Typically I only post in my engine specific forum but I believe I have some faulty wires that pretain specifically to my 91 s13 240sx. I have a swapped ca18det (insert ca18 joke here) and finally had it running correctly after replacing a bad camshaftwhich had a faulty alignment pin which connects to the CAS. However, I am experiencing an intermittent problem which seems to be getting worst... So here it goes.
My car runs fine until my intermittent speedometer starts working, as soon as it does when ever I take my foot off gas during a cruise at ANY speed my aem wide band reads (+18:1 is the max my gauge reads before displaying ----) off the chart lean! If I hit a bump or ban the dash the speedometer will quit working and my afr I back to normal according to my wideband. - also, no sure if its related to the intermittent operation of the speedometer but recently it will sometimes idle off the chart lean ----. Again tho is all intermittent operation symptoms, when running correctly it reads, 14.5:1 at idle, 11:1-12:1 wot, 14.5:1-15.5:1 during cruise, and 12:1 if I take my foot off the gas at any speed.
Last night I figured, I'd try snipping the speedometer signal wire off the ecu lol. To see if I made a difference, And yet my speedo still worked intermittently! Then I noticed for the first time my fuel gauge was, for the first time, would stop working (showing completely empty) and then come back alive displaying the 1/4 tank of gas that was in it. - then another symptom arose, when I would turn off the switch which controls my two 12" slim radiator fans it would reset my oil pressure gauge and dim my wideband.
I'm thinking this is a wiring problem specific to the 240sx stock wiring... I figured I would post my troubles for a second opinion. As I'm about to embark on tearing out my dash to check the wires, hopefully I will be able to find the area of loom that is affect by vibration by wiggling it while driving. I know the s13 speedometer going out is a common problem but mine is showing evidence of negative effects on engine operation.
One thing I was thinking of is maybe my positive bAttery lead is hacked together not supplying the required energy. I have either a 2-4 gauge cable running from my relocated battery in the trunk to the engine compartment where everything taps in. I will supply a picture to show how I've got all my wires spider webbing off of my positive battery cable which is fastened by a bolt.
My thumb is on the 2-4 gauge cable that connects to my battery in the trunk
As you can see I have wires with eye hook connectors fastened together with a bolt.