Thread: Battery Woes

Tweet

Nice clean installation, looks great and should be worry free.

And you were worried about no room....

Roger - that looks like enough room for an Optima sized battery (and I just happen to have an extra one complete with bracket)

Originally Posted by IC2

Roger - that looks like enough room for an Optima sized battery (and I just happen to have an extra one complete with bracket)

Nope, the guy pointed me to a "car sized" AGM plate type, but I simply did not have the width or depth for it. This PC1200 is only 7.8"front x 6.54" deep x 6.69" tall, but has 550CCA with an initial "push" of 1200A. He did have a class 25 wet cell that is almost exactly the same size for less than half the cost, but then you're dealing with really needing to have it in a box that's vented outside of the vehicle.

I had an "Oh NO!" moment yesterday morning. Loaded the cooler & chair into the trunk to head into the local Ford dealer's place for their annual All Ford show, hit the starter and it gave me the "extended crank, no fire" syndrome once again. When it lit after three or four tries it was loaded up pretty good, so I just noted the exact coolant temp (84F) on the ECU programmer and headed into town. Later, after sitting at the show for seven hours I checked the coolant temp before cranking (102F) and again it took three or four short starter bursts, and seemed too rich. Had to make a quick stop on the way home, and at coolant temp 189F it started right. Looking at the Crank Fuel vs Coolant Temp correction curve, the area from 73F up to 125F is the steepest part of the curve, where a few degrees in temp makes pretty big changes in the injector pulse width. I had to wait for the engine to cool down completely, so this morning I hooked up the laptop and hit the starter. Again, it did not fire immediately at 83F so I dialed back the closest value on crank fuel a hair and it hit immediately. As I warmed it through 110F I stopped near each break point on the curve, and ended up leaning out three points to get the best starts. What's amazing to me is that these "changes" are soooo small. The injector pulse is in micro-seconds (seconds x 10-6), and by changing my correction curve value from 1.508 down to 1.5 it reduces the pulse width by 0.000028 seconds! That tiny change makes a huge difference in response!

Thinking about it, during crank the air coming into the throttle body is flowing into the huge 'tunnel ram' plenum area, and the injectors are squirting right into the intake runner ports at the heads. Charge velocity is pretty low (near stagnant?), and mixing turbulence is almost nil so I guess it makes sense that a very small change in fuel dumped in can make a pretty big difference in the cylinder mixture. One thing that really helped me out was Jeff at Edelbrock pointing me toward re-defining the breakpoints on my crank fuel curve, eliminating temperature extremes that could never, ever be seen (like -58F low, +320F high) to get improved resolution in the middle of my curve. Once again I think I've got the starting mixtures pretty much dialed in, but I'm pretty sure that I will be tweaking things again in the Fall/Winter as ambients fall around here.

Sorry to get into so much detail, but its intriguing to me how all of the curves inter-relate, and it's a rush when things start coming together!

Thanks for that last update Roger. It amazes me also when you talk of mili-seconds and the tiny changes your making to them. I am also confused by the "batch fire" principle.. I guess I have some more efi educatin' to survive.. 8-)

Originally Posted by 34_40

Thanks for that last update Roger. It amazes me also when you talk of mili-seconds and the tiny changes your making to them. I am also confused by the "batch fire" principle.. I guess I have some more efi educatin' to survive.. 8-)

One of the tid-bits that my Edelbrock tech shared last time we talked, trying to understand my starting woes (before I focused on the battery) he mentioned to me that one of the features of their system is that on initial crank the injectors are firing "batch mode", meaning that all eight injectors fire together rather than triggering sequentially as each cylinder reaches it's "normal" point in the timing. If the engine fails to light during that initial starter crank, in each subsequent crank (without powering down the ECU, "start" back to "on", then to "start" again) the ECU reverts to sequential mode, firing each injector individually. With my PB start system I hit the "start" button, which closes a momentary relay for the starter, but also "sets" the "on" relay so that as I let off of "start" it "seals in" for "on", maintaining power to the ECU and coil to run. However, if it fails to start I have to press "start" again to break the seal, powering down the ECU, and then press "start" again to engage the starter in a new start cycle. This means that for me, every "start" attempt is a "first start", and my injectors fire "batch mode" for any start attempt. It makes my crank fuel correction more consistent (no change from batch to sequential), but also much more sensitive to flooding as every cylinder gets an injector pulse at the same time, regardless of piston position. One thing that many people don't know is that the early Ford EFI's, which have eight individual port injectors, fire in batch mode, not sequentially. Sounds goofy, but when you're running at mid to high rpm the difference in injector timing is so very, very small it's really moot for a street application.

