seen4ever

Ok, June 23rd, I go to the local 1/8th mile track to test out the new setup. car was running a bit rich but it still managed to run consistant 102mph passes in the 1/8th.


notice how voltage kind of drives to 12.5v at the top of 3rd

Now fast forward to 7/28, a street racing event at the 1/8th mile track, car is mis-firing in 3rd gear every run, I keep adding fuel and max out the 1000s... tonight i removed the MSD 6a and tried again. I didn't datalog tonight but same issue. So I pull up datalogs from the other night and start looking at stuff i normally never look at, aka battery voltage and i'm surprised to say the least, notice voltage is goin got 16.5v... and the fuel pump is going really lean, so that makes me wonder what is going on. I have 4 datalogs from that night and every time in 3rd gear it would go lean.



So what makes voltage change this much?

is it my fuel pump relay? is it a ground issue?

the alternator is maybe 2k miles old. the battery is old, could that be it?

seen4ever

i think i have a few of these running around in the car...

seen4ever

oh yea, a follow-up note, the voltage spike is only happening at WOT pulls, cruising around like normal, the car is the normal 13.2-13.9v it always has been.

RTW DC2R

I dont know too much about the electrical systems, but I would assume if it was a problem with the battery being old or the alternator, the voltage would be too low, not spike upward.

seen4ever

well i wonder about the regulator in the alternator, maybe its just shooting to the moon. then again, i'd think if the voltage was that high, I wouldn't be going lean, the car would go pig rich due to the pump flowing more. almost makes me wonder if its a false positive situation.

RTW DC2R

I didnt even realize battery voltage can play a part in running rich/lean lol

LST2

This is such a coincidence. I think I have been running into the same problem over the last few weeks. I will be running fine and then all of a sudden I will run about 2 points richer (across the map). Then a few minutes later it will go back to where I tuned it. I think I am loosing voltage somewhere causing the injectors to act slower (basically increasing the duty cycle). I have not/can not datalog my voltage but I think this is the problem. Going to get my battery and alternator checked out.

Is there a pin with a 5v output on the ECU I can tap to datalog the volatage output of the batt/altenator?

wade

iTrader: (1)

bump for sean.

why do we need to know what MPHs your car runs in the 1/8?

seen4ever

because it was 14mph faster than you at end of June and then last week i was at the same MPH due to my car falling on its face.

This seriously threw me for a loop, i thought maybe a fuel filter was screwing up, or my fuel pickup tube was having problems, now i found this voltage problem and its a whole new world.

LST2

seen4ever, how did you datalog the voltage output. Do you have a datalogger that can accept a 15v input or is there a pin that has a 5v reference output?

Thanks

B18 CYA

bump for some answers since I believe I have the same problem

Chris22215

bump for some answers too

*I'm just curious* Grounds maybe?

Race Egr

Maybe the voltage regulator in the alternator is taking a crap? Have you checked all your grounds? Maybe try all new ground wires there pretty cheap

seen4ever

datalogging is through hondata. I'm going to take it out for a spin tonight to try and see what my turbo timer reads during the mis-fires. well I need to find another alternator and test it first.

I wondered if it could be the ELD (aka underhood fusebox) since it regulators alternator voltage right? I mean, thre are fuses to prevent stuff like this i thought.

I still wonder why the car is going so lean though.... I mean 16v through the bosch pump shoudl kick up its output pretty good, rather than the opposite.

I went through more datalogs and when i was on the dyno earlier this year, it was solid at 13v.

when the engine was out this winter, I went back and re-soldiered all the wires for the battery and alternator/cutoff swtich circuit so i was sure it was all a solid connection, rather than just crimped.

Lonnieboosted

Same exact thing happened to me, I changed the alternator, the fuel pump relay, but it happened to be a bad battery. So I did this and haven't had a problem since.

seen4ever

for the battery voltage playing wtih a/f ratio. I have the Bosch -044 pump wired up through a relay directly from the battery through big gauge wiring to ensure it has a steady power, changes in voltage will affect how the pump performs. I have 3 relays by my battery, so I'll pull out the battery & nitrous bottle and check all the grounds & power. I have a ground distribution box and a power distribution box, maybe a wire has gotten lose.

