PR8urVtec

iTrader: (1)

Hey guys,


So I have P28 chipped with hondata s300 on my 90 Acura Integra. It's obviously converted to obd1. I'm having a problem where my voltage drops down to 12.5v and slowly gets lower if I'm idling with my headlights on only. While I'm driving with headlights on, the voltage is at or above 14v. If I don't have my headlights on, the voltage will stay at or above 14v as it should. I have my wideband hooked to the ELD (D10) and disabled the ELD in Smanager. My o2 feedback is great.

Now, I have posted this problem to hondata's forum and still can't find answers. They have suggested to depin the ALTC wire (A16) from the ECU. I also looked to see what wire is the ALTC on an OBD0 harness and that would be pin B5. I went to my car and found pin A16 and traced it through the jumper harness and it leads to B5 on my integra wiring harness. I don't have a wire at B5 on my harness. This is a stock harness other than clipping pin D10 and running my wideband to it.

I'm wondering why I don't have that wire in my harness when all the ECU pinouts have this wire in the ECU weather it's obd0 or 1. I think I have an obd1 alternator but didn't think there was a difference between obd0 and 1. Now I'm starting to think that the alternator is relying on the ELD to kick in the alternator when the lights are on. Has anyone had this problem? The alternator is new and works other than when my headlights are on at idle. I was going to unhook my wideband and connect the ELD wire back and enable it in SManager to see if that is the problem.

Anyone have some suggestions?

OneBadTurboCRV

What do the logs say from the S300? You can disable all the alternator stuff completely. A friend was having similar problems and turning off everything work for a while but it ended up being his alternator was failing.

PR8urVtec

iTrader: (1)

I disabled the ALTC in Smanager and it did nothing for me. I don't have an ALTC wire in my harness at all. It's a stock wiring harness so I'm confused. Spunkster on HONDATA said that the ELD should not affect my problem. I guess I'll try to exchange the alternator and see if that is the problem. I wouldn't be worried about this to much if the voltage wouldn't start dropping in the 11v range If I idle for a while (mostly worried about being stuck in traffic and my battery going out. Eventually I will start to have fuel problems if the volts get to low. It just seems like the alternator is not working at idle with my headlights on.

OneBadTurboCRV

Yes, but what do the logs show? I have seen issues where the voltage would mess up after certain alternator controls would try and kick on. Sorry for be vague but I don’t have SManager open in front of me right now.

PR8urVtec

iTrader: (1)

Send me your email and I'll email you a datalog from tonight. I have a long drive and datalog.

PR8urVtec

iTrader: (1)

Hey I sent you an email with my calibration file and datalog.

VegasInvasion

I think this is most likely mechanical, either the alt needs an overhaul or the belt is just loose and may not be making noise (fluid leak perhaps).
The ELD doesn't detect voltage - just current - it doesn't regulate the alternator. So you could be getting a voltage drain from improper wiring, corroded terminals, defective auxiliary electronics (alarm?) or a bad battery.
I've also seen a couple cases where this happens strictly because the idle is too low and/or the mixture is too lean. Logically that appears unrelated, but I've seen it nonetheless.

PR8urVtec

iTrader: (1)

I'm going to check the belt. I felt it and it seemed tight but maybe it's just not tight enough. The alternator is pretty much new albeit it's from a parts store and not OEM. I will see if I can find a flowchart on troubleshooting the alternator itself.

Wiring is stock outside of using a jumper harness at the ECU and deleting my resistor box for my injectors. No alarm installed. No electronics installed other than my oil pressure, a/f, boost gauges, and turbo timer. The battery is good and pretty much new as is the alternator. Never been on a charger other than the cars charging system.

I also thought about the idle just being to low to kick it up to 14v but the idle stays at 900rpm with or without the lights on.

I will check the alternator and update. Thanks

VegasInvasion

If even one of those gauges is defective or has a short it will cause enough voltage drain to see this problem. Disconnect them all from power just to be sure.
Additionally if your resistor box delete happens to be raising resistance or shorting to the chassis that could definitely be the cause, so a continuity and resistance check should be in order (from each injector clip to both battery terminals).
At any rate, as long as it's tuned well and the problem isn't getting worse or causing operating issues, I don't see the harm in lower voltage.

OneBadTurboCRV

Sorry for taking so long getting back to you - your e-mail went to my junk folder haha.

