350GC

Sorry for the long read, if your Z is having problems with hesitation, it may help out.

My 07 HR hesitated around 1500 rpm, regardless of if I was taking off slow or punching it, no CEL and idled perfectly. Not necessarily in this order I did plugs, air filters, cleaned throttle bodies, tracked down and replaced a lazy A/F sensor, cleaned the MAF sensor, checked for vacuum leaks, Seafoam thru the brake booster, replaced the PCV valve, reflashed the computer, checked the VTC solenoids and probably a couple more things im forgetting. One thing I found was that my fuel trims were running unusually high and for some reason I couldnt get the car in throttle body relearn mode.

It wasn't until I saw a thread where people were claiming to have seen performance gains from those aftermarket grounding kits and others were calling foul that a ground kit cant yield horsepower. (They were both right) While the grounding kit wont produce a performance gain to an already properly grounded engine, it is possible to restore original performance back to a vehicle that has a grounding issue.

(The fix)
I set my fluke to ohms and checked first from my neg battery post to the battery clamp, as expected 0.0 ohms. Then I went from my neg battery post to the engine, 1 ohm, ah ha, that's an issue. Then from neg battery post to chassis, again 1 ohm. After looking for a minute I realized that the factory grounds were all grounded to painted surfaces. This is not good. I then removed the grounds listed below, sanded and cleaned the connection points and tightened them back down, this time bare metal to bare metal. At this point I now had 0.0 ohms from neg battery post to chassis and engine. I hopped in the car and it immediately went into throttle body relearn mode. I followed the steps, carried it down the road and it hasnt hesitated in weeks now.

Battery chassis ground (right next to the battery)
Two engine grounds (top of the engine on the front)
Two engine chassis grounds (drivers side inner fender toward the front)
Chassis ground (passenger side inner fender toward the front behind washer fluid)

amr_electron

iTrader: (8)

Thanks for sharing,

But maybe it was just the ECU reset that happened after disconnecting the ground terminal !

carbuffguy

"my neg battery post to the battery clamp, as expected 0.0 ohms. Then I went from my neg battery post to the engine, 1 ohm, ah ha, that's an issue. Then from neg battery post to chassis, again 1 ohm."

350GC

Nah, disconnecting the battery was probably the first thing I did when I started noticing the hesitation. Probably did it about a thousand more times throughout the troubleshooting process.

Also, forgot to mention, after correcting the grounding issue, all fuel trims are now within spec.

rancor

It's better to check the voltage drop across the connections than trying to directly measure resistance assuming there is current flowing through them. Directly measuring the resistance will be prone to errors as you will also be measuring the resistance of the probes and their contact resistance. If you have a DMM capable of 4 wire resistance measurement this would be best.

Otherwise take your multimeter and connect the probes to one bolt on the ground strip. This reading should be the resistance of the probes and their contact resistance. Null the meter to this reading or manually subtract this from your readings. It would be good to take this measurement a few times until you figure out what force you need to press the probes with to get consistent readings.

The truth is most 3.5 digit multi meters will not be able to read the resistance of a short wire like this but may be able to catch a bad connection.

TLDR: If you are having this problem and your multi meter isn't showing high resistance it still might be good to try cleaning the connections as your meter is likely not accurate in the 100s of milliohms.

A-Town-Z

iTrader: (4)

I'm having the exact same issue with my Z. Hesitates at 1500rpms, regardless of how much throttle input. I'll have to give this a shot before I have my tuner take a look at it.

A-Town-Z

iTrader: (4)

**UPDATE**

Installed a 6 point grounding kit. 4ga wire. Additional to the factory grounds. And the hesitation is gone. My volts are reading ~14 constantly. Starts are good as well.