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Back at the end of January I sent a spare set of Injectors to Witch Hunter Performance to be cleaned and flow tested (figured it would be a good idea after 22 years of service). I received them back at the beginning of Febuary and just swapped them in today only to have a very poorly running engine with a misfire in cylinders 5 and 6. I thought I better pull out my noid light and check to make sure I didn't accidentally break an injector wire somewhere since things get brittle over 22 years. Test showed all injector wiring to be working correctly, next was to listen for injector pulse which was also good. Now I figured it would be a good thing to start disconnecting injector wiring with the engine running to determine which cylinder(s) I'm having an issue with. Turns out that cylinder 2, 3, 4, and 8 made no change as to how the engine runs. I ended up reinstalling my original injectors and now it's back running properly again. My thoughts are that either I let the injectors sit too long before installing them or they never worked correctly after they were cleaned and flow tested even though they supply a flow chart with before and after results.

Needless to say the old saying still holds true, if it ain't broke dont fix it.
 

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I have to say I am not too impressed with that company I sent some TBI fuel injectors there years ago. Cleaned, checked, flow tested ETC. I do believe one of more of the fuel injectors leak and the testing they do is not done under "heat" or elevated operational temperatures which could cause a injector to malfunction. A cold test is not a valid test. I may deal with Southbay fuel injectors, Some dude frank in New York. They charge 20 bucks to clean them which is slightly lower or the same as most these days. Or ill just get a set of Bosch 3's from them. Big sale going on now


These cars have gen 2 mutitec injectors,, starting in 1994. They are supposedly better than the earlier ones 89-93? that were even used on TPI vehicles but I still hear they are no good for E10 gas and they are not good Candidates for cleaning as the internal coil can short out easy. I have a 47k car. 4 leaking multi tecs, crank case reeks like gas, starts terrible sometimes warm or cold, like almost like its flooded extended cranking. I may just give up on these injectors apparently the Bosch 3 will work but it MAY req some tuning because they have way less delay that the multi techs have a good amount of. They could overfull even being 24lb. All info is GONE now websites gone. Sad really. So much info is lost on what people did even 5-10 years ago .



I finally got off my lazy ass and decided to dig. Glad I found an issue.
 

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they are not good Candidates for cleaning as the internal coil can short out easy.

I had the same experience recently. I managed to get 250K miles out of my factory-installed injectors, and I thought I could get away with a professional cleaning instead of buying a new set. A few of them failed soon after reinstallation, so I ended up having to buy a new set anyway.
 

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Bummer. Had a similar experience w/ some NOS injectors once.
KILLED my engine, raw fuel coming out the tailpipe. On removal and inspection 3 were defective(missing parts) So rather than a spray were just faucets dumping insane amounts fuel into the cylinders.

I've always used Mr Injector - Home and always had excellent results/no issues.
 

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They could overfull even being 24lb. All info is GONE now websites gone. Sad really. So much info is lost on what people did even 5-10 years ago .
which websites? Finding good injector data is amazingly difficult. Places like Racetronix don't even advertise anything besides flow rate on their website. Does anyone know if they have it in their support forums? If you don't set the short pulse adders and voltage offsets, your car will not crank or idle well.
 

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which websites? Finding good injector data is amazingly difficult. Places like Racetronix don't even advertise anything besides flow rate on their website. Does anyone know if they have it in their support forums? If you don't set the short pulse adders and voltage offsets, your car will not crank or idle well.

Just General specs to injectors or some baseline tables people may of started with. All links gone. Used to be some LT1 tuning pages. All gone . I Did find some long page it seems to list every bosh injector and some specs with the part numbers and flow rate at __ psi



So Bosch injectors are going to give me issues? Think its easy for someone like myself to DIY tune it? I think the Standard (Cheaper priced maybe the same as ACD) And ACD injectors are the style that the delphi (gone) stock fuel injectors used to be. They have a more squared off look on the body of the injector if that even means anything. Probably not. They should be drop ins Just not confortable throwing 180 or so at old 25 year old multitchs unless I come up some way to pulse the injectors. Ultrasonic cleaning tanks have become CHINESE and cheap priced. DIY cleaning could work
 

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was told 20yrs ago fuel injector cleaners some will damage the coils. so most likely the cleaner guy used a harsh solvent that damaged the coil.. measure the resistance should all be the same.. I think it is 11.5 ohms ..insulation of the coils will break down when solvents eat at the coils insulation so sitting on shelve will also cause this even if not used ..
 

