Help with injector selection

[Redrubicon2004]

I’m working on a 1998 TJ and I’m installing an ATK HP24 4.7L engine. I’m trying to find the correct injector for this application.

I’ve read guys are using 99 sable injectors, but I’m pretty sure they have a different connector on them. Is there a conversion connector/adapter for them? Similar injector with different connectors?

[Cummins90]

Correct me if I am wrong but ATK specifies to use the stock injectors.

Yes there are conversion connectors but why bother when you can pick up the right size with the correct connector? 98 TJ were still EV1 I think. 99 or 00 went to EV6.

[Cheromaniac]

Since that's the base engine which is rated at 205 crank hp, the stock '98 injectors should be fine.

[Russ Pottenger]

98 and down EV1
99 and up EV6

[stroker]

24lb ev6 + good fuel pump like dw300 or aem

[TJryder]

Hi,

I was crousing the forums and Youtube and mainly based on this video
https://youtu.be/7aO09VjqKa8
I bought those injectors.

Now, a couple of months later and reading more I am wondering If I made the right selection.

2000TJ build, 0.60 over, mild porting, 10 DCR


Next question I would have is how do you guys get AFR under control.

Step one I guess is AFR gauge (or can this be avoided?)

Reset the PCM unit and let the adaptive control and lambda gauges do their job?

BR M

[Russ Pottenger]

Hi Matjaz,
I’m guessing you’re going to need more injector.
A EV6 4 hole Bosch injector rated at 27 pounds would be a minimum place to start if your at a 10.0:1 static.

[TJryder]

Could I get a beter result with adjustable pressure regulator?

[SkylinesSuck]

Hi,

I was crousing the forums and Youtube and mainly based on this video
https://youtu.be/7aO09VjqKa8
I bought those injectors.

Now, a couple of months later and reading more I am wondering If I made the right selection.

2000TJ build, 0.60 over, mild porting, 10 DCR


Next question I would have is how do you guys get AFR under control.

Step one I guess is AFR gauge (or can this be avoided?)

Reset the PCM unit and let the adaptive control and lambda gauges do their job?

BR M

Proper injector sizing and tuning. Google Flyin Ryan Performance.

[TJryder]

Hi,

I was crousing the forums and Youtube and mainly based on this video
https://youtu.be/7aO09VjqKa8
I bought those injectors.

Now, a couple of months later and reading more I am wondering If I made the right selection.

2000TJ build, 0.60 over, mild porting, 10 DCR


Next question I would have is how do you guys get AFR under control.

Step one I guess is AFR gauge (or can this be avoided?)

Reset the PCM unit and let the adaptive control and lambda gauges do their job?

BR M

Proper injector sizing and tuning. Google Flyin Ryan Performance.

Hi,

I am aware of Flyin Ryan and his fine work. I read the thread diagonally. I need to do it again I guess.

But there is so much info, a lot of changes in recepies through years, Renix, Bosch, Chrysler...

But being a keen DIY-er - I want to do it myself if possible.

So a more content rich help would be welcome.

Maybe a new thread, dedicated only on AFR recipies with ore defined form would help?

[SkylinesSuck]

For your year, tuning options include a MAP sensor adjuster (very impresise, WOT adjustment only, and no timing control), some sort of piggyback like an SAFC (I ran one and again, WOT adjustment only, and no timing control, but a bit more precise), get somebody to tune your ECU (full fuel and timing control for both closed and open loop), or something like a Megasquirt standalone (I have no experience here and I'm not sure it'll run the factory gauges).

Correctly sized injectors will only get you into the general ballpark at WOT only because it relies on the factory tune to open the injectors up the same amount it always does, but those injectors are now larger (or hopefully they are depending on what you install lol) so more fuel gets injected to feed the extra cubes. The closed loop still works out because the ecu can see if it's rich/lean (compared to 14.7:1) via narrow band O2 sensor and adjust accordingly. This still only works to an extent because the injectors are only marginally bigger and it's still within what the ecu considers a normal range of adjustment. You could easily have too big of an injector that the ecu would have to work too hard to adjust and it could throw a code or just not run properly.

[Cummins90]

I have seen some evidence of the JTEC using the last closed loop 02 reading to alter closed loop AFRs.

Long ago I had checked my AFRs on my 96 while in stock form and it seemed to target 12.5 AFR in WOT power enrichment.

If Ryan, or anyone else who can see the stock algorithms, would like to chime in that would be helpful.

[TJryder]

For your year, tuning options include a MAP sensor adjuster (very impresise, WOT adjustment only, and no timing control), some sort of piggyback like an SAFC (I ran one and again, WOT adjustment only, and no timing control, but a bit more precise), get somebody to tune your ECU (full fuel and timing control for both closed and open loop), or something like a Megasquirt standalone (I have no experience here and I'm not sure it'll run the factory gauges).

Correctly sized injectors will only get you into the general ballpark at WOT only because it relies on the factory tune to open the injectors up the same amount it always does, but those injectors are now larger (or hopefully they are depending on what you install lol) so more fuel gets injected to feed the extra cubes. The closed loop still works out because the ecu can see if it's rich/lean (compared to 14.7:1) via narrow band O2 sensor and adjust accordingly. This still only works to an extent because the injectors are only marginally bigger and it's still within what the ecu considers a normal range of adjustment. You could easily have too big of an injector that the ecu would have to work too hard to adjust and it could throw a code or just not run properly.

Thanks for reply.

I read before about the many options. But getting deeper into project - things got blurred with so may models and controls, different tune levels.

First I wanted to go with minimum stroker - now I ended up with parts list at Russ that will push me well over 260HP mark.

Before that I already bought those 12 point injectors - that now seem to be questionable for proper AFR at WOT.

So I was wondering it I could get more flow out of them with higher fuel pressure. Otherwise I will just swap them with suggested size.

MAP adjuster sounds attractive, but I will try to find a local tuner. Local FB group gave me a couple of good leads, mainly race shops with dyno capability. Anything special with tuning of those post 99' Jeeps? I read on the way that the do not respond well to tuning?

I also e-maild Ryan - but no response yet.

BR M

[HCE]

2004 WJ which is chrysler, non renix system, the ev6 27 lb worked well, as did the stock 22lb. Use part number 0280156048 to find the 27lb injector. Ecu seems to be very adaptive. I doubt you will loose anything in driveablity without tuning the ecu, although there may be some power to gain. Not that I would rely heavily on cr as a injector determiner, but for reference I am about 9.5. Jumping for 9:1 to 10:1 is good for a 4% hp increase,in peak hp. About 12hp at the 260hp level.

[SkylinesSuck]

Try finding Flyin Ryan on FB and message him in there. That's the best way to reach him.

And just for reference, the map adjuster adjusts the map voltage across the board the same amount and basically lies to the ecu about how much air is going in to the motor. That also throws off the timing. If you are just tweaking it a little it's not a huge deal.

Tuning the ecu gives you full control of everything. Right now your injectors will only ever open the max percentage the ecu tells it to with the stock tune. People are just putting bigger injectors in so the same percentage equals more fuel. If you change the ecu tune, you can tell it to open the injectors to as much as 100% (wouldn't advise cutting it that close though) and stock injectors might be enough. You would have to look at max hp vs max flow of the 6 injectors at your decided FP.