WJ 4.7 injector upgrade - JeepForum.com

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post #1 of 26 Old 10-24-2013, 06:34 AM Thread Starter
SSS
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WJ 4.7 injector upgrade

Did as much research as I could find on the subject and found there is very little info. out there on how far you can push the 4.7 from its factory 19lbs. So i did kind of a trial and error. I bought three sets of injectors and ran each set for around 1000 miles. First was napas OEM 2 port ($100) not much dif. from factory 20bls all I gained was about 1/2 an mpg. The second set was the ford 4.6 21lbs OEM mustangs (Junkyard $95) they were a massive improvement with the stock air box. Gains were in both a 3mpg increase and in an 1.5 second drop from 0-60mph. Now for the real thing to put in. My third choice was a set of Bosch 23bls 4 port MDH-94-855 Fuel Injectors ($165 ebay) which are still in. The gains were twice as much as the Mustangs, with an mpg jump of almost 5.5 mpg from factory and a 2.25 second drop in 0-60mph. The only real thing that you have to do with the bosch set is an after market cold air intake. I went K&N and will do a complete write up on the how to build your own soon.

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post #2 of 26 Old 04-04-2016, 04:05 PM
TheHoneyBadger
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I know this is an old thread, but I can't find anything about the 23# injectors. I tried various searches .... eBay Google Ect
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post #3 of 26 Old 04-05-2016, 12:19 AM
ShinyWJ
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Mine has Ford 4-hole injectors from a V-6. I believe they are 24 lb. Previous owner swapped them in. If I can remember to, I'll try to get the numbers off one of them but surely someone here will post some info anyways.

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post #4 of 26 Old 04-05-2016, 05:33 AM
Darnice
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The OP's numbers are totally unrealistic. Gains like that from just an injector swap are not happening.
He did not post what his numbers were before the swaps, so they mean nothing.

As you noticed, no one responded to the first post.
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post #5 of 26 Old 04-05-2016, 11:02 AM
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I know, but in my search I found his same post on another forum and it received lots of replies. Also this post is in the wrong subgroup so that narrows the active interested members to initiate discussion. IMO it should be in the WJs or Grand Cherokee general subs
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post #6 of 26 Old 04-05-2016, 11:03 AM
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I just can't find anything about the Bosch 23bls 4 port MDH-94-855 Fuel Injectors
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post #7 of 26 Old 04-05-2016, 11:05 AM
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And dang it looks like it has been moved to the right section!! Hopefully we will get some answers
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post #8 of 26 Old 04-05-2016, 12:49 PM
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Quote:
Originally Posted by Darnice View Post
The OP's numbers are totally unrealistic. Gains like that from just an injector swap are not happening.
He did not post what his numbers were before the swaps, so they mean nothing.

As you noticed, no one responded to the first post.
Yeah, look at his 'mods' in the drop down under his name. Hood mounted spare? lol... must be a troll account or something. Definitely agreed on his numbers, there's no way. I'm sure there is a small gain but nothing like that. Also find it odd how it says he has 6 posts, then go to his profile and it says 4, but you can only find one post, the OP here, when searching.

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post #9 of 26 Old 04-05-2016, 01:24 PM
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I have a used set of Ford 19lb (I think unless they were 24lb stock - just don't recall since been years) injectors from a Mercury Marauder from when I upgraded them when installing an s/c on that car.

But...I don't think I want to waste the time installing them in my WJ because I really don't see how changing fuel injectors on a stock motor with stock intake and no tuning will make any darn difference at all, much less actually SAVE fuel.
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post #10 of 26 Old 04-06-2016, 03:53 PM
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I got some Bosch aftermarket 4 hole and I've went from about 17.5 mpg to 22.5mpg, I can get 25mpg if I set the cruise on 60
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post #11 of 26 Old 04-06-2016, 04:14 PM
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Quote:
Originally Posted by mightytitan9 View Post
I got some Bosch aftermarket 4 hole and I've went from about 17.5 mpg to 22.5mpg, I can get 25mpg if I set the cruise on 60
On the evic....or hand calculated? Ignore the evic......it won't "know" you have different injectors injecting a different amount of fuel so will be miles out. I can't honestly see why changing injectors well make any noticeable difference in mpg if the rest of the engine remains as it was. Finer atomization will make next to no difference (unless your old ones were shockingly bad) and if you can't flow more air your O2 sensors will only allow the same amount of fuel as before to keep the mixture right. I bet you guys who noticed a real hand calculated improvement would have measured about the same gains by replacing your worn 12-15 year old injectors with new stock ones. Anyone one reporting 5 and over mpg improvements with no evidence to back then up except evic reading...well I'm sorry but I find that very hard to believe.

