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1999 Honda Civic Dx Sedan
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Discussion Starter · #1 ·
I'm nearly finished with the mini me swap for my 99 dx auto sedan and was wondering if running the p2e ecu for a little while will hurt anything aside from not having vtec. Should I run the y7 injectors til I get the new ecu?
 

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match the injectors to the ecu.

y7 injectors will only work with a Y7 ecu.


If you swap to any other ecu in the civic or integra lineup, yopu can run any of the 92-00 civic or integra injectors, as they are 240cc versus the Y7's 190cc injectors.



So for the time being, yes, you can run the y7 injectors and ecu and just be sure to NOT rev it beyond 4000-4500 rpms, where the ecu is gonna wonder why the engine is starting to run super rich due to the limited airflow.
 

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1999 Honda Civic Dx Sedan
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Discussion Starter · #3 ·
match the injectors to the ecu.

y7 injectors will only work with a Y7 ecu.


If you swap to any other ecu in the civic or integra lineup, yopu can run any of the 92-00 civic or integra injectors, as they are 240cc versus the Y7's 190cc injectors.



So for the time being, yes, you can run the y7 injectors and ecu and just be sure to NOT rev it beyond 4000-4500 rpms, where the ecu is gonna wonder why the engine is starting to run super rich due to the limited airflow.
Why would it start to run rich with stock injectors and fuel map? If anything wouldn't it lean out slightly due to the bigger y8 cam and higher flowing head? Just want to make sure I'm understanding how everything works, this is my first Fuel injected project car.
 

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93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
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The low speed lobe is actually a tad bit smaller on the vtec cams, but the real issue is after where vtec shoukd kick in, since the vtec does not engage the higher lift lobe and the y7 lobes are a tad larger than the low speed lobes on the y8 the ecu thinks more air is flowing than actually is. these systems calculate air entry into the engine based on throttle position sensor and intake air temp sensor data, so when changes are made like cams, throttle bodies, ect they can only trim so much fuel before they throw a code. But if you are driving it easy and keeping rpms under 4200 or so you should be ok, might be just a tad slow on hot starts.
 

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Run the y7 ecu and y7 injectors for now until you wire up vtec and do the final switch to the y8 ecu and y8 injectors.

Pinch the fuel return line if it runs lean enough to run like shit.

Keep rpms below 4k

Or run the y8 ecu and y8 injectors, and with the vtec solenoid not wired up, the ecu will know it is gone, and not try to engage vtec or the fuel and ignition map of vtec.
 

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Discussion Starter · #6 ·
The low speed lobe is actually a tad bit smaller on the vtec cams, but the real issue is after where vtec shoukd kick in, since the vtec does not engage the higher lift lobe and the y7 lobes are a tad larger than the low speed lobes on the y8 the ecu thinks more air is flowing than actually is. these systems calculate air entry into the engine based on throttle position sensor and intake air temp sensor data, so when changes are made like cams, throttle bodies, ect they can only trim so much fuel before they throw a code. But if you are driving it easy and keeping rpms under 4200 or so you should be ok, might be just a tad slow on hot starts.
Strange according to my Haynes manual
Y7 cam
1.3897 intake
1.4678 exhaust
Y8 cam
1.4479 primary intake
1.5068 mid (I assume vtec lobe)
1.4592 secondary intake
1.4964 exhaust

Then again I guess that doesn't account for overlap or duration really, so I suppose that makes sense.

Run the y7 ecu and y7 injectors for now until you wire up vtec and do the final switch to the y8 ecu and y8 injectors.

Pinch the fuel return line if it runs lean enough to run like shit.

Keep rpms below 4k

Or run the y8 ecu and y8 injectors, and with the vtec solenoid not wired up, the ecu will know it is gone, and not try to engage vtec or the fuel and ignition map of vtec.
I've got a vtec solenoid coming in the mail but I need to wait a few weeks to be able to afford the ecu. Return line is the one with the regulator on it correct?
 

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rocker ratios are different as well. example, if you have 1.0 inches lift with a 1.5 ratio rocker, it will act the same as a 1.5" lift and 1.0 ratio rocker

dunno how different they actually are, but slightly.

Yes, return line is the regulator side, as the regulator closes it off to raise the pressure. Dont get too finicky here, only do it if the car acts up. It is very easy to run too rich doing this and foul up the plugs
 
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