Doppelgänger

iTrader: (12)

I was wondering that. So part of that wondering spurred me to look at some of the settings/values between my old map and the one Jeremy sent me. I found a few things different- knock threshold being one, along with some of the idle speed settings. I copied some of those old values over to the new map and in my short drive, looked promising. I'll have to wait for traffic to settle down so I can find some space to go do some proper pulls and record data to see if there is any difference.

*With the new settings, idle and the droop issues with running lights/blower/blinkers has been eliminated, but CEL still comes on at full load over 6k. Its always fun to break traction in 4th on a damp road lol

Doppelgänger

iTrader: (12)

Bump. Finally got my hands on a multimeter and will be taking readings... hopefully when I get off work today. Still baffled by the CEL @ WOT over 6k issue.

Doppelgänger

iTrader: (12)

OK, I probed things..and here is what was seen. No electrical systems/draw was going on other than the car idling after a 20 minute drive. No measurements were taken when the radiator fan was cycling/on.


Alternator post + block = 15.10 - 15.15

Alternator post + chassis = 15.10 - 15.15

Alternator post + fuse panel (positive) = -.10 (steady)

Block/head + chassis = -0.02 - -0.01

Fuse Panel + chassis = 14.99 - 15.02

Battery terminals = 14.95 - 14.99
Battery positive to chassis = 14.92 - 14.96


Hydra set to 14.0v
Hydra display/reading 13.96 - 14.04



Clearly what the Hydra is set to/sees is lower than actual. But why? Is this normal? Perhaps a power/grounding issue with the Hydra itself? Would dropping the settings/reading to see "actual" values close to 14.0v be the correct/simple thing to do?

Doppelgänger

iTrader: (12)

Well, for ***** and giggles, I set the target voltage on the Hydra to 13v and took the car out real quick spin. CEL came on at a higher RPM still. Also put a new WBO2 in and AFRs are steady and not dithering. I'll get a proper log of driving/pulls and post it up later. Didn't have much time just now. AFRs are much smoother with the new WB02 though.


*added csv datalog

patsmx5

iTrader: (16)

My comments in bold.

Good. Now we have data, and problem is much easier to spot now. Looks like ECU is seeing a different voltage than your meter.

Next test:

Voltage between ECU +12V and ECU GROUND.
Voltage between Battery + and Battery -
Voltage between Alternator + and Engine Block

If ECU is getting the same voltage as battery and alternator show, I'd say your ecu is just reporting the wrong voltage for some reason. If so, I'd just adjust the "target" to whatever gives you the correct voltage at the battery and alternator.

If the ECU is in fact getting about 1 Volt less than the battery or alternator shows, then you got a wiring problem.

My guess is you meter is right, and you have a wiring issue causing the ECU to actually get less voltage than it should. If not, then the ECU is just off a bit in which case I'd adjust the target in the ECU until the system voltage reaches what you want.

SOOO much easier to help now that we have a meter and data!

fredb

iTrader: (1)

Subscribed ! I've been dealing with a similar problem . Hydra voltage reads less than measured, weird afr readings . A new O2 sensor helped for a while. New NA alternator ( Hydra not controlling voltage regulation ) . Hope your able to solve this and I can apply your solution. I'm about done for the season , getting frosty here in the mornings now and the R1Rs don't stick so well ! Good Luck . Fredb

codrus

My Hydra (2.5) always read half a point below a voltmeter at the battery. My MS3 does the same.

--Ian

Doppelgänger

iTrader: (12)

Wow, sorry, just saw I had replies.

I already did batt +/-, and alt -> block.

Ugh, so the car has started a new problem. Since all of this started, starting the car has been slow...like a low/dying battery. On several occasions now, it won't even attempt to turn over...just nothing when the key is turned. On a couple of occasions, it has done a slow turnover and after letting it sit for a few min, turns over and fires up. On the times it hasn't turned over, I put the multimeter on the batt and saw 12.8v or so.

I'll measure the ECU voltage when I get home today.

Come to think of it, this all started when I got a new base map with R28 f/w upgrade. Is it possible to undo the f/w update? Hmmmm

Braineack

iTrader: (62)

your ECU voltage should match what you're seeing at the injectors, not the battery.

