Clogged Injector
Thread Starter
Heel & Toe
Joined: Dec 2022
Posts: 23
Likes: 22
From: Central Ohio
Clogged Injector
I’ve had my ‘04 Z06 for a few years now and it has had an intermittent, random misfire at low engine speeds that cleans up under load. I grabbed a fuel pressure gauge from autozone this evening and ran an injector test using my gearwrench scanner. All cylinders dropped to 48 psi after finishing their pulses except #1, which only dropped to 52 psi.
I’m new to diagnostics, so looking for some validation. Does this signal a clogged injector?
If so, what can I do to clean it? Should I just buy a new one?
I checked the resistance on the seemingly clogged injector and it was just above 14 ohms, same as the others.
i have also misted the engine bay in the past thinking this could be a spark issue, as well as shooting a little carb cleaner in spots where a vacuum leak might occur. None of that got me closer to figuring this out.
I really like this gearwrench scanner my wife got me for Christmas. Hoping it’ll help me retire the parts cannon. Thanks for any thoughts you can share.
I’m new to diagnostics, so looking for some validation. Does this signal a clogged injector?
If so, what can I do to clean it? Should I just buy a new one?
I checked the resistance on the seemingly clogged injector and it was just above 14 ohms, same as the others.
i have also misted the engine bay in the past thinking this could be a spark issue, as well as shooting a little carb cleaner in spots where a vacuum leak might occur. None of that got me closer to figuring this out.
I really like this gearwrench scanner my wife got me for Christmas. Hoping it’ll help me retire the parts cannon. Thanks for any thoughts you can share.
Thread Starter
Heel & Toe
Joined: Dec 2022
Posts: 23
Likes: 22
From: Central Ohio
Thanks for the suggestion. Unfortunately, the Z gets a pretty steady diet of Techron due to the typical fuel sending unit issue. While that has improved with treatment, the misfire has not.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,595
Likes: 4,057
From: Cape Coral, Florida
Yes, sounds like a clogged injector...if I were you and it is within your budget I'd replace all of them...no Amazon or EBay though !!..if you have a vacuum leak your fuel trims will be elevated...if over 10% raise the idle to 2 to 3,000 RPM...if they decrease you have a vacuum leak...if you want to learn diagnostics you won't learn it turning wrenches...watch the Scanner Danner YouTube channel...he will teach you...beyond plugs and wire the DIY'er will usually have no success.
Last edited by C5 Diag; Apr 28, 2026 at 10:07 PM.
Burning Brakes
Joined: Sep 2019
Posts: 928
Likes: 615
From: Navarre, Florida
I was having problems with my injectors and decided to buy one of those injector cleaning kits where you hook it up to a power source and spray cleaner through them. I also replaced the o-rings and baskets while I was at it. Prior to cleaning them, my LTFT's were around -14% steadily and would peak around -30%. When I had my car retuned by a local tuner, my IDC was 65% at peak and my LTFTs ended up around -4-5% at worst. I have a CAI, BTR Stage 4 cam, ARH LTH w/o cats and stock C5 Z06 injectors.
Thread Starter
Heel & Toe
Joined: Dec 2022
Posts: 23
Likes: 22
From: Central Ohio
@C5 Diag - thanks for the advice. I will check out the Scanner Danner videos. You suggested replacing all the injectors. I can certainly do that. Should they have dropped farther than 48 psi? Is there a brand to go with? Are the remanufactured ones ok?
@-ZEEOHSIX- as far as fuel trims go…both short and long term trims appear to be fine in my case
@-ZEEOHSIX- as far as fuel trims go…both short and long term trims appear to be fine in my case
Advanced
Joined: May 2025
Posts: 53
Likes: 14
From: Howard, Ks.
Not to change the subject but I saw Techron and fuel sending unit in the same sentence. I don't use it very often but I do have a sender problem when I'm down to a half a tank. It drops my gauge to zero and kicks the light on. Any suggestions? Thank you
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