pulswidth ???

[DaBears1285]

I know that a general rule for injector pw at idel is 1.5ms, however I read on V8sho that our cars have a 3-5ms pw at idle, mine is currently having some drivablity issues and my pw is 2.9ms at idle, any feed back would be great.

thanx

 

[SHOZ123]

Stock injectors?

 

[DaBears1285]

yes, they are stock

 

[SuperHO]

 

[SHOZ123]

The only recording I have shows 1.1-1.2 ms at 2700 rpm and 75 mph.

 

[DaBears1285]

SHOZ123, do you remember what kind of reading you got from your M.A.F(voltage or gm/sec)? Cause mine apears to be out of spec but I dont like to trust all data specs, they tend to be genaric.

thanx

 

[SHOZ123]

At that speed or what? I suggest a xXcal 2 and a laptop. Best you can do if you are indeed curious.

$1000 gets you Xcal2, SCT Advantage software, WB O2 sensor and the SCT tuning manual.

 

[DaBears1285]

I have access to the NGS at school so its no big deal, but maf value at idle would be great.

thanx for the help

 

[SHOZ123]

At idle

Load = .175
Air flow # minute = 438
MAF counts = 148
rpm = 765

 

[DaBears1285]

DAMN, at idle in P or N my load is 25%, and what do you mean maf counts? do you mean iac, also your air flow # is that supposed to be 4.38?

My numbers:
MAF: 5.25-12.3 gm/sec
Load: 25%
INjct PW:3.0ms

again thanx for your help

 

[SHOZ123]

The PW numbers came for Autotap. The other numbers came from the SCT datalogging. Don't know how they compare to your hardware and software as far as the numbers.

 

[Axianator]

DAMN, at idle in P or N my load is 25%,

25% engine load is within the normal range for all stock SHOs - both V6 and V8.

and what do you mean maf counts?

Before the PCM can work with an analog signal (such as MAF voltage), it must first convert that signal into a useable digital value. The resulting digital value that you see is referenced in A/D (analog-to-digital) counts, which have a range from 0 to 1020. In order to convert these values back into a meaningful scale, you would need to divide the A/D count value by the appropriate divisor (or in this case, 204).

Example: 500 A/D counts divided by 204 would give us a MAF voltage of 2.45v.

also your air flow # is that supposed to be 4.38?

Paul probably meant 43.8, which would put his MAF voltage around 1.5v.

My numbers:
MAF: 5.25-12.3 gm/sec
Load: 25%
INjct PW:3.0ms

On a stock SHO, MAF voltage at idle will usually hover around the ~1.0v mark, which should yield 20-29 kg/hr on the Gen 3.

 

[DaBears1285]

thank you for the insight, the problums i am having are strange, my idle is rough and my HWY fuel economy is at about 14-15mpg at a 70mph cruise. The 02's show a rich condition and as such have atempted to lean out the mixture(LTFT=-9), My injector pulswidth is 3ms, and my M.A.F. reading at idle ranges from about 14-5.2gm\sec, but here is the best part, KOEO the maf show 3.06gm\sec of air entering the engine, which is imposable on a non running engine. With this problum I assumed the maf had been contaminated and cleaned it, to no change, so I ohmed out the wireing from the pcm to maf and it apeared to be in spec. So I replaced the maf thinking it could be noting else, with the new maf is I recieve the exact same readings. I almost forgot to mention, if I unplug the maf my scaner still shows 3.06gm\sec of air. Every teacher I have asked seems stumped by this car, I personaly think it is the pcm, but i was hoping for some insight. Please feel free to ask any ??? about data.

thank you

 

[SHOZ123]

I don't thgink I have ever seen my FI pulsewidth at or over 3 ms, even at WOT and high rpms. For this to be the O2s must be telling the PCM that things are quite lean or in fact they are.

 

[DaBears1285]

not quite, the fact that the long term fuel trim shows a negitive number(-9) shows that they know the car is rich.(a negitive number = rich, a positive = lean) so i know they are good, pluse they are new.