civic1990si

Hi, I have some problem with my MAP sensor. I did some test i when i go to 5500 6000 rpm and boost at 7 or 8 psi, I have a CEL 3(Map sensor). If i'm at 5 or 6 psi, i don't have the code. So i really don't know what is my problem. I check the connection of the SMC on the ECU. So maybe it is the MAP sensor??? I can't put check valve because the SMC controle with the MAP sensor. Or it's my SMC but i have the same problem with the SMC standard and the SMC plus.
Someone can help me please?

Thanks

civic1990si

bump

ImAcracker

Maybe you gotta lean it out a bit. What size injectors you got?

falcongsr

code 3 means the ecu is seeing too much voltage. did you hook it up correctly?

zip

Did you connect the SMC green wire to ground? If so, that defeats the internal map clamping that's used for factory turbo ECUs. Wrap the end of the SMC green wire in electrical tape and leave it unconnected.

civic1990si

no i don't connect the green wire. It is Wrap in electrical tape.

The code 3 is MAP sensor. I don't think that have effect with the mixture.

With the SMC i don't need to put check valve. Only leave it in the stock position.

i really don't know what is the problem??



[Modified by civic1990si, 11:03 PM 1/25/2003]

civic1990si

no i don't connect the green wire. It is Wrap in electrical tape.

i really don't know what is the problem??

KingDsi

Do you have a turbo or JR charger?

Smashback

By leaning it out he means adjust the SMC more to provide less voltage to the ECU. This is the way the SMC works.

civic1990si

ok but on my autometer air/fuel, when i'm on boost, it's just correct. 1 line in stoich and 2 or 3 line in rich.

if i send less fuel, i'm gonna go in stoich and maybe lean.

What ever, with 450cc injector, i can boost to 14 psi, so if i have code at 8 psi, i'm gonna have a code a 14 psi.

i'm with a turbo of mx 6 set at 8 psi.

So do you have any idea??

Thanks

civic1990si

ok so you think that i run to rich so the SMC + get me a voltage to high so my ECU give me the Cell 3.

but on my autometer air/fuel, when i'm on boost, it's just correct. 1 line in stoich and 2 or 3 line in rich.

Can i run to stoich or it's beter to be in rich??

Thanks

Joseph Davis

You want to be rich when in boost - stoichiometric will blow up your engine.

One or two bars on your AF meter tells me nothing about how rich you're running. I have no idea how your AF meter is calibrated... a stock O2 sensor is not an accurate way to measure exact AF (except at stoichiometric), but if you tap into the wire the AF meter reads and see .900-.925 volts under boost you should be safe.

It sounds like maybe you're running past the limit your fuel injectors and SMC can work together, which is odd to me - your stock MAP can't read past 9.25 or 10.65 psi depending on it's era. Upping fuel pressure might get you to boost to the max of the OEM MAP, but your idle will really start to suck. Most AFC/SMC/MAP hacked Hondas run rich at idle as the minimum allowed pulsewidth at idle is still too big.

civic1990si

so i can plug a meter on the o2 sensor wire and what if i'm on .900 or.925??

i was thinking to put a FPR that can give me more fuel pressure like 4 lbs per psi of boost, so this will help me in boost and i will show less fuel with my SMC.

What do you think about that???

thanks

ion_four

I don't believe this is true. I am of the understanding that Honda's use a 2bar MAP sensor (1 ATM = 14.7psi or 1bar) so, you can run 14-15. This makes logical sense and there are people on here that are running upwards of 14psi on a stock MAP.
I think the confusion comes from the fact that you can't run more than about 10psi with 450cc injectors and stock fuel pressure, without running lean. SO, if you're using a stock MAP sensor, you will throw a code beyond that, merely because it's seeing more than 5 volts. I have thrown a code at 9psi, but that is because I was SOOOOO rich, it's not even funny

Does this make sense?

civic1990si

ok so you have a code 3 because your running to rich???

And you think that i don't have enought to the injector so it's for this a have a code 3?????

To resulve this problem, i can put a fuel pressure regulator and give more fuel pressure and decrease the Fuel on the SMC??? this will give me more fuel and decrease the SMC signal to the ECU.

Does this make sense??

Thanks


[Modified by civic1990si, 12:36 PM 1/27/2003]

Joseph Davis

Sorry, no. Since the referrence voltage sent to the MAP, that an AFC modifies, is 5 volts, there is no way the referrence voltage will exceed 5 volts. The OE Honda ECU code doesn't recognize any input beyond 3 volts, which is "atmospheric pressure," as it has no fuel/ignition maps for anything beyond that... and that is when you trip a code 3.

The Honda MAP is not a 2 bar MAP. It's "theoretical" range, if it were to return the full 5 volt referrence back to the ECU, goes as high as 11.8 psi above atmospheric pressure, but due to construction (ie - the internal silicon diaphragm can't travel any further) the 85-91 MAP reads up to 9.25 psi and the 92+ MAP reads up to 10.65 psi.

USDM_ED9/Dropshop was the first to notice this, and I've verified it. Monitor your MAP sensor output while monitoring your boost gauge and watch where the boost keeps climbing, but the MAP output peaks. Pretty fucked, huh?

FYI, www.zdyne.com confirms the OBD0 MAP max to be "9.3 psi."

Hondata claims 11.3 psi because Doug, bright guy that he is, was thinking about something else when he was doing in/Hg and psi to mBar conversions, kept rounding off decimal places, came up with the theoretical max of the scale to be 11.3 psi and never thought to check the actual max output of the Honda MAP. I'm not criticizing Doug - the first time I went thru the conversions to modify my fuel and ignition tables for the AFC boost hack I rounded off a bunch of numbers and came up with 11.3 psi instead of the correct figure = 11.8 psi. I never would have noticed the max output of my MAP sensor if Jon hadn't pointed it out to me, either.

civic1990si

ok but i do not boost at 10 psi. i boost 8 psi.

So i'm not supose to have a code 3

Joseph Davis

You have the SMC adjusted so that the MAP outputs more than 3 volts at 8 psi, or (wild guess based on nothing) the SMC is defective. Period.

zip

You shouldn't provide advice based on conjecture if your not familiar with the product.

The SMC is not defective, he has had two different SMCs (SMC and SMC+) but has encountered the same problem CEL3. No SMC user have had this problem since each SMC is QC'ed twice before shipping. I'm suspecting a wiring problem or faulty MAP sensor. The SMC and SMC+ have an internal electronic MAP limiter that prevents CEL3 for Honda ECUs. The electronic limiter can be defeated by grounding the green wire.

Joseph Davis

I may be unfamiliar with the SMC, and I did state that my supposition of a defective SMC was a "wild guess based on nothing." I have no desire to defame someone else's product.

I do, however, have experience with fiddling the MAP voltage of Hondas for forced induction, as well as the electronics background to build an SMC clone if I so chose. The ECU is seeing over 3 volts on MAP input, for whatever reason, period.

civic1990si

yep so i will try to change the MAP sensor. i'm sure that i have not connect the green wire, so the other is too change the MAP sensor.

thanks a lot for all your support.