I put this here because the car I have the code on is a 94 gsr with jrsc dsm 450 injectors , vafc hack,
I was driving home from school last night and it was a nice cool night in the 50's which is awesome for here and the car was loving it as was I. But it was a bit wet out so I was not gunning it to bad. Well the school is about 20 miles from my house I got within a mile when suddenly the engine light came on, the car started to idle bad and didn't have much for power so I eased up and got home granny style trying not to be in boost. I pulled in the parking lot turned her off and puit my wires in to check the code. was a code 3 , checked my book was map sensor so i did a reset to see if it would come back on and it did not(at least not yet) Now looking in the book it basically just talks about loose wires , shorts etc, I was wondering if there was any other reason why there would be a code for the map other than loose wires etc? Any help on this would help. Remember I had just set the trim for the vafc hack a few days back had no codes up until last night and still not sure about the crossover points 4000k and 4500k on the narrow and wot lvt and hvt, when I am in vtec should I lesson the fuel or give it more? thanks( not sure if the vafc hack has anything to do with it but wanted to let that be known just in case it might)




[Modified by RaVeN, 6:00 PM 10/15/2002]

 

The AFC hack modifies the MAP sensor signal that the ECU "sees". Normal full scale on the MAP sensor is 5 volts at 11 psi. But it'll throw a CEL at anything over about 1 psi, 3 volts. The hack scales down the MAP sensor voltage so 5 volts becomes 3 volts at 11 psi. If you don't apply a large enough percentage cut the MAP sensor voltage will exceed 3 volts under boost and you'll get a CEL. THat's what I'd guess did it.

 

thanx . kinda green on the vafc and all still trying to figure it all out

 

i have the vafc hack with dsm 450's on my LS crx and for some reason when my car is cold.......... and when i leave my house and drive down this hill which is next to my house, where i coast down in second gear at about 4000 rpm....it takes a second then i get a cel for map sensor??? it happens everytime unless i push the clutchin and coast at idle....and then i have no more problems while driving!?!?!?! WTF could be causing this????? it pisses me off since i have to poull over and reset my ecu everytime!
ohh yah and at the end of the hill there is a stop sign and everytime my car will bogg and stutter at like 1200 rpm even when i floor it, it just kinda bucks along...my vacuum gauge will go to 0 at wot and my car just bucks across the intersection for a few sseconds and i shift into second and it usually does it for a second then start going fine??? WTF could cause this too!!
this stuff really pisses me off since i cant figure it out!
thanks!


[Modified by boostinb18, 8:36 AM 10/17/2002]

 

anyone?

 

What percentage cuts are you applying?

Here's the problem (I think). Most people run a constant across the board cut in fuel of about -35% to -40%. This doesn't take into account the fact that larger injectors take longer to open so you get less fuel out of them than you would think at small pulsewidth. So first off I'd try adding 20% to your fuel at 1k maybe 15% at 2K. You can't boost at those RPM so you won't throw a CEL. If you are coasting at 4K, I think you are probably getting a very high vacuum and tripping the MAP code for too low of a MAP sensor voltage. You've got to add some fuel (voltage) to the map sensor signal up there too if you want to do that. The problem is that the MAP cut generated by the AFC is RPM dependant rather than MAP dependant.