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Just General specs to injectors or some baseline tables people may of started with. All links gone. Used to be some LT1 tuning pages. All gone . I Did find some long page it seems to list every bosh injector and some specs with the part numbers and flow rate at __ psi

So Bosch injectors are going to give me issues? Think its easy for someone like myself to DIY tune it? I think the Standard (Cheaper priced maybe the same as ACD) And ACD injectors are the style that the delphi (gone) stock fuel injectors used to be. They have a more squared off look on the body of the injector if that even means anything. Probably not. They should be drop ins Just not confortable throwing 180 or so at old 25 year old multitchs unless I come up some way to pulse the injectors. Ultrasonic cleaning tanks have become CHINESE and cheap priced. DIY cleaning could work
Injectors seem to be designed and manufactured in families, so probably best to figure out which family of injectors is ethanol resistant. Perhaps a call to an injector service company could give more info?

For me, I'd always get the newest injector and injector design that I could. After that, it's really a question of where to obtain the data. Once I get characterization data, then I can make a final choice from there.

I switched over to newer Ford injectors as Ford's characterization method is far more elegant AND they publish the data online so you can actually figure out the GM voltage offsets and short pulse adders. If you read around, you can find how to create GM values from it.

My fallback would be newer GM injectors; you'd need to lift the injector data out of factory PCM tunes and then either use or massage it to fit the LT1 format. That data's hopefully available in tuning forums like HP Tuners etc.

If you get a set of injectors cheap but have nothing but a flow rate, if you're willing to play with the tune you can reverse engineer the short pulse adders. Get your stock injectors cleaned and tested, get the car in good shape mechanically (no exhaust leaks, a sealed intake and exhaust, preferably the factory intake setup), then tune the car perfectly. Then, swap out the injectors and start playing with the short pulse adders until idle and part throttle fuel trims clean up. If the trims are adding fuel, increase the short pulse adders. If the trims are pulling fuel, reduce them. Use a curve fitting tool and/or a spreadsheet tool to modify the stock short pulse adder curves.

Coincidentally this is why places like Injector Dynamics sells injectors for ridiculous prices. It's not that their injectors are significantly better than OEM, it's that they're characterized. You're really paying for that characterization data. A number of tuners mandate those injectors before they agree to tune a vehicle, for that specific reason.
 

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Then, swap out the injectors and start playing with the short pulse adders until idle and part throttle fuel trims clean up. If the trims are adding fuel, increase the short pulse adders. If the trims are pulling fuel, reduce them. Use a curve fitting tool and/or a spreadsheet tool to modify the stock short pulse adder curves.
Could you be more specific about where in the LT1 tuning environment (TunerCat or EHack) the fuel delivery at idle can be affected.?After removing the stock time delay on the factory injectors there seems little that can be tuned in the LT1 OBDI environment to stop the PCM from it's pre programed idle which is too rich in my case.



When I installed a set of bosh/ford injectors several years ago several reputable members suggested I would have issues with rich idle. I have not been able to prove them wrong. The newer injectors have very little opening delay compared to factory injectors.


As a total amateur at tuning I have tried affecting the PCM by reducing the cylinder size or changing the MAF tables.



The other issue with new injectors is spray pattern. I have wondered if the spray pattern of other injectors may be too "long" or too "wide" for our cylinder.


Like the professional injector cleaners some of the cleaning and testing can be done at home.



First step would be coil resistance measurement, better practice would be to scope each one in a running engine. Electromagnetic parts can do strange things in the heat of a engine compartment.


Next would be general cleaning. A Arduino programed to pulse the injector at a low duty cycle in a ultrasonic cleaning tank may work. For a chemical OTC Inject-RKleen(7000A). Do NOT add this to your gas tank.


Pressure test to see if the injector closes properly. Look at the spray pattern. Use the Arduino to match injectors flow rate.


You can also buy pinnacle caps and the filter inside the injector.


I think I have had better luck by just purchasing re manufactured units with a long warranty. (New if I could afford it)
 
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