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Post by aurorabrain on Jun 7, 2007 11:47:30 GMT -6
Has anyone on here tried the EPROM (just the IC chip) from a '95 Eldorado ETC on their '95 Aurora? I have one on order, and will tell of the results within a week or so. It should net a 6500 rpm shift and a 150mph speed limiter.
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Post by austinator on Jun 7, 2007 12:58:11 GMT -6
Out of curiosity, how much did you pay for it? I've thought about ordering one of the reprogrammed chips that kill the limiter and all of that stuff. I never really thought about a Caddy chip. Let me know how it works out and I might be interested. First I just need to get it running right though...
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Post by Aurora40 on Jun 7, 2007 13:02:46 GMT -6
wouldn't it also result in about 15% too much fuel in open loop driving? Also, didn't the early motors need stiffer valve springs to rev that high? I though the '95 had a 6k rpm limit or so because of this?
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Post by Marc on Jun 7, 2007 14:06:26 GMT -6
westersgarage.eidnet.org/GM.htm already has a chip for the 1995 Aurora.....specs: 1994-1995 Oldsmobile AURORA 1994/1995 V8 4.0L 32-Valve Engine -- Speed limiter removed, performance tuned **Hot** 7/10 second difference in 1/4 mile E.T (3.42 diff ratio car) $329 Memcal $329.00 SD
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Post by aurorabrain on Jun 7, 2007 14:25:46 GMT -6
First i'm going to remind everyone that this is only for a '95 with a 3.71 gear ratio.
Retail for a #16210492 (the EPROM in question) is $93.63 but i paid around $40 for it. To answer Aurora40's question, no it wouldn't run rich (in closed loop, but probably would in open loop) after the PCM corrected LT fuel trim, but it may run at a -5 to -15% long term fuel trim all the time. I run LS1 injectors in my '97 and run at a constant -20 to -30% LT FT. The PCM is always trying to achieve a 14.7:1 A/F ratio under normal driving, and a 11.x-12.x at WOT so it will adjust to an extent. The valve springs (all 32 of them) on a 95 4.6(y), 4.6(9), and a 4.0(c) engine are all the same part number up to 1999.
Mark, i decided to try this because of the price difference. I know someone with a '95 that doesn't care if he blows it up, its due for a new engine anyway. 280k miles i think?
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Post by Aurora40 on Jun 7, 2007 16:04:56 GMT -6
To answer Aurora40's question, no it wouldn't run rich (in closed loop, but probably would in open loop) after the PCM corrected LT fuel trim, but it may run at a -5 to -15% long term fuel trim all the time. I run LS1 injectors in my '97 and run at a constant -20 to -30% LT FT. The PCM is always trying to achieve a 14.7:1 A/F ratio under normal driving, and a 11.x-12.x at WOT so it will adjust to an extent. The valve springs (all 32 of them) on a 95 4.6(y), 4.6(9), and a 4.0(c) engine are all the same part number up to 1999. Aren't the trims based on zone or block, though? Wouldn't high throttle/map and rpm (or whatever a MAF system uses to determine which trims to use) be different at wide open throttle? I was of the impression that even if it learned at part throttle, and as you say would simply have largish negative trims, wouldn't at WOT it still go with the programmed map and no trim? Interesting about the springs. It came up a while back on cadillacforums.com, and the guy saying the earlier motors had springs that could float a valve at the higher rpms was a GM powertrain engineer. Could be my memory is fading. I'm surprised even if the springs are fine though, that they wouldn't be different part numbers for the 300hp motors just because the cam profiles are different. Sounds like for $90 on a car that needs a motor anyway you've got nothing to lose. Let us know how it works out. |
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Post by aurorabrain on Jun 7, 2007 16:44:45 GMT -6
It will only run rich in open loop fueling mode. This is the only mode that runs the car from preset values. This excerpt is from the service manual...
While in Closed Loop, the PCM monitors the heated oxygen sensor signal voltage and adjust fuel delivery based on signal voltage. A change made to fuel delivery will be indicated by the long and short fuel trim values which can be monitored with a scan tool. Ideal fuel trim values are around 0%; if heated oxygen sensor signal is indicating a lean condition, the PCM will add fuel, resulting in a fuel trim above 0%, 100% is maximum lean. If a rich condition is detected, the fuel trim values will be below 0%.
So while in closed loop fueling, the PCM is adjusting to match O2 readings to the pre-programmed A/F ratio 14.7:1 (depending on what throttle angle and % (WOT is a different mode of operation, could be anywhere from 14:7:1(cruising) - 11.x:1 (WOT)) desired no matter what you throw at it. Thats why it's hard to increase performance of a stock engine without custom programming.