After looking at the logs I feel confident saying that I don't believe your belt is slipping. I understand the ELD is disabled but it is ALL over the place in the logs and helps diagnosing. IF you are confident that your grounds are all good I would definitely check your alternator/replace it. Although your battery voltage is actually low in the 11s before start-up so I would make sure it is fully charged and checks out as well. In my opinion from the way the log looks the alternator field is messed up. The longer the car ran the worse the issue got.

Also, the tune isn't the best in my opinion either, but I don't think it has anything to do with your problem.

PR8urVtec

iTrader: (1)

I didn't get it to the dyno yet. It's just a basic street tune. I'm assuming your talking about the ignition map not being the best?

I will check my grounds and bring the battery and alternator in for testing. Might have got sold a bad alternator and it should be under warranty. It's only a few months old.

Thanks for taking a look. I appreciate the feedback.

OneBadTurboCRV

No, even the AFRs are all over the place. Look at the fuel maps in 2D and you will see what I mean. No problem though, hopefully you get it sorted out. Please let me know what you find out either way.

PR8urVtec

iTrader: (1)

I guess I'm not following b/c my fueling hits my targets and I have no drivability problems. I have no lines crossing and they are pretty uniform and parallel albeit they could use some smoothing. When I datalog part throttle it averages pretty much at my target (14.2) in part throttle. It runs in closed loop off my wideband with no problems. So I'm confused how it looks all over the place if I'm hitting my target a/f. I don't see much S trim correction % happening either. Can you elaborate a bit? Just trying to figure out what I'm missing here. The datalog I sent you was in open loop. I'm trying to get the AFR closer to my target in open loop but in closed loop it sits pretty close.

I do have more work to do and by no means is this a finished tune. As you can see in the 3000rpm on little throttle I have to get the A/F closer to my target in open loop. I added more resolution to that area and need to clean it up.

PR8urVtec

iTrader: (1)

I just checked my grounds with a voltmeter and they are all good. Checked voltage at the alternator and getting 12v. What I have noticed is that with no power on I have 12.0v at the battery. With power on the voltage goes to 11.8v. Start the car for a few seconds and voltage goes over 14v and turn the car off. I checked the voltage again at the battery and it shows 12.5v and then it will slowly start to decrease to 12.4, 12.3, 12.2 ect... with no power on. I'm going to unhook the battery and see if I get the same draw on it. Maybe I have a parasitic draw going on from something.

Thanks for taking the time to help.

OneBadTurboCRV

I PMd you about it but it is sine-wavish (which could be engine issue) and some big gaps. Maybe I will send you a tune of mine to show you what I am talking about so you can compare - if I get the time.

OneBadTurboCRV

Something I didn't even look at though and I just thought about is if you are running open or closed loop? I wasn't trying to upset you, I was focusing on the charging issue and not your tune. I just glanced at stuff while reviewing the datalog.

PR8urVtec

iTrader: (1)

I forgot to mention that the datalog is in open loop ( I edited my post above) I was still working the fuel map for part throttle and should have mentioned that earlier.

No worries man. I'm not upset by any means and glad to hear feedback. I'm a big DIYer kind of guy and always looking for feedback on what I have. If you don't mind sending something to compare I would appreciate it. All I can really go off is comparing maps to see if It's looking right or not and going by Hondata's help and tech files ya know what I mean. I wouldn't consider myself a tuner by any means. But I like to do my own work b/c I have two cars on S300. One all motor and one turbo. I learn more and more each time I mess around with it. I do all my own work and don't want to rely on someone else to fix my things. There is always room for others to critique my work.

OneBadTurboCRV

A GREAT manual on how to tune is actually in this very thread. Check out VegasInvasion's Crome Tuning Manual. It is in his signature. Try not to get sidetracked with the detailed CROME stuff but pay attention to how he explains to tune for different things. He did a really good job in my opinion and deserves all the donations he gets.

There is a ruff guide on a competitor website for Preludes that gives some insight to tuning from a DIY perspective but is nowhere near as good as Vegas's.

PR8urVtec

iTrader: (1)

Good call on that write up. I will def give that a read tonight. I have read some other write up on CROME as well. I think it was different than this one. There are some other good write ups I found on D-series.org. Articles on theory of tuning and such. I find my answers in the least likely places it seems and after I read the article over and over lol.

I pmed you back.