rdymond

Hello all.
First I need to say it is really impressive to see the builds posted in this group, lots of talented and dedicated people!

I really like the LSx for many reasons you all know. I bought a 1999 Porsche 911/996 C4 LS3 conversion completed by Renegade hybrids. It has been a very problematic and expensive car, the Renegade hybrids build is full of defects, both with their kit, compatibility with the car and just bad decisions made in the build.

The car has a 2013 LS3 crate engine as far as I know. It registered as a 2013 Camaro on the emissions test.

The current problem(s) we are working on:
The car starts fine when cold. After running 15 min, the car comes up to temp (180-215). The engine stalls when stopping at a light or simply pushing in the clutch at speed. When attempting to restart, starter can't turn over the motor. After leaving the car off for 5+ min car can sometime be restarted with difficulty. I have a Blue Driver ODB2 reader and app. No codes are are showing up in the GM ECU.

Tests done:
1. Battery is good, tested. Rated at 650A cold crank and 810A max crank.

Cold Start: measured current draw at cold start: 512A
Hot Start: measured current draw at hot start: 810A!!!! Barely turns over the motor. Voltage plummets.

Idle: Current to Battery 9A
Idle: Current from Battery 8A
Voltage at battery terminals when off 12.5V
Voltage at battery terminals idle cold 14V
Voltage at battery terminals idle hot 13V

2. Alternator is a new GM alternator
Measured 30A draw at idle
Measured 14v at idle

3. Cable resistance from alternator to battery at idle Vdrop=.12V
0.12V/9A=.013 ohms
The alternator cable runs to the starter then to the fuse panel then to the battery.

Other observations: After a hot start the car runs rough, like it is missing, timing is a bit out, something.
When the car is hot and idling there is a rhythmic clanking noise when the clutch is in, goes away when it is out.
There is a lot of heat coming out of the engine area.
Battery is not staying charged when driven.

Test to do (from reading here): Try turning crank bolt with a wrench when the car is hot to see if it it easier or harder to turn then when cold.

Other problems that may or may not be related to this issue.
Accelerating hard uphill causes the whole car to jolt hard, engine cuts out, then backing off the throttle the engine comes back on.
After filling the car with gas and parking it the whole garage stank of gas.

Won't bore you with the full list of problems

FYI Repairs completed to date:
Replaced alternator
Replaced broken C4 transmission with rebuilt TT transmission
Replaced C4 trans adapter/flywheel/clutch with new TT trans adapter/flywheel/clutch
Replaced Porsche starter with new GM starter (required by TT LS3 trans adapter)
Replaced shifter cables and shifter to fit TT trans
Replaced slave with BBI clutch slave conversion kit

Any smart people with insights or previous experiences?
Thanks,
Robin.

Fierofly

iTrader: (1)

Have you had anybody do a tune? I've been driving mine for about 2yrs 10K miles now and LOVE it. One problem I had was when A/C was on I'd have to do a quick rev before depressing clutch or it would stall. My starter has worked great. Take a look at my build thread if you'd like to see pictures of how I did mine. I'd take it to a good tuner and see what he has to say.

rdymond

I saw your build a while back, great job! I appreciated that you put the air filters in the wheel well and away from the heat soaked engine compartment. Also that you moved the engine back so there was space to mount a proper intake instead of box with half the width of the intake and a 90 degree turn. Also you don't have your alternator practically dragging on the ground and exposed to all kinds of road nastiness.

I expected that renegade hybrids, since they did the build, would have also done the tune.

I don't understand how the tune would make the cranking amps go from 500A cold to 800+A when hot, causing the voltage gauge to crater and all the dashboard lights to go dark.

Fierofly

iTrader: (1)

If the tune is improper it will affect the timing and heat, could be running too lean. whats the plugs look like? Mine is a 480hp crate motor/Ecu and still hasn't been tuned. I think I'm going to have to hook up the speed sensor so I won't have to keep blipping the throttle with the A/C on.

dcd215

You certainly have all the right pieces .Few questions-have you done a fuel pressure test ?Does the car use any water ? The hot start issue sounds a lot like a hydro lock .
I would pull the spark plugs and look for a steam cleaned plug .

BLKMGK

Beware of that BBI conversion, the GT2 setup uses easy to find OEM parts and the pushrod remains straight, the BBI setup ***** it. If the clutch pressure is heavy SillyRabbit makes biller clutch masters that may help.

