LS Start Up Issue
 

Alright fellas, my GFs car is acting dumb now.
I changed the head gasket, head was in really good shape, got it hot tanked and cleaned up real nice. Got all new gaskets, if it was attached to the head or intake manifold it got a new gasket.

So here is the issue.

It will only start if you give it full throttle while cranking. Once started it cannot idle on its own, you must give it around 10% on the TPS for it to stay running. Vacuum is low, -3" to -8", ignition timing is all over the place, base timing is dead on. Car idles better, but still like shit, if you remove a vacuum plug.

I think its an issue with the IACV or something related to just not getting enough air during start up and idle. Increasing the duty cycle on the valve helps some but not much.

Anyone run into this issue before? I'm open to all suggestions.

I've had that issue. It was a bad TPS. Apparently they can be wired in reverse. Id look into that. Any codes?
I doubt its IACV cause I don't even have one. Its just tucked away plugged in but not on the manifold.lol
I've only encountered an IACV issue if it was bad.

I dont have any codes, and I'm pretty sure the TPS is working right too, I was watching it on the smanager and it was responding well. Idk what's going on with it though, a full throttle start is telling me not enough fuel or air. And by the smell of it while cranking I'm getting my fuel lol.

Start with checking sensors.
If the map sensor is on the firewall instead of throttle body make sure the vacuum is connected.

Make sure the harness clips are going to the right sensor. Some clips look the same and will fit other sensors

everything is plugged in correctly and by the looks of it the sensors are doing their jobs too. MAP isn't reversed with the TPS, althought I did try to switch the plugs and got no change in performance.
Before the head gasket was changed it idled like shit too, but I attributed it to coolant in the cylinders.

Spray the engine with break clean too see if there is a leak in a gasket or something. It will die if sucking in brake clean.

Check compression, depending on how much coolant was leaking you could have washed out a cylinder or damaged rings since coola t is not compressable.

^^^
That's the next thing id do. Check compression.

I haven't checked compression yet, dont have the tools to do it so ill get on it.

As long as u return it i have a spare compression tester among other tools if u need them

Thanks, but I'm down past Casa Grande. It might be time to just buy my own.

Update:
Car is running smooth as ever now. I did a valve lash adjustment and in the process found out my intake cam was a tooth off. Working on cars in the dark isn't always the best idea...
Car gets hot now, but a simple thermostat replacement should fix that right up.

Good to know. So where's that catch can? Never heard from ur dood....

Stfu. You serious???

I've got a Civic with LS engine that just won't turn on, it cranks like it wants to, I checked all fuses, changed the spark plugs, fuel filter and even new fuel pump, its getting fuel and spark to all foucylenders (did the spare spark plug to each wire and jumper cables test, and theyre good). While starting it it backfired so I turned it off, took off the valve cover, saw a rocker arm had broke so we fixed that, all looked fine, it still won't start after fixing the fuel problem it had. While at TDC the intake cam looks a tooth to the right, barely off, can that cause it not to fire up? That's the only thing I can think of left is take the timing belt off and reposition everything perfect. Also might as well replace the tensioner, since it was lose enough to skip a tooth. Thanks in advance!