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Discussion Starter #1 (Edited)
Mazdaspeed mx5 Denso 321cc 23250-74050 injector info

I have been tracking these Denzo 23250-74050 injectors down & I am pretty sure now that they come from a 88-89 Toyota Celica GTS Sport L4 2.0L 3sgelc.

I purchased my injectors from rockauto.com & they got them from GB Remanufacturing. I asked Rock Auto to ask GB Remanufacturing how many Denso 23250-74050 injectors GB Remanufacturing had left in stock & they said 10. I purchased 4 of the ten. I also asked Rock Auto to confirm with GB Remanufacturing that the part number on the injector was 23250-74050 because these injectors come from a specific car.

http://www.rockauto.com/

People who have installed these injectors on their Mazdaspeed mx5 say they are the largest injectors you can use with the stock ECU & they help get rid of the lean air fuel ratio the Mazdaspeed mx5 ECU has at lower rpm's.




Mazdaspeed mx5 Denso 321cc 23250-74050 injector green tops from 1988 1989 Toyota Celica GTS Sport L4 MFI (S) 1998cc 2.0L 3sgelc










To make it easier for other Mazdaspeed mx5 owners who are interested in installing these injectors on their MSM to track these injectors down I provided the car they came from & info about it so they can narrow down their searches.

Engine Type: L4
Engine Size: 2 liter
Fuel Type: GAS
Engine VIN: S
Eng Desg: 3SGELC
Country: USA/CAN

Toyota 1988 1989 Celica GTS Sport L4 MFI (S) 1998cc 2.0L 3sgelc

According to toyotacelicaonline, the LC designation would mean Laterally mounted California Emissions, L means laterally mounted & C means California emissions. I think the reason these injectors are so hard to come by is because the engine # has a California emissions designation in it leading me to believe they may have been sold mostly in California

I called Aus injection & talked with a man there & we talked about the injectors he said he had two left. I was wandering if they were 320cc injectors so he was kind enough to do a flow test on one of the injectors he had & he said they were 320cc @ 43.5 psi.
AUS injection says they have two of the Denso 23250-74050 injectors left in stock.

http://ausinjection.com/

If the moderator of mazda-speed.com could lift the life sentience over petty stuff, I could share information I know with my other mazdaspeed mx5 owner brothers & sisters that I know would be interested in it. Being that there is not that many of us mazdaspeed mx5 owners to share info with one & other, the more information the better.
 

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Discussion Starter #2
The difference between the stock injectors & the Denso 321cc 23250-74050 injectors.



 

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Discussion Starter #3 (Edited)
Start engine & unplug fuel pump relay (below), wait for engine to stall, then turn ignition key to off. Fuel system is now depressurized. On 1994 & later models fuel pump relay is above accelerator pedal.



I removed throttle body (below) to get to intake manifold bolts that were below the throttle body. I cleaned the throttle body a little while I had it removed.



I removed the exhaust gas recirculating valve (pictured below) near the end of the fuel rail.



Intake manifold metal seal. (below)



Intake manifold (below)



While I had the intake manifold off I used a wire brush to brighten it up then used some chrome tools to shine it up by rubbing the chrome tools over the surfaces.





Fuel rail spacer/bolt holes up close and fuel injector bores up close



Fuel rail spacers & bolts (below)



Fuel injectors stayed connected to the rail as I removed the fuel rail & injectors from the engine.





Inside fuel rail (below)



Fuel injector electrical connector (below)



 

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Discussion Starter #4
A picture of what the fuel injector looks like fully seated in the bore

 

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Ok I went on a few drives & my first impressions of the denso injectors are

1. The denso injectors do not get rid of the hesitation before the ECU goes into open loop mode. I dont think getting any injector will fix the ECU pre open loop hesitation problem. The ECU needs to be fixed some how if that is possible or the ECU needs to be replaced or you can disconnect the throttle position sensor.

2. The larger injector size seem to supply more fuel as to be able to run more boost than stock injectors.

Im glad I got the injectors so I can run higher boost than the stock injectors.
 

