Injector Question - 2.4L swap

[Low-Speed]

Everyone states you need 24 lb/hr injectors for a 2.4 swap.

From the information I've found -

Stock 98 injectors out of a 2.4 are 0-280-155-782 Bosch Injectors, part number 04669772.
21.3 lb/hr @ 43.5 psi.

Stock 96 injectors out of a 2.4 are 0-280-155-703 Bosch Injectors, part number 05277739AB.
16.75 lb/hr @ 43.5 psi.

Stock 97 injectors out of a 2.4 are 0-280-155-740 Bosch Injectors, part number 4669471AB.
21.1 lb/hr @ 43.5 psi.

That having been said, the numbers appear the be the same for 2.0L engines of the same year models.

Most everyone always says you need 24 lb/hr injectors for a 2.4 swap, but it would appear that 95-96 computers would be tuned for 16.75 lb injectors, and 97+ computers would be tuned for the 21ish lb injectors.

That having been said, why would the 16.75's not be preferable for 95-96 PCM'd swaps? It would appear the PCM is tuned for that size injector, and that running the richer injector would simply cause the PCM to run rich, and have to pull fuel.

It's been a theory of mine for years, after seeing a select generation of Chrysler's run fuel strategies that were lean by default, and richened to compensate idle rough, then seeing them lose 2-3 mpg across the board one year, and the difference be the smooth idle with a rich by default, pull fuel to compensate strategy, that it would be more ideal to force the PCM to add fuel anyways, so long as it's not out of bounds for the PCM.

Incidentally, the PCM allows for 25% enrichment prior to running out of range....

Just curious if it's still recommended to run the larger injectors with the earlier PCM's, and why that would be the case.

[DOHCRT]

I don't know where you got your info from, but it doesn't seem correct. All 2.0L's came with 19lb injectors as did the 2.4L engines. You need bigger injectors when running a 2.4L on a neon PCM because the PCM still thinks its running a 2.0L. It gets pretty obvious that you need more injector when you reference a wideband on a 2.4L swap.

If you swap in a bone stock 2.4L, you might be able to get away with just a 58psi regulator from a 2nd gen.

I've had built 2.4's run lean with 24lb injectors and a 58psi regulator.

[fuzzyneon]

19lbs=need 58 psi regulator but once you start egtting into mods you want 24lbs ones

[charger440neon2.0l]

http://www.fuelinjector.citymaker.com/p ... 782443.htm

True the neons injectors are supposed to be 19 lbs but the average flow rates on certain injector body numbers is much more accurate. I dont think that the pcms are programed based on the injector used. since the thin gen 3 bosch injectors (thin mostly plastic) that came originally on my 95 are said to flow 17lbs and the gen 2 bosch (large aluminum body with four hole disc type nozzle) are said to be 21.3 lbs. that came in alot of 95 neons. So why would they program them for each car?

[charger440neon2.0l]

http://www.rceng.com/technical.aspx

[Low-Speed]

I don't know where you got your info from, but it doesn't seem correct. All 2.0L's came with 19lb injectors as did the 2.4L engines. You need bigger injectors when running a 2.4L on a neon PCM because the PCM still thinks its running a 2.0L. It gets pretty obvious that you need more injector when you reference a wideband on a 2.4L swap.

If you swap in a bone stock 2.4L, you might be able to get away with just a 58psi regulator from a 2nd gen.

I've had built 2.4's run lean with 24lb injectors and a 58psi regulator.

The actual flow rates for the injector part #'s. Not one has a 19 lb injector. In fact, the early 2.0's and 2.4's (95-96) used a very small injector, and the later ones used a different, though higher flowing injector.

All of these appear to be the smaller form factor injectors. It is my understanding the plugs are different on the 98+ as well.

I just find it quite interesting that a computer with the ability to add or subtract 25% would have problems with a 98+ Injector, on a basically stock 2.4. It doesn't seem to have that much of a fuel need, unless for some reason beyond my understanding the BSFC jumps through the roof on a 2.4. Power levels are almost identical between the 2 engines. The 2.4 has milder cams, a long-stroke design, and other factors that indicate it should have a better BSFC, though it's displacement is a contributing factor. Enough for a 25% difference though?

