and the run the teed off line to a check valve with the other side of the check valve venting to atmoshpere. You need to orient the check valves so that if you blow through them they will allow the boost to blow out to atmosphere. But if you suck they should close and allow the map sensor to see all of the vaccuum. This will bleed off all of the boost before it gets to the map sensor but allow it to work properly in vaccuum. You will need at least 3 -4 to fully bleed the boost, start with three and then add more untill the CEL goes away.

 

[swift]

holy crap...3 check valves? Maybe we should drop him a pic of a vacuum diagram? I may have time. Either way Mikey is right...if everything is hooked up properly and working then there should be no CEL correct? He may not have enough fuel but..

 

[Mikey851]

Swift, those three checkvalves will all be in series with the MAP sensor vacuum line, so as long as he knows which line that is he's good.

Kyle I would recommend going back to using only the checkvalves and make sure they are bleeding off boost. As a matter of fact, you should be able to pop the hood and hit the throttle a little bit and feel the boost blow out of the checkvalves.

 

[beav]

Heres some pics, like I said the key is to make sure you have them all the right way. Blow through them and make sure you know which way the air flows through them and which way blocks the air. Then set them up so the boost can leak out but if you suck they should all close.