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1994 turbo hatch
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110 Posts
Discussion Starter · #1 ·
hey all. i got a problem with my fuel injectors. i installed 440cc injectors, and got them to idle ok but never get it to drive. i found out that the walboro 255 pump i had was bad so i swapped the stock one (worked when i pulled it a week or so before) and it wouldn’t run on the 440s so i swapped those back to the stock ones too and it ran fine but i didn’t drive it. i bought some ebay 550cc injectors (they sent 850s lol) and i installed those and it ran great for about 5 minutes and the suddenly died and wouldn’t start again. i put the stocks back in and same thing. ran for 5 mins then died.

don’t even know where to start
 

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Registered
93 Civic HB SI
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1,309 Posts
Were the 440's you installed saturated/high impedance type, or peak and hold/low impedance?

The physical coils inside the injectors are different between the two types, low impedance injectors will ohm out using a multimeter between 2-4 ohms, high impedance between 10-14 ohms.

If you installed low impedance injectors without installing a resistor box to accompany them, you very well could have damaged the injector driver transistors inside the ECU.

Also, the ebay injectors (unless from a reputable brand) are 95% junk and a complete waste of money. Zero quality control on the electrical or the flow rate characteristics from the cheap chinese crap brands.


Also, when you're swapping these injectors around, are you recalibrating the ECU for the size differences? Do the injectors come with a dead time slip? Initial sizing parameters programmed to the ECU is important, but also flow rate and duty cycle characteristics when the engine starts to warm up change between injector types. Usually when you install different injectors, especially between different flow rates or electrical design types, you really need to retune idle fuel using the ECT correction modifiers.

Do you have a wideband to be able to retune idle fuel correction? When the engine starts to die at 5 mins, what does air/fuel do when it starts to die? Does it lean out hard or run pig rich?

Has this car ever been tuned?

Does any of what i just said sound familiar? If not, go directly to a tuner, do not pass go, do not collect 200 dollars.
 

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Registered
1994 turbo hatch
Joined
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110 Posts
Discussion Starter · #3 · (Edited)
Were the 440's you installed saturated/high impedance type, or peak and hold/low impedance?

The physical coils inside the injectors are different between the two types, low impedance injectors will ohm out using a multimeter between 2-4 ohms, high impedance between 10-14 ohms.

If you installed low impedance injectors without installing a resistor box to accompany them, you very well could have damaged the injector driver transistors inside the ECU.

Also, the ebay injectors (unless from a reputable brand) are 95% junk and a complete waste of money. Zero quality control on the electrical or the flow rate characteristics from the cheap chinese crap brands.


Also, when you're swapping these injectors around, are you recalibrating the ECU for the size differences? Do the injectors come with a dead time slip? Initial sizing parameters programmed to the ECU is important, but also flow rate and duty cycle characteristics when the engine starts to warm up change between injector types. Usually when you install different injectors, especially between different flow rates or electrical design types, you really need to retune idle fuel using the ECT correction modifiers.

Do you have a wideband to be able to retune idle fuel correction? When the engine starts to die at 5 mins, what does air/fuel do when it starts to die? Does it lean out hard or run pig rich?

Has this car ever been tuned?

Does any of what i just said sound familiar? If not, go directly to a tuner, do not pass go, do not collect 200 dollars.
they are all high impedance and i have been adjusting the battery offsets as needed

yes i have been recalibrating the ecu

i do have a wideband but it’s not setup to data log yet

it suddenly leans out then dies

i made a basemap that ran ok for about 20 miles before the fuel pump gave out but never had a full tune. i plan on tuning it with stock injectors first if i can get it to run

EDIT: thinking it might be a fuel pump issue again. pump priming sounds weird and i cracked the service bolt and not much pressure there but idk.
 
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