Earth / Grounding for 2ZZ Exige

[DrSuds]

Ladies and Gentlemen 

I’m working on isolating an issue with a 2ZZ NA Exige. I’ve had an issue where the TPS drops out. Reading and seeking advice everywhere, I’m suspecting it’s a grounding issue. Having read about other hallmark grounding issues, speedo dips periodically, starter awhile back fired but wouldn’t turn over until multiple attempts. This leads me to believe there’s a grounding issue that the aftermarket ECU is sensitive to fluctuations. 
 

I’ve checked the diagrams for the grounding routes. Additionally I’ve noted the VVT solenoid on the pulley side is grounded to the fuel filler neck point, potential ground loop. I’m seeking the following advice,

 

- Should both VVT solenoids be grounded?

- Additional ground from ECU plate to the frame still advised as an improvement?

- Any common failures to inspect other than regular corrosion?

- Any potential improvements to be made over the OEM configuration?

 

Appreciate the help in advance. 
 

Suds

[Andy wright]

Diagrams that I have show the VVT as two wire oil valves, with Green/pink as the 12V supply and green/ orange and grey/ blue as the connections to the ECU . No extra Earth. 
As for your other problems, they smell like earth issues. Start with the battery terminals. Take them off, Clean them really well and. Re connect . Earth points. The main one in the engine bay is in the nearside chassis rail. Remove it. Clean all the ring terminals that go to it , really well, then reconnect . The one at the front is near the bottom of the heater box housing. That will be a dog to get at , so start with the others and see if you get any change .

 

[Andy wright]

Oh. You mention aftermarket ecu . Which one? And no,under normal circumstances the ecu casing should not require a separate Earth . 

[DrSuds]

Thanks for the response Andy. 
 

It’s the ECUMaster Black series. It’s okay as a bit of kit, nowhere near as slick as the Haltech I have on the S2K. 
 

The VVT ground one is external on the loom. Little spade connector that goes to the body of the solenoid (gearbox side unit). The car had one on VVT pulley side, which feels like a Celica hangover. 
 

Thanks for the advice on the grounds. In preparation I’ve bought some 16mm2 cabling to add some heavier duty grounds. Car is used for hill climbing, and will be checked regularly for fatigue. I expect the front ground to be difficult looking at the diagrams. I guess that’ll be a clam off job to sort. 

[DrSuds]

Main ground strap not super pretty. Made up some double 16mm2 lengths to replace. Will re-terminate the battery negative as that doesn’t look amazing either. Noticed there’s a small ring terminal on the effective star point, which goes into the body loom. Not sure what that one references. Will keep y’all posted on progress. 

[DrSuds]

Sweet Louise, here’s a catch boysies. Ground wire from the loom, likely the signal GND, on a double nutted stud. Rear nut on the plate side is painted. Can’t be helping. 

[Andy wright]

Good photographs.Those grounds are not ideal. They really do need to be clean and bright. A 0.1v Earth offset is more than enough to mess up a throttle pot voltage . 

[Lithopsian]

For an electrical connection to the chassis, you really want to sand down the contact patch to remove any anodising.  The S1 uses a special stepped alloy washer, over a non-flush rivnut, so that the ring terminals make good contact with the chassis.  Connecting through a nut probably isn't great even if it is clean steel.  Maybe the stud has good electrical contact already, but who knows?

[DrSuds]

I cleaned the studs with brake cleaner, wire brush, red scotch brite and finished with electrical contact cleaner. I also used an anti-shake washer as semi cutting tool to cut the surface back between cleaning. Likely as good as they can be. Reassembled the grounds with new ground straps with fresh nuts and anti-shake washers. Car started and runs without issue, TPS was stable throughout. Will need a bit more time to confirm all is well.
 

Appreciate the feedback chaps. 

[Andy wright]

Glad all,is sorted.