Injector going bad?
Thread Starter
Former Vendor
Joined: Nov 2005
Posts: 8,995
Likes: 2
From: Spring Texas
St. Jude Donor '08
Injector going bad?
On cold starts, my 97 gets a slight misfire about every 1-5 seconds. after about 60 seconds, I get a smooth idle. I have a hunch this is the result of an injector going bad and not pumping out until the fuel pressure gets into the operational range?
I ran a bottle of Lucas fuel system cleaner through it and it stopped the problems for about a week.
questions:
a) Does this sound like an injector problem? If not, suggestions?
b) I'm currently running Lucas 32/lb injectors. If I have to replace them, where can i find an equivalent set?
I ran a bottle of Lucas fuel system cleaner through it and it stopped the problems for about a week.
questions:
a) Does this sound like an injector problem? If not, suggestions?
b) I'm currently running Lucas 32/lb injectors. If I have to replace them, where can i find an equivalent set?
Burning Brakes
Joined: Apr 2008
Posts: 877
Likes: 4
From: Nouvelle Ecosse
Try running a can of seafoam thru your gas tank, it may do a better job of cleaning your injectors out. Although I've used that lucas stuff before and it seems pretty good.
I think that injectors are either good, dirty, or bad and there is not much in between.
I think that injectors are either good, dirty, or bad and there is not much in between.
Drifting
Joined: Apr 2008
Posts: 1,316
Likes: 2
From: St. Louis Mo
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
- First things first,, check each on of them for coil resistance. They should ALL read the same.
- Use a stephscope to LISTEN to each one. They CLICK when they fire. If one sounds different than the others, it could be bad.
- Use EFI Live or HP Tuners and data log your engine during the issue. (if you know someone that has either software, a data log is free) See the exact cylinders that are misfireing. Then swap coils and injectors around and see where and when (coil or injector) the mis-fire moves cylinders.
You jumped right on an Injector. You need to check the secondary ignition also.
BC
- Use a stephscope to LISTEN to each one. They CLICK when they fire. If one sounds different than the others, it could be bad.
- Use EFI Live or HP Tuners and data log your engine during the issue. (if you know someone that has either software, a data log is free) See the exact cylinders that are misfireing. Then swap coils and injectors around and see where and when (coil or injector) the mis-fire moves cylinders.
You jumped right on an Injector. You need to check the secondary ignition also.
BC
Tech Contributor
Joined: Jan 2007
Posts: 19,354
Likes: 1,126
From: Dyer, IN
Hmmmm...operational range? The fuel pump is constant, so you either have fuel pressure or not. Have do performed a test at the rail to see if you have any bleed down? Have you pulled the plugs for inspection to help isolate the cylinder of concern?
Pro
Joined: Dec 2003
Posts: 654
Likes: 1
From: chandler az
I've done this for another car before, but I'd imagine this would work. I modified a chemical spray pump and attached it to the injector, filled it with gas and pumped it up. Then fired the injector by putting a 9 volt battery across the injector. If you have another set of hands you can hold the injector in place or rig something up. If you see a good spray pattern, you are probably okay. If you see a dribble or stream, its clogged.
BTW, thats kind of a PITA to set that all up. There's people you can send your injectors out to have them cleaned and flowed for about a hundred bucks. A good fuel injection company will make sure all your injectors are flowing with 5%.
BTW, thats kind of a PITA to set that all up. There's people you can send your injectors out to have them cleaned and flowed for about a hundred bucks. A good fuel injection company will make sure all your injectors are flowing with 5%.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
To be honest with you,,,,Ive owned Two C5's and a C6 and have worked on hundreds and have never seen ONE injector clog or fail.
I know that they do but,,,,,,it a pretty low chance that is and injector. If it were me,,,I would do a lot of easy checking first. Meters and swapping components is pretty much a no brainer and most of the time, you will find the issue easily.
Early Gm TPI style injectors were a horse of a different color and YES, I have seen several of that era injector issues
BC
I know that they do but,,,,,,it a pretty low chance that is and injector. If it were me,,,I would do a lot of easy checking first. Meters and swapping components is pretty much a no brainer and most of the time, you will find the issue easily.
