Bad Injector?
Thread Starter
Intermediate
Joined: Aug 2013
Posts: 36
Likes: 0
Bad Injector?
My C4 has been acting up a bit. And I'm hoping all the symptoms are coming from the same source problem.
The first start of the day or just after sitting for a few hours the car starts just fine but idles a bit low and "stumbles." It also puffs out a little white smoke from the exhaust (fuel I assume). And if I throw it in reverse or drive without letting it run for a minute or two my rpm's drop and it feels as if it is about to die. Car runs fine once moving and warm.
When I stop and get out of the car I can smell fuel and I think is comes from the exhaust even after the car stops running.
After looking at the injectors I did notice that around one of them there seems to be fuel around it where it has been leaking.
I'm thinking it may just be the o-rings on the injector (at least I hope that's all it is). What do you think?
The first start of the day or just after sitting for a few hours the car starts just fine but idles a bit low and "stumbles." It also puffs out a little white smoke from the exhaust (fuel I assume). And if I throw it in reverse or drive without letting it run for a minute or two my rpm's drop and it feels as if it is about to die. Car runs fine once moving and warm.
When I stop and get out of the car I can smell fuel and I think is comes from the exhaust even after the car stops running.
After looking at the injectors I did notice that around one of them there seems to be fuel around it where it has been leaking.
I'm thinking it may just be the o-rings on the injector (at least I hope that's all it is). What do you think?
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
Check the Ohm readings on each injector.
Any reading below 12ohms, the injector is no good. If they are the original Multec injectors they will all have to be replaced since multec injectors are not Ethanol fuel compatible and will eventually dissolve the coil insulation.
Fortunately, on your 93 Vette, fuel injector replacement is very simple.
Any reading below 12ohms, the injector is no good. If they are the original Multec injectors they will all have to be replaced since multec injectors are not Ethanol fuel compatible and will eventually dissolve the coil insulation.
Fortunately, on your 93 Vette, fuel injector replacement is very simple.
Drifting
Joined: May 2013
Posts: 1,736
Likes: 31
From: Reno Nevada
Check the Ohm readings on each injector.
Any reading below 12ohms, the injector is no good. If they are the original Multec injectors they will all have to be replaced since multec injectors are not Ethanol fuel compatible and will eventually dissolve the coil insulation.
Fortunately, on your 93 Vette, fuel injector replacement is very simple.
Any reading below 12ohms, the injector is no good. If they are the original Multec injectors they will all have to be replaced since multec injectors are not Ethanol fuel compatible and will eventually dissolve the coil insulation.
Fortunately, on your 93 Vette, fuel injector replacement is very simple.
Thread Starter
Intermediate
Joined: Aug 2013
Posts: 36
Likes: 0
Okay guys I've read your suggestions and applied them today! 
I was low on coolant but haven't had a chance to add it yet. So that should hopefully fix my white smoke issue.
I did the ohm's test and they all passed. I went ahead and replaced all the o-rings on the injectors (2 were bad.) Yet still my morning start-up issue remains.
After looking at and cleaning them with some carb cleaner I'm thinking more and more that the injectors aren't my issue.
Any more suggestions? And would it help if I posted a video of my gauges on the first start of the day? Thanks for all the help guys!!
I was low on coolant but haven't had a chance to add it yet. So that should hopefully fix my white smoke issue.
I did the ohm's test and they all passed. I went ahead and replaced all the o-rings on the injectors (2 were bad.) Yet still my morning start-up issue remains.
After looking at and cleaning them with some carb cleaner I'm thinking more and more that the injectors aren't my issue.
Any more suggestions? And would it help if I posted a video of my gauges on the first start of the day? Thanks for all the help guys!!
Instructor
Joined: Aug 2012
Posts: 136
Likes: 2
From: Reno Nv
If your low on coolant and your getting white smoke, adding coolant will not fix the problem, you will need to find out where it is coming from,
head gasket, intake manifold, cracked head, a leakdown test will need to be preformed
also a compression test,
head gasket, intake manifold, cracked head, a leakdown test will need to be preformed
also a compression test,
Last edited by envirotrans; Jan 26, 2014 at 10:58 PM.
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
If the engine is losing coolant on a regular basis, the head gasket could've failed causing coolant to be sucked into the combustion chamber and burning with the air/fuel causing the white smoke.
