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S Chassis Technical discussion related to the S Chassis such as the S12, S13, S14, and S15.

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Old 01-29-2020, 09:15 AM   #1
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SR20 swap no longer cranking

Alrighty, for one I'm going to apologize ahead of time... this is going to be a long post.

I honestly hate making posts like this, but I'm running out of ideas and simply want to bounce off my situation with your guys and hopefully brainstorm a solution before I completely rewire my entire chassis.

Before I get started and into my exact situation I want to give you a little background. I have wired multiple engines and cars, and never have I had this situation happen. I have a pretty good understanding with automotive electrical systems but I'm not going to go over the top and say I'm an expert. I at least know enough to have confidence in understanding how a 12v electrical system works.

So, Let's dig deep. This is going to be a little long, but I want to make sure that you guys know what I have already tried so that we can all know where I'm at and you don't have to ask, "Did you check your grounds".

About a month ago I got back into 240's and purchased a fairly clean s13 coupe. Swapped a redtop SR20 into it and got it running on my first try, I realized it was idling a little rough so I did some troubleshooting and found my igniter to have been damaged either during transportation or when I was installing the engine. The damage was causing cylinder Number 4 not to have spark. No biggie, ordered a new igniter waited a week for it to come in. One thing to note, while I was able to get the SR started with the original igniter running on 3 cylinders I did notice that when cranking the starter kinda built up speed, so that means it's getting alot of resistance essentially meaning it needs a better ground. None the less, I do want to clarify that I had started the motor a good 3-5 times. While installing coolant, checking timing, etc. etc. Never had an issue cranking over during those times and they weren't all on the same day.

Also to clarify the car is running on the stock chassis harness, stock redtop harness, and a brand new Optima Redtop battery located in the trunk. The main battery wire is 1/0 guage running up to the engine bay with a power distribution block that it connecting to all the stock positive connections on the harness. The battery is grounded straight to the chassis in the rear and I sanded the grounding point so that it has a bare metal connection. This setup is still exactly the same as when it was able to crank over.

1 week later, the new igniter comes in, plug it in and now I am not able to crank. No click, no nothing. All electronics in the car still work. Except with a weird issue with the windshield wiper motor. With the key out of the ignition cylinder the windshield wiper would go off even with them turned off. As soon as the key was inserted into the cylinder even without rotating the key, the windshield wiper would finish its motion and stop going. Odd, but I ignore it for now and start troubleshooting.

I verified that the starter was getting 12v from the battery to the main post - Good.
Verified that the starter solenoid is getting it's 12v signal when cranking via the ignition cylinder - Good.

At this point I sanded the contact points for the grounds going to the frame rail of the car and I ran a brand new ground from the intake manifold to the frame rail.

Still no crank or click. At this point I think it's the starter. I order a new starter, pulled the old one out and bench tested it. Solenoid worked and whenever I tried to crank it, it didn't crank super fast at first just like it was doing in the car, so I figured it wasn't generating enough torque to turn the motor over anymore. New starter came in, installed it and same thing.. No click, no nothing. I do also want to clarify that whenever I try to start the lights on the dash and the clock would get dim, so that tells me that it is sending a current.. somewhere.. So At this point I run a ground cable from the negative of the battery itself to the intake manifold - No go.
Then I'm thinking maybe that battery just doesn't have enough amperage for whatever reason. So I install my jump pack on the battery - No Go.

I tried running a positive cable just to the starter itself and jumping the solenoid, Sparks were made at the battery but still no go. At this point I'm thinking that it's the chassis wiring and there's a possibility that something is majorly messed up under the dash. Especially considering the odd windshield wiper issue that's still happening. So I pull the dash looking for signs of mice or cheap ass 240 hackery. Nothing, the harness actually looks pretty flawless and untouched. No frayed or split wires anywhere under the dash.

Next I look in the engine bay, especially since I should be hearing a relay click when attempting to turn the starter. Find that the previous over had deleted the start relay and simply jumped the connections so that the starter was always hot. Thus the reason for never hearing a relay click.. There is no relay. I think that this may have caused the ignition cylinder to fry internally as the ignition cylinder would now be taking the load of the starter directly with no relay in place... But then I check again and see if I get 12v to the signal on the starter solenoid and sure enough I still do!

So this is where I'm currently at. I'm a little stuck but I think I'm going to try wiring the starter and solenoid to it's own wire straight from the battery along with it's own push button start and relay that is completely separate from the stock chassis harness. Before I go ahead and do this, does anyone have any other ideas of what I should try and check?

Sorry for such a long post but I wanted to give as many details as possible so you fully understand what I've already done without this turning into another post asking me if I know how to search.

Thanks in advance for any possible help with this odd issue.
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