You can't. I was just repeating what I said in the first post and what HeyYou said. However, good to know you used NTK. So, I'd go back to the stock Tstat and go from there. It also wouldn't hurt to check the IAT and ECT sensors per the Haynes or service manual from the FAQ section.

 

Never heard of that brand, and WOW you overpaid for them. It doesn't even give a flow rate. I am guessing that those aftermarket injectors are the culprit.

 

Could be I suppose. After he posted the part# and brand, I did some research. Nothing to be found. Best I can tell, is that they are rockauto's house brand.

Edit: but I imagine even if they are the problem. They are still just stock replacements. Or are suppose to be anyway.

 

I have no doubt that they are "stock replacements." But how rockauto decided that THEY had correct flow rates is the question. I know that the flow rates differed from 1994-2001, ranging from 19lb/hr to 21 lb/hr. But you never know if those ratings were at 39, 43.5 or 49 PSI Rockauto could have looked somewhere and saw, "Hey, these things flow at 21 lbs/hr. Lets make a 21 lb/hr injector the stock replacement." However, if they are rated at 21 lbs/hr at 39 or 43 PSI, then you will run rich. BUT, if you get 19 lb/hr injectors that are rated at 43.5 PSI, you will be sitting around 20.5#s at 49. THAT was my point.

I don't think you can go wrong with 19 lb/hr injectors, because the max they could flow on our engines is about 21 lbs/hr. For 63 less dollars, you can get the Bosch Design III 19 lb/hr injectors with 4 holes. I have heard of Bosch, and dodge uses bosch/siemens.

 

No argument there. I'm just saying, I don't think rock auto is going to sell something if it's not stock spec. They could be and might be junk as far as quality goes, but all I'm saying is that they are not 90 pound injectors for example.

 

and to add another twist to the injector saga:

if a manufacturer makes a run of 400 injectors, they flow test them and break them down from most to less, in fifty piles of eight injectors.. if you were to put together a set and were unlucky enough to purchase from a manufacturer that didn't do this, you may find that injector one flows quite a bit more than injector five, but less than seven.. "quite a bit" being the operative word.. to add to that problem, I don't know of a single control system that monitors each and every cylinder, which means you could be running one tube lean, and another rich, and not have a clue.. ever.. until you pulled a plug and inspected it months later..

many 're-branded' injectors are either rejects from the factory, meaning way out of spec- or, they are re-built injectors. In this case, you'd WANT to have the reman'd set.. because at least someone likely bothered to test 'em out before launching them.

injectors are tough little rascals.. even when they start to jack up, they can be cleaned and re-introduced by the owner for a good long time.. knowing now what I didn't know when I swapped them, I would have never swapped them in the first place..

and, since this is winded anyway- I'll continue:

FiveO may know injectors, but they(he) doesn't know these engines. He may quote what is a 'stock replacement' based on a cursory glance at the specs, and see that 21# is what is called for- but he doesn't know that 21# isn't at 43.5psi.. He doesn't know that dodge calls them 21# at 49psi, and they are likely 19# injectors at the somewhat industry standard of 43.5psi.. Likewise, he'll look at the specs of the injectors (and understand now, Bruce KNOWS injectors), and see that those FSM 21# injectors are rated at 39psi (psi of the ford rails on that gen of mustang) and do some quick math on paper and see that they are comparable to the 22# 'red' injectors.. what he doesn't know is that under 49psi, the characteristics of that particular injector change dramatically, and they are pumping 25.5#'s at an engine designed for 22#.. er, pig rich..

and the plot thickens:

the PCM on these rigs is figuring that it will have to curve fuel.. so, it does.. but the window for curving fuel is smaller than what you would think. If that thing can curve 1/2 a # I'll kiss your ***.. it's designed to offer tiny changes to adjust for environmental alterations on the fly.. tiny, like maybe 1/4#.. if it could scream, it would likely be screaming "CAPTAIN!! I'M GIVING HER ALL SHE'S GOT" in terms of shortening the duty cycle.. that 1/4# of delivery could be the difference between 14.0:1 and 11.0:1 I would argue.. One is dangerously lean, the other is wasting and gunking.. A programmer can alter the tables, and shorten the cycle even more, but at some point even it can't do what you need it to do..

your rig is a '94 which makes it even more difficult.. you are running 40psi or so at the rail, no?

there are two ways to go about this.. One is legit, the other is making a Guinna Pig out of you.. You can swap back to KNOWN good injectors, re-install the OE ones, or put a fuel line return and pressure regulator on that thing.. With pressure regulated, and a decent wideband a/f gauge, you could dial the pressure to match the flow.. and hope- fingers crossed and all- that the flow characteristics of the injector are consistent across the psi range you decide to use.

 

Ok, just to toss a monkey wrench into the works here......

On flow rates: Not only is it important to know at what pressure injectors are rated at, also, at what DUTY CYCLE. (percent open time) An injector that flows 25 pounds at 80% duty cycle, will flow even higher at 100%. (basically, always open.) The computer gets a certain 'window of opportunity' to inject gas at 'just the right time'. On our engines, that starts very shortly before the intake valve actually starts opening. Stock injectors have a pencil stream of gas, aimed at the back of the intake valve. This serves two purposes, cools the valve, and by doing so, atomizes the gasoline quite nicely. (basically boils it.....) So, as you can see, just having a constant spray from a low volume/high duty cycle injector, just won't work very well.

Even though the computer has a great deal of latitude on what it can do with pulse width, the injector has to flow enough gas AT THE RIGHT TIME in order to do its job most efficiently. Also, the injector can't flow so much gas, that even with a minimum pulse width, (defined by tables the computer uses to idle the engine), it can't inject too much gas either. (running rich, in all reality, at idle, in park or neutral, the computer leans out the mixture......)

You can get flow balanced injectors. (all in a set flow pretty damn close to the same amount) Doing so can improve fuel economy AND power....... (not to mention make O2 sensors, and cats last longer.....)

To me, the ideal solution for a stock, to mild engine, would be grab a set of stock injectors, and send them out to be rebuilt, and flow balanced.

 

This is all great info(as is the other numerous threads going on about this topic). Only one problem, the OP was assuming he was just getting stock OEM replacements. And that's what RockAuto or any other place he gets them from should provide. Quality aside.