dailydriver

What is the minimum battery voltage needed to actually power the ignition system/fuel pump/injectors on start-up (along with cranking the starter), and keep them going??

My 4 year old, Mexican built, Johnson Controls, Red Top (<-YES, I know some will say THAT'S the problem right there!) shows 11.7 volts unloaded, and drops to 10.4 during cranking a brand new Remy starter.

Does that not leave enough power to run everything else to even allow the thing to start, or if it cranks, it has enough power to run everything else??

It also has a BRAND NEW crank position sensor, MAP sensor, Wix Gold fuel filter, intake gaskets (ALL of them), valley cover and knock sensor gaskets, ALL new fuses AND relays, and everything is torqued down to spec, and every contact point, connector point and ground I could get to (all except the dreaded firewall side of left head #110/112 grounds) is clean and torqued down.

The alternator is a 1.5 year old (bought brand new) Remy/Delphi OEM, and the cam position sensor is < 1 year old.

When it cranks I can smell the raw fuel coming from the exhaust, but could it STILL be the fuel pump (my hearing is almost gone, so don't ask if I can hear the pump priming on the ignition key turn )??

I do not have access to a fuel pressure gauge, but is that the ONLY indication of a functioning pump (could there STILL be a problem if it reads the required pressure)???

There are NO misfire codes, or now any other set, stored, or pending codes showing.
Could plugs be bad enough to cause these problems without setting even one PO300 DTC?????

Thanks in advance,

Dave H.

RockinWs6

10.4 is plenty, usually anything below 9.6 cranking is cause to replace the batt. That is on a fully charged batt.

wssix99

iTrader: (5)

More importantly, what is the voltage you see when the car is running?

dailydriver

OK then, what is the minimum voltage output from the alternator needed to KEEP the engine lit (ignition/fuel systems) after starting??

Thanks for the responses so far.

trans_am7935

iTrader: (15)

IDK about the LS1 system, but i have been able to start my jeep on as little as 7.2v. Usually anything under 9v and you are asking for trouble. now the exact shut off point i would think it would be around 6v or so.

1 FMF

iTrader: (1)

what exactly is your problem? is it simply the engine cranks but won't fire and run?

when you load test a car battery (lead-acid wet cell) the 'specification' is that under 1/2 the rated cold crank amps being drawn from the battery the voltage should not drop below 9.6 volts. whatever the electrical devices that need power (pcm, fuel injectors, ignition coils) if they are getting 14 volts then they pull so many amps. power = volts x amps. if the volts drop in half, then amps will double to keep the power number the same, whether the battery can handle that is what will determine if the engine keeps running or not. if i had to guess, if the electrical system never fell below 10.5 volts but kept up with the amperage requirement everything would probably be fine. In the engine computer programming there may be a minimum voltage setting, you would want to ask that under the tuning section. but generally when you go to start the car, if the starter solenoid engages and doesn't make that clickety-clickety sound and the starter cranks the engine over then you have plenty of power where the engine should fire and run.

and with a battery load test at half the CCA rating of the battery, that's somewhere around 300-400 amps for around an 800 cca rated battery. the starters aren't more than 1.7kw and only draw around 100-150 amps at most.

dailydriver

Thank you for that info!
My new starter is rated at EXACTLY 1.7kw.
I just wanted to have an idea of whether or not I should also 'throw' a new battery at this problem before anything else, since I do not like flooded lead acid deals, and the AGMs I like, and would think worth putting into the car (Odyssey/Die Hard Platinum), are well over $220.00!

It cranks very well, without that 'wear down, slowing starter' sound, and I can smell that raw fuel/hydrocarbon smell coming out of the exhaust right after cranking.

Could the PCM be fried, and is the PCM INTERNALLY grounded, or is there an EXTERNAL ground for it I should be checking/cleaning???

What's perplexing to me is that there are NO PO300 misfire codes AT ALL, which would indicate that the coils/plugs/wires are fine, no?