[Low-Speed]

19lbs=need 58 psi regulator but once you start egtting into mods you want 24lbs ones

This takes the 16.75 injectors, which run 17.7 in our application (49 psi) and pumps them to 19.3 (58 psi).

Assuming you have a late-model injector, you would actually make 24.6.

Interestingly, at the maximum recommended calculation for BSFC on the RC site, on a stock 4 cylinder, at 140 hp, with 49 psi, and a very conservative 80% duty cycle, you would only need 20.61 lbs/hr to feed the engine.
Even at 150 hp, you only need 22.1, and a 98-99 injector should provide 22.6 at the stock fuel pressure.

I guess I just want to know the reason they are so horrible on fuel consumption.

[DOHCRT]

I just find it quite interesting that a computer with the ability to add or subtract 25% would have problems with a 98+ Injector, on a basically stock 2.4. It doesn't seem to have that much of a fuel need, unless for some reason beyond my understanding the BSFC jumps through the roof on a 2.4. Power levels are almost identical between the 2 engines. The 2.4 has milder cams, a long-stroke design, and other factors that indicate it should have a better BSFC, though it's displacement is a contributing factor. Enough for a 25% difference though?

Your not thinking about this correctly. While the PCM can use it's adaptive strategies (fuel trims) to compensate for the larger engine, the fuel trims are not used during open loop operation. With a speed density system, the air fuel ratio will become lean because the PCM still beleives the engine displacement is 2.0L. If injection time was based on a mass airflow system, you would be ok (as long as you didn't exceed the MAF sensors range). Since the neon uses a speed density system, you have to increase injector flow rate to compensate.

[Low-Speed]

You don't have a great understanding of speed density.

It calculates airflow, as opposed to measuring it. It's also constantlly adapting the fuel to a "caculated" amount, between values on the map, as opposed to a MAF, which calibrates to the richest point close to the measured airflow. It's why Speed Density cars generally get better mileage than MAF cars.

I've had a lot of people say that some swaps run lean on 24 lb/hr injectors, and require a 58 psi regulator in addition. While other say you can do either/or.
So, how is it, that a 58 psi regulator, which will only pump the flow to 17.7 lbs on early injectors, is good enough for some swaps?

Anyways, it would make sense, if a 98-99 pcm was used (calibrated for 21.3 lb/hr injectors) in a 96 Stratus motor swap (with 16.75 lb/hr injectors) You'd probably need 24 lb/hr injectors, and a 58 psi rail to get the pressures close enough for the fuel map to be able to adjust.

Then there's the scenario of a 98-99 pcm, on 98-99 injectors, where simply using a 24lb injector probably provides enough additional fuel to get it close enough for the PCM to adapt, as would a 58 psi regulator alone on the stock injectors.

Last but not least, I propose there is another route, which would be easiest, except for sourcing the parts, and that's a 96 DOHC MTX PCM with 97 injectors.

I will let you guys know the results IF I can find the parts needed.

Anyone with a DOHC MTX 1996 PCM, let me know. Same goes if you have stock 1997 injectors.

Incidentally, SOHC engines used 23.2 lb/hr injectors throughout their lifespan.

[DOHCRT]

You don't have a great understanding of speed density.

I have a great understanding of speed density, obviously more so than you. I run MS, so this understanding is a necessity.

Speed density systems calculate airflow based on a few different factors. Engine speed, manifold absolute pressure, and intake air temperature. Each cell in the fuel map represents a certain percentage of VE specific to a given engine. If the engine displacement is increased, the values in each cell are no longer accurate. Since you cannot change these values, you have to install larger injectors to compensate. If you could modify the fuel table, you would need only to increase the values in certain cells. Injector duty cycle would be your only limit.

Speed density cannot accurately calculate airflow if the fuel table is inaccurate.

I've had a lot of people say that some swaps run lean on 24 lb/hr injectors, and require a 58 psi regulator in addition. While other say you can do either/or.

It depends on what modifications the engine has. A stock 2.4 with no bolt ons can run off a 58psi regulator and stock 19lb injectors. It will run a little lean, but not dangerous. When you start adding modifications, especially cams, you need to get the larger injectors.

Then there's the scenario of a 98-99 pcm, on 98-99 injectors, where simply using a 24lb injector probably provides enough additional fuel to get it close enough for the PCM to adapt, as would a 58 psi regulator alone on the stock injectors.

