I recently have been trying to modify some vehicles for personal use by adding new or replacing engines and transmissions with my own. I have not been changing the modeling of the engine but what I do is copy and engine or directly replace one, change the torque numbers and the rpm parameters, and add a new engine sound and I have modified a transmission which worked. What's happened to two of the engines I've done (they're on separate cars and are the only two that I have renamed) is when I try to accelerate on the first one of them I get serious torque converter slip. It's supposed to be a diesel so it can barely pass 3000 rpm and the issue is the stall is at 2100 rpm so if I hit the gas it instantly revs up to that and stays until the the speed of the engine and transmission nearly match. Then after that point like if I reach the redline in gear 1 at 3100 rpm for example, if I let off the gas it drops down to 2500 rpm which seems to be the true gear ratio speed. Is there any way to lower the rpm at which this happens and fix the rpm drop issue? The second issue is on a manual on a different car. I took a default engine for a car copied it, renamed it, changed its performance, and gave it a custom engine sound. This car does not have a specific transmission file nor is there a specific one in the engine file or on the parts selection. The default engine works fine, but mine will climb to 500 rpm normally which is the biggest increase of torque but after that, regardless of what gear it is in, it revs right to the redline much life flooring an automatic stuck in limp mode or in its high is gear as if it is simulating a torque converter. The clutch input reads at 0 and it happens on all transmission settings. If someone can point me in the right direction that would greatly be appreciated.