1 FMF

iTrader: (1)

well i don't think there will be any misfire codes since the engine isn't even firing in the first place.

so far it sounds like you have a good battery. but if you keep cranking the motor and it never starts and runs, make sure you put a charger on the battery. otherwise you will need a new battery if you let it sit too long discharged.t

so the starter is cranking the engine over no problem, but it's not starting, and you are smelling lots of fuel. this seems to indicate you are not getting spark, so the next logical step is to see if you are getting spark at a few spark plugs. for example- if you use a timing light and attach the magnetic pickup to a spark plug wire then crank the engine and hold the timing gun trigger, the gun should flash. if it doesn't flash then try a few other spark plug wires on one bank then the other. that would be easier then pulling a spark plug then holding it to ground and observe spark. chances are you have an electrical problem and something is not wired properly. if the wiring to the coil packs is not connected, or ground wires from the frame to engine are not attached that may cause it. The PCM is not internally grounded. First, Ground is the negative post of the battery. Then if the neg. post is connected to the engine block and frame of the car, then Ground becomes that as well. The PCM knows nothing of ground unless a wire connects to it, what pin numbers out of the 50+ that connect to it i don't know.
generally, as long as one good wire connects battery negative to the engine block and frame you're good. the problem is in the wiring harnesses where a wire comes out at various places that connects to ground (engine block or frame) and will be the ground connection for various circuits. if you are missing one of those then that may be causing your problem, like if it was a ground wire out of the harness that grounds out the ignition coil packs.

dailydriver

Thanks again!

It sometimes catches and runs rough/lousy for 10-30 seconds, and then slowly dies, so what I meant is that there are no codes from that much running time. (Which I'm guessing is not nearly long enough to throw even the most critical, quick acting, codes??)
It also did not throw ANY codes initially, when the engine just died while driving along normally at the start of this problem.

I found and cleaned every ground I could get to, except for the #110/112 grounds attached to the back of the left side (driver's) head, where NO ONE, even a baby, could possibly get their hand into to check/clean, maybe even with the intake off (for the 4th time this year!).
IS this the main PCM/engine harness ground?

IF I can get a fuel pressure gauge on the rail shraeder valve, and it reads good pressure, is there absolutely NO chance that it is still the fuel pump??

IF it were the VATS problems that everyone talks about, would there necessarily HAVE TO BE a code thrown in order for that to shut down the engine while DRIVING??

Thanks in advance.

1 FMF

iTrader: (1)

what is the history of the car? are you the original owner? is it stock or has motor work other than an air filter intake been done? did the car ever run good, and when/how did it start not running bad or not starting?

you almost never have to go off cleaning ground connections unless someone f'd with the car and either forgot to reconnect them or broke wiring being a gorilla mechanic.

from what i know when you turn the ignition key on prior to start, the PCM runs a bunch of diagnostic checks on the entire system. I don't know how long it takes maybe 1-2 seconds at most which may overlap into when the engine runs if you whip the key to start and the engine immediately fires. this is when things like bad radiator fan relays, emissions sensors, coolant sensor can trip a check engine light and DTC if they are bad. once the engine is running it's always in open loop mode first then goes to closed loop, how fast it goes to closed loop varies if the engine is hot, can be as quick as 3-5 seconds. so the longer the engine runs the more DTC's become available to be set. regarding your question about p0300 specifically, a misfire dtc probably won't set because a set of conditions has to be met before the pcm will even determine if data provided by the crank and cam sensors show a misfire. from my service manual some of those conditions are: engine rpm betwen 450-3000 rpm, ignition voltage between 10-18 volts, coolant temp between 19°-266°F, abs system not active, trans not changing gears, secondary air injection diagnostic not in progress. those are some and i don't expect the manual to be 100% accurate but the air happens at startup and that may be preventing a p0300... to give you an idea. and you may not even actually have a misfire, not what the pcm programming defines it to be based on programming. from the sound of what you've described so far i would guess if it's not an electrical problem then you have an intake vacuum leak or possibly internal motor breakage. i would first put a fuel pressure guage on the rail and check for good pressure as a sanity check, should be 50+ psi. drain pressure out of the rail then turn the key to run, the pressure should jump right back to 50 psi. if it does then it's not solely a fuel pump problem and the engine should start no problem. if engine does briefly run then dies, check the fuel pressure it should always be around 50 psi. from there i would run a compression test on all cylinders and confirm > 140 psi all cylinders, unless you know for sure the internals are good i do not know history of car.

the way vats works is at startup, if the resistance from the ignition key is not correct it will prevent anything from happening when you turn the key to start, the engine will not turn over and the security light will be on in the cluster. once the engine is running vats will never cause it to shut off. so if the starter always cranks motor when key to start, it's not a vats problem.

