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General ?s, need some help with a no-start.

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Old May 9, 2020 | 09:27 PM
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Default General ?s, need some help with a no-start.

Hello,

Not sure if this is correct place for this or not.

I'm working a ls swap, I do not have the mass air sensor hooked, nor do I have one, so is that my issue of this no-start situation? If not, I did a cam swap also, and made a stand alone harness. With that being said, there could be a number of different reasons for my no-start.
I will do a compression check tomorrow, and depending on that out come, I may or may not pull the front cover, and double check my timing marks. If none of those are my issue, I will grab another computer from the pick & pull, and just try it without removing vats.

Thanks.
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Old May 10, 2020 | 09:29 AM
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Not to be mean, but, there are about 100 different things that can cause a no-start. The first time you take a pair of dykes to the wiring, you invoke at least 90 of them.

NOBODY OUT HERE is going to be able to tell you what's wrong after "made a stand-alone harness". My best guess would be, it has something to do with that.

No MAF won't cause it. It'll cause a run-like-crap, a Check Engine light, etc.; but it should at least start.
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Old May 10, 2020 | 10:45 AM
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So you took a random gm v8 from 98 onward, spliced a bunch of wires, left out some sensors, matched it to a random pcm and it doesn't start? Who'd have guessed.
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Old May 10, 2020 | 10:29 PM
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Originally Posted by Stampede4ever
Hello,

Not sure if this is correct place for this or not.

I'm working a ls swap, I do not have the mass air sensor hooked, nor do I have one, so is that my issue of this no-start situation? If not, I did a cam swap also, and made a stand alone harness. With that being said, there could be a number of different reasons for my no-start.
I will do a compression check tomorrow, and depending on that out come, I may or may not pull the front cover, and double check my timing marks. If none of those are my issue, I will grab another computer from the pick & pull, and just try it without removing vats.

Thanks.
it should start with no maf hooked up

#1 cause of no start providing your harness is proper is the power to the ecu being interrupted when the ignition is put into the start position. That effectively turns off the ecu when you’re trying to start the engine. You need a power source to switch on the ecu when the key is on AND cranking.


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Old May 11, 2020 | 05:56 AM
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Hey Guys,

I did a quick compression test, only the first 2 cylinders on the front on each side, ranged from 150-180 cold. I have spark, I'm in the process of checking ignition timing, but for some reason my timing light is not working. Going to get some noid lights tonight, just double checking everything!
As for my power source, it's hot at all times, this is just a make shift test setup, just to make sure it runs.
My DD will not start if the MAF is disconnected, that's why I was asking, didn't want to chase my tail for nothing.

Thanks.
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Old May 11, 2020 | 06:53 AM
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Originally Posted by Stampede4ever
Hey Guys,

I did a quick compression test, only the first 2 cylinders on the front on each side, ranged from 150-180 cold. I have spark, I'm in the process of checking ignition timing, but for some reason my timing light is not working. Going to get some noid lights tonight, just double checking everything!
As for my power source, it's hot at all times, this is just a make shift test setup, just to make sure it runs.
My DD will not start if the MAF is disconnected, that's why I was asking, didn't want to chase my tail for nothing.

Thanks.
and the VATS is deleted in the ECU?
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Old May 11, 2020 | 10:55 AM
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Originally Posted by big hammer
and the VATS is deleted in the ECU?
This is a biggie...
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Old May 11, 2020 | 11:03 AM
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I'm still wondering if your pcm and engine match. If one is 24x and the other is 58x you're never going to find the problem with hand tools.
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Old May 11, 2020 | 11:36 AM
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Yes, and no, 1 of the pcm's has had the vats removed, but there is more to that story, and the other no. But if it only runs for 3 seconds, I'm good, atleast I know it's good.

Stampede.
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Old May 11, 2020 | 12:23 PM
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Are you getting spark? Fuel? What if any DTC's are you getting?

Have you done any data logging?

Are you getting an RPM signal while cranking?

Basics man...basics.
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Old May 11, 2020 | 02:14 PM
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Originally Posted by Stampede4ever
Yes, and no, 1 of the pcm's has had the vats removed, but there is more to that story, and the other no. But if it only runs for 3 seconds, I'm good, atleast I know it's good.

Stampede.
did it fire up?
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Old May 11, 2020 | 10:27 PM
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Well, I tested all of the injectors with a noid light, all checked good, checked ignition timing, looks good, I redid the main power connection, making improvements to the fuel setup, and using the other pcm. I see no reason for this not to fire up, and run for 3 secs till vats kills it. I won't do another test fire till this weekend.

Stampede.
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Old May 12, 2020 | 07:39 PM
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How did you "check" ignition timing on one of these engines?
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Old May 12, 2020 | 08:42 PM
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I used a camera scope to bring number 1 cylinder top dead center, put paint mark on the balancer, bolted a piece of welding rod to the block, and bent it close to the mark. Then I used a timing light to see how close the "spark" is in relation to the piston.

Stampede.
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Old May 12, 2020 | 11:17 PM
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ok.....
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Old May 13, 2020 | 05:53 AM
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Sloppy mechanics has some youtube videos also.

Stampede.
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Old May 13, 2020 | 06:51 AM
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Delete your vats brodingo
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Old May 13, 2020 | 09:08 AM
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I will, just takes money.

Stampede.
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Old May 13, 2020 | 02:37 PM
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It ain’t gonna start
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Old May 13, 2020 | 08:42 PM
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I know, it should atleast want to start, I wasn't planning on using this pcm.

Stampede.
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