I recently picked up an 88 bronco ii that the P.O. swapped a 4.0 into. It was a pretty clean swap and everything is working like it should, except for the tach. It reads about 1300 at idle. It is idling at a normal spot it's just the tach is off. The tach rises and falls with the engine just fine I just have a feeling there is something different between the 2.9 and 4.0 that causes it to read wrong. Is there anyway to fix this? Ive head of newer rangers being able to ground one wire and it fix it. The 4.0 is out of a 92 ex and it's still got the b2 a4ld.