The issues do sound like a tune is needed at the least. How much heat is the starter soaking up, any shielding?

ekmxryda

I second the hot starter and solenoid thought. Especially if you don't have shielding, it sounds like hot starter wires as well, they just cant carry the Amps when hot. How long are the cables and what gauge?

Cheese Weasel

I'm glad that I'm not the only one who looked at the hot-start issue & wondered if it might not be (at least partially) fuel-related... 15 minutes is admittedly a fairly-short period of time for this to be happening, but it might be worthwhile for the OP to review question #3 in this FAQ, & then run a quick eyeball over the Porsche's fuel system setup, just to see if that might be part of the problem. If nothing else, it could eliminate some possible/potential issues.

I hope this is helpful, - OP, please post a response once you've solved the problem.

rdymond

Thanks for the suggestions everyone. Been busy with work.

I will pull the plugs and examine for steam cleaning and check to see if there is any moisture in the cylinders.
I will do a fuel pressure test, measure alternator wire and starter temps for heat soak (how hot is too hot?), and re-measure cable resistance when hot.
Will check engine resistance turning the crank when hot and cold and compare effort with a torque wrench.

I am still very puzzled by the cranking current jumping from 500A cold to over 800A hot. I don't understand how a fuel starvation issue could cause this.

My buddy thought I should change the oil filter, open the current one up and look for metal filings. That suggestion plus the hydrolock idea caused some anxiety. The car has been sitting all winter.

rdymond

Thanks for the suggestion. I took a look at the FAQ, and I don't think #3, fuel pump cavitation due to hot fuel is the issue. This LS3 has a single line feeding a two rail system, there is no return line from the rail to the fuel cell. Also this issue happening in cool to cold weather. The fuel tank is in the front of the car away from any engine heat in the rear of the car. I will review the fuel supply system. thanks!

Fierofly

iTrader: (1)

The 99 has a external regulator and a fuel return line. The 2002 and newer has a regulator in the fuel tank and no return line.

dcd215

Several points :Lean fuel condition will cause engine to run hot .Not sure how you are measuring engine temp -the Porsche gauge reads way low .The best answer is to monitor engine temp with a obd scanner .As far as fuel pressure you are looking for 58 psi engine running .
I would also check the steam lines from the heads they should be plumbed to the expansion tank and be a clean flow .The other tricky area is eliminating air pockets in the cooling system -don't know how your system is set up but air pockets will cause problems .At the risk of oversimplification -hot start problems -weak battery-bad ground -engine too hot and borderline seizing or uncompressible fluids in a cylinder (s).I guess a heat soaked starter or non high torque starter could also play a role .

rdymond

According to OBD scanner, temp was from 98C to 105C. 105C=221F

I ordered an infrared temp reader so I can measure temps on the starter.

Cooling on this car is odd. I don't think there is a thermostat installed (it came from Vegas).

JIMB

iTrader: (2)

If I recall correctly if the thermostat is missing the coolant doesn't circulate thru the water pump correctly.

Also in regards to the air pockets I've had the best luck with getting the engine warmed up a bit and then loosening up the temp sensor in the left head just so it will let a little coolant out and then tighten it back up. Be careful with the hot coolant.

I have a E36 LS swap and it's tight in the engine compartment. The header on the right side is very close to the starter. I have a stock heat shield that clips to the solenoid and then I used some DEI heat shield on the heat shield. I've never had a hot start issue. It's a stock OEM LS3 starter.

Outlaw 911

Dcd mantioned this and i will also , is the engine block grounded to the chassis? If not do it, no block ground will cause a bunch of cranking issues.

rdymond

Thanks Everyone. Will be poking the bear this weekend and will report back what I find.

rdymond

Minor update: Looks like potentially two separate issues, starter failing due to over heating, and fuel supply dropping after running a while.

Old Geezer

iTrader: (3)

"and fuel supply dropping after running a while."

Check the tank venting.

shanghai_todd

iTrader: (2)

What size wire do you have from the starter to the alternator and to the battery? My last LS swap had similar issue that left me stranded multiple times if I turned the car off while warmed and stalled a couple times at the light. I had battery connection and ground issue and resolved by replacing my battery terminals and torqing down some grounds. Seems the cells of the battery would heat up due to the current draw and poor connection and would only start cold. Once heated I had to wait 20-40min and would start right up.