How to use datalogging to diagnose no start after head gasket replacement
#1
How to use datalogging to diagnose no start after head gasket replacement
Hey guys.
As the title says, my turbo Miata doesn't want to start after I changed its head gasket. It's a 99, non-vvti head. The car didn't overheat, and started fine before the replacement.
Trying to diagnose what's going wrong, and was hoping to use datalogging from my Hydra nemesis 2.7 to help me.
Does anyone have any tips/pointers on what to look for in the logs, or what values to log? Any advice is appreciated.
I've already double checked timing, and have a compression tester and ignition tester on the way.
Thanks.
As the title says, my turbo Miata doesn't want to start after I changed its head gasket. It's a 99, non-vvti head. The car didn't overheat, and started fine before the replacement.
Trying to diagnose what's going wrong, and was hoping to use datalogging from my Hydra nemesis 2.7 to help me.
Does anyone have any tips/pointers on what to look for in the logs, or what values to log? Any advice is appreciated.
I've already double checked timing, and have a compression tester and ignition tester on the way.
Thanks.
#2
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Join Date: Dec 2016
Location: North of Shelburne Ontario, Canada on 100 acres
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If you simply changed the headgasket datalogging won’t help. Something isn’t connected or you have broken a wire moving things around during the work. I would follow FM’s Hydra and turbo installation guides to verify everything is hooked up correctly. If it ran before and won’t start now, it is 100% something you touched removing and installing the head. There are trigger tests, which I know nothing about, but as I said the Hydra settings should be fine. A head gasket change has zero effect on the ECU. Also, what prompted the head gasket change?
#4
Give us some more description of this "no start".
1. Does it crank when you try?
2. Are you able to check spark and how is it? (you don't need a fancy tester just another person to crank while you hold spark plug ground against any ground)
3. Are you able to check fuel (hint pull spark plug is it wet?)
4. Any connectors in engine bay not connected to anything.
1. Does it crank when you try?
2. Are you able to check spark and how is it? (you don't need a fancy tester just another person to crank while you hold spark plug ground against any ground)
3. Are you able to check fuel (hint pull spark plug is it wet?)
4. Any connectors in engine bay not connected to anything.
#7
Give us some more description of this "no start".
1. Does it crank when you try?
2. Are you able to check spark and how is it? (you don't need a fancy tester just another person to crank while you hold spark plug ground against any ground)
3. Are you able to check fuel (hint pull spark plug is it wet?)
4. Any connectors in engine bay not connected to anything.
1. Does it crank when you try?
2. Are you able to check spark and how is it? (you don't need a fancy tester just another person to crank while you hold spark plug ground against any ground)
3. Are you able to check fuel (hint pull spark plug is it wet?)
4. Any connectors in engine bay not connected to anything.
2. I used a inline spark tester to check, was getting spark. Not sure how to determine if it's strong enough, but it was sparking.
3. I am smelling fuel in the cylinders. I tried spraying carb cleaner in the intake before cranking, but did not make a difference either.
4. Feel like i've double checked every connector at least 3 times...is there any specific connector you guys would suggest connecting that could be the culprit?
#8
I've confirmed with Flyin Miata that my trigger test is working as well. I had them compare a trigger test from 12 months ago when the car started to one now when it's not starting.
They said 'the cam sync is occurring a little earlier in the cranking trigger pattern (on the no start test). However the igniter output is still solid so i don't think it's a problem.'
Which puts me back to square one. Kinda unsure how to proceed now honestly.
They said 'the cam sync is occurring a little earlier in the cranking trigger pattern (on the no start test). However the igniter output is still solid so i don't think it's a problem.'
Which puts me back to square one. Kinda unsure how to proceed now honestly.
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