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Post by Aurora40 on Jun 7, 2007 18:05:19 GMT -6
Right, but every GM I'm familiar with is in open loop when at WOT. The O2's cannot provide any sort of meaningful feedback at that point because they are narrowband sensors. I believe the 11:1 or whatever AFR is set at WOT is determined from all the various other values and parameters, not from any actual feedback. I've never seen block learns anything but 128 (0% fuel trim) at WOT when scanning my cars (mostly the 'vette). I'm reasonably sure it will run quite rich at WOT, but I'm certainly no expert. But you've got nothing to lose by tossing it on there and seeing what happens.  |
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Post by aurorabrain on Jun 7, 2007 19:36:18 GMT -6
Right, but every GM I'm familiar with is in open loop when at WOT. The O2's cannot provide any sort of meaningful feedback at that point because they are narrowband sensors. I believe the 11:1 or whatever AFR is set at WOT is determined from all the various other values and parameters, not from any actual feedback. I've never seen block learns anything but 128 (0% fuel trim) at WOT when scanning my cars (mostly the 'vette). I'm reasonably sure it will run quite rich at WOT, but I'm certainly no expert. But you've got nothing to lose by tossing it on there and seeing what happens. WOT is not open loop, its PE (power enrichment) mode. When you're actually tuning for power, you want LTFT's to be around 0%. This is an excerpt from a good tuning article. It talks about PE mode and how it works from programmed tables and last known LT fuel trims. I just bought a MAF translator and am working on getting things right on my '97 so i don't run a constant -30% LTFT. When you enter PE, the PCM takes the last known Long Term Fuel Trims and uses them for the base fueling, then looks in the Power Enrichment table for a percent value to add or subtract fuel from that baseline. The most important thing is to have the LTFT?s near zero or slightly rich before entering PE. If the trims are zero or rich, the PCM defaults back to zero for the baseline before adding the PE fuel. If the LTFTs are lean, the PCM will continue to add the extra fuel it was using to compensate for the lean condition, in addition to the PE fuel, to prevent you from blowing up your motor. The point here is that the car should have a good part throttle tune first, otherwise future part throttle tuning changes will throw off your PE fueling. |
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Post by aurorabrain on Jun 11, 2007 13:32:48 GMT -6
Got the PROM chip today. It does exactly what i thought it would. 6500rpm shifts and no emissions programming. Have yet to see if it goes 150, will post later tonight with a video if i get time.
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Post by macadamiaman on Jun 11, 2007 15:54:25 GMT -6
6500rpm is high!!! Sounds pretty sweet.
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Post by austinator on Jun 11, 2007 16:07:47 GMT -6
Sweet!!! Do you have a speedo/gps that goes up to 150 or are you just going to see how far you can bury the needle on this? How does it run in open-loop? Also, is the car mostly stock or do you have different injectors etc. on it?
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Post by Marc on Jun 11, 2007 18:15:28 GMT -6
Aurorabrain.......To see if it will exceed 150 mph, watch the tach. Whatever the RPMs are at 60 mph on your 1995 will be 2 1/2 times that at 150 mph.
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Post by aurorabrain on Jun 11, 2007 20:27:12 GMT -6
Well, after doing some test driving with me in the car i found some problems. I even tried it on 2 '95's with 3.71 gears. When i posted earlier i had dropped the chip off to my roommate who installed it and took it for a drive. He then called me to let me know that it was working. He failed to mention the no 1st gear problem that it has, he didn't notice it at first. It also has no communication with the Tech2 (so i can't see whats going on), displays no coolant temp, and displays no fuel parameters on the DIC. Other than that we took it out and buried the speedo, although i don't know how fast we were going, i just know it was over 140 by a bit. I'm thinking about trying a different choice on the EPROMs from the parts catalog, because the one that i have now has no emissions options and may be a special chip for a special vehicle. There is a normal prom chip listed that i didn't order for a stock Eldorado ETC. I may also try a STS depending if i can find a cheap one or not.
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Post by macadamiaman on Jun 11, 2007 23:34:32 GMT -6
Awesome. If you don't find another one that works better, just keep it on hand in case you need to get somewhere really really fast And no, Marc, it's not that easy. There's all sorts of things like exponentially increasing air resistance (you know, physics), increasing drag on the wheels and less efficiency/HP at higher RPMs (varying power curves) and all that jazz |
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Post by Marc on Jun 12, 2007 7:44:56 GMT -6
And no, Marc, it's not that easy. There's all sorts of things like exponentially increasing air resistance (you know, physics), increasing drag on the wheels and less efficiency/HP at higher RPMs (varying power curves) and all that jazz I know about that......the horsepower requirement goes up as the cube of the increase in speed. That is, if you want to double your speed, you need 8 times more HP. |
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