Need some suggestions - struggling with EFI tune

D

dversaw

Member
Hi CACC Braintrust,

I've been struggling getting my Cobra tuned. It shouldn't be all that difficult with the system I have, but I'm stumped. Tried everything I can think of. It's been running great for years, but after sitting for a while during Covid, forgetting to plug it in and running the battery down to nothing (losing EFI computer settings), I can't get the idle anywhere close to a decent level when running a new tune. As soon as the engine warms up, the idle sways all over the place, down to almost nothing, where it stalls out. Now it is starting to backfire, so the mixture seems off. My first thought was old gas, but I've diluted the old gas (which there wasn't much) with new high octane. So I don't think that is it. O2 sensor seems to be working normally.

The simplified setup:
351W with a FAST EZ-EFI.

Does anyone have experience with this type of setup that would be willing to help me troubleshoot ideas?
 
I think it is still in the learning process. Drive it for a bit and see how int acts after that.
 
I have used Brake Kleen and sprayed that around the intake area. If that gets sucked in, you can hear the idle change.
 
Also exhaust leak if the O2 sensor is near the sidepipe joint. If it is leaking typically it will make the car run pig-rich.
 
I recently had a similar issue. Had to recalibrate the O2 sensors.

I have the Pro-M set up tho. Not sure how the EZ-EFI works.
 
It’s sounds like the fuel propto-energizer reciprocating idle driven transponder!
 
Wandering idle......... backfire...., unmetered air getting sucked could cause those symptoms, or O2 sensor issue? Keep us posted. Have you looked at your plugs?
 
Don Gaboury said:
So, how does one recalibrate the O2 sensors??
Click to expand...
Stand on your left foot. Put your right foot behind your left ear……oh wait, that’s something entirely different!

I have the Innovate O2 sensors. They come with a controller box that you can use. But, general rule of thumb. Disconnect the sensor from system and remove from exhaust.
Turn key to ON for ~30 secs
Turn key OFF
Connect sensor. Still not in exhaust.
Turn key ON for ~60 secs to allow it to rise to temp.
Turn key OFF.
Install in exhaust.

At least that’s what Innovate says to do.
 
Mike Holt said:
Stand on your left foot. Put your right foot behind your left ear……oh wait, that’s something entirely different!

I have the Innovate O2 sensors. They come with a controller box that you can use. But, general rule of thumb. Disconnect the sensor from system and remove from exhaust.
Turn key to ON for ~30 secs
Turn key OFF
Connect sensor. Still not in exhaust.
Turn key ON for ~60 secs to allow it to rise to temp.
Turn key OFF.
Install in exhaust.

At least that’s what Innovate says to do.
Click to expand...
Wow, I guess your sensors are heated ones.
 
I took my Fast EFI to a professional racer/tuner mechanic. He tunes race cars for a living online. In the end, he spoke with Fast technicians and friends on how to tune it. All efforts failed and replaced it with a Holley Sniper. Problem solved. I did not want to go that route, but it beats a tow truck every week.
 
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