I think that 'ground' describes the result of using a mortar and pestle, while 'grounding' is the process itself.Hah, I think you did! I had the same questions and conclusions. Never thought to hard about it until I stumbled on this thread.
For your next trick, you could try to explain the difference between ground and grounding to a retired EE
I’m revoking my internet license thru the end of the week.
Grounding Cylinder Head Test Results (2024 CX-5 Turbo)
- Thread starter AL Cx5
- Start date
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- Tags
- cylinder head ground wire
AL Cx5
2024 CX-5 Prem Turbo Tuned Lowered Forged Wheels
It's gratifying you guys dove into why I'm reading 5 to 10 amps at the engine to chassis ground. The other question is why do these ground cables improve performance ever so slightly?
When I took these readings, the motor was running, HVC fan on high and headlights were on. It would have dropped about 50% if I had turned these two items off. The headlights and HVC fan motor are not attached to the engine but are part of the entire chassis ground circuit.
On my race car, we run a small nicad 16v battery. We have separate power and grounds to the ECU, TCU and coils, {16} 40,000 volt coils in this case, wired directly from the battery terminal. This avoids "noise" from electric motors like the fuel pump and radiator fan. The other devices, fuel pump, trans and rad fans and all the other sensors are powered from the battery and ground to the chassi.
The dirty circuit and clean circuits overlay each other where they attach to the battery terminals.
Maybe you will explain why this works. My theory, the battery absorbs the noise from the electric motors and the noise does not backfeed to the ECU, TCU or coils.
When I took these readings, the motor was running, HVC fan on high and headlights were on. It would have dropped about 50% if I had turned these two items off. The headlights and HVC fan motor are not attached to the engine but are part of the entire chassis ground circuit.
On my race car, we run a small nicad 16v battery. We have separate power and grounds to the ECU, TCU and coils, {16} 40,000 volt coils in this case, wired directly from the battery terminal. This avoids "noise" from electric motors like the fuel pump and radiator fan. The other devices, fuel pump, trans and rad fans and all the other sensors are powered from the battery and ground to the chassi.
The dirty circuit and clean circuits overlay each other where they attach to the battery terminals.
Maybe you will explain why this works. My theory, the battery absorbs the noise from the electric motors and the noise does not backfeed to the ECU, TCU or coils.
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- '23 CX-5 CE
The battery is essentially a big capacitor so it does filter out a lot of noise. The ECU and TCU are designed with internal filtering and grounds to block or eliminate noise from getting in or out.
I worked for the automotive electronics division of GM for 24 years. The EMI/RFI testing was the hardest part of validating a new product design.
AL Cx5
2024 CX-5 Prem Turbo Tuned Lowered Forged Wheels
That had to be interesting work!
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- '23 CX-5 CE
It was. I got to drive the first prototypes of the ZR1 while it was being developed.
AL Cx5
2024 CX-5 Prem Turbo Tuned Lowered Forged Wheels
It says alot for Mazda an automotive EE owns one.
What are your impressions of the Mazda wiring system? I've been impressed with the attention to detail, supports and attachments. I compare it to my 06 Dodge Ram diesel. The Mazda wiring makes the Ram wiring look like a high school kid wired the truck.
Maybe wiring doesn't have to be supported as often or loombed as well as Mazda. My truck just turned 20 years old. I keep repairing everything but the engine. It runs great. LOL
Also, do you replace engine management sensors at some mileage/time intervals or maybe you don't keep your cars that long? I've kept this truck longer than any vehicle. Living in Alabama, we don't have the corrosion issues. The body and frame are rust free.
I wonder if the engine block also acquires some sort of capacitive charge (due to all of the moving parts or some such) that interferes with the injectors, throttle body controls, etc., and when discharged to the frame, improves performance of the engine electrical devices. 5-10 amps of current through the ground wire is not trivial, and the engine surely must be electrically isolated by rubber mounts for the potential difference to develop? I'm not very smart with these things; Koko, any additional insight?
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- '23 CX-5 CE
I have not dug into the wiring on our CX-5, I have not had a need to do so. We usually keep our cars about 6-8 years so replacing sensors has not come into play. Being retired, I hope to keep this car longer. Our previous car was an Audi Q5 which practically fell apart (engine mounts and turbo failed) right after the warranty. It will be the last Audi we own. Our CX-5 is our 4th Mazda, all of them have been trouble free. My daughter had a 2016 CX-5 that she just traded to get a minivan for their growing family. Her CX-5 was trouble free as well.
