Hard start when cold

[87geeinn]

Can't figure this one out. I've posted over on TT to see what Eric might be able to come up with.

Issue: On cold start up only, car will fire and then immediately die. On second try, car will fire and basically stumble to life. Car runs absolutely tip-top after that even at WOT @25-26psi. No smoke or signs of fuel/oil/coolant leaking into cylinders. Car starts perfectly when warm.

Background: I've tried everything I can think of and have several backup parts to which I've narrowed out possibilities by swapping known good parts and/or readjusting existing parts. I've eliminated coil pack, module, plugs, plug wires, injectors, fuel regulator, fuel pump, fuel filter, grounds, battery, battery cables, IAC motor, TPS, MAF, alternator, starter, cam sensor cap/adjustment, crank sensor, compression, ECM, fuses, bulkhead/fuse panel connections, fuseable links, and coolant loss/leak in to cylinders. This has been ongoing for about a year now and started shortly after I shipped the car here to Hawaii. It did not appear after doing work on the car or anything like that. I replaced the entire wiring harness with a Casper's plug and play unit about three years ago with no issues.

Additional info: The embedded video corresponds to the attached log taken at the same time. I notice that the cranking volts are very low, even considering the ~1V lower reading usually seen at the Scanmaster/Powerlogger, and this may be the root of the problem. Also, there's a complete dropout of all readings between the two attempted cranks at frame #449. A/F ratio seems extremely rich, even taking into consideration the cold start fueling but not sure if this is normal. From frames 5132-5153, car goes into closed loop for no apparent reason...again, not sure if that's normal either.

 

[buddy]

Have you tried the ECT sensor? Maybe it's broke and engine thinks it's warm? My lt1 did exact thing.

 

[87geeinn]

Have you tried the ECT sensor? Maybe it's broke and engine thinks it's warm? My lt1 did exact thing.

According to the log, the coolant sensor is reading properly. Never seen anything during normal driving that would indicate it isn't working either.

 

[87geeinn]

Okay, so at least I know now that it is something internal. Pulled the plugs to have a look. The attached pics are from the passenger side. Cylinder six and it's accompanying plug is by far the worst. You can see where I gently scraped the surface of the #2 piston with a screwdriver just to show the extent of the oil deposits. When I recently replaced the plugs, I did so with the engine fairly warm which would explain why I didn't really notice the deposits or wetness...and I don't remember really taking a good look down the spark plug holes either. Car has been sitting over 36 hours when pics were taken. Guess I gotta pull the valve covers and at least check the valve stem seals. I hope it's not valve guides or rings since this is a relatively new Weber stroker with less than 15k on it. I did recently put full synthetic in on the last oil change for the first time in the car's life. Maybe switching back to dino will help a little.

CYLINDER #2

CYLINDER #5

CYLINDER #6

#5 PLUG

#6 PLUG

 

[87geeinn]

Update on this: Changed ignition switch and no change other than I get better voltage readings everywhere (Scanmaster, "M" and "P" connections at the CCCI harness, etc) and a nice solid feel to the key. Also changed valve seals, even though they looked fine. Compression test checked out fine...all cylinders within a few PSI of each other. No more oil contamination after switching back to regular dino oil. I am at a loss and have tried everything I can think of. Car consistently does not want to fire on the first go when engine is cold or has been sitting for about 15 minutes; it wants to fire one cylinder violently...almost a backfire and then dies. Next try, car cranks and cranks until finally stumbling to life. Feathering the throttle helps get it going a little better. Starts perfectly if restarted within about 15 minutes of shut down. Tried a brand new set of injectors as well as sending my current ones off for ultrasonic cleaning. No change. Good fuel pressure, injector pulse, and cam signal. WTF am I missing. Heeeeeellllp.

 

[John Larkin]

For free, inspect the reluctor ring and crank sensor. There may be a clue there.

Just thought of this: when I start my car on E85, it sometimes stumbles on the first attempt, especially when cold out. Second crank is fine. Sounds similar, maybe bad gas? Looks like you are down to 1/4 tank. Worth pumping it out and trying fresh gas? You can put this gas in your other car so it won't start either, lol.

 

[TurboTdr3.8]

I did notice one thing your maf is reading numbers with just the key on , kindly like its showing grams per sec and not running . That may be your problem , swag

 

[87geeinn]

For free, inspect the reluctor ring and crank sensor. There may be a clue there.

