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Discussion Starter · #1 ·
Do injectors get "old"? I mean, like I should replace them (or upgrade them) in the same way as spark plugs?

I've got an '88, so they're easy-to-do-math 20 years old now, but it never occurred to me before to "replace" them in the same way as spark plugs.

I took them out a few years ago, (say 5 years ago), and as far as the nozzles were concerned, they were just as shiny and spot-free as the day they were born. I replaced the litttle "O" rings, (which were as dead and brittle as glass!), and then just stuck them back in.

Is there any benefit to getting a pimped-out "hi-performance" set?
 

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you can ultrasound clean them and check for flow, and with other injectors you can get more flow so you can make more power or get more psi from the turbo without getting lean
 

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There may not be a need to replace them... but after 20 years it probably isn't a bad thing to do.

I know injectors are on my list for replacement soon enough.
 

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they can be cleaned ... 2 parts in the injector will require periodic cleaning

there is an SS screen at the top of the injector ; to clean this you need to back flush the injector

also the nozzle portion will over time accumulate deposits leading to a poor spray patterm or possibly reduced flow

I remember seeing an injector cleaning kit somewhere with a large aerosol bottle and a special fitting to fit over the tip of the injector such that you can back flush with the pressurized solvent in the bottle ; IIRC it was like a 12-16$ kit ..
 

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Discussion Starter · #7 ·
As long as they're spraying fine there's no need to replace
I guess it comes down to that. I can't think of a way to make sure they're "spraying fine" though-- not without shooting gasoline all over the place!

I see in the part of the book about depressuring the fuel system where it tells you to hot-wire an injector a few seconds at a time. It says that you can hear it spraying while there's pressure; when it stops, the pressure's gone.

Ok, so I guess I'll just do that for each injector and listen for one injector not being as loud as the others or something. Otherwise...?
 

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you can pull the whole fuel rail leaving the wiring, injectors, and fuel lines hooked up; then point the thing up in the air and have a buddy turn the car over for 4-5 seconds ; you can visually verify the spray pattern of each injector this way

*no smoking* and just in case you may wish to have a fire extinguisher handy; open the doors to the garage too ;)
 

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Discussion Starter · #9 ·
...point the thing up in the air and have a buddy turn the car over for 4-5 seconds...
Yikes! Yeah... I might try that-- if I can find a friend with twenty square feet of fireproof blanket to cover up most of the engine. (Any firemen out there in the Hollywood area?) Maybe a big sheet of plywood soaked with water?

Seriously, if the injectors are working fine, they will just mist the place up, right? Which is already bad enough, but suppose one of them is clogged, and what comes out is a squirt-gun type of stream that falls right into the alternator, which... :eek:

Hmmm I dunno man... Maybe if I cover up the rest of the engine compartment, at least; but I guess you're right, it's the only way. I'll work on it.
 

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It's really not as big a deal as you might think... People do it all the time with no harm done. If I were you, before you do it, just go get some new O-rings & Syl-Glide or Vaseline to lube them. With a 20-year-old car, they're almost certainly dry & hard. Spark plug boot grease works too, but it's pretty expensive. Syl-Glide is, too. I usually leave them nozzle-down, resting on a relatively small piece of cardboard. The amount of time they're going to pulse isn't really going to allow much fuel to come out. The fuel coming out should be like a cone. Any deviation from that means they're dirty. Just get some Mopar fuel injection cleaner. Cars came into the dealership where I used to work barely running. One or 2 bottles of that stuff later and they ran like new. You could get something from the parts store, but it's so hard to know which ones are effective or little more than a $12 bottle of K1 Kerosene. The Mopar stuff has proven itself, at least to me, time & time again. Be careful with the injector harness, the insulation is probably brittle.
 

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cleaning injectors is all fine and dandy as they say, but there is another issue of the seal point being dented and the electrical part failing. Many old ones don't completely shut, then out the window goes the mileage. At this point in time it is just a good idea to buy new MP injectors, they are super cheap. They'll open when they are supposed to for the best power and close when they are supposed to to eat less fuel. The ones in my CSX and my colt turbo don't work right, both eat too much fuel and lack power. 1 Colt turbo injector cost more than 4 +40s ack. Clean the harness and use dielectric grease if I spelled that right lol. Use motor oil on even brand new O rings. I am hyper and destroy little things like that. Consider a new fuel filter? How many of keep those changed .....
 

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Discussion Starter · #12 ·
Ok guys, I would like to do both things: pull the fuel rail off and squirt gas all over, (just so I know what has been happening), and also get new injectors, (let's face it-- they're 20 years old).

One problem remains: according to the knizefamily guys/the minimopar site, ( the page here,):

* There was a mid-year change in 1988 from the 27 lbs/hr to the 34.85 lbs/hr injector

Yeah, well-- I've got a "mid-year 1988", so I might have either flavor.

Let's assume for the moment that what is in my car today is the more wimpy injector. ( I pulled the fuel rail off a few years ago, just to clean things and look for obvious problems. I don't recall the injectors having any markings on them, but perhaps they did and I just don't remember them. )

Then there would be two relevant possible cases regarding that change:

A) The engineers made that change IN CONJUNCTION with some other change they made; say the Fuel Pressure Regulator and/or it's variables in the SMEC. In this case, I should get injectors which are THE SAME wimpy ones that are in there now.

