First thing, find the dead cylinder. Squirting water on the header/manifold tubes will find it quick.
This method works being either spark or fuel, or lack of compression.

Of course a scan tool with give the cylinder number of the misfire as well.

Timing light should light if the coil is shooting power thru the spark plug wires, so that's a good idea as well.

Swapping two wires around can check if it's a wire issue.
Swapping two coils around, same thing.

 

Well, I worked up the courage to dig into this. It's all new to me. So, I'm a little timid.
Started it up and let it warm. #5 is the coolest. I removed the plug wire from the coil and started the engine. Yep. That's the one. I could also see and hear the coil snapping a spark from the coil to the coil mounting bolt. A good strong spark. I put the wire back on and started it again. No evidence of spark leakage while running, but still not running on #5. So, the #5 cylinder has good spark.
So, on to the injector. Must be plugged. I see no evidence of any loose or frayed wires.
At this point would a fuel injection cleaner in the fuel tank help anything?
It appears that the fuel rails are held with 4 bolts. I can get them off alright, but I don't know what the next step is. It looks like both rails come off at once. Does the fuel rail come loose from the injector with the little clip at the top of the injector?
Maybe a YouTube video is available. I will look. I like to come here first though.
Yes, there are a lot of videos. I think I better watch a couple of them and probably come back with more and better questions.
Thanks

 

Just make sure to release any pressure in the fuel rails before dismantling.

Did you try a test lite on the injector wire?

 

Just make sure to release any pressure in the fuel rails before dismantling.

Did you try a test lite on the injector wire?

Hey! Thanks for the help
Yeah, I noticed a Schrader valve on the left side fuel rail. I reckon that is to release any pressure in the rail?
No, I haven't checked power in the injector wire. To check this would I pull the connector from the injector, turn the ignition on, and check for power on the orange wire?
I did watch a couple of YouTube videos last night. Changing the injectors seems to be a pretty straight forward operation. Should be easy to handle.
I checked last night for new injectors. The number on the injector is 12561462. I have found some with that number. Checking on Amazon and Ebay, I find the 12561462 injectors to be priced anywhere from $44 new from unknown manufacturers to $350 for rebuilt Bosch injectors. I don't mind spending the money, but don't want to spend more than necessary. Some of the descriptions say that these injectors may need ECU tuning. I assume because they flow more than a stock injector. I definitely don't want to get involved in all that.
Any suggestions on where to get the proper injectors?

 

did you hit the basics?
how is compression?
did you swap the injector with another cylinder to verify the issue stays with the injector?
did you swap the coil with another cylinder to verify the issue does not stay with the coil?

yes, all injectors can be cleaned and flow tested.

injector cleaner you dump in the fuel does nothing

stay away from injectors on ebay.

 

Have not checked compression or done any parts swapping yet. That #5 cylinder is the 2nd worst plug to get at (the worst one, #7, is damn near impossible to get at). Right now, I can't even get the wire off the plug yet. But I did hook up another plug wire and plug to the coil on #5 and started the engine. Good strong spark at the grounded plug. So, I am eliminating ignition problems. However, I will check the plug condition and compression as soon as I can get the wire off the plug without destroying the wire. At this point I am pretty sure it is the injector. While researching I discovered that the injectors should be cleaned at 40K to 60K miles. I didn't know that, and it hasn't been done.
I think now all I need to do is source a good set of injectors that don't require an ECU retune. I've got the number memorized, 12561462.

 

To check operation of the injectors you will need a NOID light. Not to expensive at the local parts store. As a side note the way injectors work is they have power all the time and to fire them they are grounded thru the ECU.

A noid light will flash each time the injector is fired. No flash for just one injector would mean (to me) that there is a break in one of the wires going to that injector.

For the modern engines you should get several new tools. Noid light, scanner (use your phone and an app) and a non-contact thermometer (Harbor Freight).

 

If you have spark, then either fuel or compression will be the issue.
Have you performed a compression test?
To check an injector , unplug it and check the resistance
And yes, one of the 2 wires to each injector have battery voltage with key on, so check for that. The other side of the injector ,the computer controls the ground side of each injector, as it is sequential injection not batch fire
The injector is a small pintle vale that opens and closes by the use of a coil ,inside each injector.It is effectivley an electrmagnet of course ,like a starter solenoid, only smaller
Check the ground side to see if the injector is recieving its"pulse" or ground on off signal, while the engine is running
Do so by using a small light bulb, not a large bulb, use a 194 or something .wire a couple leads to it and plug it in to the injector harness. Remember , you already verified power to the injector plug? yes ?no?
So if it has power , plug in the 194 , start the engine..look for the light to blink,no blinkie means no ground path
As master 39 eluded to , sounds like a wiring issue,probably mice

So... to sum it up....
Check for B+ at of the injector terminal for #5
Ohm the injector, compare it to a known good injector reading
Look for injector pulse on the ground side of the injector connector, with engine running

One of the 3 out of spec will reveal something

 