Doppelgänger

iTrader: (12)

Will take that advice and check mine when I get home. I'm also going to try to find R35 s/w and R27 f/w to go back to, to see if anything changes. I'm starting to wonder if something is mixed up or if a change/setting from to the other is causing a problem.

patsmx5

iTrader: (16)

I know you did, I read your reply.

I said measure those 3 voltages at once as they are relative. If you measure ecu voltage today at 13.2V that doesn't tell us much since we don't know if the alternator is at 13.2 or 15.0. We're looking for a voltage drop so conditions/time when measurements are taken for comparison have to be as identical as possible. Ideally you'd measure voltage at all 3 places at once, but that's not practical with 1 multimeter.

So trust me when I ask you to measure something, it wasn't an accident or oversight.

Doppelgänger

iTrader: (12)

Oh, I see. The measurements I took were all done back-to-back in a 5min time frame.

Wouldn't a battery with 12.8v at least turn the engine over? The low power-ish sound cranking is really f*ing weird.

patsmx5

iTrader: (16)

Measure battery voltage while it does this. If the battery has good voltage when this happens, you've got a voltage drop happening somewhere. Bad ground, bad contacts in the starter solenoid, loose wire in starter, battery post connection bad, etc. Somewhere there's an issue. If the battery voltage drops to crap when it won't crank, battery is just low. Why is it low? You'll have to figure out the cause.

Doppelgänger

iTrader: (12)

Yeah, my next step is to monitor batt. voltage during start up (successful and/if on a no-start condition). So I had the ECU set to 13v target, and the batt w/car off was showing 12.8v , I bumped target up to 13.5 to see if the batt/slow crank would change. Did a 2 hour drive....no difference after the bump.

I really want to downgrade to r31 s/w because that's when this all started , but I can't figure out what previous map f/w was before R85...and where I'd find it to go back.

Joe Perez

iTrader: (8)

Batteries can fail in very interesting ways.

Float voltage, by itself, is not an adequate indicator of the battery's ability to power a given load. While lead-acid batteries typically have a very low internal resistance (which is what makes them great for starting engines in the first place), their internal resistance can greatly increase with age. Primary culprits here are to sulfation (the accumulation of lead sulfate crystals on the cathode surfaces) and less commonly, corrosion / dissolution of the grid plates themselves.

In such a battery, the unloaded (float) voltage will appear normal when the battery is full charged. But under load, the voltage will drop much lower than is typical of a normal battery.

Or, you gotta measure it while cranking.



FWIW, 13v is *way* too low for normal charging of a lead-acid battery. Ideally, you want around 2.3-2.35v per cell. That comes out to 13.8 - 14.1v for a 6 cell "12 volt" battery. If you've been charging at 13v for a while, you've probably killed the battery. Undercharging is a primary cause of hard-sulfation.

codrus

Well, the ECU has control algorithms that care about the voltage at the battery (for alternator), injectors (for fuel trim), coils (for dwell trim), and probably a few more I can't remember right now. They're all different on my car, by a few tenths of a volt. The differences aren't completely linear, either.

That said, there aren't any obvious problems caused by this.

When cranking, the voltage at the ECU does this:



The MS3 appears to have enough capacitors in it to ride it out, although the LC-2 controller resets which is sort of annoying.

--Ian

Doppelgänger

iTrader: (12)

Thank you for the info Joe. While target voltage on the ECU is set to 13, actual measured voltage is 14v on the battery with the car idling. I've not run the car with the system less than 14v.

Dammit, I'm anxious to leave work so I can start digging in on this.

Doppelgänger

iTrader: (12)

OK- car did a slow turnover/no start, and a "not ****" when turning the key. Since I didn't have a hand, I took some video of the multimeter.

Slow crank/no start- Starts at 12.78v, when cranking it drops to 11.15 (dithers +/- .2v until I stop cranking...where it jumps back to 12.7v pretty quickly.

On the "not **** happening" start, it started at 12.64v and when trying to crank, it drops to 12.18-12.22v.

W T F ????????????

aidandj

iTrader: (5)

Starter solenoid going bad? Can you bypass it.

patsmx5

iTrader: (16)

Bad connection somewhere in the starting circuit. I'd start by checking all the grounds and power wires that go to the starter.