Stuttering/Misfiring issues after battery died and jump-started.

[B-lackGSX99]

Car died for an unknown reason (no lights were left on, the interiors may have been left on due to door not being tightly closed, but I am unsure), after jump starting it, it hasn't driven normally since. My SAFC-ii settings were all saved and un changed by the ECU restart, but it just doesn't see as though they are registering.

At a range of RPM (I noticed it's generally around 2500-3000) the car will begin bogging down (same way it would if it had a boost leak), and will continue doing so whether I floor it, or just keep the pedal at the same place. It does not occur if I am bogging at 3500 rpms, and down shift...then it moves through the entire RPMS (in the lower gear) normally.

When it "bogs", the AFR goes far right, registering the highest lean reading possible. It can continue to accelerate (through the RPM's) and build boost...it just does so slowly, and the car sounds like it's gargling (not that there's any liquid involved, just sounds this way...stuttering kind of). The car does seem to be idling normally.

I removed all my spark plugs (NGK BPR7ES's) and cleaned them (brushing the white off) as best I could with a brush and paper towel. After replacing them, the car is still behaving equally poorly. I will put in an old set of BPR6ES's that I have laying around, these worked in the car previously without issue.

If the plugs don't change anything, I would like to check my wires. To do so, do I just run the car (idling) and unplug the wires one at a time to see if anything changes??

Any other ideas on what may be causing what i'm describing??

So, cleaned BPR7ES's didn't work (they were only a few months old to start with!), and the old BPR6ES's didn't make a lick of a difference either. I will purchase a new set on the way home and see how they fair...although I am coming to believe that none of this has anything to do with my spark plugs.

Can anyone confirm the plug wire test procedure for me??

Any other ideas on what it might be??

I was thinking that it may be the fuel pump going, but I have no been able to find any threads discussing a slowly dying fuel pump...only been able to find threads about fuel pumps that are not working at all, and therefore car is not starting. I am assuming then that they are either a GO or NO GO type machine, no in between like I am experiencing.

Clogged fuel injectors??

Car seems to run relatively well if I push it hard. I am going to also attempt to reload an old SAFC-ii datafile...one not quite as finely tuned as the last one, but definitely a working datafile. I would like to do this to see if the drivability or stuttering points change at all...this way, I will at least be able to determine if the SAFC-ii is being recognized properly by ECU.

I am also suspecting the ECU of being scrambled from the jumpstart...does anyone else think this may be a possibility, or are the symptoms non-reflective of that kind of damage?

 

[Rex2342]

Sounds like your loosing fuel pressure. Usually a pump will just die but sometimes they slow down and then die. Do you have a way to check your voltage? If something was left on overnight and the battery died you could have killed the battery and not be getting the proper voltage to the pump. Check the battery first and then check for voltage at the pump.

 

[B-lackGSX99]

I agree, after much thinking, it seems way to coincidental for the battery to have died and these problems to have arisen exactly after jumpstarting it. They must be linked. I have been doing a lot of reading, and it looks like a blown alternator could be causing the problems I am describing (as the ECU apparently requires constant voltage in order to function properly). I have read that to check whether the alternator is bad, you simply idle the car, and disconnect the positive (red?) terminal from the battery. If the car dies, then you know the alternator is bad...

I don't have a portable voltmeter. Inside the car, I always have my radar detector set to show me the voltage of the battery...it has been sitting pretty at around 13.1-14.1V, so I assumed that the batter was charging normally. Also, since the car has not died again since last friday (~5 days ago), this also made me assume the battery/alternator were not the issue.

Either way, can someone confirm for me if the above mentioned technique is a safe method of checking whether or no the alternator is blown? If it may be unsafe (due it it volt spiking and being potentially harmful to parts of the car), i'll see if there is a place that will load test it for me...unformately we do not have Autozone or anything here, but perhaps Canadian Tire or my friend's dealership will be able to lend a hand.

I appreciate the suggestion of the fuel pump possibly being the culprit...if it doesn't turn out to be the alternator/battery, the fuel pump will be the next thing I check out.

 

[B-lackGSX99]

Well, after over 50 miles of city driving, the car finally decided to start running almost normally...it's never taken this long to relearn on my previous SAFC-ii settings, so this was very surprising.

At this point in time, it is no longer bogging/stuttering, but is idling higher than normal. It bounces back and forth between 1000 and 1250 while idling...i'm willing to assume at this point in time that it just needs a little more time to learn.

So for future reference to anyone that suffers from a dead battery, yes it can take over 50 miles of driving before you'll be running back to normal.