Cranking no start with cold weather

[edcmat-l1]

It was backfiring out of the intake but I think that's because I had the fuel injectors unplugged creating a lean condition.

I've unplugged injectors a thousand times at least and never once had them pop in the intake.

That also contradicts your original post.

pedal to the floor flood mode can hear engine firing out of exhaust.

No matter what that engine should start on a bone stock tune. It sounds to me like something may have happened to the engine. If it ran fine before, now it won't start and it's backfiring either out the exhaust or in the intake, that sounds like it broke a timing chain or some other type of valve train failure.

Check the codes. Don't know if you ever mentioned you did or not. If there's a cam sensor issue it'll make them hard to start and they make funny popping noises when they don't start. But typically you can cycle the key off then back on and they fire right up.

[Alvin]

Looks to me like it just needs tuning.. Pretty stock looking VE table. The website isn't real clear on what cam is in it. Could be really rich on startup or it could be short on airflow but your airflow tables are already too high IMHO.

[RiggsStubbs]

You said it started in warm weather. It ran and idled ok? Then it's adjustments.

Give this a shot. Do a little flood clear first to make sure there's no residual fuel puddled up on the pistons.

Had a few minutes to try this tune last night and now I can hear it trying to fire out the exhaust while lightly pushing on the gas pedal. going to buy new battery and try again tonight maybe mess with the FA Mult stage 1 vs time section under cranking fuel. Unless anyone has any other suggestions based off of that information.

[RiggsStubbs]

Ok I replaced the battery and with that tune it starts now thank you all and especially SiriusC1024

[SiriusC1024]

You're welcome. Look at the changes to cranking VE, Spark, FA. Dial it in along those lines as needed.

Btw don't pay attention to the change in Primary VE. Don't know how that happened, and that table isn't used during cranking.

Next step is getting the full cam data for ICL (intake centerline) so that Injection Timing can be set (attached). Then tune the airflow side.

Ah. Found it:
https://www.howardscams.com/hydrauli...cams-196765-12

Put those specs here and then into the attached.
https://www.summitracing.com/newsand...ing-calculator

ATK HP109 EOIT.png

[edcmat-l1]

I'd start by diagnosing it as a no start. Everybody always thinks "It's the tune!" and it's rarely "the tune".

Your voltage while cranking goes as low as 9.6 volts. Maybe start there.

Battery voltage is so low because this was recorded after many cranking attempts with charger on battery. I have done all the basics I can think of. I'm getting fuel to cylinders, I have good spark. I haven't checked for any intake leaks, maybe ill do that next. Ill double check everything again.

No matter what that engine should start on a bone stock tune.

Ok I replaced the battery and with that tune it starts now thank you all and especially SiriusC1024

I love it when you tell someone what's wrong with their vehicle and the reply is basically "Nah, that ain't".

[RiggsStubbs]

I love it when you tell someone what's wrong with their vehicle and the reply is basically "Nah, that ain't".

I tried it with that original tune and the new battery same result as old battery. new battery with new tune it fired right up so.... sorry you feel that way but I'm glad somebody else believed me.

[RiggsStubbs]

You're welcome. Look at the changes to cranking VE, Spark, FA. Dial it in along those lines as needed.

Btw don't pay attention to the change in Primary VE. Don't know how that happened, and that table isn't used during cranking.

Next step is getting the full cam data for ICL (intake centerline) so that Injection Timing can be set (attached). Then tune the airflow side.

Ah. Found it:
https://www.howardscams.com/hydrauli...cams-196765-12

Put those specs here and then into the attached.
https://www.summitracing.com/newsand...ing-calculator

ATK HP109 EOIT.png

Thanks for the guidance and also once i have the numbers from the calculator how do I apply it to the table?Capture.PNG

[SiriusC1024]

See the stuff that says Open/Close: BTDC, ABDC, BBDC, ATDC? That goes into the spreadsheet. The rest automatically updates. You'll end up with an answer like I provided in the pic.