Your still not getting the closed loop/open loop concept. The PCM will not use fuel trim under open loop operation. Since WOT is open loop, this is what you need to be concerned about.

[charger440neon2.0l]

98-99 pcm was used (calibrated for 21.3 lb/hr injectors)

The pcm is not calibrated for 21.3 lbs. all stock pcms 1995-2005 are all calibrated for 19 lbs. Just the actual flow rates of the injectors vary. I always see fuel trims at +/- 5% because of this. 0-280-155-703 were stock in my 1995 and I've seen them in many others and some other 95s used 0-280-150-965 which flow 21.05@43psi, both injectors use ev1 plugs, so do you really think Chrysler would write different programs for each neon going down the assy. line?

[charger440neon2.0l]

To make things simple for you just get a set of bosch gen 3 injectors 0-280-155-715 from a 2.5 DOHC Ford Taurus or Mercury Mystique, they are 24lbs @49psi, they are blue, they are ev1 plug and they are the same body size as 0-280-155-703 so they fit in no leaks. Some even came in an ev6 plug. I sold the set I had so I don't have the body number but they are the same other than the plug.

Or if you need ev6 plug (97 and newer) use 0-280-155-934 from a 3.9l v6 Dakota, Durango or 5.9l Ram they are 25lbs@49psi, they are red, ev6 plug, and fit the same as stock neon injectors.

If you want to go this route I have both the 0-280-155-934 and the 0-280-155-715. give me a pm if your interested.

[Low-Speed]

you have 2 tables. One for spark, one for fuel. VE doesn't directly factor. The mappings on the fuel table and spark table correlate a MAP and RPM point with a fuel injector pulsewidth. Its a very simple system. The MAP indicates load, at a given RPM. In open loop, there's no need to run on a trim. Its using real-time calculations from the table to ensure safety. The reason 25 percent is the limit regardless of open/closed loop operation, is the factory calibrates for 75% duty as the normal max on the injectors. That leaves margin. from there, it applies a percentage richening based on IAT, etc. But, the table runs a percentage.

So yes, I do understand speed/density quite well. Enough to know that +/- 5% fuel trims comes from normal differences in the motors from production. Some generate more vacuum, some less, some have 1% leakdown, others 10%, etc. My SRT4 idles at 20-21 inches of vacuum, while most have only 18. Odds are, my exhaust cam is slightly retarded from lack of maching quality.

But, to go from a 16.75 to a 21.3 lb injector, you HAVE to recalibrate the injector pulsewidth on the table for the same engine. On top of that, there are around 6-10+ different maps for each year model. Many of the calibration changes would have been made to improve emissions.

Therefore, the 96 PCM should be able to run a 97 2.4 on stockers, if its not modded. 97's, to my understanding, still use EV1 style clips, so that combo should be plug-n-play.

As for me, as I am doing more research, I need to find 28-30 lb injectors. Having to run a 2.4 on a SOHC pcm sucks. But the Stratus has a BCM output, which runs the gauge cluster! [/list]

[Low-Speed]

And I come from the world of Crome. If you can do wiring, its even cheaper than megasquirt!

[Low-Speed]

To make things simple for you just get a set of bosch gen 3 injectors 0-280-155-715 from a 2.5 DOHC Ford Taurus or Mercury Mystique, they are 24lbs @49psi, they are blue, they are ev1 plug and they are the same body size as 0-280-155-703 so they fit in no leaks. Some even came in an ev6 plug. I sold the set I had so I don't have the body number but they are the same other than the plug.

Or if you need ev6 plug (97 and newer) use 0-280-155-934 from a 3.9l v6 Dakota, Durango or 5.9l Ram they are 25lbs@49psi, they are red, ev6 plug, and fit the same as stock neon injectors.

If you want to go this route I have both the 0-280-155-934 and the 0-280-155-715. give me a pm if your interested.

I am almost sure the 965 is a SOHC injector. And yes, I am sure they made changes. Not for every car, but cali pcms are different to 50 state, and there are multiple flash codes per year, different tunes for atx vs mtx, SOHC vs DOHC, much less the fact almost every year is unique to itself. Each year, emissions were tighter, and fuel strategies have to change. Plus, by the very nature of the system, you can't put in injectors 26% richer for the same engine, without throwing red flags up in multiple areas of the pcm's fuel curve...