If you have spark, then either fuel or compression will be the issue.
Have you performed a compression test?
To check an injector , unplug it and check the resistance
And yes, one of the 2 wires to each injector have battery voltage with key on, so check for that. The other side of the injector ,the computer controls the ground side of each injector, as it is sequential injection not batch fire
The injector is a small pintle vale that opens and closes by the use of a coil ,inside each injector.It is effectivley an electrmagnet of course ,like a starter solenoid, only smaller
Check the ground side to see if the injector is recieving its"pulse" or ground on off signal, while the engine is running
Do so by using a small light bulb, not a large bulb, use a 194 or something .wire a couple leads to it and plug it in to the injector harness. Remember , you already verified power to the injector plug? yes ?no?
So if it has power , plug in the 194 , start the engine..look for the light to blink,no blinkie means no ground path
As master 39 eluded to , sounds like a wiring issue,probably mice

So... to sum it up....
Check for B+ at of the injector terminal for #5
Ohm the injector, compare it to a known good injector reading
Look for injector pulse on the ground side of the injector connector, with engine running

One of the 3 out of spec will reveal something

I'm sorry. I am about as electrical as a brick. I probably shouldn't be anywhere near this LS engine. But I'm damned if I want to take it to some shop.
I just checked for 12 volts at the orange injector wire. At first, I didn't get anything. I then checked #1 and found 12 volts. Rechecked #5 and still nothing, but I scraped the point of the test light around in the terminal and got power. I thought that corrosion might have had the circuit open, and I thought that might fix it, but no go.
I have power at #5 now, so now I need to check for the ground pulse from the ECU. Is the NOID light that 39 master alluded to the same as your 194 light? I have a small 12V 3W bulb. Do I solder leads to each terminal of the bulb? Where do the 2 leads hook to? One to the ground side of the injector plug, and the other to ground?
To ohm the injector, just check across the 2 injector terminals? Is there a number to shoot for, or just that they are all in a fairly close range?
I appreciate the help! Sorry about all these dumb questions. My 1926 and 1927 Model T hotrods don't have a computer anywhere near them.
LOL! I did find a chewed-up acorn under the coil covers when I pulled them last night. A couple of years ago, I had a mouse problem. Then I took in a stray cat to live in the shop. No more mice. I think the mouse problem was eliminated with the appearance of Katy Kat and was well before the injector problem showed up. Still could be a problem though.

 

FWIW, my neighbor has a 2006 ZO6 that he rarely drives, has about 25k on it. He drove it about 30 minutes and stopped at a store. When he started it to leave it had a dead miss. I checked with a cheap scan tool and it said cyl 1 misfire. Replaced that spark plug and still had a miss. Checked it with HPTuners and it said cyl 3. Replaced that plug and misfire was fixed. Plugs looked like new but went ahead and replaced all 6 others.

 

Yes, it could be a fouled plug. And I intend to check that as soon as I can get the damn plug wire off without destroying it. The master cylinder and booster and I don't even know what that other thing is are right over the #5 plug. I have changed the plugs once before, so I have had it off. I will get it off if I have to destroy it. New plug wires wouldn't hurt anything. But I'd rather not.
I checked the DIC. It is showing 3 codes. P0300HC- engine misfire detected, P0200HC-not on the code list I checked, and P1416C- AIR System Bank 2. Not that this helps me.

 

The computer grounds the injector the hot side is always at potential but obviously no current flows till the computer cycles that injector to ground.

Injectors do grow old and die from electrical or mechanical reasons, so do computer circuits at least from electrical and/or electronic reasons. Unfortunately there isn’t a lot that can be tested for in shops not up to modern standards for this EFI equipment, this is what has pretty much killed the private repair shop from engine work as the cost of equipment and training is pretty much out of reach.

Bogie

 

Unfortunately there isn’t a lot that can be tested for in shops not up to modern standards for this EFI equipment, this is what has pretty much killed the private repair shop from engine work as the cost of equipment and training is pretty much out of reach.

Bogie

You said a mouthful there, Bogie! But it's not just the EFI systems. I replaced a rusted brake line on my wife's newer car. I couldn't even bleed the brakes. I called my buddy with a shop. He laughed and said come get my little black box. I went and picked it up. He told me to be careful with it and bring it right back. It cost $11,000. Long story short, it let me bleed the brakes. You can't even do your own brakes without a lot of expensive equipment. Excuse my language, but Horse S#*t.

 

Your test lite goes into the injector pigtail. Start the engine and it should pulse.

What you are checking now is no more complicated than any other repair experience you already have under your belt. Just a bit different.

 

I made an injector tester /cleaner setup years ago. With the newer disc style injectors they are self cleaning ( seems to be ) so not much need to clean them. Most of the time a cleaner for the fuel system cleans the deposits off the back of the intake valve (very good actually) but with Gas Direct Injection that doesnt happen. Also with GDI the backs of the intake valves can get crudded up with oil/burnt oil/ crust

 

With GDI, an intake/valve clean is recommended at least every other oil change.