[RiggsStubbs]

Ok so since I got it started consistently over the past couple of weeks I have ran into the same problem once it got a little colder so i added some cranking timing and adjusted cranking VE table a bit. Then I started fallowing this forum on idle tuning https://forum.hptuners.com/showthrea...e-(w-pictures) Was going well but now the weather here has been ranging from 15-40 degrees and I am back in the same situation with cranking no start. It seems I cant get the adjustments right any suggestions? What am I missing? its like its just on the brink of starting right up.
actual idle airflow tuning 1 WITH CRANKING VE ADJUSTED and 3 degrees cranking spark added.hpt
2004 gmc sierra 2500 start up tune_trial_SiriusC1024 (2).hpt

[edcmat-l1]

Where's the data log? That's going to tell you more than the tune log. Include battery voltage and engine RPM.

Do you have a fuel pressure gauge on the vehicle?

You shouldn't need to do any "tuning" to fix a cold weather no start. Unless it has much larger injectors or is otherwise drastically different than stock, it should need little if any changes made to fix a cold weather no start.

[SiriusC1024]

The changes I made were so you could start the vehicle and begin tuning. Get the VE tuned, cross it over to cranking VE, and return the changes I made back to stock one at a time.

For now, do what you did except one change at a time. Start by bumping around cranking fuel. Then cranking VE. I think you went too far with spark.

[RiggsStubbs]

Where's the data log? That's going to tell you more than the tune log. Include battery voltage and engine RPM.

Do you have a fuel pressure gauge on the vehicle?

You shouldn't need to do any "tuning" to fix a cold weather no start. Unless it has much larger injectors or is otherwise drastically different than stock, it should need little if any changes made to fix a cold weather no start.

I do fuel pressure is in spec. Also has stock injectors. Here is a log I just took. Thanks
no start log 222.hpl

[edcmat-l1]

Try hitting it was some spray.

It still looks like it has a battery issue. Voltage at the beginning of the log before you start cranking is 13.3 so I assume you have a charger on it. During cranking it goes as low as 10.9 and cranking RPM is still kinda low at 170 rpm. Should be 200. If you still have to put a charger on it, and with a charger if it drops to 11.0 or lower, you probably still have battery issues.

[SiriusC1024]

You might just have a weak starter. That cam doesn't make much vacuum so the engine should turn over easier than stock. Plus that's a lot of voltage drop. Grab a Delphi off RockAuto. I replaced mine with one, as a preventive thing, and it did a much better job cranking.

[RiggsStubbs]

You might just have a weak starter. That cam doesn't make much vacuum so the engine should turn over easier than stock. Plus that's a lot of voltage drop. Grab a Delphi off RockAuto. I replaced mine with one, as a preventive thing, and it did a much better job cranking.

I have replaced both starter and battery from Napa a few weeks ago, Also tested for voltage drop across both side power and ground side circuits to starter both read less than .2 volts. Today I took a few spark plugs out and notice they were pretty fouled from idle tuning when it was running. Watched spark while cranking and noticed it did not look healthy. So I cleaned the plug up and tested again comparing to another fouled plug and spark looks a lot better. Going to try cleaning up all the plugs tomorrow night and see if that makes a difference if not I will look into a different starter.

[SiriusC1024]

If it's a new starter already then don't worry about it. Napa has good parts.

[edcmat-l1]

New don't mean good. There's something going on to pull the voltage down as low as it is. It's not like I'm imagining things. It's right there in the data. Spark probably looks weak because the voltage is being pulled down.

[RiggsStubbs]

After cleaning plugs spark looked good again, only tried starting it a couple times after cleaning plugs going to try again tonight. I already have new starter and battery, all connections are good, no excessive voltage drop anywhere, I am thinking maybe the stock stuff just isn't enough to crank this higher compression engine over fast enough. Is there some sort of starter or battery upgrade I could do to make it crank faster?

[edcmat-l1]

Where is the battery mounted? How large are the battery cables? How long are they? What is the CCA of the battery?