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anyone knows how to remove the speed limit? I got a jdm type r swap with jdm ecu and it cut off at 120 mph. any infor is helpful. thanks
 

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maybe i'm missing something here, but if you simply disconnected the sensor so the ECU doesn't know your speed, wouldn't that result in VTEC not engaging properly?

a controller would be the much preferred option, i would think
 

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Yes the ECM receives signal from VSS which is attached to the transmition.
I you cut the signal to the ECM other problems might occur (I read about it somewhere but can't remember).

HKS makes SLD (speed limit defencer) . It alters the signal from the VSS to the ECM.

one question I have , does the ECM on GSRs uses the car speed as an engine calibrating parameter?
 

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95gsrturbo on Sep/15/02 said:
are yo guys sure -- i thought vtec engagement was rev based? hhmmm-- ill have to look into this one---
am I sure? yes I am sure.

VTEC activation is dependent upon:

rpm, TPS, oil pressure, engine temp,and speed inputs to the ECU.

So if you have a low oil level, for example, your VTEC won't activate since the ECU does not read a high enough oil pressure input signal to send the "go" activation signal to the VTEC solenoid. All 5 inputs must be satisfied before the ECU releases the activate signal to the solenoid. Hook up a VTEC activation light and then rev to 4400 rpm in the GSR that is standing still and on a cold start and see if VTEC activates...it doesn't.

I hate to tell you this but I have been tinkering in this hobby with Honda engines for 7 years now. About 5 years ago we couldn't get VTEC to activate at the track. I had to work out why. This is how I learned. When I was a newbie like you, I used to think only rpm activates VTEC. It is because no-one told me what to read or any info on it back then. Trust me, yes I am sure. We traced the problem to a fried distributor rotor due to an MSD 6AL ignition amplifier sending too much current back then. Actually, 5 years ago Shawn Church, who is the Temple of VTEC editor, was referred to me by Al Vasquez, the then head manager at DPR Racing. I had just gotten my head ported by DPR and we ran into this VTEC problem at the track. Al hooked me up with Shawn in California and we went through different causes and eliminated them one by one. That's learning on the fly.

As I said to all beginners like you, the Helms service manual, if you have not purchased one already, is a great book that everyone working on their own engines should have. That way you aren't guessing and using wrong info or specs (especially assembly info like when the VTEC does not activate).
 

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I looked at the diagrams, and the VSS is an input to the computer and T's off to drive the speedo, etc. I didn't look at the diagrams before I posted and forgot about the VTEC stuff - was tired and rushed last night.
Apparently, the VSS input is used strictly for VTEC activation. Is this correct? A defenser circuit should be quite easy to build. I, however, don't know how to do it. Any electrical engineers out there?
 

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http://www.blitz-uk.co.uk/delim.htm

easiest way to inactivate the speedlimiter without disconnecting anything or getting an ECU reprogram. I'm not familiar with the HKS one but I'm sure it works just as well...cost them out to see which is the better deal. If you are in need of a VTEC controller though, the Field has speedlimiter deactivator built in that you can activate as well....
 

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The ECM does not check oil pressure before it activates VTEC. It checks the oil pressure after it has sent the VTEC on signal to verify that the VTEC switchover has taken place. The VTEC pressure switch is after the VTEC valve, not before. I tested this to make sure - with the car warmed up, running and revved all over the place - the switch never changed states.
 

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Rhetorical question?
I have been stating this for awhile, and all the information I have available verified that this was the case, but I hadn't actually tested it myself. Hopefully someone else will confirm this. If I am the only one saying something isn't right and I do the tests, I probably still won't be believed.
 

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when you connect the Acura hand held diagnostic box for CEL codes, it gives you the VTEC solenoid Go signal and oil pressure input.

My friend Ron who is an Acura/Honda tech and pit crews on John Sherk's Grand Am NSX team did the diagnostics with me along with Shawn Church way back then. If you don't get the 55 psi oil pressure threshold, the solenoid Go signal on the PGM diagnostic doesn't register. So the order of events is: check rpm, check oil pressure, check tps, check speed go.

kelly's mistake is precisely the same mistake Apex integration made when they first released the VAFC. As you recall they had a rash of complaints from first time owners that they were getting a CEL code 22 VTEC solenoid failure. Apex assumed, like kelly, that the oil pressure was after the VTEC solenoid had received the Go signal from the ECU. You will notice NOW that Apex has an UPDATED INSTRUCTIoN telling owners to connect their VAFC auxillary harness wire called the VTM to the 31 pin of the ECU on a B18C (oil pressure). The ORIGINAL INSTRUCTIoNS failed to account for this resulting in a CEL 22. They can thank people like me who phoned them 5 times a day for tech support when they got their VAFC and kept getting this code when we hit the set VTEC switchover on the box. So yes, gentlemen, BOTH must go (oil and rpm) to the ECU BEFORE it releases. Otherwise it has no indication of the state of the motor in terms of engine load. Otherwise it gets 2 confusing inputs. No pressure (STOP) and rpm (GO)...triggering a CEL.

So there are 2 examples to show you that your hypothesis is in error.

kelly, perhaps you are looking at the Toyota setup?
 

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Haha, kelly argued with me on another thread about this telling me to change the VTEC article. I unfortunately did not have the information from an Honda tech and pit crew member on the NSX team to say otherwise.

