LS1 No start conditon

[Accelo]

I purchased two of LS1 coil harness from Ebay some time ago. My motor was missing them when I purchased it.

This week I attempted to start the 1998 LS1 motor, for the first time, and immediately blew a 15A ignition fuse.
It turns out the harness were pined backwards (like they were assembled by looking at the wrong end of the plug) All coils were grounded at ign pin so they were all pulling 6 amps each and of course wouldn't fire any plugs this way.

I have sworn off of any electrical products purchases from eBay. With the column switches the lone exception. Too many junky products without any quality controls.

Good news is the system no longer blows fuses and I have spark and fuel.
Bad news is this evidently isn't the only issue and I still haven't been able to get the motor started.

This is a bugger as the tech that builds harness was unable to find the issue. Computer is powering up. Codes can be read. Coils are hot. Fuel pump comes on for three seconds and stop when the key is on. Fuel pressure is perfect. We have tried more than one computer, re-flashed the computer, confirmed the grounds, the system will flash a noid light, changed out the cam sensor. Has spark. Reading the motor temperature correctly.

Motor has a new stage 1 BTR truck cam other than the cam it's stock.

I am going to confirm the compression as an academic exercise tomorrow.
After that I am unsure what to do. ECM Harness Tech guy is working with me and answers all my questions and is very knowledgeable.

Scratching for anything about now.

[CarlsLQ9SS]

Have you confirmed the fuel injectors are pulsing and have adequate fuel pressure? Also could be a problem with the crank sensor. If the harness is an aftermarket, I have ran into the crank sensor plug being pinned wrong. I can't remember for sure but I think the sender wire and ground wire was backwards. But if your getting spark it may not be in the crank sensor. May also check to make sure you still have ignition power while the engine is cranking.

[Accelo]

Have you confirmed the fuel injectors are pulsing and have adequate fuel pressure?
yes to both questions. Even pulled the fuel rail and visually confirmed the injectors were pulsing fuel.

Also could be a problem with the crank sensor. If the harness is an aftermarket, I have ran into the crank sensor plug being pinned wrong. I can't remember for sure but I think the sender wire and ground wire was backwards. But if your getting spark it may not be in the crank sensor.
Harness is a professionally converted stock harness. Only aftermarket parts were the short harness to the coil packs.
I plan on confirming the wiring to the computer from the crank sensor today.
If I have time I will confirm using a scope.

May also check to make sure you still have ignition power while the engine is cranking.
Used the noid light and pulled one plug to confirm the spark.

This is a tough one. I am confident the cam was installed correctly. Hoping to confirm that with the compression test today.
Appreciated you diving into this one. Open to any suggestions.

__________________

[Joyridin]

This is a long shot, but you do not mention if the harness was the original one from the engine.

This was a long time ago, so I am going by memory. I believe it was a TPS adapter that came with the GMPP wiring kit was wrong. There were different versions and they were wired differently. I checked everything you checked, but the engine would not start. This was a new crate engine, so I assumed all the sensors were good etc. The adapter for the TPS (I think it was the TPS) had 2 wires switched. Apparently somewhere along the line, GM changed the wiring. I switched the 2 wires (it had 3) and the engine started in 2 seconds.

I am not 100% sure it was the TPS, but that is what comes to mind.

[Accelo]

Joyriding Thanks for the input.
I have looked at the scanner values and it is showing good voltage and % of throttle and is good up to 100% opening of the TPS. I will however check it out as I am covering my bases.

The Camaro had an oil level sensor which I eliminated when I changed pans. However it does show low oil on the scanner. I doubt it does much but tattle on the level. Motor continues to run even with the light on, at least it did on my Silverado about the same vintage vehicle.

Only codes, on the reader, are the ones for the alternator, which is unhooked.
Temperature is withing range. I had a truck once what wouldn't start. No codes but the temperature was reading -30deg F. Which was a valid range so no code. A new temp sensor and it fired right up.

[ls1nova71]

Is it the original harness to the engine? 98s are a one year harness and PCM if its from an F body, 99- up won't work unless you use a newer PCM as well.

