Hesitation during acceleration

[DC871F]

Installed resistor. Any offerings on how to set it? Trial and error?

I set it mid-way and saw no change. Back it off a little, then went towards the other direction, still no change.

There is definitely a sweet spot to where the car does accelerate cleanly, flooring it acts as if a cylinder is dropping off.

Re-checked vacuum, found a small leak, but didnt change anything appreciable.

[DC871F]

Mic check 1,2..

[Zed Head]

Trial and error is the way.  With mine, I can kill the engine easily by adding too much fuel, by adding too much resistance.

The way I've set mine is just by throttle response.  At full throttle the ECU adds a lot of extra fuel via the signal from the TVS.  It's mid-range RPM and throttle that the potentiometer will have an effect.  The typical lean problem is mid-range, idle and full throttle will be fine, but mid-range will stumble and hesitate, maybe even pop back through the intake manifold.

I'm not familiar with the zcardepot device.  Do you know what the resistance range is?  Is that the one you got?

[siteunseen]

@Captain Obvious had a good chart showing the resistance of the CTS.

If you google "purrs like a kitten fastwoman classiczcars.com" she also has some good info on her Zs resistance with the potentiometer added. 

I ran mine in the cabin and tuned it by feel for a few months then taped it down.  

[DC871F]

6 minutes ago, siteunseen said:

@Captain Obvious had a good chart showing the resistance of the CTS.

If you google "purrs like a kitten fastwoman classiczcars.com" she also has some good info on her Zs resistance with the potentiometer added. 

I ran mine in the cabin and tuned it by feel for a few months then taped it down.  

Man, another great idea, thanks. I got mine up on the front of the fuel rail.

I really dont think the resistor is going to fix my problem. I tried it 10 different setting from high to low. Its the ZCarDepot resistor.

I'm waiting for a distributor to arrive to hopefully find a cure. Accelerating through the gears, by the time you are up towards halfway through 3rd, it just stops accelerating, foot buried. But if you modulate your foot, you can find the sweet spot and it will go. I swear its dropping a cylinder. Timing is correct. 

 

 

[DC871F]

44 minutes ago, Zed Head said:

Trial and error is the way.  With mine, I can kill the engine easily by adding too much fuel, by adding too much resistance.

The way I've set mine is just by throttle response.  At full throttle the ECU adds a lot of extra fuel via the signal from the TVS.  It's mid-range RPM and throttle that the potentiometer will have an effect.  The typical lean problem is mid-range, idle and full throttle will be fine, but mid-range will stumble and hesitate, maybe even pop back through the intake manifold.

I'm not familiar with the zcardepot device.  Do you know what the resistance range is?  Is that the one you got?

ZCardepot resistor. I assumed it was 10 ohms, but reading it actually doesnt say. When I get back to it I'll measure it.

[siteunseen]

If you can wire it with a male on one wire and a female on the other   and just split one wire to the ecu, speaker wire worked for me.

[Captain Obvious]

3 hours ago, siteunseen said:

@Captain Obvious had a good chart showing the resistance of the CTS.

Thanks Site!  Here's my chart:

 

[Zed Head]

3 hours ago, DC871F said:

Accelerating through the gears, by the time you are up towards halfway through 3rd, it just stops accelerating, foot buried. But if you modulate your foot, you can find the sweet spot and it will go. I swear its dropping a cylinder. Timing is correct. 

 

 

This is the most descriptive description so far.  Stuff to ponder.  Nothing comes to mind.  An alternative ,or complementary (practicing my words), description might be that it "bogs" in 3rd gear at a certain RPM, if the gas pedal is held to the floor, but picks up again if the pedal is released a bit.  It feels familiar, back from my carb'ed car days.  

When you release the pedal, you're throttling the air flow.  Maybe making it match a stuck AFM vane.  That just came to mind.  The AFM vanes have been known to get stuck.  They're delicate, meant to respond only to air.  A stuck vane would cut air flow slightly, but reduce fuel enrichment, a lot.  The air would slide by, but the ECU would only see vane position.  You might check that.

[rcb280z]

27 minutes ago, Zed Head said:

A stuck vane would cut air flow slightly, but reduce fuel enrichment, a lot.

Would the potentiometer make up for that dead spot?

[Zed Head]

I think that you'd have to make it super rich everywhere else to overcome a stuck vane.  It's more of a dead end than a dead spot, I think.  Air flow blockage might factor in also.  And it was just a thought.  Could be something else.  Never seen a stuck vane on this forum though, so that would be a new one.

[rcb280z]

Makes sense. This is a weird one for sure.