Dave, heres the test results of the second car in sig. test was 03/16/2001. up for retest next month. the combo is unchanged since it was tested last including ported irons with no egr and a jay carter street 93 chip. HC GPM reading:2.0 limit: 4.70 CO GPM reading 14.43 limit 45.48 NOX GPM reading: 3.86 limit 7.21 CO2 GPM 978.42 and their little computer estimated fuel economy at 8.74 mpg. he he.
Emissions and injectors
- Thread starter MSDGN
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How you figure? If PW is 2mS and AE is a .6mS PW, and you drop 3psi FP, PW goes to 2.4mS and AE PW is still .6mS, how you lose pump shot? I can see what you're saying if the ECM didnt compensate for the loss of pressure, but if its basing its calcs on 14.8 and it IS 14.8 then a .6 (or whatever) AE pump shot is still delivering the same (roughly) amount of fuel. Unless you mean just because there is a slightly different spray pattern from the injector when you drop the pressure, then I gotcha... I know what you mean now, but isnt this negligable?
Exactly why I posted he must have run a cam with a lot more exh duration and/or overlap. But if this were the case, another gas would have been sacrificed. typically HC. He went on to mention it was a stock cam. Theres no way I believe this. Either the inspector fudged it for him, it WASNT a loaded mode test, OR the state at the time didnt do a 5 gas NOx test. We do.
Ever run a IM240 trace? Its a lot harder than you think... I've gotten ASM5015's to the point I can pretty much stab the gas and be right on in most cars, but idle, then accel, then cruise, then decel, then cruise, then accel to a point in an amnount of time, the hold, then coast...thats rough.... If you can do it "easily" you're a better man than I....
sixgun86gn
six offender
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Jim, I think you and I are fighting a lossing battle here (and all these related smog threads). Seems to be a lot of "new" expertise about what will pass emissions tests. I've heard some pretty radical claims the last several months! But not a single verification with data, etc.
I guess you missed my thread where I listed my emmissions readings a few months ago
.Since you are the only"expert"Know it all here I won't bother to re post.I do recall Jim replying to it though.So as far as real results to back it up,I delivered and you at me.I don't care how much you think you know ,but thats a crappy way to be towards someone.NOW,there is the end of your subject.
I guess you missed my thread where I listed my emmissions readings a few months ago
.Since you are the only"expert"Know it all here I won't bother to re post.I do recall Jim replying to it though.So as far as real results to back it up,I delivered and you at me.I don't care how much you think you know ,but thats a crappy way to be towards someone.NOW,there is the end of your subject.Screw it, you guys are right. I just dont care anymore. I have the dyno here, I have the machine here (5 gas and sister PC to log engine/scan data). I've tested probably 1500 cars in the last year, from Corolla's to a blown 32 deuce coupe. I think I have a pretty good idea what I'm talking about.
I guess it really shouldnt matter to me unless you present your car to me for emissions inspection....
I'm done....too many guru's here
I guess it really shouldnt matter to me unless you present your car to me for emissions inspection....
I'm done....too many guru's here
Jim why are you getting so testy? nobody here has called themself a "guru" i took both my cars in and they failed, i said what i did to get them to pass and showed the numbers and you still call me a liar. how would you like it if i did that to you? i can tell you that this is an im-240 test here in RI and i didnt even know the testers name till i saw it on the printout.
The ecm does calcs based on commanded AFR and some based on time. The AE, crank injector PWs are a few of those that are governed by time. If you reduce the pressure, and the time remains the same, there is less coming out of the injector. BTW, the AE decay is also time domained.
Think of a 30PPH injector for .6msec, and then a 36 PPH injector, if they are both on for the same amount of time the larger injector will flow more, all other things being equal.
The ecm doesn't account for F/P, in closed loop it accounts for fueling changes based on the O2 feedback.
Technically true, yes
but it sorta does in a loose way. As you've correctly pointed out on many occasions, the change in fuel pressure is seen as a mixture change by the O2 sensor, and the ECU then changes the BLM's to compensate (erase) the change in fuel pressure. It's obviously too early and I haven't had enough coffee yet! I see that's exactly what you said in your quote above 
That's why I always have to roll my eyes a little whenever I hear claims that a 5-10# adjustment in fuel pressure "got me through" the smog test. Something may have, but not the fuel pressure change. Not unless those BLM cells were already so close to their limits anyway.
