Injectors go to zero when engine is running...

s300 and SManager software questions & answers
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MB_Greg
Posts: 5
Joined: Sun Jul 25, 2010 4:58 pm
Location: North Jersey

Injectors go to zero when engine is running...

Post by MB_Greg »

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?
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1995 Civic CX w/ B16A (SiR-II)
GTMcoupe
Posts: 110
Joined: Sat Dec 10, 2005 6:39 am
Location: In a Kitcar in Oxford in the UK

Post by GTMcoupe »

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
Its Small, Its Red, Its Mid engined, It has a B18 fitted, 250hp+per tonne + nitrous
MB_Greg
Posts: 5
Joined: Sun Jul 25, 2010 4:58 pm
Location: North Jersey

Post by MB_Greg »

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?
1995 Civic CX w/ B16A (SiR-II)
crucian
Posts: 199
Joined: Sat Dec 10, 2005 9:42 am
Location: Lowville, NY

Re: Injectors go to zero when engine is running...

Post by crucian »

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.
MB_Greg
Posts: 5
Joined: Sun Jul 25, 2010 4:58 pm
Location: North Jersey

Post by MB_Greg »

Cool. Glad to hear it might be a simple fix. Thanks!
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1995 Civic CX w/ B16A (SiR-II)
crucian
Posts: 199
Joined: Sat Dec 10, 2005 9:42 am
Location: Lowville, NY

Post by crucian »

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.
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