Ok, I have been looking everywhere for a answer. I swapped a Jdm odb1 p30 ecu b16a motor into my 98 hatch. First time. Had a few bugs but working them out. One I just can't seem to figure out though is a voltage drop and a weird misfire that is most noticed at idle. When mis happens voltage at battery drops sometimes to 11. volts. Not sure if the two are related but I was thinking that low voltage may be causing this. I have changed plugs and wire (ngk), cap and rotor, alt. rebuild, pulled wire harness and rechecked. There are no cel's. I have done a Mishimoto radiator Aem intake, Peak Performance headers, Obx twin loop muffler, Moroso oil pan and thats about it. Clutch, timing belt, water pump, and other misc. maintenance. I wouldn't think that it would need to be tuned on a dino yet but shop had told me that might be something that needs to be done.... They get $ for that you know. Anyways any help would greatly be appreciated.

 

Warm up the motor and jump the car from a running vehicle with a strong alternator. If the problem doesn't occur when being fed from another charging system then either your alternator isn't putting out enough power or you have an electrical drain somewhere. Check the belt to see if it's loose/worn. Using a belt tension gauge is the best way to check tension. Tightening the belt too far can cause it to snap. Check the resistance across the positive and negative connectors of the harness with the battery disconnected to see if there are any electrical shorts. You can also take the alternator to an Autozone or similar parts store to have it tested.

 

Hey thanks a lot for the response. I have replaced the belt and had the alternator rebuilt. I will try the jumping to check though just to recheck their work. I will also do a cable check. So what would be the best way to check the cables? With a multimeter set on...? I talked to a guy at Hasport today that told me that it was just something that the b-series does..... Hummm :/ I don't think so. So what would be the best way to check the cables? With a multimeter set on...? Thanks again for the help.....