I figure that the strong launches are having an effect on this somehow, that's really all that has changed on my car. I've just been goign to the track more, so it either has to be something has come loose due to the strain of drag racing or... alternator/battery is taking a ****.

This is an old battery, anyone ever see a battery do stupid shti like this before? Normally i just see stuff go dead, never had something like this though.

but new turbo arrives today, so i'd like to figure this out before i throw on the big boy.

seen4ever

so just a new battery then?

i guess i'll throw in my little tiny race battery and see if it works, then i'll just buy an optima.

Lonnieboosted

Try a new one

B18 CYA

I use one of these batteries, do you think it may be the problem since its so small? maybe doesn't have enough output... :

http://cgi.ebay.com/ebaymotors...ZWDVW

full Circling

with the car off, you should be getting around 12 volts. with the alternator running, you should be getting over 14. your battery voltage chart should pretty much be a flat line over 14 volts. in the first chart, your voltage was pretty low. then in the second chart, your voltage started going over the place. it's off the charts in some places.

this is your problem. replace your alternator, or at least get a new voltage regulator.

also, get your battery LOAD tested to see if those crazy voltage spikes screwed anything up battery-wise. if you battery is old to begin with, i would go ahead and get another one after it seeing voltages like that, just so i'm not kicking myself when i'm stranded somewhere due to the battery. did any of your accessories take a ****? there is so much misinformation in this thread it's ridiculus.


Modified by ^^whatnoobsearchthenGTFO at 1:51 PM 8/2/2006


Modified by ^^whatnoobsearchthenGTFO at 1:51 PM 8/2/2006

seen4ever

battery was load tested earlier this year with no issue, just told it had a low charge, which was expected after sitting for a few months.

I know it should be over 14v, but in the 4yrs i've had the car and multiple engines between, the voltage has always hovered in the 13v range (this is with multiple batteries as well). This is another reason I re-soldiered all the connection to and from the cutoff switch and battery to ensure good connections.

currently all accesories work in the car, during part trottle driving, the car is just like normal, its only once boost gets turned up. even at my street gas tune of 14psi, the car pulls just fine, without any noticable mis-fires or anything or going overly lean. its just when boost gets turned up.

EDIT: with the car off voltage is 11.9 to 12.1

full Circling

hmmmmmm...

i'm really stumped. this is gonna bug me until i can come up with something else for you to try.

jeremydde

Have you considered the possibility that as a high current draw part fluctuates in reliability ie fuel pump, ignition, that the voltage would spike until the voltage regulator is able to compensate for it. From your datalogging it seems like your voltage regulator is functionioning correctly. You all of a sudden have a lean condition and voltage spike...Perhaps your fuel pump is taking a $%&*. On a Mazda 323 GTX that I am currently tuning I would get an extreme lean spot above 4000rpm everytime, and according to the Wolf3d display screen the voltage was hitting 15volts during the lean spot until we let up on the throttle. I slapped a new fuel pump in the other day, and VOILA no lean condition, no voltage spikes.

seen4ever

sounds interesting, but these Bosch pumps are known for thier reliability, i'd think 900 miles would be a bit soon for one of them to take a crap... either way, that is an interesting theory..

I removed the MSD 6a box, because well its MSD, could be a POS. jesus, this is like running in circles.

jeremydde

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by seen4ever &raquo;</TD></TR><TR><TD CLASS="quote">sounds interesting, but these Bosch pumps are known for thier reliability, i'd think 900 miles would be a bit soon for one of them to take a crap... either way, that is an interesting theory..

I removed the MSD 6a box, because well its MSD, could be a POS. jesus, this is like running in circles.</TD></TR></TABLE>

The 323 had a Bosch inline fuel pump....