Sounds promising! Now it's the annoying wait to get home from work to try it... I know the feeling all to well!
Sounds promising! Now it's the annoying wait to get home from work to try it... I know the feeling all to well!
In reply to AWSX1686 :
Yeah. And the sometimes crushing feeling of your best idea not being the solution.
In reply to NickD :
Trust me, I feel ya.
I was having electrical issues with my stock 94, and eventually gave up an sent it to the shop. Hopefully they'll find something this week. Unfortunately on your side, the MS makes that option a lot more limited. Hopefully the grounding idea works though!
In reply to AWSX1686 :
There is a shop an hour or two away that does sell, install and tune MegaSquirt (planned on having them dyno tune it), so I could probably have them figure it out, but it also puts me at the mercy of another shop as to when they will get to it. And I hate paying other people to work on my cars. But if I can't figure it out soon, I'm thinking that'll be my answer.
In reply to NickD :
I hear ya. I wish you luck tonight, keep us posted!
NickD said:Waaaaaaaaaaaaaaaaiiiiiiiiiiiit a second, I just had a lightbulb moment!
I'm running MiataRoadster's phenolic intake manifold spacer, which puts a 1/2" phenolic spacer between the manifold and the head and phenolic washers under the intake manifold nuts. So my grounds that I have on the intake are likely not grounding, correct? Last week when it was running, we had the fan thermoswitch ground to the cylinder head via a wire due to the broken sensor. Is it possible that that jumper was thus serving as a ground for other things and now that I've hooked the thermoswitch up normally, they aren't grounding properly? I think I either need to jump that thermoswitch connector back to the head or relocate those grounds off the intake manifold.
Sounds like a good place to start to me!
BTW - LS valve covers are electrically isolated...
yeah, we figured that one out after some troubleshooting...
Keith Tanner said:yeah, we figured that one out after some troubleshooting...
Are you saying this specific case, or that you encountered this before?
Knurled. said:NickD said:Waaaaaaaaaaaaaaaaiiiiiiiiiiiit a second, I just had a lightbulb moment!
I'm running MiataRoadster's phenolic intake manifold spacer, which puts a 1/2" phenolic spacer between the manifold and the head and phenolic washers under the intake manifold nuts. So my grounds that I have on the intake are likely not grounding, correct? Last week when it was running, we had the fan thermoswitch ground to the cylinder head via a wire due to the broken sensor. Is it possible that that jumper was thus serving as a ground for other things and now that I've hooked the thermoswitch up normally, they aren't grounding properly? I think I either need to jump that thermoswitch connector back to the head or relocate those grounds off the intake manifold.
Sounds like a good place to start to me!
BTW - LS valve covers are electrically isolated...
I didn't know that, but thinking about an LS valve cover, it makes sense. This is not an LS engine though.
NickD said:Keith Tanner said:yeah, we figured that one out after some troubleshooting...
Are you saying this specific case, or that you encountered this before?
We have encountered problems with attaching grounds to an electrically isolated intake in the past. Specifically, grounding to the fuel rail on an LS engine is not a great choice. I'm very curious about what you find.
Brought home my multimeter and had ~800-1000 ohms at the intake manifold bolt hole with the ground strap attached there. That seems awful high
Relocated the ground to a valve cover bolt and we have less than 2 ohms. Much better. Also ohmed out all the grounds that I touched and had less than 2 ohms at them as well. Cycled the key and everything acted normal and the car barked to life. Reset the base timing and it settles right into a 900rpm idle at 14:1 AFR. Time to street-tune. And likely scare the devil out of myself getting used to ~240whp, compared to the old 1.6L's 92whp.
Great to hear that!
It's always the grounds, isn't it?
In reply to BoxheadTim :
Reminds me of my Advanced Vehicle Electrical teacher in college hammering into our head "You can't have a bad ground. Ground can't go bad. You can't go buy a box of ground. You have a bad connection to ground." God save the student that answered that there was a bad ground when he presented us with theoretical electrical issues.
The other suggestion my father had for why it ran last weekend was that maybe the manifold studs were contacting the manifold when it was running last weekend and grounding, and then once everything heat-cycled and cooled, it shifted a little and stopped making as good of contact.
So, the moral of the story: Always check your grounds
The long version: If you run MiataRoadster's phenolic intake manifold spacer, make sure to relocate any grounds from your intake manifold to the valve cover or cylinder head.
Glad to hear it worked!
NickD said:
Brought home my multimeter and had ~800-1000 ohms at the intake manifold bolt hole with the ground strap attached there. That seems awful high
Relocated the ground to a valve cover bolt and we have less than 2 ohms. Much better. Also ohmed out all the grounds that I touched and had less than 2 ohms at them as well. Cycled the key and everything acted normal and the car barked to life. Reset the base timing and it settles right into a 900rpm idle at 14:1 AFR. Time to street-tune. And likely scare the devil out of myself getting used to ~240whp, compared to the old 1.6L's 92whp.
You should be checking with voltage drop, not ohms. A 30-gauge wire would show zero ohms but will not pass enough current to power anything heavier than an LED or two.
For testing circuits, I'm kinda lazy, I won't bother with that, I'll just get my Power Probe and put the ground clip on one end of the circuit and apply power to the other end and see if I can blow its 10A breaker. Very few automotive circuits could be unhappy with a circuit that passes the 10A test. (Air pumps, radiator fans, and of course starters/alternators need more oomph, just because it can pass 10A doesn't mean it's good... but for anything else? Works a treat)
If you want "scary", I did a plug n play install on a Certain 80s GM Vehicle (not a MegaSquirt, think four letter word that is also an acronym) and measured about 1 volt of voltage drop on the power side of the PCM, all lost in the factory wiring harness/ignition switch. So I ran a relay and a 10 gauge wire straight from the battery. I want to do that to ALL aftermarket PCM installs now.
Knurled. said:You should be checking with voltage drop, not ohms. A 30-gauge wire would show zero ohms but will not pass enough current to power anything heavier than an LED or two.
I think there's a bit more process required here. Measure resistance FIRST, and if it's low THEN try to measure voltage while operating. With a resistance this high you won't get a voltage that means anything.
Matthew Kennedy said:Knurled. said:You should be checking with voltage drop, not ohms. A 30-gauge wire would show zero ohms but will not pass enough current to power anything heavier than an LED or two.
I think there's a bit more process required here. Measure resistance FIRST, and if it's low THEN try to measure voltage while operating. With a resistance this high you won't get a voltage that means anything.
Sure you will. Turn the key on and measure the voltage between the intake manifold and the negative battery cable. It should be close to zero. If the ground was completely open, you'd see battery voltage, since the "load" in the system is the internal resistance of the voltmeter.
It lives again. I will admit, I wish Rotrex superchargers sounded cooler. It just sounds like a noisy A/C clutch. Not sure why "quiet operation" is listed as an advantage
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