4.5L INJECTOR SIZE? Double checking before buying

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fsjeep13
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4.5L INJECTOR SIZE? Double checking before buying

Post by fsjeep13 »

Hi,
I have a 2000 TJ which I ruined the motor in. I'm planning on getting a 4.5L motor from West Coast Engines, aka Motor Works out of Spokane, WA. http://www.westcoastengines.com/#/shop/ ... KER/534413

I already have a PIPK from K&N, Banks header, high flow exhaust which I will swap over.

This engine being an advertised 259 HP, using the formula for what rate of flow I should shoot for when getting my injectors is 26.9 lbs/hr.

After reading on the forum here, accel 24# injectors seem to be close, with a flow of 25.47
http://www.summitracing.com/parts/ACC-150624/

However; a 24# injector gives me a calculated 244.5 HP, so I'm cutting myself short of 15HP right?

I want to get the engine installed, swap my intake, exhaust, and injectors and drive a dependable vehicle. Is that all I need to do? I want to ask before commiting and making a mistake on my daily driver. Thanks,

John
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by Missourian »

John,

You want to purchase injectors that will fit your FI connector and have the preferred four holes versus one for increased atomization of the fuel into the cylinder. I too have built a 4.6L STROKER for my 2000 Jeep Wrangler and I chose the BOSCH/FORD 24# Injector a part number: 0 280 155 849. I did buy these used/good injectors via EBay.com.

There are several injectors to choose from, research the site and you will find all the information you seek.

Best of luck to you in your endeavor, it has been an education for me. :cheers:
I have a 4.6L STOKER in my 2000 Jeep Wrangler with 4.5" lift on 35" BFG MT and 4.56:1 gears.

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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by SilverXJ »

Missourian wrote: You want to purchase injectors that will fit your FI connector and have the preferred four holes versus one for increased atomization of the fuel into the cylinder. I too have built a 4.6L STROKER for my 2000 Jeep Wrangler and I chose the BOSCH/FORD 24# Injector a part number: 0 280 155 849. I did buy these used/good injectors via EBay.com.
Those are not 24# injectors. They are actually 27# on the 49psi fuel rail. Way too large.

For a ~25# injector for the late model 49psi rail you want either the Jeep 4 hole 53032704AB used on the 04-06 Jeep 4.7L HO or the Bosch 0280155784 injector.
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by Missourian »

SilverXJ wrote:Those are not 24# injectors. They are actually 27# on the 49psi fuel rail. Way too large.

For a ~25# injector for the late model 49psi rail you want either the Jeep 4 hole 53032704AB used on the 04-06 Jeep 4.7L HO or the Bosch 0280155784 injector.
NO! Not more money wasted... :frustrated:


MOPAR 53032704AB -or- Bosch 0280155784, I will get this engine together sometime soon I hope. :idea:
Last edited by Missourian on January 1st, 2012, 9:16 pm, edited 1 time in total.
I have a 4.6L STOKER in my 2000 Jeep Wrangler with 4.5" lift on 35" BFG MT and 4.56:1 gears.

Check out Metro Crawlers Image
fsjeep13
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by fsjeep13 »

SilverXJ wrote:
Missourian wrote: You want to purchase injectors that will fit your FI connector and have the preferred four holes versus one for increased atomization of the fuel into the cylinder. I too have built a 4.6L STROKER for my 2000 Jeep Wrangler and I chose the BOSCH/FORD 24# Injector a part number: 0 280 155 849. I did buy these used/good injectors via EBay.com.
Those are not 24# injectors. They are actually 27# on the 49psi fuel rail. Way too large.

For a ~25# injector for the late model 49psi rail you want either the Jeep 4 hole 53032704AB used on the 04-06 Jeep 4.7L HO or the Bosch 0280155784 injector.
Why are they too large? Calculated, it looks right on the money. Is it becuase the CPU or whatever adds 10% or something past a certain rpm? I read that somewhere. So those are the injectors to buy, but then you need that piggyback electronic thing?
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by SilverXJ »

I don't know what the PCM wants or how Jeep calculated the injector size to begin with, but those calculators are wrong.

Before a piggy back I would recommend a wide band O2 sensor so you can see what the air fuel ratio is. I ran an injector similar to the Ford 0 280 155 849 "24#" injectors (pretty much the same flow ratings). Without correction via a piggy back, letting the stock PCM control, the AFR was so rich that it blew black smoke at WOT and pegged my wideband. Also, you have to take into consideration that that 24 lb (its actually more like 25 using independent test data) is taken at a pressure of 43.5psi.
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by fsjeep13 »

So there is not a definitive answer?

stock 4.0 injectors were 22.5 at 49psi, was perfect

24# running at about 25.5 at 49psi was too much.

So has anyone installed injectors that actually flow at 24 lbs at 49psi?

I need to get my jeep back on the road and wanted to have a decision today on which engine I am to get. Stock or Stroker. Its my DD. I don't have a lot of time becuase I don't have a car as of now. There just does not seem to be a lot of info for the later model 4.0L. Has anyone had good results with a late model 4.0 stroker?
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by SilverXJ »

fsjeep13 wrote:24# running at about 25.5 at 49psi was too much.
The ones I have used MOPAR 53032704AB -or- Bosch 0280155784 run about 24.2# on the rail. They are still a bit rich, but have been the closest match I could find. The 49psi flow rating is usually calculated and flow rates are not linear, which can lead to error. For example, I used a set of XR3Z 9F593 A4B injectors which are said to flow 22.8 @ 43.5 psi, same as the MOPAR 53032704AB -or- Bosch 0280155784. However, they proved too small on the 49ps rail and returned AFRs similar to the stock injectors, even though their calculated flow on the 49 psi rail is 24.2#.

