Dawson21

i think i may need to change my injectors, but i am wondering if anyone else every had this problem

DaX

iTrader: (1)

On the hondata board, they say that the DSM injectors do not work well with Hondata. Some people have had success, but from Hondata's testing, Hondata and DSM injectors can not play nicely.

danl

I got some DSM 450 cc injectors to work nicely in my buddies crx. Its even a low compression 8.5:1 motor that shouldn't idle as well. I don't see what the deal is. I got Uberdata on a p28 to play nicely with a non-heated O2 sensor low compression motor.

Maybe DSM injectors react quicker or slower than saturated injectors and that is messing people up?

slipslap

What is the problem exactly? And why would DSM injectors be different from say RC 450cc injectors? What makes them different for the problem?

danl

Peak and hold injectors have a slightly quicker response time than saturated. They tend to open sooner as well. A half a millisecond delay is a pretty big deal at idle when your talking a 2 ms injector *on* time. Its something you have to keep in mind. When the injectors open up for a longer period of time the 0.5ms delay becomes allmost negligable. So you have to curve the fuel maps for the injector.

Its not that hondata can't work with 450's, you just have to understand how the motor uses fuel.

Hondata now by default does a funky scaling procedure for bigger injectors. It adds a ton of fuel at low vacuum levels and slowly meters out the fuel it added by the time the map value is at the 0 psi boost collum. I've found that DSM 450's DO NOT LIKE TO BE SCALED AT ALL OR VERY LITTLE on a low compression d16z6. So in hondata you have to reverse how hondata adds fuel when making a base map.

Anybody confused? I can't explain worth a s***................

slipslap

I will use Uberata and still not understand, I mean I understand the peak and hold stuff. But I don't see why you can't put the info needed in the Hondata system and it work. I mean for all that money it should be capable of being programmed to work with whatever they use.

danl

Ok, its like this.

On a 240cc injector you need x ms of fuel at idle. On a 480cc injector (twice as big right) you should need 2x the ms of fuel at idle. However the bigger injector has more inertia and theirfore takes 0.5ms longer to open than the stock injector. So for the bigger injector you need (2x) - 0.5ms of fuel.

Reality:

Say your stock 1990 honda crx si needs 4 ms of fuel at 20inHg and 750rpm (typicall idle). You add 480cc injectors (twice as big). So your cut your injector pulse width in half to 2ms. However these larger injectors take 0.5ms LONGER to turn on. So the injectors are actually only staying on for 1.5ms and your car runs leaner at idle by 25%.

At low injector pulsewidths the 0.5 ms delay is a HUGE deal. At higher pulsewidths its allmost negligable.

The soloution, Hondata has incooperated into newer versions of their software is to automatically "scale" their injectors for this discrepency (this is what i've gathered from a tech note on their website). What Hondata is unable to correct for is the differences between a peak and hold 480cc injector that has say only a 0.1ms extra delay over stock and a saturated 480cc injector that has 0.5ms extra delay.

In uberdata I origionally wrote a basemap for DSM 450's incooperating a Hondata style injector "curve" manually. The car ran like crap (too rich). Then I just did a linear scale and the car ran like stock. Figures, all my hard work scaling the car was for not.

On my other buddies car I wrote a non-scaled basemap for his saturated 525 cc injectors on a stock d16y8. Surprise surprise the car runs LEAN at idle. This car needs the Hondata style injector "curve".

Dawson21

alright, so basically the injectors are useless with the basemap and i need the car tuned to get them working properly.
Next question, do you know of any peak and hold injectors that will work with hondata that are close to 450cc (just so i can get to the dyno)

sporkcrx

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by danl &raquo;</TD></TR><TR><TD CLASS="quote"> However the bigger injector has more inertia and theirfore takes 0.5ms longer to open than the stock injector. </TD></TR></TABLE>

What do you mean more inertia?

DaX

iTrader: (1)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sporkcrx &raquo;</TD></TR><TR><TD CLASS="quote">

What do you mean more inertia?</TD></TR></TABLE>

The inertia of the larger pintle/disk.

I don't know what it is about DSM 450's but in a lot of cases Hondata doesn't like them. You can get a set of RC 440's, 550's or any others to work perfectly with Hondata. Check it out here:

http://hondata.com/forum/viewtopic.php?t=432

danl

Ha ha, that link to the hondata board is funnie. He says that DSM 450cc injectors will not work properly on a honda ecu resistor pack or not. I got DSM 450cc injectors to work fine with a resistor pack on a p28. I can see why they might not work well (impedance mismatch) but you can get them to work well. The car starts and idles fine etc..... Pulled a 13.7 at 102mph on a d16z6 and 6 psi boost so power is not lacking either.

slim9300

They just say that BS on the Hondata page so you spend money on some RC 440cc or 550cc and buy them from Hondata. There are thousands of people running DSM 450cc successfully with Hondata. I think your problem is yourself or your tuner, bro.

danl

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slim9300 &raquo;</TD></TR><TR><TD CLASS="quote">They just say that BS on the Hondata page so you spend money on some RC 440cc or 550cc and buy them from Hondata. There are thousands of people running DSM 450cc successfully with Hondata. I think your problem is yourself or your tuner, bro.</TD></TR></TABLE>

Yeah, I think your right.............