4.7 stroker 99 wj- off idle stumble

[superstingray77]

I still have not resolved the off idle stumble. It does not do this in cold aka open loop mode.as soon as temps reach 150+ and scanner shows closed loop it stumbles.
tps new and reads .7 idle 4.0 wot and smooth transisition
stock or bored 63mm tb is the same just has more power with larger tb.
injectors are 4 nozzle #27 a 50psi
fuel system solid 51 at idle or wot under full load
still have header leak but wouldn't that make engine rich not lean? Plan to double up gaskets and fix that noise next wk.
engine pulls hard to as high as I dare rev it, great power and 24-26hwy and 17.8 city/hwy combo validated by math and obc.
tried MAP adjuster didn't affect at all down to 3v or up as high as 6.5v
no wideband yet so dont know true af
no codes all clean and clear.
minicats are "high flow converted"
main cat in place still stock system.

any thoughts?
AEM piggyback? Injector swap?
thanks guys

[Muad'Dib]

Sure seems like you have some very large injectors in there with high fuel pressure...


Need a Wideband to really know whats going on.

[Cheromaniac]

The WJ 4.0 operates with a fuel pressure of 49psi so that's not the problem. His engine runs too lean and that makes me wonder whether those injectors really are 27lb'ers. A MAP adjuster is almost useless on DIS 4.0 Jeep models.
My advice is to install the wideband so you can datalog the AF ratios under light throttle and WOT. Then post the results.

[SilverXJ]

I don't see any indication that he is running lean, but those injectors are too large. What are fuel trims like now? Since you have had a few problems, what have you done? have you fixed that header leak you had?

[superstingray77]

Turned out the injectors were actually 24# at 42.5 psi and 27#at 51psi. The engine was running good once i fixed the header leak, the banks torque tube copy I used had a missing weld seam in the rear collector where the 3 pipes merge into one which happens to be right above the rear 02 sensor. Fuel trims were whacked as a result. Fixed leak installed new 02 sensors and it ran great in closed loop and ok at WOT. Ordered an AEM wideband which will be coming soon. Now the engine is coming apart again as it appears a cam lobe started to wipe out.

[jeepman]

I don't see any indication that he is running lean, but those injectors are too large?

Not to get too far off topic but Why are they too large?

In my 1989 Jeep Comanche pickup Converted to OBDII which is a NON Stroker 4.0L with External mods producing roughly 240HP @ the crank and I am running 25.8lbs Injectors @ 50psi and acording to my air fuel Guage I am only slightly rich with an A/F of around 14:1 so I can not see how 27lbs injectors in a 4.7L stroker is too large but I am still new when it comes the 4.7L stroker as my 4.7L Storker is still only a short block as I have not had time to get the Head Port/polish and Larger Valves done yet...

But if his are too large then mine should be too but the Data does not agree with that...
My Current CTY/HWY Avg MPG is 20MPG and HWY is 23MPG
My Truck Stock CTY/HWY MPG was 15MPG and HWY was 18MPG
Which is Better then when my truck was new if it were a stock Truck and it is far from stock and a heavier truck now as well which is why I can not figure out why I keep hearing "those injectors are too big"

[SilverXJ]

If your PCM can't get the AFR to what it wants, 14.7:1, then it has maxed out its long term and short term fuel trims. So, your injectors are too large. And from experience 27lbs is too large for OBDII stroker. You are mistaken if you think your stock engine is producing 240 hp with bolt ons unless one of those bolt ons is forced induction. Are your getting your mileage numbers from the overhead console?

[jeepman]

If your PCM can't get the AFR to what it wants, 14.7:1, then it has maxed out its long term and short term fuel trims. So, your injectors are too large.

Yup I Figured Mine are too large but not by alot since my A/F is 14:1 so I am Damn Close to right on the money and I am only using these Injectors Because I had them on the shelf...
But if 27's are too large for a 4.7 then I should be running soo rich I would not only see it out the tailpipe but my Mileage should be soo horrible that I wouldn't want to use my truck...

And from experience 27lbs is too large for OBDII stroker.

Interesting because 27lbs Injectors should be good for upto 276HP sholdn't they? And the average stroker should be around 240-280HP i would assume depending on the recipe...

You are mistaken if you think your stock engine is producing 240 hp with bolt ons unless one of those bolt ons is forced induction.

No Forced Induction here YET...
I origonally Ran 24lbs injectors when I modded my engine But I cracked my Brand New Header due to a Very bad Lean engine to the point my Header was extremely RED Hot, that if it was touched it would have poked a whole in it...
I know my Engine so please do not tell me what I have or do not have...
It was Dyno'ed once awhile back so Yes I am running around 240HP @ the crank estimated as the drivetrain loss is hard to be acurate on and I did not Dyno the engine by itself, and I say around as I can not remember exactly as it was done a while ago so Not exactly 240HP but close enough for me to round up (lol)...

Are your getting your mileage numbers from the overhead console?

Yes From the Overhead Console as well as a Computer Program monitoring thru the OBDII Diagnostic Connector and also confirmed with my Fuel reciepts as I log all my Fuel fill ups and Distance Traveled and get my Avg and Exact depending on Where I am going...