There is plenty of info on late model strokers. Internally they aren't any different from any other stroker. My problems were cam bearing issues, which seem to be solved for the time being and a true cause was never isolated. However, the theory is that the cam was bouncing back and forth due to the factors spring and pin setup. I'm just doing some fine tuning on a cold start issue, which may be related to the cam.
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by fsjeep13 »

There is a lot of build info, but not much after that. So how rich are you running? Do you have to take your plugs out and clean them often? Are you running 91 octane? Is there visible smoke when running for SMOG? Is your jeep running the way you want it to?
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by SilverXJ »

I am running 91 octane. I haven't tried running midgrade yet, but it pings on 87.

As for the plugs and rich you need to understand how the fuel system operates first. A quick summary: There are two modes of operation. Open loop and closed loop.

In Closed Loop the PCM monitors the O2 sensors to adjust the AFR. It wants 14.7:1 AFR (stoich) in this mode. This would be considered lean. The PCM is in closed loop during cruise, hot idle, and accel up to about 70% throttle. In relation to injectors size the PCM can pull fuel to reach the 14.7:1 that it wants, which is good. The amount of fuel it pulls out at a given point (throttle opening, engine load, rpm, etc) is added to memory, called the long term and short term fuel trims. I don't know how much of the fuel trim data is uses in open loop, if any. You will be driving mostly in closed loop operation.

The other mode of operation is Open loop. This is when the PCM ignores data from the O2 sensors and goes off a fuel table based on the other sensors and based heavily on the MAP sensor. This is where a MAP adjuster would come into play. Open loop is used for cold start, engine warm up (roughly for 1.5-2 minutes, or until the O2 sensors are up to temp), decel and WOT (Wide Open Throttle). This is also when too larger of an injector will cause the engine to run rich and too small an injector will cause it to run lean.

In closed loop the PCM can adjust for too larger or too small of an injector with in reason. Its in Open loop that injector size becomes important. I know for a fact that a stock sized injector will cause problems due to too lean of a mix at WOT and is generally unsafe. A too large injector can cause issues like washing down the cylinder walls and a loopy/surging cold start idle, but generally is safer. With a too large injector you will run rich and lack power in open loop.


My stroker runs fine aside from a cold start issue and a minor rough idle. I am still working on getting the tune where I want it. I don't have SMOG tests and would most likely fail just from a visual inspection.
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by fsjeep13 »

Thanks for the info.

Do you plan on trying 23.5 lb injectors? If that is even something out there...

Can somebody tune the PCM differently or MAP sensor to make it operate smoothly?
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by fsjeep13 »

If closed loop if hot idle, you technically should not be having a rough idle right? Thats weird. I have to have this pass smog, otherwise there is no point!
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by SilverXJ »

fsjeep13 wrote:Thanks for the info.

Do you plan on trying 23.5 lb injectors? If that is even something out there...

Can somebody tune the PCM differently or MAP sensor to make it operate smoothly?
I had my PCM tuned by a company a while ago. I didn't have the cold start at the time so I didn't address that. That company that I dealt with in the past no longer does that. I was recently searching on ebay for a hesco aluminum head (always keeping my eyes open for a used one) and found another guy that does the PCM tunning. He had an option to address cam problems with the PCM. I have been emailing him and sending him data in hopes to send him my PCM to re tune with some changes. He seems pretty sharp and very knowledgeable with tuning.
fsjeep13 wrote:If closed loop if hot idle, you technically should not be having a rough idle right? Thats weird. I have to have this pass smog, otherwise there is no point!
Well, while in closed loop the PCM doesn't rely 100% on the o2 sensors. It also takes into account the other sensors, which include the MAP. Usually when a cam doesn't play well with the PCM its usually caused by a MAP signal that is erratic. Off idle it runs just fine. And really the hot idle isn't that bad, but I feel it could be better. As for smog issues you would have to ask some other members. The comp 68-231 and 68-232 that I ran in the past didn't have the idle and start issues.
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by xjcody »

I just bought the same 4.5 stroker for my 2000 xj. Only problem I had with Motor works/ West coast engine is that they sent me an engine with a thrust plate cam in a non thrust plate block(98 based on casting number). I sent it back and they drilled and tapped the bosses and installed a thrust plate. i have about 60 miles on it and just got back from the smog place and it passed with flying colors. When i was leaving the check engine light came on and just got home and read the codes p0300, p0301, p0304, p0305. i am running the BOSCH/FORD 24# Injector a part number: 0 280 155 849 and after reading this thread, are they way too big and causing my problem? Slightly rough idle but otherwise runs great and has great power. Hopefully this is of some help to you.
Sorry for hijacking your thread.
-Cody
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Re: 4.5L INJECTOR SIZE? Double checking before buying

Post by xjcody »

Oh and same engine from Motor Works can be bought through Engine Authority for $200 less
http://engineauthority.mybigcommerce.co ... hp-305-tq/
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