Shigun

iTrader: (2)

Here's the scenario:

S2000 5.7 LS1 swap, stock internals, all bearings updated and replaced before swap, car runs and drives great.

Car cold, press the starter and it will start up perfectly fine. Drive around for a bit, turn the car off, then go to turn it on and there is usually a 70% chance that the starter will turn over slow, kind of like a "whrr...whrr....whrrr" thing. Usually I can press the starter again and it will start up nice and quick, no problem. About half the time it will keep doing that slow start for a few times, sometimes just stopping with a clicking sound, before it finally kicks over.

I originally had the wiring for the battery positive going through a 100A kill switch that I changed out to a 250A thinking that might be the case, but no change. Outside of that, the starter positive goes straight from battery to distribution block, to the starter. I've replaced the starter with a brand new one. All results in the same.

I have a fuel pressure gauge and have confirmed that I have consistent fuel pressure, so I doubt that it is. I'm at a loss for what could be the issue here, nor how to go about diagnosing this. Any help would be greatly appreciated.

To add, battery is an optima redtop that I've never had any issue with for cranking, and I don't think this would be the issue as it can start up perfectly fine every other time. I've also replaced O2 sensors with brand new ones for a different situation, probably unrelated but wanted to throw that in just in case.

Project GatTagO

iTrader: (7)

Check your grounds. You should have one from the battery directly to the engine block. Then from the engine block have a couple more to the chassis.

Andrew

Shigun

iTrader: (2)

Battery is in trunk, but I have one from battery to chassis, then 2 more from chassis to block, one on each side of the block. Wiring from battery forward is 2/0awg to distribution block, then 4awg from block to starter (and 4awg from 100a fuse to rest of car, but that is probably irrelevant)

Project GatTagO

iTrader: (7)

You need to have a 2/0awg ground from the battery straight to the engine block. The grounds from the block to the chassis can be smaller.

Andrew

Shigun

iTrader: (2)

Kind of confused for the logic on that. I have had my battery in the trunk for 2 other separate motors (stock F20C, SR20DET) and neither of those had any issue with starting. Can you explain the reasoning for needing the 2/0 for the LS motor? Honestly curious.

Project GatTagO

iTrader: (7)

It sounds like when your starter gets hot, you have issues. I am no electronics genius, but electricity flows in a loop and the system is only as strong as the weakest link. The starter gets grounded to the block and if you don't have a large gauge wire ground from the battery to the block then that becomes your weak link. I also never put a fuse inline with the + lead from the battery to the starter. GM never does, which is good enough for me. The starter draws a lot of amperage and any extra splice/connector/junction can be a point of extra resistance to the starter circuit.

If you don't want the large + lead from the battery to the starter to be "hot" all the time, then you can mount a Ford style starter relay in the trunk. This has been done many times.

Andrew

Shigun

iTrader: (2)

I'll look into running a ground directly from battery to block. Can't really do another 2/0, the one 2/0 I have there already takes up most of the space for running wires, but I can possibly add in a 2awg or 1/0.

Project GatTagO

iTrader: (7)

Is the exhaust close to the starter?

Andrew

Shigun

iTrader: (2)

Long tube headers, so basically right on it, yeah.

Project GatTagO

iTrader: (7)

The 5gen Camaro starter is inexpensive and has mounts for a neat heat shield. I used it on my Cougar build.

Andrew

truckdoug

iTrader: (25)

yeah sounds like heat soak to me. have you tried a different starter?

I use the clip-on truck heat shield w TBSS longtubes and it turns pretty over plenty fast.

33willys

iTrader: (1)

The conductivity of the frame is only 20% of a battery cable according to Ron Francis. I've always used a direct battery to block ground and never have had a "hot start" problem.

oldgoat69

I agree with several points. Run a ground from the battery to the block. And try the mentioned starter. Heat soak and worn starter bushings are very common. If the armature is not concentric to the field strange things happen.

Shigun

iTrader: (2)

For some reason I am only just getting the notifications for these last 4 posts, weird.

I definitely agree it is heat soak, I just don't know if it is related to the starter itself, or the power going to the starter. As for the basis of the worn starter bushings, it's brand new starter, less than 2000 miles and 2 months.

As for running the other ground, still have to get a cable long enough that I can run, but I am working on it.

DW SD

Why not measure voltage drop between the battery ground and the starter body during cranking as a first step?

If there is significant voltage drop, a dedicated ground from battery to engine block might be merited. I'm thinking of the voltage drop across the chassis is 1.0V or more, it'd be worth running a dedicated ground. But some internet research would reveal, I'm sure, what is acceptable starting voltage during cranking. There will be a drop of some sort across every cable.

You could remove a fuse powering the PCM or fuel pump to make sure the engine doesn't start while measuring the drop.

Doug

Pop N Wood

iTrader: (1)

Try bypassing the ignition switch. Either run a jumper wire straight to the S terminal or jam a screw driver across the two big lugs on the starter.

Very common problem. This is the reason people put in a remote start (Ford) solenoids. The voltage drop through the ignition key circuit reduces the juice to the starter solenoid just enough that it doesn't fully engage.

You can also take the solenoid apart and clean up the copper disk that gets pushed into the back of the two big solenoid lugs.

I agree with everyone saying to run the negative battery cable straight to the engine block. Never rely on rusty old sheet metal to carry current. American cars from the 70's and earlier were built with "planned obsolescence" in mind. They wanted the car to need replacing in 7-10 years, so saving $10 by using chassis grounds instead of ground wires was a win-win for them. This is part of the reason they lost market share to the Japanese cars of that era. If you look at a modern car they all run ground wires everywhere.

By the way 2 gauge wire is noble but overkill.

Shigun

iTrader: (2)

So, interesting thing. Long cable for battery to block is ordered, however...I haven't had an issue with it starting in the past few days. Dunno if it is just lower ambient temperatures or so, but I've gone on 30-45 minute drives and, with it having sat for 2-3 minutes, can come out and it starts right up.

Still going to do the other block and everything but I am a little perplexed.

Pop N Wood, I've got a solenoid relay lined up as well, will be getting that at some point in the near future. Shouldn't have to do any cleaning with the solenoid as is, the starter is basically brand new.

As for the statement of never relying on rusty old sheet metal, car is an 03 and I have quite a number of ground wires all over the place for harnesses and what have you. Just the 2 to the block, but I've got another couple that I'm going to toss on as well just to help out if possible.