keebler65

in my quest to find out why my car doesnt start well with the DSM 450s, i ran into a question. i was wondering, when i crank my car, what is telling the injectors to flow x amount of fuel? is it reading the map sensor at all? or is there just a preset map in the ecu? the reason i ask is, if the computer is sending the same signal to the 450's as it would with smaller injectors, then this means its probably flooding the engine thus making it harder to start. i have a feeling that it is getting too much fuel because once it starts i can smell fuel for a 15 seconds or so.

all thoughts and input are welcome

Deltax75

Its just your injectors. I had hard starting with my dsm's, then i replaced them with 550's at that and never had a problem again. So either get a different set of dsm's or talk to Viren about some new ones. And to answer your question about fuel maps, when you start your car it will run off your preset fuel map until the O2 sensor warms up then your ecu will make adjustments off that (closed/open loop)
-Mike

tony1

The computer has a cranking fuel map that it runs off of when rpms are below a certain rpm (usually 250-500 rpms). You can't get into this map unless you have a hondata...

SiRkid

or aem

keebler65

thats what i was afraid of. i wonder if i could make a circuit that pulsed the injector signal to reduce the amount of fuel until it starts. thanks for the help.

scttydb411

use afc to cut the pulse...are you using the "hack"?

keebler65

i'm using the SMC+. have you tried that on the afc or are you just guessing? has it cleared up any starting problems?

scttydb411

with dsm injectors i'm assuming you are using the resistor box if you have a newer car. prime your fuel pump by turning the key to on, but not turning the starter. once you do that crank it. when cold it will start right up. when warm after sitting 20min-1hr do the same thing, but when turning the starter slowly press the accelerator until the engine fires up. i have no problems and car starts everytime. i've got my corrections at lo throttle -46 across the board w/ exception of 1k rpm at -47. the -46 brings the 450cc inj to appx 240cc which is stock.

oh yeah, when you first start your car whether it's cold or not it goes to a cold map until the o2 sensor heats up and reads. if your engine is still warm it will just take longer. you can test this out by starting your engine and watching your a/f gauge. it will look like it's not working properly because the o2 is not reading yet, but once your rpm start to drop to normal warm idling it will start reading normally.

good luck.