[Accelo]

The main harness was converted from a Corvette.

The coil harness from eBay was listed this way;
2 X New Ignition Coil Wiring Harnesses For 99-04 Chevy Camaro Corvette LS1 LS6.
That's the one he had to re-pin to keep it from blowing fuses.

The guy that modified my harness has done hundreds of them. I was assuming he checked on any mismatched parts. However, I will certainly double check with him. Like I said, I have to run down every possibility. A good argument for only getting motors with everything attached. My bad and I am regretting it. .

[ls1nova71]

What year was the Corvette harness, do you know? 97-98 harnesses and PCMs are different than 99-04.

Do you know exactly whatyear of PCM you have? Did the harness guy have your PCM? A guy who has done a lot of harnesses may have assumed you had the matching PCM if he didn't actually see it.

[jjzepplin]

subbed

[LockDoc]

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I had something similar on my Panel Truck when I first put it together. LS1/4l60e, modified stock harness. I forgot to hook one ground wire up for the ECM. It went to the back of the driver side head. I don't remember what pin it went to.

LockDoc

[Accelo]

Another thing to confirm. Thanks
I will pull the schematic and confirm all the grounds. My bet is it will be something like this.

Update; All the ECM grounds are confirmed. This is a bear of an issue.

[ls1nova71]

There's a lot of left out info in this thread. What is the engine out of? F body or Corvette? DBW or DBC? What is it in? Going back to your first post, it says you have fuel and spark, so as long as it has air and the timing is close, it should at least try to start, but you have never said if it has, or if its just cranking and never even trying to start. Going to the only thing really messed with, are you sure the cam was installed right?

[Accelo]

Yes I agree. Let me answer your questions.

What is the engine out of? F body or Corvette? DBW or DBC?
1998 Camaro DBC.

What is it in?
1970 C10

Going back to your first post, it says you have fuel and spark, so as long as it has air and the timing is close, it should at least try to start, but you have never said if it has, or if its just cranking and never even trying to start.
Fuel pressure is right on at 58lbs. Even pulled the fuel rail with the injectors on it and cranked the motor. We could see fuel spraying from the injectors.
Now I have spark. At first the spark was missing. This was repaired when the coil harness(s) were repined. Even replaced all the coils with one I had from a 2000 Corvette to eliminate any issues the bad wiring could have caused. No Joy.


Going to the only thing really messed with, are you sure the cam was installed right?
I sure hope so. The cam is a BTR Stage 1 truck cam. Engine has lots of compression when rotated to connect the automatic transmission. Stock push rods were used. Compression check is in the works. Been so long I have to find where I put the Compression Gauge.

I have a 1999 set up, wiring and computer. Any differences between this and a 1998 have been address by the harness guy. I have a lot of faith in them.

No work was done to the crank. Maybe the reluctor slipped? I don't know.
Motor was used but I had no indications it was ever taken apart.

Motor kind of coughs sometimes on the first roll over. Zero indications that I may start after that.

I have a two channel scope. I am hoping I can correlate the reluctor and cam signals. Never done it before but I know it can be confirmed without tearing down the mtr.

[Joyridin]

I think ls1nova is asking if you can hear it hit at all or does it just crank without ever even a pop or something?

Did you replace the timing chain or upper gear? Most of the aftermarket cams are 3 bolt. Did you use the correct upper timing gear if you went this path? I highly doubt the reluctor on the crank slipped. What computer are you using?

[ls1nova71]

Ok, so let's assume for the time being that the cam is installed correctly, that pretty much leaves it at wiring or a bad PCM. You almost never see a bad PCM in the GenIII stuff, so I would say for arguments sake, that isn't going to be your problem. Leaving it up to a wiring issue. I would get a schematic and start checking wire colors between the PCM and coil connectors to make sure they are right. You don't by chance have the left and right sides swapped do you?

[ls1nova71]

Also, is the MAF plugged In? Going the right direction?

[Joemomma1]

Originally Posted by Accelo

The main harness was converted from a Corvette.