The main arguement lies in the VTEC pressure switch, which according to the Honda Tuning handbook checks after the solenoid has activated. Is the book simply incorrect or is the VTEC pressure switch used for something else?
 

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The ECU needs as many indications of engine load as it can get especially in open loop. Oil pressure is one indication that the engine is a) running properly and b) at an appropriate load.

I remember Shawn (who was doing his mechanical engineering graduate PhD degree at Pepperdine University at the time) told us to hook one of those Honda PGM diagnostic handhelds up and it would make life simpler. So Ron brought one home from the dealership and we did a couple of runs on the highway with the box hooked up.

You can actually see the voltage changes as the rpms climb.

What is the second function of having a sufficiently high oil pressure threshold?

The pressure switch tells you there's enough pressure to push the VTEC pin in. one of the first cure alls for a failing VTEC activation people tell you is to disconnect the solenoid and clean out the filter basket in the solenoid itself since not enough oil is getting to the pin which locks the 3 rockers in place during VTEC.

Yeah it's pretty cool when you have friends who are "in the know" and in the professional road racing scene...they set you straight on a lot of misconceptions and have major hookups. Unfortunately John didn't run the NSX this year since Honda Canada was claiming the car back to be crushed. He still has the SiR and may even run a GSR next year in Grand Am. Rob Baxter ran a Mazda Protege this year and Ron and Randy pit crewed for him during the Speed Channel touring Car race up here in Mosport. The Mazda engine makes a lot of power but uses cheap parts and grenaded during qualifying and the race. It is a stock series and you have to use some cheap factory parts (the seals and head gasket went unfortunately). I couldn't make it up to Mosport for that weekend unfortunately. Randy and Ron spent the whole night tearing down the engine and rebuilding it for the race. They did it 6 hr. Amazing. Randy can disassemble andput back together an NSX engine blindfolded like those marines who can put together an M16 machine gun in their sleep.

cheers
 

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I tested this circuit most of last night and still haven't quite figured it out. The VTEC switch is closed when the engine is stopped and I used an ohmmeter connected directly to it to see if it would switch with the car stopped, running and revved - it never did. If I disconnected the VTEC solenoid, I got no check CEL and the car ran just like it would if it didn't have VTEC. If I disconnected the VTEC switch and jumped it, I got no code and VTEC worked. If I disconnected VTEC switch and left the circuit open, the car would freak at the VTEC point - moving or not moving. If I left the circuit connected and hooked up a voltmeter between ground and to the BLU/BLK wire to check for a voltage change as the Helm's suggests, the car would freak out at the VTEC point only when moving; I would not get a voltage switch. If you study the circuit you will understand that these are strange results. I am particularly curious as to why the computer does the freak out routine instead of just running like it does when the VTEC solenoid is disconnected. It seems the safer default mode would be to simply not engage VTEC if there is a problem instead of doing the freak. I am going to investigate further.
Any explanations MD?
 

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the "freak out" as you call it is a kick start into safe mode. you forget that going to a bigger cam is very harsh on the engine. If the engine is not in a state to withstand this conversion to the bigger lobe at higher engine loads, then it could result in the engine grenading. safe mode or limp mode as it is popularly called, retards the ignition timing map, reduces the redline, and indeed deactivates VTEC (fails to send the GO signal to the VTEC solenoid). The 5 inputs to the ECU as criteria to allow VTEC to activate serve 2 functions: 1) provide as much confirmatory input on engine load status (since we are in open loop mode) and 2) confirm that the engine is ready or "healthy" enough to accept the sudden changeover.

If you by default just prevent VTEC from activating and say the oil level is low and the engine is still cold, revving to the redline with the nonVTEC lobe on the standard ignition and fuel map may result in engine damage. So the freak out not only stops VTEC from happening but also triggers the limp mode (CEL).

The natural AF ratio around VTEC is richened according to the standard factory ECU fuel map. If you do an UEGO sensor analysis, the AF ratio at 500 rpm before, during and after VTEC is in the neighbourhood of 11.5:1-12:1 AF ratio with the stock ECU. So the Honda engineers protect the engine from detonation risk at VTEC by deliberately running a very conservative rich mode.

VTEC is a very violent transition for an engine.
 

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SurferX on Sep/16/02 said:
I unfortunately did not have the information from an Honda tech and pit crew member on the NSX team to say otherwise.
the more you stay at this hobby, the more you will find yourself meeting people who have similar interests. The chance to work with someone who is generous enough and kind enough to consider you worth helping and sharing info with is a rare find. You've experienced this when you met John over at HyTech. You build a network of people who aren't loud and fairly low key but know their stuff. The majority of people who race Hondas/Acuras don't frequent chatboards. They are a waste of time to them since the info circulated is not at their level and when they do present info on their experience the people on chatboards don't have the background or advanced judgement to hear out a non-conventional approach that is sound from a mechanical engineering standpoint. All the theories about making power and going fast is based on physics. It's only physics. once you understand this, the mystery and magic is transformed to different ways of skinning a cat who is a basic science.

So, if you follow your passion and don't become too sidetracked by hype, you will meet these people as long as you first learn to avoid the ****y attitude and go in wanting to learn.
 
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