Early Gm TPI style injectors were a horse of a different color and YES, I have seen several of that era injector issues
BC
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Burning Brakes
Joined: Apr 2009
Posts: 946
Likes: 2
If you don't have a mechanic's stethoscope, you can put a long flat bladed screw driver on the side of the injector and put the handle next to your ear. You will be able to hear a faint clicking when the injector opens (this is harder than with the stethoscope for obvious reason). You can also pull plugs for the old spark plug read -- black and oily = rich, white / light grey = lean, brown / dark grey = "good".
Check all your sensors that can effect idle fuel (IAT, MAP, MAF, TPS, EC, and even volt sensor) and make sure the plugs are tight etc. Then you can pull the injectors and test the gaskets -- cracked or hard o-rings will cause the car to run poorly.
Since you have them out, bench clean the injectors and test for leaking injectors (http://www.mikeponte.com/volvo/injectors.htm -- yeah it's about volvo injectors, but an injector is an injector...).
Check all your sensors that can effect idle fuel (IAT, MAP, MAF, TPS, EC, and even volt sensor) and make sure the plugs are tight etc. Then you can pull the injectors and test the gaskets -- cracked or hard o-rings will cause the car to run poorly.
Since you have them out, bench clean the injectors and test for leaking injectors (http://www.mikeponte.com/volvo/injectors.htm -- yeah it's about volvo injectors, but an injector is an injector...).
Advanced
Joined: Jul 2012
Posts: 63
Likes: 6
injectors lasting
To be honest with you,,,,Ive owned Two C5's and a C6 and have worked on hundreds and have never seen ONE injector clog or fail.
I know that they do but,,,,,,it a pretty low chance that is and injector. If it were me,,,I would do a lot of easy checking first. Meters and swapping components is pretty much a no brainer and most of the time, you will find the issue easily.
Early Gm TPI style injectors were a horse of a different color and YES, I have seen several of that era injector issues
BC
I know that they do but,,,,,,it a pretty low chance that is and injector. If it were me,,,I would do a lot of easy checking first. Meters and swapping components is pretty much a no brainer and most of the time, you will find the issue easily.
Early Gm TPI style injectors were a horse of a different color and YES, I have seen several of that era injector issues
BC
I ran a ton of injector cleaner and sea foam through it first, but that didn't do ****.
Apart from the knock gone, the vette is so much more responsive I feel like driving a new car. The old ones all were 'fine', the plugs had no indication of lean running, etc. The injectors were just old and worn. Replace those bitches! I got a set for under $200 on ebay, with great service, from Sam in Texas. They are new OEM plugs, I have no idea how he can sell them so cheap. They work fantastic, so even if it turned out they were rebuilt, in this case I wouldn't really care and the price can't be beat. He also seems to often sell the Standard Motor Product injectors, well I looked them up they actually manufacture in the US, so hey.
Pro
Joined: Aug 2010
Posts: 622
Likes: 169
From: Montgomery Texas
Have you put a fuel pressure gauge on the engine? If it takes 60 seconds to build fuel pressure, your problem is not an injector. You should see full pressure within a second, or two.
I would suggest that you test the injectors for both spray pattern and flow volume, before getting your check book out. But, as Bill correctly mentions, there are several preliminary items that should be checked first.
One other item that you may want to keep an eye on is the coolant level. It only takes a couple of drops of coolant in a cylinder to cause the brief misfire on a cold start, that you describe. Make sure that you are not loosing coolant and check to see that the cooling system will hold pressure on a hot engine, after it is shut down.
I would suggest that you test the injectors for both spray pattern and flow volume, before getting your check book out. But, as Bill correctly mentions, there are several preliminary items that should be checked first.
One other item that you may want to keep an eye on is the coolant level. It only takes a couple of drops of coolant in a cylinder to cause the brief misfire on a cold start, that you describe. Make sure that you are not loosing coolant and check to see that the cooling system will hold pressure on a hot engine, after it is shut down.