The coil harness from eBay was listed this way;
2 X New Ignition Coil Wiring Harnesses For 99-04 Chevy Camaro Corvette LS1 LS6.
That's the one he had to re-pin to keep it from blowing fuses.

The guy that modified my harness has done hundreds of them. I was assuming he checked on any mismatched parts. However, I will certainly double check with him. Like I said, I have to run down every possibility. A good argument for only getting motors with everything attached. My bad and I am regretting it. .

Best advice for newbies and is always what I say when asked. Other than aesthetics, there is no need to remove things from a complete pull out. Just add fuses/relays and go.

My no start was due to the brake booster port being left open.

[Accelo]

Is the MAF plugged In? Going the right direction? Yes, checked both.

Now the compression on #1 cylinder was 30psi. With a hand held gauge!
So that got me checking the push rod length.
I am way short. The lifter isn't even preloaded.
My bad for not checking this as it's easy! So I am off to order a variable length push rod. Sad thing is I have to wait for the tool before I can order the push-rods.
Sure appreciated all the input as I know how difficult this is remotely.

BTooley site gives you the option of ordering the stock 7.4" push rods only.
I was unable to find the base circle diameter the cam was ground on.
I made an assumption. If there is better information on this mild cam push-rod length requirements I haven't found it.

I promise feedback when this gets corrected.
Hoping for the turn key I thought I had.
Cheers.

[LS short box]

Looks like a bit of progress.
I've run a number of LS engines with aftermarket cams. Kind of small to medium duration cams.
I would not run an aftermarket cam with out replacing the valve springs and push rods with good aftermarket parts.
I have an aftermarket adjustable push rod checker that I would be happy to loan you if can't find one available. PM me to let me know.

[Accelo]

Thanks for the offer LS short box, guys are too kind.
I should have a checker here in the morning.
I have .005 clearance with the rocker arm tightened down.
I am planing on .050 preloading. .005 + .050 + the stock,measured length, 7.4
7.455 should be close to the required length.
I am waiting for the variable length push rod to confirm the length before ordering anything.
Still seems weird as I need a longer push rod. Most the issues are from milling the heads and require shorter push rods. Wish I could find more info on the cam base circle?

[Joyridin]

ok. If you are short, that would mean the valve isn't opening, which might cause it not to start (it should still hit though), but, that would not account for your low compression of 30 psi. It would more than likely be the opposite or normal. If you only have 30 psi, you have another issue besides the pushrods being too short. If the pushrods were too long and it was holding the valve open, then you would have low psi.

[Accelo]

Joyridin
I agree (I have other issues). I believe you are correct on the compression analogy.
To keep from complicating things I have decided to only make one change at a time.
I plan on dealing with the push rod length and then checking the compression.
Then moving on from there.

[LS short box]

On all my LS swaps I didn't measure the clearance between the rocker and the valve spring. IIRC I just made sure the cam was on the base circle and torqued the rocker arms down to 22 foot pounds one by one.. Double check that foot pound number. Why would you have .005 clearance when the rocker is torqued properly?
As said above very odd you only have 30 pounds in one cylinder.

[Accelo]

Well I may be able to answer why the compression was only 30psi.
Right now I am not sure how it got there?

The pistons have exhaust valve kisses on them.

[Accelo]

All eight exhaust push-rods were bent. I don't now how it could possible happen unless the cam wasn't installed correctly. It did rotate over harder than I though it should (by hand). Amateur mistake? Installed the cam dot to dot. I guess I have a road ahead of me. Maybe long term counseling will help. Or I hear they have better drugs for Alzheimer's?

LSX motor are not zero clearance motors. Shouldn't be able to do this. I'm digging up the cam specifications. Could the exhaust lobes have too much lift? Not if it's the cam I ordered. Lots of questions, not many answers.

Moving Forward;
I could do a leak down test to see if the exhaust valves are damaged/bent.
I also own a new set of hardened push-rods in the stock length.
And a rebuilt set of 243 heads.
Unsure where to go from here.

A picture of the piston taken with a bore-scope.

To cover my butt it's likely best to pull the heads and cam shaft. Start anew?