If you can't fix it with a hammer, you've got yourself an electrical problem!
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post #12 of 26 Old 04-06-2016, 04:30 PM
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The only gains I found on my previous 4.0 with the 4 hole eBay injectors were a smoother idle and slightly better throttle response. MAYBE a 1-2 mph difference, but I didn't notice it. All of that may have been because of swapping out the old injectors. But I plan on doing it again, because it really did smooth things out and it really did help throttle response.
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post #13 of 26 Old 04-07-2016, 08:27 AM
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I'm away at work right now but should be home in about a week or so.

Currently I'm getting about 11.8MPG 4.5 lift on 32s with a roof rack, light bar & a winch with no front bumper. This is out of my 01 4.7 with 240k miles super chips in 91performnce tune.

When I get home I will replace injectors and will document the new vs the old along with part numbers and results over 1-2 tanks. My Evic is pretty close to accurate but I will get my numbers by taking the the total number of miles into gallons used so there will be no questioning it

I also have ordered the parts to split my fuel rail and further increase efficiency. I'll have approx $300-$400 into this project and will update results. I will do this in a new thread.
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post #14 of 26 Old 04-07-2016, 03:06 PM
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Quote:
Originally Posted by TheHoneyBadger View Post
I'm away at work right now but should be home in about a week or so.

Currently I'm getting about 11.8MPG 4.5 lift on 32s with a roof rack, light bar & a winch with no front bumper. This is out of my 01 4.7 with 240k miles super chips in 91performnce tune.

When I get home I will replace injectors and will document the new vs the old along with part numbers and results over 1-2 tanks. My Evic is pretty close to accurate but I will get my numbers by taking the the total number of miles into gallons used so there will be no questioning it

I also have ordered the parts to split my fuel rail and further increase efficiency. I'll have approx $300-$400 into this project and will update results. I will do this in a new thread.
Just realize that the EVIC numbers will be totally useless if you install injectors that have a higher flow rate. Why? Because the EVIC and ECM are hard-coded with the stock injector flow rate. The EVIC has no ability to actually measure the amount of fuel that is being consumed. Instead, it calculates the amount using injector pulse widths and the stock injector flow rate. (I.E. it is pre-programmed to know exactly how much fuel comes out of the injectors for a given pulse width).

When you install higher flow injectors (with no other engine mods), the ECM will automagically shorten the injector pulse widths until the O2 sensor reading tells it that the engine is running at the proper air/fuel ratio. End result? The engine is still using the same amount of fuel for a given scenario, BUT, the ECM is sending shorter pulses to the injectors. This fools the EVIC into reporting absurdly high mileage numbers because its calculations are still based on injectors that flow less fuel for a given pulse width. So it thinks it is injecting far less fuel than it really is.
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post #15 of 26 Old 04-07-2016, 04:28 PM
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Quote:
Originally Posted by HarryH3
Just realize that the EVIC numbers will be totally useless if you install injectors that have a higher flow rate. Why? Because the EVIC and ECM are hard-coded with the stock injector flow rate. The EVIC has no ability to actually measure the amount of fuel that is being consumed. Instead, it calculates the amount using injector pulse widths and the stock injector flow rate. (I.E. it is pre-programmed to know exactly how much fuel comes out of the injectors for a given pulse width). When you install higher flow injectors (with no other engine mods), the ECM will automagically shorten the injector pulse widths until the O2 sensor reading tells it that the engine is running at the proper air/fuel ratio. End result? The engine is still using the same amount of fuel for a given scenario, BUT, the ECM is sending shorter pulses to the injectors. This fools the EVIC into reporting absurdly high mileage numbers because its calculations are still based on injectors that flow less fuel for a given pulse width. So it thinks it is injecting far less fuel than it really is.
And this is why I said I wasn't using EVIC .... But I will be able to compare my actual MPG to EVIC
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