Do you see any current at all through the ground with the alternator unloaded? This makes me wonder how the alternator may contribute to the engine ground current.
Oh, and apologies to all for my propensity to be a smart-ass at times. Its my nature, I guess!
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- '23 CX-5 CE
I have never heard or seen any capacitive issues other than stray capacitance that can be the result of how the ECM/TCM circuit board is designed. We had to be careful how signal traces were routed on the circuit board to not cause stray capacitance in circuits that were sensitive to capacitance and signal rise/fall times.
The rubber engine mounts do offer some electrical isolation of the engine block depending on the design of the mount. A rubber cushion sandwiched between an engine block and metal frame won't isolate the engine electrically if a bolt goes through the cushion and contacts the block and the frame. You do want a good connection between the block, chassis, and battery negative terminal. Wire has resistance and smaller wire has more resistance for a given length. That is why I said measuring voltage from the battery (-) to the block would be a good test of how good the block is grounded. The voltage drop in that ground path is voltage taken away from the injector, etc. that is being actuated.
AL Cx5
2024 CX-5 Prem Turbo Tuned Lowered Forged Wheels
I started replacing engine management sensors at 7 to 8 years at 100k mi on our 09 Accord. I always hand Calculate FE per tank. I noticed better FE after replacing sensors such as O2 and map. Starts were better and so forth.
I have replaced all the sensors on my 06 ram. I picked up about 2 mpg changing out engine management sensors. I changed the other sensors so I didn't have to chase CEL codes, one after another. Stuff like wheel and transmission speed sensors.
On the Cummins forum, we started comparing resistance across old vs new and counterfeit sensors. Is this a valid test? We found the old sensors OHMed different than new sensors. Parts store and counterfeit read different from new OEM sensors as well. I had a non OEM MAP sensor last about 14 months before it died. I drove about 300 miles home without a MAP sensor. My FE and power took a nosedive.
I have an efi managed drag race car. I learned that tuning with old, out of calibration sensors, the tune was effected when replacing with new sensors. On a new race engine we start with a known quality and new sensors. No parts store or from a questionable source.
Pic of SBE 6.4 for the 1st half of 2026. We will swap in a billet block mid season and either sell this one or keep it as a spare. Both engines should set records in their classes.
This max effort SBE 6.4 Hemi has (16) Ign 1A coils that produce 40,000 volts per coil. These are powered and grounded to the battery terminals. The instructions say in bold letters to ground the cylinder heads, plural, to the chassis and power/ground to the battery. Battery is in the truck or I would have shown it in this pic....
CX 5 in the background.
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RedBaron
2014 & 2019 CX-5 Touring(s), 2023 CX-50 TPP
In most cars (anyway) the alternator is grounded via the engine block, so ALL the alternator 'return' current goes through the ground strap(s).
I had said:
But this has now finally been answered by @AL Cx5's response below. If he'd said this earlier on, then given all that load on the charging system, my question would not have arisen.
Thanks for connecting the dots! Makes sense!In most cars (anyway) the alternator is grounded via the engine block, so ALL the alternator 'return' current goes through the ground strap(s).
I had said:
But this has now finally been answered by @AL Cx5's response below. If he'd said this earlier on, then given all that load on the charging system, my question would not have arisen.
AL Cx5
2024 CX-5 Prem Turbo Tuned Lowered Forged Wheels
Gotta love that attitude @RedBaron!But this has now finally been answered by @AL Cx5's response below. If he'd said this earlier on, then given all that load on the charging system, my question would not have arisen.
SO when are YOU going to turn a couple wrench and install grounds? Or you just a keyboard Mazda critic?
Have a lovely day....
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- 2023 CX-5 2.5 Turbo AWD Auto
RIP 8/23:2013 CX-5 Sport FWD Auto 120k
To be fair, I did take what I think was a hilarious tangent on the previous page of the thread. Got that social misstep out of the way prior to a major critical design review at work this week 
We eventually got there when I suggested if it could be items like the headlights being on.
Keep at the experiments all, I’ve really been enjoying the process and seeing the data shared. Going back to my self-imposed internet license revocation.
We eventually got there when I suggested if it could be items like the headlights being on.Keep at the experiments all, I’ve really been enjoying the process and seeing the data shared. Going back to my self-imposed internet license revocation.
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Indeed! There's a lot of knowledge here and now that I'm past my smart-assery, I'm learning a lot!Friendly reminder for everyone to keep it friendly...
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- 2017 CX3 AWD
The discussion was so technical that I didn't know it was less than friendly.