I am not New To Vehicles and Jeeps Especially Or Repairing them but I am New to Strokers Engines Which is the only Reason I Asked Why you thought the injectors were too Large since I Know mine especially are good for upto 260HP...

Just Curious for more information is all so please do not take offence to anything writen here as I am not hear to debate just getting more info for when I finish up My 4.7L Stroker which will be getting Supercharged after the engine is broke in a little... My Stroker will get Dyno-ed to get the Actual Crank HP as that is the best then again once in the vehicle to get a more acurate loss thru the drivetrain...

[SilverXJ]

Yup I Figured Mine are too large but not by alot since my A/F is 14:1 so I am Damn Close to right on the money and I am only using these Injectors Because I had them on the shelf...

Not even close. Your injectors are way too large if the PCM can't even control them to get the desired 14.7:1 AFR. I m sure your fuel trims are pegged at -32%.

but my Mileage should be soo horrible that I wouldn't want to use my truck...

See below

Interesting because 27lbs Injectors should be good for upto 276HP sholdn't they? And the average stroker should be around 240-280HP i would assume depending on the recipe...

According to the online calcs 27 should be ideal for the strokers. But the online calcs are garbage. 27 is just too larger for the common stroker and probably too large for a 5.0L stroker. As stated time and time again, 24-25 lbs is right.

I know my Engine so please do not tell me what I have or do not have...

obviously you have no idea. All the common bolt ons will not give you 240hp. Sure, maybe if you add up all the various claims together, but that doesn't work.

but close enough for me to round up (lol)...

this isn't horseshoes.

Yes From the Overhead Console as well as a Computer Program monitoring thru the OBDII Diagnostic Connector and also confirmed with my Fuel reciepts as I log all my Fuel fill ups and Distance Traveled and get my Avg and Exact depending on Where I am going...

That is BS right there. The PCM calculates MPG based on injector pulse width. It has no way of knowing exactly how much fuel goes into the engine. Putting larger injectors in will give you better MPG as displayed on the OHC because the injectors are being held open for a shorter period of time. There is no way that the OHC can match actual calculated MPG with larger injectors. And there is no way to change the PCM to accommodate for larger injectors to get a correct OHC reading. Also, your numbers aren't even close to real numbers. 23 mpg? please...

Just Curious for more information is all so please do not take offence to anything writen here

I am not taking offense, but what you have posted is 100% false.

[jeepman]

Sorry But Yor a complete idiot...
I have actually verified my information so I really do not care what you think nor did I ask you...
All I wanted to know is WHY you thought the injectors were too large and you failed to explain anything and sorry "because you said so" is not good enough because your nobody other then a guy on the internet...

I am not here to brag about my engineI just posted my info and my conclusions... I know what my truck is and what it can do and I know my stock 4.0L with many addons is easily clearing 23MPG or better on the HWY all day long which makes your information, as little info as it is out to lunch...

As already stated I know my injectors are a little oversized so your not winning any points there and I know what my fuel statements are since I record all my fill ups and mileage and know the AVG and exact MPG so sorry your engine is a guzzler but mine is not the best but it sure is not that bad...

This was not meant to be an argument but for some reason you think your cool by starting shit that needs not get started....

I am done with this and by the looks of things the OP is doing fine now with his 27lbs injectors which again makes you more wrong so take care and good luck...

I will add no more to this topic so you can keep thinking your the hero that saved everyone from the evil guy who asked a question....

[Muad'Dib]

Lets tone it down a little with the name calling shall we?

It seems odd that you could be getting 240HP at the crank without an internally modified Engine. This is what some guys get building a basic stroker. You did say you Dyno'd it, but you did not say whether it was Dyno'd at the wheels or at the crank... Dont forget that our Jeeps have about 33% drivetrain loss.

The injectors are too big thats plain and simple as you already noted. If your computer cant maintain stoich then thats a great deal off. Its been proven time and again what size injectors are the right size for Strokers and Non-Strokers. Personally, i run 23# injectors and im still slightly rich at WOT with my RENIX ECU (4.7 Stroker). Most run 24#.. but then again it depends on the build. Non of us have needed large injectors that you are running on a stock engine... with our community being as big as it is, its just something that is proven with real results.

Its your Jeep do what you want.

[SilverXJ]

Sorry But Yor a complete idiot...

Is that what your OHC told you too?

I have actually verified my information so I really do not care what you think nor did I ask you...

obviously you haven't as none of it makes sense other then your injectors are too large.

All I wanted to know is WHY you thought the injectors were too large and you failed to explain anything and sorry "because you said so" is not good enough because your nobody other then a guy on the internet...

What else is there to say? They are too large. The PCM doesn't like it, the fuel trims are all out of wack, WOT is rich as hell and blows black smoke, open loop start has a jumping idle, etc. Typical of an over sized injector.

. I know what my truck is and what it can do and I know my stock 4.0L with many addons is easily clearing 23MPG or better on the HWY all day long

thats funny right there... 23 mpg. But at least you verified it with the OHC. I have some 60 lb injectors you could thow in.. I bet you could make it to 40mpg with those.

