You can copy and paste this link to share: Ī very common question goes something like this, “How can I use the LS1 PCM on my Gen I small-block engine when the firing order between the two engines is different?” To answer this question, let’s take a look at how General Motors addressed this issue. In model year 2001, General Motors released Gen I small-block and LS-series engines that all used the same PCM (GM# 12200411). The firing order for the Gen I small-block engine is 1-8- 4-3-6-5-7-2.
The firing order for the LSseries engines is 1-8-7-2-6-5-4-3. Notice that cylinders 4 and 7 have swapped, and cylinders 3 and 2 have swapped. When you compare this PCM’s fuel injector wiring diagrams for the Gen I small-block with the LS-series engines, you see something interesting: General Motors simply swapped injector outputs 4 and 7, and 3 and 2 within the engine wire harness to address the firing order change. This schematic represents proper wiring of the eight ignition coils for Gen III and Vortec 8100 8.1L big-block engines with the firing order 1-8-7-2-6-5-4-3. Now compare this PCM’s fuel injector calibration details for the Gen I small-block and LS-series engine. EFILive reveals that General Motors also changed the injection bank assignments table values to follow the wire harness fuel injector assignments. The PCM must be calibrated to know which injectors are assigned to bank 1 (cylinders 1, 3, 5, 7) and bank 2 (cylinders 2, 4, 6, 8) so that fuel trims are applied to the proper bank of cylinders. If the injection bank assignments are wrong, fuel trims are extreme and the engine runs poorly and may even stall.Īlthough the PCMs are the same, the ignition systems are different. Gen I Vortec V-8 engines use a fourpulse, low-resolution, crankshaft signal for single coil and distributor ignition. LS-series engines use a 24-pulse (24x), high-resolution, crankshaft signal for coil-percylinder ignition. However, the same logic applies here if using a Gen I small-block engine with the LS-series engine’s 24x crankshaft signal. The wire harness requires that ignition coil assignments for cylinders 4 and 7, and 3 and 2 be swapped.ĭTCs are assigned to ignition coil control circuits.
#Xnip engine software#
The calibration table for the assignment of these DTCs is not available within most tuning software packages. A changed firing order may result in an incorrect DTC notification.įor instance, let’s say you have a PCM from a 2001 Camaro with the LS1 engine. You installed a 24x conversion on the Gen I small-block and made the necessary wire harness and injection bank assignment updates.
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