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Nice write up. Good info and pics!
 

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Nice John!

This is very helpful. I am surprised you did not feel any difference during the closed-loop fueling cycle. Others report that these will lessen the effect. At least you can safely run a few more pounds of pressure. :) What are you going to set boost at? 12-13?
 

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Discussion Starter #8
Nice John!

This is very helpful. I am surprised you did not feel any difference during the closed-loop fueling cycle. Others report that these will lessen the effect. At least you can safely run a few more pounds of pressure. :) What are you going to set boost at? 12-13?
I have a water meth kit that allows me to run 2 to 3 more psi than you can with injectors alone. Im already at 14.5 psi.
 

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I used this guide to install my Denso 321cc injectors tonight. I think I observed more of a difference than you, because they definitely changed the torque band for me. I think it is more obvious because I am only running 9lbs of boost and do not use methanol. Thanks for the write-up again. it was very useful.
 

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Discussion Starter #10
I used this guide to install my Denso 321cc injectors tonight. I think I observed more of a difference than you, because they definitely changed the torque band for me. I think it is more obvious because I am only running 9lbs of boost and do not use methanol. Thanks for the write-up again. it was very useful.
I think if a person runs 9 psi they will notice more of a difference but as the boost is turned up more & more there is less & less of a difference. Even these larger injectors have their limits. But yes at 9 psi these injectors seem to supply more fuel than the stock injectors.
 

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lol ive changed my injectors 4 times already. Ive got it down to a 15 min job. Last time i changed them was in the parking lot of my job during my lunch break
 

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Reviving an old thread here, but I'm going to be purchasing some of the Denso 321cc injectors soon. I found them on RockAuto's website just need to find out if they are in stock. After swapping these in I won's have to worry as much about hitting boost cut at 10.5-11lbs of boost on the stock ecu right?
 

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Discussion Starter #17
When I had these injectors on my car I felt they did not really get rid of the hesitation problem that occurs below 5,500 rpm's completely just a little. The less boost you run the less hesitation you feel below 5,500 rpm's. The more you turn up the boost the more you can feel the hesitation below 5,500 rpm's on the Mazdaspeed mx5

I was able to run a little more boost with these injectors along with my water meth injection kit than before the injectors. I mostly tested the 321cc injectors with my water meth injection kit turned on & at 14 psi of boost & above.

If you get 321cc injectors & turn up the boost to 11 or 12 psi your going to still have the below 5,500 rpm hesitation problem.

Without changing the stock computer I think the best thing to do is to just disconnect the throttle position sensor when you know your going to drive aggressive & connect it back when you are just casually cruising around. And purchase a water meth injection kit. Disconnecting the TPS takes care of the below 5,500 rpm hesitation problem & the water meth injection kit allows you to run higher boost.
 

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Reviving an old thread here, but I'm going to be purchasing some of the Denso 321cc injectors soon. I found them on RockAuto's website just need to find out if they are in stock. After swapping these in I won's have to worry as much about hitting boost cut at 10.5-11lbs of boost on the stock ecu right?
No, your boost-cut will still be apparent. That is signaled by boost pressure, not fuel delivery. If you want to get rid of boost-cut all together, you need to do the resistor mod. Then you can run higher boost, and that is where these injectors will come in handy. They will supply a little more fuel so that you don't go as lean as stock injectors on high boost. The 321cc injectors alone will lessen the hesitation below 5,500 rpms when you are running around stock-ish boost.
 

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I still have yet to get them. I'm waiting for the holiday season to be over so I'll have some extra cash. I'm also getting FM's o2Mod with them and installing a wideband. I then plan on doing the mod off mazda-speed.com's website with the zenor diode. That way I stay in closed loop the whole time and the o2mod can actually do what it's supposed to do.

I will definitely update with my results.


Update: Lol Verwah you posted while I was posting! I plan on leaving it at 10.5lbs of boost. Maybe 11lbs. That is when I pick up an intake. For now I'm still using the stock intake. so 9lbs of boost for meee!
 
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