Eric Stage I
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It seemed like when Carl Ijames was getting his car to pass emissions with his 72lb injectors, that he found at least some effect with fuel pressure. I think he mentioned something about spray quality (not necessarily the amount of fuel). But maybe this was only a concern because he was using huge injectors and the pulsewidth was so small.... I dunno.
But I agree, in all normal circumstances, when the ecm is in closed loop, if you change the fuel pressure the computer will compensate and you end up with the same 14.7 a/f.
Another interesting note, if you go into the chip and change the parameter for the closed loop a/f. Say from 14.7 to 15.0. The computer will still compensate and you end up at 14.7 again!
Regards,
Eric
But I agree, in all normal circumstances, when the ecm is in closed loop, if you change the fuel pressure the computer will compensate and you end up with the same 14.7 a/f.
Another interesting note, if you go into the chip and change the parameter for the closed loop a/f. Say from 14.7 to 15.0. The computer will still compensate and you end up at 14.7 again!
Regards,
Eric
I posted my results about a year ago, both here and on the gnttype list. I used a HC/CO machine and varied the fuel pressure from the high 20's to mid 40's and for my 72's with saturated drivers the optimum was about 32 psi (under static conditions either idling near 750 rpm or holding near 2000 rpm in gear on the brake to get some load with a 2800 stall D5 converter, so no AE effects). The idle PW was near 2 msec over most of this range because I was right at the limit where the injector response time was rearing it's ugly head. Lowering fuel pressure increases the pw so response time isn't such a problem but eventually the spray pattern has to start getting worse and I think that that's what I saw below 32 psi. I also leaned out the chip some, but not in a big series of steps; I just did one or two steps. I saw the hc and co fall and had no way to measure nox. All this was without a cat and with egr using a chip based on the bbjk emissions recall chip (Jim, your table left out the cmw 86 chip). Then I put on a cat and fast passed the MD IM240 test (which I don't think has much of an idle component since the driver mashed the gas as soon as the start light came on). If you look at the GM chips they steadily leaned them out from cmw to acxa to bbjk maybe to the tta chip (I'm not digging out my notebook right now) to the GM stage I chip image someone sent me, so I think that they may have been a little rich of stoich to begin with. I don't recall differences in egr or timing in the TR series but haven't really looked that closely.
Ah, now remember back to when folks were unplugging the Cam sensor, and passing with the engine in batch fire mode, which gets you seriously better atomization. Gotta remember it atomisation at overlap the gets the fuel finally burnable for the last instant. So tinkering with overlap can be a critical item. The first .08 msec of injector opening time is just a big dribble. About 1/2 of that is just the injector reacting to the electrical pulse.
So, you're saying the change in F/P has no effect on the AE part?.
On a IM240 that can be a big contributor to failing.
Least on the data logs I've seen. Just as a point if trivia, the cross fire wasn't offered on manuals, due to the closed throttle emissions during a shift. It's easy to go right past the finer details an have problems.
Yep, takes more then just changing the commanded AFR to get the ecm to do other then 14.7...
And the lean cruise AFR doesn't work, with out a patch to the code, just as a FWIW for any new guys looking in.
Eric Stage I
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Yeah, AE is one area that is not compensated. In fact, that's how I troubleshoot AE issues sometimes, by cranking the fuel pressure way up or way down just to see the effect on stumbles and such. Then I know what I might have to do in the chip.
Eric
Eric
UNless you change the high and low correction windows to reflect that 15:1 AF ratio yes. Because despite the target, the windows are still correcting to a 14.7:1.
Been there done that.
BTW: I will also mention I got a friends car thru with a dead O2. Set it up I guess you can say open loop. Went thru no prob w/009's. Took me 2 tries, but it went.
Bruce, I know this is a little off subject but have a question:
A little background: I have what I believe to be a fairly good working and somewhat accurate heated (switching) O2 sensor.
I also run the latest Extender. and I keep it in open loop idle mode.
I have noticed the following during warm-up and regular idle (just took the car out of the garage to exercise the engine).