This was not meant to be an argument but for some reason you think your cool by starting shit that needs not get started....

no, but I know BS when I see it.

I am done with this and by the looks of things the OP is doing fine now with his 27lbs injectors which again makes you more wrong so take care and good luck...

Fine, but he posted a thread with problems.. really?

[jeepman]

Is that what your OHC told you too?

No where did I say add larger Injectors to get better fuel Mileage so Your a little out there if some how that is all you got from reading my MPG

obviously you haven't as none of it makes sense other then your injectors are too large.

Again Your NOT Reading anything just making assumtions as I have multiple comparisons not ONLY reading my OHC I go by my Actual Fuel used when I fill up my Tank...

What else is there to say? They are too large. The PCM doesn't like it, the fuel trims are all out of wack, WOT is rich as hell and blows black smoke, open loop start has a jumping idle, etc. Typical of an over sized injector.

Again You have no Idea what your talking about because if you were right I would be blowing black smoke but guess what I AM NOT because my setup is slightly over sized at best...

thats funny right there... 23 mpg. But at least you verified it with the OHC. I have some 60 lb injectors you could thow in.. I bet you could make it to 40mpg with those.

Funny your saying 24lbs injectors is all anyone needs but yet your profile shows your running 26lbs injectors so that must mean your a a super hero and only Your application can possible run larger injectors...

Fine, but he posted a thread with problems.. really?

Your talking BS is all and He fixed his problem as far as he is concerned so you were not helping anyone by creating a problem with me...

The Fact is your talking shit and blanketing all things as your way is the only Way when You have no clue what I have or have done and NO Way NO how am I going to tell you about your vehicle is because guess what I do not know or care about your setup and another thing is NO TWO SETUP are Ever the same so you can call BS all you want but there are better ways to have avoided any of this but you have your Hero Cap on so look out...

I am Confident in my Vehicle and my Mileage and the more you spout off the worse it looks for you as I am not worried one bit...

[jeepman]

Lets tone it down a little with the name calling shall we?
It seems odd that you could be getting 240HP at the crank without an internally modified Engine. This is what some guys get building a basic stroker. You did say you Dyno'd it, but you did not say whether it was Dyno'd at the wheels or at the crank... Dont forget that our Jeeps have about 33% drivetrain loss.

My Jeep Comanche Pickup was Dynoed at the rear wheels with the rear wheel HP noted and calulated for a 30% loss thru my drivetrain added to come to the 240HP and I Also Said around as the losses can not be 100% calculated without both an engine dyno and athen again on a chasis dyno...

The injectors are too big thats plain and simple as you already noted. If your computer cant maintain stoich then thats a great deal off.

It is @ 14:1 where 14.7:1 is ideal for fuel economy not as a must have Air Fuel Ratio...

Its been proven time and again what size injectors are the right size for Strokers and Non-Strokers.

Where is the Proof? I have not seen any REAL Results as I have data to back up my setup, which is why I asked the first time why He thought they were too large not for him to go off on me about things he has no idea about...

Personally, i run 23# injectors and im still slightly rich at WOT with my RENIX ECU (4.7 Stroker). Most run 24#.. but then again it depends on the build. Non of us have needed large injectors that you are running on a stock engine... with our
community being as big as it is, its just something that is proven with real results.
Its your Jeep do what you want.[/quote]
That Is Great But I also Stated I ran 24lbs injectors origonally and was so lean my Header was hot enough to melt so needing 24lbs injectors is not an acurate statement as each setup is different and should be tested to be verified what is best for that vehicle and I can understand it as a guidline for a starting point but by no means is it for all applications...

I have seen it over and over again that 24lbs injectors are the norm but they are only good to 230HP so they will be too small for any real stroker so that must mean that the storker recipes out there are fabricated data and Jeep runs too small an injector from the factory to aid in emmisions which is the number one reason the stock exhaust manifolds crack over time due to a lean engine at WOT...

I can understand ad respect each individuale setup but I will not respect someone telling me what I do or do not have in my Jeep...

[SilverXJ]

Again Your NOT Reading anything just making assumtions as I have multiple comparisons not ONLY reading my OHC I go by my Actual Fuel used when I fill up my Tank...

Once again there is no way actual mileage would match what the OHC says with larger injectors

my setup is slightly over sized at best...

Yeah, thats why the PCM can't control the AFR properly.

Funny your saying 24lbs injectors is all anyone needs but yet your profile shows your running 26lbs injectors so that must mean your a a super hero and only Your application can possible run larger injectors...

That hasn't been updated in a while. 25 lbs and they are a bit on the large side still, but best fit I have found so far.

I have seen it over and over again that 24lbs injectors are the norm but they are only good to 230HP

Based on calcs that don't work with the Jeep PCM/injector combo

d Jeep runs too small an injector from the factory to aid in emmisions which is the number one reason the stock exhaust manifolds crack over time due to a lean engine at WOT...

Wrong, the engine goes rich at WOT. And the manifolds crack because of weak engine mounts and un supported exhaust system

Stop spreading your BS here or your visit may be short lived.