I buy that stuff 6 at a time

Regarding testing. The noid light can be used to test the coil and the injectors (both with sinking grounds by the ECM)

 

OP: Disregard the direct injection stuff in your situation. You don't have that.

 

OK! Finally got that plug wire off. Found the easy way. Plug looks good. Compression is 160 psi. Also checked #3. Plug looked good. 170 compression. I don't know what it should be, but that's enough to make it run.
Ohm reading across the #5 injector was consistent with the reading on #1 injector at 12.4-12.6 ohms
Haven't checked the ground pulse yet.

 

sorry double post

 

If you dont have an injector pulse (-) then look at the wiring real well.
Rodents dont ya know

 

My light is winkin' and blinkin'! I have compression, power to the injector, ground pulse verified, spark at the plug.
The suspect #5 injector and the #1 injector both Ohm'ed at about12.5. Does this mean that the #5 injector is probably good but clogged?
On our 410's we would blast the crap out of the mechanical injectors with brake clean and put them in a small ultrasonic tank. I don't suppose that would be advisable with these EFI injectors.

 

The injector sounds like it is OK electrically. It is in the correct resistance range, so OK
Maybe the pintle is stuck/varnished and it wont open
Try tapping on it with a hammer while the engine is running to see if it will clear

 

I had a dirty injector from a super beetle , it wouldnt spray . I had the pulser hooked up and fuel pressure from a pump (on the bench) so I slammed it down on the bench while it was being pulsed and it started spraying and it cleaned up.
Car had been setting for 6 years
Not exactly a scientific approach, but hey it worked
Tap the injector on the side , not too hard

 

Tap the injector on the side , not too hard

LOL! I guess since it is no good the way it is, I could rap it with increasingly harder taps until it breaks if it doesn't clear. I gotta buy a new one any way! Thanks for the help! I might just win this one.

 

If the injector is hard to reach ,use an extension like a punch, or an extension ...LOL

 

actually, ijector cleaner is mostly toluene ,or xylene, or both, and a top cylinder lube.Thats it.
brake clean is usually just acetone, and wont hurt them either, but it will eat lots of other stuff on a car..LOL

 

If tap tappy doesn't free it up.
Key Off, Engine Off. Apply 12v to the injector via jumpers and listen for it to click. You can also try to the same off car, while shooting some carb cleaner or brake cleaner into it.
I've also had the winding fail. They would fire off car, but wouldn't with 60psi behind it.

 

there are several places local to me that clean injectors with high pressure solvent. I think they flow them in both directions. and can watch the spray pattern and volume to see if they are functioning ok. I would still just stick a new spark plug in there and try it.

 

I didn't get a chance to work on this yesterday, but decided this AM that I would go get a set of new NGK plugs to replace the old AC Delco plugs. Probably a set of wires also, figuring that I would kill a plug wire or two trying to get them off the plugs. I would rather go to the dentist than change those plugs! I am going to change the plugs before messing with the injectors, though. I haven't ordered a set of injectors yet.
Thanks, you guys, for holding my hand

 

Don’t beat up your injectors! lol.

Just take them all out (as you should do every 50-60k anyway) and send the off to be cleaned and flowed. They will immediately be able to tell you if that #5 was clogged or not flowing. (mark that injector) They will also have ultrasonic tubs to toss them in and can usually clean and cure injector issues. If you don’t have anyone local I’ve used Eric for years. Great prices and great guy to deal with.

Derrmain@twc.com. 502-381-4678

Derr Injection Service
Eric Derr
2220 Window Court
Bowling Green, KY. 42104

Also… Id throw in iridium plugs and you won’t need to change them for 100k miles… aka likley never again!

 

So, they do use an ultrasonic bath to clean these EFI injectors? As I mentioned earlier, we put our mechanical injectors in our little ultrasonic tank (bought just for injectors) to clean them, but they are just a hunk of brass with a hole in it with a screen over it. I have never actually had an EFI injector in my hand to know if it is all sealed up or not, or anything else about it, but I would be willing to try that if other shops are doing it. I'm betting that I would at least need to put a spare injector plug on it to protect the electrical stuff inside.
I haven't checked to see if anyone local cleans them. I'm about 60 miles from anywhere

 

Yes, super common. The standard EFI test flow bench tools usually have a sonic cleaner on top built in. The injectors are pulsed as the bath cleans them. You get flow numbers before and after.

 

Well, I finally got back on this today. Changed the plugs and wires. It ran better on all cylinders except #5. Still not getting fuel. So, I went after the injector with a small beater. Started with easy taps. I got to about the 3rd level and I'll be darned, #5 kinda stumbled a little and came alive. I took it for a 100 mile test trip this afternoon, and it runs out great. I think I got a couple extra MPG according to the meter in the car.
Now I need to find someplace close and get all the injectors cleaned.
Thanks guys, for all the help and information. I got a good basic idea of what is going on with EFI now.
I am a member on the Corvette Forum, but I just don't feel as comfortable there.
I'm not really a Corvette guy. I just happen to own one. I'm really a HotRod guy!