With a "commanded" A/F ratio of 12.5:1, my O2's were hovering in the 760's(very consistently)
With a "commanded" A/F ratio of 13.4:1, my O2's were hovering right at 700mv +/- 5mv.
All this with a idle cell BLM value of 138.
With what you've seen with a wideband, do these correlate to anything near accurate??
As a follow-on I just went out and reset the idle cell to 128 and locked it there by re-engaging OL idle. This brought the O2 values from the previously mentioned 700 range down to consistent 680's.
HTH
The oem O2 sensors, heated or not just need a light off temp of about 600dF. Using a heater just gets it to that temp faster, and guarantees a MIN operating temp.
On the other hand a WB such as the Honda one used in most of the WB setups, has a min operating temp of 850dC, or about 1,700dF.
Now in the first case the oems will vary as the temps exceed 700dF EGT, since they are just designed for switching, in oem form, the skewing of the output due to EGR really isn't an issue.
But, you can't assign any meaningful AFR to output volatge because they are EGT sensitive.
What is good or OK for switching is just that, fine for switching.
I've had an oem O2 read 860 mv, and with the WB read a 11.8 and 12.5, at that same 860.
Now at cruise, my oem O2 may be indicating a relatively steady 30-50 mv, and the WB might be reading 15.2 to 16.5.
I have several added O2 bungs and did some comparisons and the stockers are erratic and just get worse the farther you get from stoich. If you look at the code, it looks for voltage swings of like .6 and .3, and that's just a sanity check to make sure the O2 is switching. All they sense, reliabily do is switch over stoich. Period. As neat as it would be for them to be able to do more, it just ain't going to happen.
And if you want to get into exhaust back pressure that just opens another can of worms.
On even the WBs they say mount them downstream of the turbo. Hmm, where is the oem GN one?. Yep pre turbo and even more skewed due to the EBP.
I know this ain't the answer you wanted, but this is how it shakes out.
Oh trust me, I understand about how turbine backpressure and EGT's can affect the stock O2's or any of them for that matter. It's the reason I've been preaching for years that the O2's fall off so quickly during a run down the track. Just the back pressure and temps radically affecting the O2's abilities.
This was nothing more than some curiosities(sp) I've noticed while the enging was idling in open loop. I have nothing better to do with the cars "put up" for the winter but back them out of the garage and get things "loosened up"
This O2 sensor (AFS 74) just struck me as being abnormally consistent (at idle) and being able to see relatively small chages I made.
One of these days I should get a couple of bungs added to my down pipe. One to move the stock sensor (Buick,s rediculous location has always puzzled me), and another one for a wideband setup (which I can't afford anyway).
I prefer to leave my EGT probe pre-turbine though. I still that's the best place if running only one.
Assuming I was to add a couple of bungs this winter, where's the most ideal location on my THDP?
Within a given set of circumstances yes a stocker can be repeatible, but with the variables hard to tell.
The turbo extracts energy from the exhuast so yes you want it pre turbo.
I have my extra bungs just behind where the Cat Converter would be. On the outside of the radius.
For those thinking about moving the oem one, there is a time setting for the ecm to allow for O2 feedback on fueling changes, but I hadn't had a problem with that, but there is always a possibility.
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I got my info from Balco Corp (R&D for SnapOn electronics-mainly their scanner). I asked him to look at the differences between the fed and CA Prom (he only compared PROMs that were CA/fed and Fed only). He explained the code indicated the FED only PROMs activated EGR at a lesser percentage than CA PROMs.
With regards to ASM 5015, that is a steady state test (meaning the emissions are sampled at a steady rate of speed. The IM147 (and IM240 for taht matter) will test at various speeds and different loads. Also, you're relying on the operator to stay within the trace parameters and not make sudden acceration and deceleration (and without relying on the brake pedal). My car also passed CA ASM test, but i noticed that the HCs rode right up on the edge of passing (135 cutpoint and 133 result). A change in injector and PROM brought the HC down to 65, with minimal effect on CO. The NOx curve is bell shaped, so less than 14.7:1 mixture will yield lower NOx numbers and more than 14.7:1 mixture will increase NOx, until around 16:1, at which point NOx will fall to the floor, because the mixture is too lean. So a little CO may not be such a bad thing as it may contribute to cooling compbustion temps.
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