Just thought of this: when I start my car on E85, it sometimes stumbles on the first attempt, especially when cold out. Second crank is fine. Sounds similar, maybe bad gas? Looks like you are down to 1/4 tank. Worth pumping it out and trying fresh gas? You can put this gas in your other car so it won't start either, lol.

1) It's my daily driver and I take it everywhere. I fill up once a week. I've tried different gas stations in the past.
2) Crank sensor is in perfect shape and all three portions of the ring pass through the slot without rubbing.

I did notice one thing your maf is reading numbers with just the key on , kindly like its showing grams per sec and not running . That may be your problem , swag

It's supposed to do that.

 

[bpman1234]

i know its new build but timing chain?

 

[87geeinn]

i know its new build but timing chain?

Got a double roller set in it but I've pondered the same thing. Not sure how I would check the condition without pulling the front cover off. Maybe check base timing at idle?

 

[bpman1234]

yes see if it bounces around, man it looks like you checked every thing some times you have to go back check it all again and do it sloow without anger no cursing ok.

 

[TurboTdr3.8]

TurboTdr3.8 said: ↑
I did notice one thing your maf is reading numbers with just the key on , kindly like its showing grams per sec and not running . That may be your problem , swag
It's supposed to do that.

On my SM AF is zero before it is running then to about 7 or 8 when started cold , I think you meant kpa as it will show numbers . yours was showing about 13 on the log and not running

 

[87geeinn]

View attachment 230751

On my SM AF is zero before it is running then to about 7 or 8 when started cold , I think you meant kpa as it will show numbers . yours was showing about 13 on the log and not running

Not sure what you're saying. I'll have to take a look at the log when I get back home to my laptop.

Edit: Didn't see the attachment at first using the mobile app. Hmmm, maybe Eric will chime in. I'm running the newer LT1 plastic MAF with regular translator. Have swapped with my older metal one and no change. Wonder if the translator could be acting a fool.

 

[Raeban]

Are you still using the EGR valve? Flow from a malfunctioning EGR valve when the engine is cold can cause cold start stalling and startup issues.

 

[TurboTdr3.8]

Not sure what you're saying. I'll have to take a look at the log when I get back home to my laptop.

Edit: Didn't see the attachment at first using the mobile app. Hmmm, maybe Eric will chime in. I'm running the newer LT1 plastic MAF with regular translator. Have swapped with my older metal one and no change. Wonder if the translator could be acting a fool.[/QUOTE

different

 

[BBCTURBO11]

Are you sure Fuel pressure not leaking down over several hours or overnight ? Happened to me , vacuum sucking fuel thru top only after sitting overnight.


BBCTURBO11

 

[87geeinn]

Are you still using the EGR valve? Flow from a malfunctioning EGR valve when the engine is cold can cause cold start stalling and startup issues.

Nope, intake is a Champion ported unit that has the hole sealed up. Fabbed up my own block off plate and siliconed it to the open ports, more for aesthetic purposes than anything.

Something is causing it to be reading MAF at 13.8 and not running , maybe be something in the translator or setting , that would make it run rich and hard to start I believe .

I'll have to take another look at my logs later. KOEO, AF is usually "4" until running. According to BobR. (aka, RmvBfrFlght) who is assisting me via PMs, the MAF has no bearing on the startup and does not come into the picture until RPMs are >400 and after a slight time delay. I think I can safely remove the MAF for now but at this point I will not rule out anything. He has a theory (and I tend to agree) that with all the moving around of the sensor and timing chaing set during cranking, it is causing havoc with the cam sensor and/or something is keeping the ICM from syncing up properly. I've already tried tweaking the cam sensor CCW about 1/8" but to no avail. Gonna mess with it some more to see if I can't find a sweet spot in it. Worth a shot I reckon.

 

[bpman1234]

why is your ecm afr reading zero?

 

[87geeinn]

What the hell? Here is same file, same frame but numbers are different. Only thing I see is that you must have a newer version of PL since there are numerous other boxes. Maybe has something to due with the .INI file parameters?

 

[TurboTdr3.8]

What the hell? Here is same file, same frame but numbers are different. Only thing I see is that you must have a newer version of PL since there are numerous other boxes. Maybe has something to due with the .INI file parameters?

View attachment 230831

You are right I did have mine set for the newer version sd2 and did not know it , as it did change the maf numbers , sorry about that . on my car that has no translator before start up the maf numbers read 0 . I was just trying to compare the difference`s , I also have one car that does not crank cold kindly like yours in a way as one day it cranks perfect and the next day I have to double start it . I have been trying to figure it out also . Good luck sorry for the confusion .