I want to boost a Quad 4 engine with an Eaton M62 supercharger 10 psi of boost. What OBD I ECM/PCM would be compatible with MAF fuel control, 7X crank trigger and waste spark or coil on plug? Or should I do this some other way such as speed density?
I want to boost a Quad 4 engine with an Eaton M62 supercharger 10 psi of boost. What OBD I ECM/PCM would be compatible with MAF fuel control, 7X crank trigger and waste spark or coil on plug? Or should I do this some other way such as speed density?
Welcome to the forum!
Sounds like you're working on a fun project. The same 1227749 that was used in some Q4 cars was also used with different code in the turbo Sunbird and Syclone. There are three variables that need to be changed to allow the distributor based $58 code to work with the quad 4 DIS module. Depending on which ecm you have now you might have an unused 1X signal from the ignition module after the swap.
I was hoping to go mass flow but the 1227749 with speed density look like it would work. The 4 cylinder is $58A. I downloaded the AKDB bin file. What variables need to be changed to make it work with the Quad 4 DIS?
I guess to go mass flow I could use the PCM and ignition from a supercharged Ecotec.
There is a definition file out there for the 95 J car 2.3. IIRC that's a speed density calibration also.
You could switch to OBDII pcm and use MAF sensor. Technically you don't need the cam signal for the engine to run. But what definition file would you use? J-car definitions seem to be the domain of HPTuner.
OBDI Saturns used MAF but agan, where to find a definition file?
The $58 code (it's really the same code, I4 or V6) has a few cool things built in. For example, if knock doesn't stop when timing is retarded, the ecm is programmed to add fuel then to reduce boost. And the ecm will control the boost control valve. I don't know of a MAF ecm for four cylinder that will do that.
The values to change are max advance, max retard, and reference angle. It's simple but not... Many definition files out there have the wrong conversions. And you want to know whether or not you're using a crank with the notches 10 degrees advanced, which would change the reference angle from 60 deg to 70 deg. If you have the correct stock calibration for your car I could likely pull the limits out of the file.
There's a working $58 definition file posted here: http://www.gearhead-efi.com/Fuel-Inj...ll=1#post26402 There's also some good discussion about the values that need changing.
There are also the options of non stock codes, such as code 59, and sAUJP. Both should support dis and 4 cylinder and boost. Not sure of MAF. Hope that helps
No need to re-invent the wheel. But we can make it better
I was using a turbo sunfire ecm with code 59 on a LO Quad-4 in a 1985 fiero and seemed to work well enough. Drove it for some years till i blew a head gasket and found cracks in the head and block.Originally Posted by ralmo94
I have gone the less DIY route and use Tunercat. He does not list a definition file for Saturns but he may have one. I'll check
Tunercat has a $58 defintion file for 6 cylinders and a $58A definition file for 4 cylinder so there has to be a difference in where the data is located or how it is scaled
The $58A AKDB calibration for a Sunbird has the following:
-spark reference angle = 6
-max advance relative to reference = 54.14
-max retard relative to reference = -5.98
The $A8 AXRM for a 2.3L W41 Quad 4 has the following:
-spark reference angle = 74.9
-max advance relative to TDC = 60.1
-max retard relative to TDC = -9.8
Curious that different references points are used. I guess that the 6 degree spark reference angle on the Sunbird is the spec for setting base timing with the distributor. The ECM needs to know this to compare the total timing to limits. So the max total timing limit for the Sunbird is 6 + 54.14 = 60.14 degrees BTDC and the minimum total timing is 6 -5.98 = 0.02 BTDC as compared to 60.1 and -9.8 for the Quad 4. Now if the spark reference angle is changed to 74.9 degrees to account for the reluctor notch location then the max advance and retard need to be adjusted by 74.9 - 6 = 68.6 degrees and the value for the Quad 4 max advance become 60.1 - 68.6 = -8.5 and the max retard becomes -9.8 - 68.6 = -78.4. Have I got this right?
Next step is to look at wiring diagrams and see how the ignitions are wired to the ECM's for a distributor vs a DIS system
Yes, that's how the math works. If you were to change only the reference angle to 74.9 the max negative limit would always be applied and timing would be "locked" at the wrong amount.Curious that different references points are used. I guess that the 6 degree spark reference angle on the Sunbird is the spec for setting base timing with the distributor. The ECM needs to know this to compare the total timing to limits. So the max total timing limit for the Sunbird is 6 + 54.14 = 60.14 degrees BTDC and the minimum total timing is 6 -5.98 = 0.02 BTDC as compared to 60.1 and -9.8 for the Quad 4. Now if the spark reference angle is changed to 74.9 degrees to account for the reluctor notch location then the max advance and retard need to be adjusted by 74.9 - 6 = 68.6 degrees and the value for the Quad 4 max advance become 60.1 - 68.6 = -8.5 and the max retard becomes -9.8 - 68.6 = -78.4. Have I got this right?
The ecm cannot create spark advance. Instead it is programmed to count off microseconds from the time it receives a reference pulse to the time it sends a spark signal to the module. The time calculation uses rpm and a constant that represents the number of crank degrees between each reference pulse along with a value that represents reference angle minus the ecm's desired timing after combining the relative constants and tables. For a distributor based calibration the reference angle is inputted as the distributor base angle and the code generates positive "desired spark" values. But the reality is that the EST pulse to the ignition module is delayed then delivered to the cylinder immediately following the cylinder that generates the REF pulse. On a 1-3-4-2 engine cylinder 1 generates the pulse that starts the timer to create spark on cylinder 3. This works because the rotor and cap have the job of directing spark and the ecm only needs to count time.
DIS is different. Reference angles are much greater with DIS, 60-70 degrees typically. The ecm math generates negative values for spark advance after subtracting the reference angle. What's interesting is that the ignition control hardware actually appears to change the time delay if the desired spark value is lower than -90 degrees.
Typically they are wired the same using the same four circuits and the same color wires. REF, EST, Bypass, and Return. Many Q4 engines used a 1X pulse signal in addition to the 4 common wires from the module. The 1X signal will not be used with the 7749.Next step is to look at wiring diagrams and see how the ignitions are wired to the ECM's for a distributor vs a DIS system
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