Crazy5.7

I am losing my friggin mind

I wanted to post this because I've found a ton of threads that were started on this issue, but went unfinished or were something simple that I've since tested with no luck. Any ideas or suggestions would be greatly appreciated!

If it's about 60+ degrees outside, this thing starts like it normally has. I say normally has because it has always taken a few seconds of cranking to get it started. If it's any colder than that it just cranks but never starts. It acts like it's trying to fire at times, but it will never fully catch and fire up.

Fuel pressure is at the rails now after replacing the wiring assembly and pump thanks to Racetronix. I've tested spark by plugging an extra plug in a wire and grounding it. Hooked up a computer to see if the coolant and air temp sensors were reading properly and they were within 2-4 degrees of each other and reading the proper temps. Oil pressure shows up on the dash while cranking.

As a test, I tried taking a blow dryer and warming up a few sensors and the oil sending unit to see if that would make a difference like the ambient temperature does, but alas still a cranking no start symptom.

I do have a noid light set I just purchased to test if the injectors are firing, but will be trying that tomorrow. So fed up and angry it was time to walk away for the night.

Another bit of potentially useful information, it has recently started to smoke AFTER a while of running. I removed the headers to check and there was some oil in a couple of the exhaust ports. The best diagnosis I have for this is bad valve guides due to it not smoking on start up and only when it has warmed up.

Thanks in advance to anyone who posts!

Kevova

Since it sounds like a consistent condition, when it won't start check for spark and pulse along with fuel pressure. A scanner would be handy. carbon in throttle body? What do spark plugs look like?

Tom400CFI

1. I'd be checking the Coolant Temp Sensor. Can you get your hands on a scan tool...or a DVOM and check the ohms of the coolant temp sensor when "cold"?
2. Noid light is a good test, but I'd bet the injectors are firing, since it starts "warm".
3. You have that backward; leaking valve guides make smoke when first started, clears up after a few seconds. Burns oil only after running a while? Intake manifold gasket leak (to the valley), maybe? That would exacerbate cold starting, too.

Crazy5.7

The temperature has been pretty nice, so I haven't been able to test much. I was able to check fuel pressure and spark last time, and there was fuel pressure at the rails. A spare spark plug fired when cranking and having it ground.

Crazy5.7

1. Wouldn't seeing a correct reading from the computer when it's cold verify the coolant temp sensor was working correctly?

2. I agree, I just want to verify 100% that is the case.

3. I read smoke on startup was valve seals, and smoke after warmup was valve guides. Intake manifold could be an issue as I wasn't the one who installed it, so I cannot verify the condition of the job done. Do you know of an easy way to verify this, or am I looking at tearing it down?

Tom400CFI

1. Maybe...I'm not sure on your year car
3. I'd start by just checking intake bolt tq. See if it's loose.

Kevova

Was fuel pressure over 42 psi? fuel filter? Spark should jump at least 1/4'. Smoking on start up typically is exhaust valve seals or worn guides. oil leaks down and when engine starts it burns off. once valves stems heat up the clearance is reduced and the smoking may stop. Smoking warm best possibility is the intake gasket is allowing oil to be sucked into intake ports of head. Re-torqueing intake bolts may correct condition. Normally smoking hot is rings or worn guides along with seals. Because of the smoking are the plugs fouled? I would also do compression/ leak down test to determine soundness of engine?

Crazy5.7

Ok, new bit of information. I apparently have 22lb/hr injectors according to my research and according to my tuner. He said they would be fine, but everything I'm finding online says I need at the very least 30lb/hr injectors for what I have.

Completely left this important information out, and I completely apologize, but I have a 383 stroker with LPE 219 cam, ported and polished heads, with a SuperRam intake.

This doesn't answer the problem about the oil leaking into the exhaust ports, but I think it does have a pretty good chance of fixing the cold start/starting issues.

aklim

Who is the tuner? Did you ask him if he changed the injector constants so it compensates for it? I would think that it is fine at idle but it might run into going static for WOT. I had that setup on 36pph injectors

Dt86

Wow. I'm running 24 lb injectors on a stock long block with a ported high flow intake. Looks like you found 1/2 your problem.

Crazy5.7

Scott Hansen. I didn't ask specifically about that, but after I sent him a data log of what he first sent when I thought I had 30lb injectors, he said the injector size was wrong. The next tune he sent out the BLM's were spot on when I checked just driving normally. He has been incredibly helpful and his customer service is above and beyond.

aklim

https://www.rceng.com/technical.aspx

Go to the section Fuel Injector Worksheet.

At 43.5psi fuel pressure and 0.5 BSFC to make 450HP I need 35.36pph injectors. At 100% I need 28.29 pph injectors. Even at 95% duty cycle I need to have 29.75. Recommended is 80% duty cycle. I had that setup and other than the garbage TFS heads I had and didn't port the intake, that setup was rated by LPE to be 430HP, IIRC. Subtract some from that figure because of the heads and intake not being ported and we settle at 400HP which based on LPE is very conservative. Go there and play with the numbers a little. 22pph works if you change the BSFC to 0.45 and you are willing to push the duty cycle to 100%. That would be something I wouldn't do myself but that is between you and your tuner. Making 420 RWHP, I am using 42 pph injectors at 43.5psi fuel pressure.

Cory Vette

Thought I would add my problem since it sounds like it's same ballpark>
I have 89 6 speed , stock motor. First startup sometimes starts right away and other times cranks about 2 seconds to start. I use to be able to just turn the key with a fast crank, stop and then start again and it would start right up. I had to put in a new battery and when I did, the start stop start trick stopped working.
Now it varys. When it takes longer to crank, it is definitely getting gas cause I can smell it after it starts. It's like it's getting flooded and not enough air flow.
It seems that after it has warmed up I can crank it over quickly but, the consistencies are too few. I took it to my mechanic and he checked the charging system, the alt, checked the FPR and injectors. He couldn't find anything wrong so, it's obviously an intermittent issue. Read another thread where the guy had poor wiring on coolant sensor but, still didn't solve issue after it was fixed. Any new resolve?