other thing that comes to mind is you mentioned car died while driving, i had a jeep that had a factory flaw where they routed the injector wiring harness on the inline-6 valve cover stud and after 45k or so miles the stud wore into the harness shorting/grounding 3 or 4 chaffed wires. in that case the jeep would just die doing 40+ mph down road when the wires happened to short, and i never had any engine codes because that kind of failure caused a complete engine computer reset, which also tripped the ignition security feature and most times i couldn't restart the engine immediately and had to wait 5 or 10 minutes. so, consider checking your wiring harness' to the injectors and around the engine. if the car is stock and untouched then i highly doubt this being the problem but if it's been worked on then it's more probable.

wssix99

iTrader: (5)

My understanding is the VATS would just keep you from starting the car. If it were acting up, you should get a Security Light illuminated.

If your fuel pressure reads good while the car is acting up, then I'd think you could rule out a fuel/pump issue.

If you can get a hold of a scanner that will give you the actual readings of the sensors, that might help. (Make sure the coolant temp sensor, air temp sensor, etc. all read rational values.)

dailydriver

THANKS to ALL above.

History; I am the ONLY owner, from ordered new in 10/99 (delivered 1/2000).

It has `158K miles on it, with maniacally OCD maintenance/oil changes with the BEST oils/filters available, but it WAS used as it was supposed to be (besides daily driving it in ALL conditions, YEAR ROUND, hence my username).

NO 'deep' internal mods, a mild CMR/Diablosport tune, barely any bolt-ons (Comp 917?? springs with their titanium retainers/pushrods, lid, Moroso Ultra 40 plug wires, Moroso air/oil separator, Katech belt tensioner, Borla y pipe, Mufflex 3.5" stainless catback with Magniflow muffler, 3.73 gears, Eaton carbon fiber clutchpack Posi, Pro 5.0 shifter, and LOTS of road race oriented suspension mods). EVERYTHING ELSE on/concerning the engine is stock/OEM, even ALL of the connected/functional emissions equipment.

It is/was used for open track/HPDE/lapping road race type activities, as well as autocrossing, and I did go for a 'personal best' time/speed at Atco (12.67 @ 113.2 after ~30 or so runs over 2 years' time).
It is rare that I EVER hit the rev limiter (set at 6300).

It was running perfectly (even good mileage) until I was coming home one night in Buckingham, and it just started 'fluttering' (tach needle dropping down and going up again) slightly going down a hill into a light at a major intersection, and then just died, and would not restart. This was more than a month ago.
I pushed it out of the intersection, had it towed home, and have been working on it since with only occasional starts for said 10-30 seconds duration.

The ONLY other time it EVER acted up like this (or left me stranded in all of it's 14 years/160K miles) was when the crank position sensor went bad about two and a half years ago. It was perfectly fine once that was replaced, until now (WHY that was the first thing i replaced-it had the same EXACT symptoms when that happened ).

wssix99

iTrader: (5)

What is your battery voltage with the car off and what do you read with the car running? When the car flutters, does your voltage gauge on the dash also flutter?

dailydriver

I have not been able to get it to run long enough to get a reading with my Kiwi wifi setup, and I did not have anything on it when it happened initially, nor did I look at the factory/dash volt gauge at that time (was more worried about getting it out of the intersection/getting killed by the drunken loonies around here).

Car off, but ignition turned to on, it reads between 11.5 and 11.7 volts.

It drops down to 10.3, or 10.2 during cranking.

wssix99

iTrader: (5)

Yea, this will be normal. There will be a voltage drop while the starter is engaging and before the alternator is spun up to supply electricity to the engine and recharge the battery.

If you aren't using a battery charger, it must be getting maintained by the alternator and 12V is fine.

RPM WS6

iTrader: (3)

These are the two things that stand out to me:

Do you mean 26918 (or simply "918s" as most call them) springs? There have been bad batches of those over the years, not sure when you purchased/installed yours, or how many miles you have on them now. Might be worth pulling the valve covers and inspecting these springs for any failures. I would think this to be generally unlikely with a stock cam, but with sustained high rpms at aggressive track events, if there was a flaw it might have finally presented itself.

