BattV Noise MSPNP / Standalone Help

[Tyler_240]

FIXED: I bypassed the +12V signal going to the coilpacks and added a switched relay w/ power from battery and the jumpy voltages have disappeared...


I hate to admit it, but I am pretty close to being defeated by this problem with my S13 SR in S13 Auto to 5SPD. I appreciate any advice or guidance.

Problem: I have been experiencing a jumpy voltage with Key ON Engine ON for a couple months according to my ECU log. I have noticed it effects my PW% and it concerns me. Otherwise, driving / AFRs are fine. I daily it. Key ON Engine OFF steady voltage. When I pulse my e-fans, fuel pump, lights, etc...steady voltage. I get steady voltage with my DVM at Battery and minimal -/+ when moving Ground Probe to engine, chassis, etc..14.2v steady with Engine ON.

ECU is seeing 13.3ish pulsing to 12v, each period.

Things left to check: Coilpacks & Injectors (I want to pulse them with Key ON Engine OFF and see if I get noise, checked resistances and they are within spec).

Nothing I have changed up to this point has made any noticeable improvement, nor has it made the problem worse. Zero Change good or bad.

What do you think?

Grounds
Battery (-) -> Frame Rail.
Intake Manifold -> Frame Rail
Alternator Chassis -> Factory Harness & Battery (-) (Tried Frame, no change)
Harness Grounds -> Back of Intake Manifold
Coil Pack Ground -> back of head
Firewall to Head Ground
ECU Ground -> Isolator Post -> Battery (-)
AEM Wideband -> Isolator Post -> Battery (-) (Tried Engine Ground as well, zero change, left it on post so it can float with battery)

I installed a Bus Bar for (+) with a very short leg from the Battery (+) to the bus bar. I have my e-fan, fuel pump, and alternator wires running here. I have replaced the wires, etc..no change.

I have cleaned every ground point with a dremel, even the back of the new alternator where they painted it.

Parts I have replaced since the issue occurred, meaning, I had the problem before/after with minimal change good or bad.

Fuel Pump Wiring (Walbro 455LPH + Deutchwerks Relay Kit)
Battery (Odyssey P680 + Factory Location)
Alternator (Quest)
Wiring Specialties OEM Engine, Coilpack & Transmission Harness.

I have a MS-PNP for the SR20 and I have the latest firmware. I also have the defaults for Battery Voltage Calibration. I have re-pinned the optional serial connector, with no change.

I have even disconnected my boost controller (MAC Solenoid), E-FANS, Boost Gauge, A\C Controls, Radio, at the same time, etc...with zero change.

I'm focusing on ignition / injector related noise at this point. Anyone with a Megasquirt or any standalone for that matter have any advice or experienced this before?

F&*# electrical gremlins

[Tyler_240]

It does it idling, under load, and cruising. There are times where it holds steady for 10s or 30s, however, I am unable to duplicate those conditions and cannot determine a known good to figure out why it smooths out, etc...

[OnTheChip]

looks like a voltage regulator issue. Have another alternator you can swap in, or have your alternator tested?

[Tyler_240]

My original sr alt was fine, i just wanted to upgrade. I have tried both alternators, no change. I even warrantied the quest alternator so its had 3 different alternators...same issue

[OnTheChip]

It might be a problem with the ECCS relay. Try swapping the ECCS relay with the fuel pump relay.

[Tyler_240]

It might be a problem with the ECCS relay. Try swapping the ECCS relay with the fuel pump relay.

I swapped the relay and it it did make a noticeable improvement. Its not perfect, but very much improved. Check it out.

I'll replace the relay itself and check back in. Really appreciate the help my friend.

[OnTheChip]

Might also check the relay socket connections for corrosion.

[Tyler_240]

Alright, I inspected the socket and wiring and did not notice any problems. Replaced the relay, no change.

The ENG CONT 10A fuse was blown, replaced it, no change. Weird?

Probed the ENG CONT 10A and FUEL PUMP 10A with ENGINE ON and noticed they were both getting about 13.8v, but every adjacent fuse I see 14.2v using Battery (-) or Chassis GROUND

The Fuel Pump is on the ECCS Circuit, correct?

Checked my fuel pump wiring and the blue/red wire coming from the pump was pretty warm. I had it ran as a CHASSIS GROUND and my relay grounded to the same spot.

My 12v Fuel Pump wire going to the battery (+) had a voltage drop from the 13.8v at the fuse to about 13.4v. It did not appear to be jumping, it was steady voltage.

I reverted the fuel pump wiring back to factory. Engine ON 12v at the pump, but now the MSPNP was only seeing 12v falling down to 11v and jumping same as before.

Changing the Fuel Pump wiring directly effected the ECU BattV reading.




Finally, I rewired the fuel pump back to the hardwire setup using the relay, except the blue/red wire I ran to the factory ground wire. It appears that the blue/red and black wire tie into the same GROUND in the harness.

Took it for a drive, same jumpy voltages, but seeing 13.6v~12.4v and there is a noticable improvement in the jaggedness. but it is still jagged 90% of the time. blue/red wire was no longer getting hot.

#stumped240life

[Tyler_240]

bump. I replaced the E.C.C.S. Relay with a new one, no change.

I started checking continuity at the ECU Harness connector. I noticed pins 46/109 had no power.

#46 - Red - ECCS backup power, connect to constant power
#109 - Red - Reverse electrical flow return circuit (alternator fail input), connect to constant power


It looks like my engine harness is missing the red wire on the grey plug by the battery. But it is on the chassis harness connector side.

I emailed DIY to see if the mspnp does uses these as i cant seem to find a circuit pinout diagram for my ecu.