Roger you are almost at this point convincing me that the 'flush toilet' I have on my intake manifold is the better way for me. I'm just starting to do doing my research as to which is the best EFI route - and that Edelbrock 1405 looks better every time I see it - but of course, it too can be a PITA. Plus I also have a $20 swap meet spare that I am rebuilding too.

Glad you are closing in on the problems though as I am with my roller rockers/mod

Originally Posted by IC2

Roger you are almost at this point convincing me that the 'flush toilet' I have on my intake manifold is the better way for me. I'm just starting to do doing my research as to which is the best EFI route - and that Edelbrock 1405 looks better every time I see it - but of course, it too can be a PITA. Plus I also have a $20 swap meet spare that I am rebuilding too.

Glad you are closing in on the problems though as I am with my roller rockers/mod

Dave,
One thing to consider, while my EFI is a programmable unit most of the later offerings are "self learn", eliminating any direct interface to base fuel/spark maps, or to any of the myriad of correction curves that I've dealt with. In fact, if I simply changed out my O2 sensor to a wide band unit, inserted a different 'plug' into a harness port, and uploaded a new firmware package (free from Edelbrock) I could convert mine to self learn. I already have a wide band O2 sensor, bought to help me tune the air/fuel map across the load range, but with all of the time & effort I've invested I'm too stubborn to change. I simply enjoy the challenge of the various curves and maps, and making small changes to fine tune things now is part of the fun for me.

I thought for sure Bob hit your problem right on the head.
I had a problem just like yours a few years back with hot starts.
I bought all new cables and 1,000 CCA battery.
And I still had problems with it starting after it warmed up.
I had cables going to the frame and engine block.
I had even used sanding paper where the cables connected
to the engine and frame. After being stranded for hours
with the thing several times. I went and got a short cable
and went from the cable on the engine block to the
starter bolt. After that all my problems went away.
Been starting right up for years now, with no problems.
Kurt

Well, in the past week I found that I had my fuel during crank leaned out too much. During the Des Moines trip I was again unhappy with my crank times, so when I got home I went back through everything and recalled that my Edelbrock guy had mentioned one day that my crank fuel was "...considerably leaner than their curve" so I loaded in his values as a test and it helped a lot. My mistake had been making adjustments in crank fuel immediately after shutdown, as opposed to finding the "sweet spot" for a given ambient/coolant temperature, and then letting the car sit for a while before trying it again at a warmer temp. It makes sense that immediately after shutdown there is still a lot of residual fuel/air in the intake, which is just waiting to be sucked into the chamber and ignited. After sitting a while, which is the normal use situation, the fuel vapors have dissipated to a very large degree and more fuel is needed for a quick start. Where I thought my engine was flooding, it was really wanting more fuel for lightoff. Bottom line, my whole battery "issue" may have been driven by me screwing up the crank fuel adjustment trying to "optimize" starts. I like having the bigger battery for potential problem times and I think that it keeps my system voltage a bit higher during crank, but I'm not sure that the little battery wouldn't have done the job with the crank mixture adjusted right. That said, I'm not willing to spend the money to buy a new 680 size just to test the theory. Just wanted to say that the little AGM's may well be OK for just about any application. Lots of guys are using them. Consider this an advertisement for "self tune" EFI systems or the problem of old engineers with too much time on their hands

I REALLY like my simple 1405 Edelbrock carb and dinky little PC680 battery, being an ancient, retired ex-engineer without much free time (tho am considering the new MSD Atomic efi)

Cleaned carb 6-2012-1.jpg

Originally Posted by IC2

I REALLY like my simple 1405 Edelbrock carb and dinky little PC680 battery, being an ancient, retired ex-engineer without much free time (tho am considering the new MSD Atomic efi)

Dave, I think you really need one of the owner tune models, so you have something to fill your free time. Seriously, that MSD unit looks really nice, and I was just reading an article in the August Street Rodder about putting a new FAST EZ unit on a SBF, and they used a programmable electronic distributor for that one, too. My next one will be one of these self learners, I imagine, because they still allow some "tweaking" for those who just cannot leave well enough alone

Yeah, I'm intrigued by the MSD unit, too. But then I have way too many other details to worry about before I get to that!

Roger, I'm glad you figured out that small battery may not have been you're problem because I'm sure hoping to use the small battery in mine! I want to build a nice little box and hang it under the passenger front fender so it's close by but out of sight.