Holley 160 lb/hr injectors sticking or tune?

[94blowncobra]

Just installed new Holley 160 lb/hr flow matched Injectors. The injectors act like one or a few are not opening & closing properly.

I have the engine idling at 850, but my AFR is going rich and lean, and causing the ECU to compensate up and down rapidly by 20% or so trying to maintain setpoint AFR. Revving the engine is the same thing.

My Base Fuel Table was dead on with the previous smaller injectors. I setup the ECU for the exact Holley part number for 43 lb/hr fuel pressure.

I rigged a tester with carb cleaner and cycled each injector today. All of them sprayed about the same. I understand this was a crude test, and doesn't tell you the flow, but was just to see if any were dead or sticking.

I bought these off Summit. They came in crappy molded plastic with no flow numbers or anything. I would think if you bough flow matches injectors you'd get a flow chart or something. Really sucks is I've had them a little over 90 days, but just got the new engine finished, and I'm sure they probably won't take them back. Sorry for the rant, and ideas for this issue? Thanks.

[94blowncobra]

On a side note, I got the AFR somewhat stable, and then disabled Closed Loop. The AFR still had random lean spikes like you would get during a misfire.

[AndyF]

If you think the injectors are suspect then take them to a place with a test stand. The local NAPA shop will flow test injectors for me while I wait and he usually doesn't even charge me for it. Just pops them in the machine and runs them for me.

If your AFR is surging back & forth you most likely have a bad tune. Get the engine fired up and keep it running at a fast idle until you get some heat in it and then use your laptop to adjust the Target AFR at idle. Or put it in Open Loop and just directly change the Base Fuel Table. Select a 3x3 set of cells around the idle spot and just up arrow or down arrow until you get a nice stable idle. It takes longer to describe than to do. Do the same with the timing if you are controlling timing. If you still have random lean spikes after that, the maybe you do have a misfire. Pull your plugs and look at them, check your ignition wiring, etc. Do you have a PCV valve or a brake booster? Those devices can generate MAP spikes which in turn cause AFR spikes.

[andrewb70]

It's also possible that you have an exhaust leak upstream of the WBO2 sensor. Andrew

[94blowncobra]

I put my old injectors back in and the engine is smooth.

I did turn off Closed Loop and tuned my idle AFR. I could get it stable at 14:1, but there are still lean spikes and my down pipe out the fender sounds like some lean popping going on out if it. This isn't cool cause I really don't need new out of the box injectors flowing inconsistently with 30 psi of boost.

I know many people have used these injectors with good success, but this batch I have is not good.
I didn't know Napa flowed injectors? I'll have to see if they do it in my area. Thanks.

[AndyF]

All it takes is one tiny particle of junk to mess up an injector. There's a chain of places called Dr. Injector on the west coast. Not sure if such a thing is in you area. Google should find them if they exist near you.

[allan5oh]

This could be cylinder imbalance. What is your intake manifold and throttle body?

[AndyF]

Do you think the cylinder imbalance tracks with the injectors? He did an A-B-A test showing that the old injectors were smooth, but new injectors were rough. I think that narrows it down to the injectors. If he has dual WBO2 sensors, he might be able to figure out which side of the engine it's coming from. With an IR gun he might be able to find the cylinder and then he'll only need to order one new injector.

[Danny Cabral]

First, quickly confirm all injectors are working (2nd paragraph below).

Originally Posted by Danny Cabral Clamping a timing light on each cylinder, works well for misfire detection (watch for consistent flashing). Test drive it with a timing light taped to the windshield if necessary. Ignition misfires cause false lean spikes. Sometimes people are shocked at what they see. Also, ensure all the fuel injectors are operating. You can use an injector noid light (LINK), an injector probe (LINK), or even a long screwdriver used as a stethoscope (placed between an injector and your ear, listening to each working injector). Other less definitive methods for MPFI applications, include infrared temp gun readings on header primary pipes, or a wet rag on header primary pipes. However you do it doesn't matter, just confirm combustion on all cylinders.

Originally Posted by Danny Cabral Testing the MSD CD ignition box ground trigger. Points Output - white wire & Magnetic Pickup - violet/green triggering: https://www.msdperformance.com/suppo...ng_techniques/ (Troubleshooting Info) Ensure the distributor's rotor-phasing is correct: http://documents.msdperformance.com/8644_tb.pdf (MSD Rotor-Phasing Document) MSD has a good video on why it's important: http://www.youtube.com/watch?v=aWMlNwGW0tM (MSD Tech Rotor-Phasing Video) For naturally aspirated engines, the rotor is usually phased halfway between minimum & maximum amount of timing advance used. For forced induction engines, the rotor is usually phased at maximum boost retard, because that's when cylinder pressure is the greatest.

[94blowncobra]

Thanks for the replies guys. Danny, "Test drive it with a timing light taped to the windshield if necessary." Priceless man! LOL, I'd definitely do it.

I bit the bullet and bought a new set of ID1300s. The car purrs like a kitten. I don't know what was up with that set of 160s, but I sent them back. I wasn't going to have brand new injectors cleaned, unless they didn't take them back and I was stuck with them. Scary to think that brand new injectors could of melted down your newly built engine!

[AndyF]

If you follow these forums for very long you'll find that a lot of people assume that new parts are good parts. They argue that since they just put a new part on their engine that it can't be that part. After all, it is new! My motto is that "new doesn't mean good". New just means it's new. Anybody who has been trained in failure analysis knows that new is the same as suspect. Failure analysis engineers treat all new parts as suspects until they prove themselves to be good. If you can retrain your brain to treat new parts as suspects until proven good, then you'll be able to solve problems faster.

[94blowncobra]

100% agree. I'm a Commercial HVAC/R tech all too familiar with new equipment and part failures.

Years ago, I got beat down installing a MSD Digital 6 or 4, can't remember which one. It failed right out of the box. Being a novice mechanic back then, I assumed I was doing something wrong. Still have a scar from scratching my head on that one.