Hondata

This isn't a Hondata issue, but I'm hoping the attached Hondata datalog helps diagnose my problem:

The car has a big choke/stutter after it coasts down in gear and I try to open the throttle. If I disengage the clutch, it "clears" with a rev, and it never stalls, but the choke is really violent. Even if I'm steady cruising on the freeway, if I lift and then get back into the throttle, it will choke.

Chokes on the datalog:

9.7s
26.7s
55.9s

Why would the injectors go to zero while the engine is running? What could be causing this? I don't see a correlation between any of the sensor values and the choke, except it seems like high manifold vacuum (over -24.8"/psi) might have something to do with it. I have the same symptoms with a stock P30 ECM.

About the car: Stock B16 with 9.5lb flywheel (Exedy.) Exhaust is all new OE components, but original-sized Civic CX (~1.5") New OE fuel pump, new distributor, new main fuel relay, new throttle body with new sensors, Rywire mil-spec harness.

Could the exhaust be restrictive enough to shut off the injectors?

I cannot look at your datalog here [at work] but the injectors shut off on overrun, have you got the tps set up correctly? and the settings for the overrun setup correctly.

West

Thanks for the reply West.

I have not changed any values in the "TPS" button in Parameters. I'll set the Scale TPS values (they're currently at -0.14% min and 99.98% max), but I'm not sure where to begin to tune the Overrun Fuel Cutoff (MAP) values. I don't drive the car much on the street, so I'll trade some mpg and popping on deceleration for response.

How do I go about tuning the Overrun Fuel Cutoff? Just trial and error?

MB_Greg wrote:This isn't a Hondata issue, but I'm hoping the attached Hondata datalog helps diagnose my problem:

The car has a big choke/stutter after it coasts down in gear and I try to open the throttle. If I disengage the clutch, it "clears" with a rev, and it never stalls, but the choke is really violent. Even if I'm steady cruising on the freeway, if I lift and then get back into the throttle, it will choke.

Chokes on the datalog:

9.7s
26.7s
55.9s

Why would the injectors go to zero while the engine is running? What could be causing this? I don't see a correlation between any of the sensor values and the choke, except it seems like high manifold vacuum (over -24.8"/psi) might have something to do with it. I have the same symptoms with a stock P30 ECM.

About the car: Stock B16 with 9.5lb flywheel (Exedy.) Exhaust is all new OE components, but original-sized Civic CX (~1.5") New OE fuel pump, new distributor, new main fuel relay, new throttle body with new sensors, Rywire mil-spec harness.

Could the exhaust be restrictive enough to shut off the injectors?

It has to be tuned out. It's a simple fix. Send me your tune. i can look at it and try to help you.

Cool. Glad to hear it might be a simple fix. Thanks!

MB_Greg wrote:Cool. Glad to hear it might be a simple fix. Thanks!

Ok I have a couple of questions. Do you have a wideband and did you try running the car in open loop to see if you had the same problem? I would say go ahead and adjust your TPS settings in the software and then go for a drive in both closed and open loop while datalogging. Oh, and invest in a wideband O2 sensor and controller.