B) The engineers made that change INDEPENDENT of any other change. IE, they said to themselves, "Ya know... with this '88 T1 engine the way we made it, we really should have gone with the more manly injectors. Let's upgrade them and call it a day". In this case, I should ignore the fact that I have the wimpy ones, and go with the more hefty injectors.

Is it clear?

It seems like pretty recondite knowledge-- you would almost have to be one of the Chrysler engineers of that time to know why they decided to do this, but I have to ask: Does anyone know which of the two it is?
 

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the injectors do have part numbers printed on them. you can look up the numbers on them on this table:

DDG- Injector Flow and Application charts

according to that table fuel pressure stayed the same througout the years regardless of the injector flow rate, so i assume this means the computer was updated to run the 'mid-88' bigger injectors at lower duty cycles to maintain an equivalent fuel supply

if you dont have some reason to suspect a fuel system problem with your engine then dont replace the injectors

bigger injectors by themselves arent going to do anything for you
 

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I don't like the older stock cals either, the engines idle like a Harley. How about a nice new custom cal with the 804s and call it good? I am not sure why, but my mint TC idled like crap, and the cruize barely worked right. Then in went a stage 3 and it is a different car that quik. Do they richen it at idle? Or do they lean it? Don't know but I can't stand stock computers anymore lol.
 

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the injectors do have part numbers printed on them. you can look up the numbers on them on this table:

DDG- Injector Flow and Application charts

according to that table fuel pressure stayed the same througout the years regardless of the injector flow rate, so i assume this means the computer was updated to run the 'mid-88' bigger injectors at lower duty cycles to maintain an equivalent fuel supply

if you dont have some reason to suspect a fuel system problem with your engine then dont replace the injectors

bigger injectors by themselves arent going to do anything for you
To add to this I do have a question. The 27 lb injectors have a log fuel rail clip and the 34.5s have a later 1 and 2 piece fuel rail clip in different spots. So that would mean 2 completely different designed 27s? :confused:
 

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Let's assume for the moment that what is in my car today is the more wimpy injector. ( I pulled the fuel rail off a few years ago, just to clean things and look for obvious problems. I don't recall the injectors having any markings on them, but perhaps they did and I just don't remember them. )

Then there would be two relevant possible cases regarding that change:

A) The engineers made that change IN CONJUNCTION with some other change they made; say the Fuel Pressure Regulator and/or it's variables in the SMEC. In this case, I should get injectors which are THE SAME wimpy ones that are in there now.
I believe this is the case ; BUT first check your current injectors to verify which they are ; I will bet they are the early 27# ; I have pulled 2 88 TIs apart and thats what they had

so assuming you do have the early 27# units, if you find you have a bad one (or more) OR want to replace them anyways, you have several options

1. replace with new 27# units ; no changes necessary to electronics, FPR etc

2. replace with new later stock '89+ "2.5 TI / TII" injectors (33 or 34,75 # depending on which website you read) ; you *should* get an AFPR to drop the base fuel P a smidge to maintain a decent WOT A/F ratio - (easy and will give you tuning flexibility), or get a custom cal ; or do neither and run rich at WOT (safe but you will give up some Hp and will use extra fuel)

3. if you eventually plan to go with more modifications (bigger turbo/FMIC, headwork/cam, etc) then you could consider buying "+20%" injectors ; this will also require a AFPR at minimum and/or a "+20" calibration to manage your WOT A/F and cold start etc

I will maintain that injectors don't REALLY get old (sorry Pope :) ); if they are clean (nozzle tip) and functioning then they are OK .. most of us are running on 20 + year old injectors ;) my +20s are who knows how old and have been handed down at least 3 times ;

all injectors will fail eventually and will either not close all the way or not open at all ; or have crappy spray patterns ; all these symptoms are relatively easy to diagnose and should be obvious to you if you are paying attention to how your car is runnning ; or can be verified by pulling rail like I suggested above ; easy 15 minute troubleshooting step
 

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Our injectors sure are cheap. Granted don't swap if you don't have too, but all of my cars have run a little better. I am also a fan of +20s, they don't drown the engine with fuel like +40s have. I actually have 2 +20 cals. I priced cleaning my injectors and it is $50 a piece, vs a hair over $100 for 4 new ones lol. Could be I spend too much on my TDs,,,,,,,,,,,,, too.
 

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Why not just get a clear plastic tub from Wal-Mart or something and shoot the fuel into that. No need to spray it all over the engine bay.

Honestly, even if you have the early injectors, just throw the 33# T2 ones in there. The computer can adjust some for extra fuel. I highly doubt you'll notice much difference if any.

Seafoam is a decent injector cleaner. And anything with Techron is supposed to be good. Also, you don't have to put it in on a full tank like the bottle says. If you want it to be a bit stronger, try adding it on a half tank or a little less. Just don't go too low because it doesn't burn like fuel.
 
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