Starter turns very slow intermittent
 

the car is 89 s5 gxl with a jdm turbo 2 engine and trans. Il start like this i was driving my car back from the gas station and half way back to my house my wiring harness cough on fire i stoped a had a fire extinguisher to put it out. when i got home to make an assessment of the damages, i found my self ready to work on my never ending project, changing my engine wiring harness; and my long wiring harness the one that behind the dash with fuse block. i got the harness from some guys in tx 915 or something like that. i installed both the harness and im close to getting it started, now the problem is that when i crank the car over it turns very slow but it is intermittent, i started with checking the basics battery voltage, i bench tested the starter to make sure it worked and it does and i just got done with the ing switch and still the slow ass crank. i would appreciate any help...

im prob going to trace the wiring and see if theres is high resistance or something that not letting the starter work properly.

sounds like a bad ground or high resistance in the grounds causing a intermitant high resistance with a loose conection. run a new ground to the block and check the pos tire to the starter.
just my 2 cents

most likely a wiring issue. There are a few things it could be, poor ground (likely), too high of a resistance power cable (more likely).

The solenoid requires a 12v signal from the key (the skinny one), so make sure it is getting a good signal.

Using a multimeter you can check the resistance in the main power wire (the fat one) to the starter

make sure the battery terminals are tight and the battery is fully charged!

sounds good to me i just to kragen to get my battery fully charged it took about 14 mins to charge it, and check out good. but im most deff going to check it out; And report my findings

ok so i check all the wiring to see if there was anything loose and i found that the engine main ground was loose i got that 14 mill bolt a tighten it and i crank the car over like brand new hell mother fucking yes!! getting closer closer to getting this fire spitting japanese dragon on the road!!