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Currently running a 3400 motor off a ODB1 7730 ECU with BFUZ bin and A1 mask. The motor idles around 1700 RPM, even though the desired idle RPM according to the datastream is around 800-1000 rpm. The IAC count hovers around 70, so my question is, why is the ECU not reducing this IAC count in order to try and meet the desired idle RPM? According to the datastream, the TPS is at 0% and the vehicle is at 0 MPH, so it should be idle mode.
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post up one of your datalogs...
BTW, welcome to 60v6! -
I attached both a CSV and TunerPRO xdl file. 3.csv 3.xdl.zip
A little backstory: this is a 7730 from a 1990 Cavalier Z24 5 speed. With the stock 1990 memcal and the 3400 motor, the car has a rough idle around 900 rpm. I do not have a chip reader, so I do not know what mask is on the chip (says ATMF on it). Since I don't know the mask ID, I can't get any logs from the stock memcal.
I downloaded and tried two $A1 bins (BFUZ and AZKK) on my emulator and they both have this high idle problem.Comment
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what injectors are in it?
There are a few people that sell a chip for this swap, the wot-tech store being the best that i've tested.Comment
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This uses 3.1L injectors. As much as a premade chip would be handy as a baseline, this is going into an endurance race car which will evetually see more performance parts on the motor. Hence, i would really like to learn the ropes myself. High idle does scream vacuum leak to me, and the MAP at TPS=0 seems high, but i have yet to find one. I am mainly curious as to why i can get under 1000 RPM on the stock 6D chip, and also why the A1 ECU does not seem to adjust the idle air count to fix the high RPM.Comment
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odd... your read idle speed is roughly double that of the desired speed.... and the ECM is acting as if it's normal, since if the read idle speed is 250 RPM above the desired idle speed for ~51 seconds, it should set the 35 - IAC code.... yet it doesn't pop up.
you don't have the checksum or any other DTCs disabled do you?Comment
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This is the stock BFUZ bin, but I did verify that the IAC codes are enabled. Checksum is verified after I download the bin to ostrich.
I also reran the stock 6D chip, and am also getting a high idle now with the same symptoms coming across the ALDL. Is it possible that there is a faulty sensor and/or the reported RPM on the ALDL stream is different than the one used to command the idle RPM?Comment
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got a spare ECM?
the fact that the code doesn't set when it's clearly in the conditions necessary is a bad sign...
the fact that you get a datastream rules out the ECM operating in limp home mode....Comment
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So I am fairly certain I found the problem: I had a fuel pressure gauge installed the nut started to leak fuel. Removing the gauge from the Schrader valve brought the idle to within range. I have no clue why the computer was compensating the way it did and not throwing codes
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wow, that's strange for sure...
Be careful with those injectors, they are not big enough for a stock 3400. You'll max them out and still run it lean at WOT. There is a huge VE difference between the 3.1 and the 3400.
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