Perhaps the new CPS wasn't as well made as the original, and has failed again. If the symptoms are identicle, then it stands to reason that this should be a consideration as well.

Those are the only two things that come to mind at this point.

dailydriver

Thanks.

The springs are whatever was the 'go to' Comp choice for stock/small cams waaayyyy back in '01 when they were installed @ about 8K miles, I now have almost 160K miles on the car/engine . I have heard of those mfg. defects before, but thought that mine were made either before or after them.
Despite the car being used as it has, I try to make it a point NOT to 'live' above about 5300 revs, even on long straights, and as stated, the limiter is set to 6300 anyway, and I do NOT miss shifts and mechanically over rev.

Would ONE cracked spring/dropped valve cause the engine to stop dead in it's tracks with NO noises/banging/misfires/etc. what so ever?
There were none when this happened, just a drop on the tach needle and no response to the throttle.
There are also NO crazy noises/clangs when the engine is being cranked now, and the oil pressure goes up to 40-45 while being cranked.

You're correct in questioning the crank position sensor since it is an AC Delco, BUT, MADE IN CHINA.
The Delphi I wanted on Rock Auto stated that it was for the MEXICAN MARKET CARS ONLY.

The one I took out was installed by the Chevy stealership, and I am taking for granted is a official GM part, probably made by Delphi in this country (but there is nothing stamped/printed on it with COA, unlike the one I installed) but I cannot be certain.

WHAT could possibly be causing crank sensors to go bad so quickly, given that it IS bad, as well as the one I removed???
I do NOT have long tubes, so it could not be excessive heat from those, there were NO marks/scratches/dents/gouges in the one I removed so it is NOT touching the reluctor wheel.
Bad grounds, power spikes/surges??????

RPM WS6

iTrader: (3)

Sounds like you either have 918s or 915s then. From what I remember, the 915s were basically at the same level as stock LS6 springs at that time - good for stock or very small cams. 918s were the first single beehive spring from Comp that could handle lift well over the ~.525" of LS6 springs. But it sounds like you could have either spring.

It just so happens that I bought a set of 918s back in '01 as well, so I remember the goings on at that time. At some point around that era, there was a bad batch with several failures, after which Comp started putting a blue stripe on the 918s, to signify the start of the revised batch. At that time, I too had thought that my '01 production springs were prior to the bad batch, but there was no way to know for sure.

IMO, ~150k miles is a lot for any aftermarket valve spring, even with a stock cam, when used in sustained higher rpm settings on regular occasion. QC has often been questionable when it comes to Comp springs for LS1 heads. It's certainly possible that a spring failure could be casuing your issue, but it's not the only possibility....

I've (thankfully) never had to deal with a failed CPS before, so I'm not an expert on the reasons for their failure or the exact symptoms leading up to the condition. But it stands to reason that the replacement sensor may have in fact failed since this instance reminds you exactly of how it failed before.

dailydriver

^^^THANKS AGAIN.

Would one spring failure (or even multiple ones) cause this no start symptom, and could/would there NOT be ANY untoward noises/knocks/clanging from said failure either when it was running (before stopping dead), OR during cranking and not starting???

RPM WS6

iTrader: (3)

The thing about valve spring failure(s) is that the amount of damage/noise/severity that will be experienced will often depend on how catastrophic the failure is and under what conditions it happened. With a single spring, there is a very good chance of serious valve/piston/cylinder damage with a failure, but that doesn't *always* happen.

The fact that it was suddenly running rough right before it cut out could indicate that the spring(s) had begun to fracture and did not allow proper/complete valve events, thus a loss in vacuum, and misfire/drop in engine speed. As it failed further, that may have resulted in the the engine cutting out completely. It's also possibile that the CPS may have begun to fail again and therefore caused the same sort of misfire/rough running symptoms. I wouldn't normally jump to the CPS as my first thought for this problem, but the fact that you had to replace it before, and that the new sensor may not have been of the same quality, makes it a possibility in my mind. Either way, these are obviously just possibilities based on what is known so far, and what *could* have happened.

It would obviously be less costly to first pull the valve covers and inspect the springs prior to buying a new CPS or any other new parts.

I realize these aren't exactly the definite answers that you're looking for but, based on the information given and tests you have performed so far, I don't really feel that there is a 100% single most likely issue here. I wish I was able to give you that 100% certain answer....