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Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
Sorry I didn't make that a little more clear for you. My thoughts: When your car is cold you are getting coolant into one or more cylinders and it is causing it to run rough. When the engine warms up, the "leak" may be getting sealed off (from heat expansion) and then the engine runs better. If you pull the plugs you should be able to tell what cylinder the water is getting into, that plug will be cleaner than the rest. Try to smell the exhaust when you first start it. Does it smell kinda sweet? If that is true, you have problems.
Thread Starter
Intermediate
Joined: Aug 2013
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First off sorry It's taken so long for an update guys. Well I performed the leak down test and the car passed with flying colors. No excessive leaking from any of the cylinders and all within the same percentage. (To my pleasant suprise.) I then started thinking the alternator might be the here's why -Low voltage at start up -volts decrease as I turn on radio headlites etc. -dimming interior lights at startup -whining noise a few seconds after start up - now the past couple days it's been hard starting (as in I have to give it some gas and it takes a couple seconds to start.)
I did a voltage test and it failed. Tomorrow I plan on taking it to get tested, and if it fails, rebuilt. I'll keep you guys posted about if this solves my issues.
I did a voltage test and it failed. Tomorrow I plan on taking it to get tested, and if it fails, rebuilt. I'll keep you guys posted about if this solves my issues.
Last edited by C4.Taylor; Feb 24, 2014 at 11:49 PM.
Melting Slicks
Joined: Feb 2013
Posts: 2,234
Likes: 14
Read through this, Its what helped me get my car going again.
http://forums.corvetteforum.com/c4-t...questions.html
http://forums.corvetteforum.com/c4-t...questions.html
Thread Starter
Intermediate
Joined: Aug 2013
Posts: 36
Likes: 0
Well I took the alternator to o'rielly's to get tested and it passed. Took the battery in and it was "still good but just needed a charge." The guy was trying to tell me something was draining my battery but I know it's not the alternator now. A fully charged battery and good alternator and still was hard to start.
I replaced the CTS and also no improvment. I'm getting a little discouraged and really not sure where to look next. I guess I'll follow larryinalabama's advice and test my injectors again.
I replaced the CTS and also no improvment. I'm getting a little discouraged and really not sure where to look next. I guess I'll follow larryinalabama's advice and test my injectors again.
Melting Slicks
Joined: Jan 2014
Posts: 2,184
Likes: 381
From: Lunenburg MA
Have you checked the fuel pressure and watched what it does when you shut off the car?
"Hard start and smells of fuel" are symptoms of a (duh) fuel problem. I don't see in this thread that you have done anything to diagnose that.
One trick (if you don't have a fuel pressure gauge) is to pull the vacuum line off the brake booster right after shutting it off and put it to your ear. If you have a leaker you can sometimes hear it through the hose. Another trick is to wait 5 mins after shut off and use something pointy to press the fuel check fitting (schrader valve). There should still be a good amount of pressure (have a rag handy). If there isn't something is leaking (injector or regulator).
Once again, if you have a leaking injector it can dilute your oil and ruin your engine. Check your dip stick and look for especially thin oil that smells of fuel.
"Hard start and smells of fuel" are symptoms of a (duh) fuel problem. I don't see in this thread that you have done anything to diagnose that.
One trick (if you don't have a fuel pressure gauge) is to pull the vacuum line off the brake booster right after shutting it off and put it to your ear. If you have a leaker you can sometimes hear it through the hose. Another trick is to wait 5 mins after shut off and use something pointy to press the fuel check fitting (schrader valve). There should still be a good amount of pressure (have a rag handy). If there isn't something is leaking (injector or regulator).
Once again, if you have a leaking injector it can dilute your oil and ruin your engine. Check your dip stick and look for especially thin oil that smells of fuel.
Melting Slicks
Joined: Feb 2013
Posts: 2,234
Likes: 14
I had the exact same symptoms, and fought it, I was going to start throwing temp. sensors and keep on going till I fixed it. The only code I had was for o2 sensor, but the engine was flooding so I knew that it was fouled. I would have never thought of injectors because they generally dont go bad.......except for our vetts, which I learned here. So I went to ohm check the injectors and I had 3 different injectors, so I ordered a set and now Im back running. No smoke and easy starts.
I had my doubts about the "fit" of the Bosh111 injectors, but they fit perfectly.
Fuelinjector connection are great folks to talk to, and Im positive that if I had a problem they would help me work it out over the phone, no business does that anymore. Fortinuately I didn't have any problems.
Ohm check may not tell you what you need to know as injectors have "coils" and may "open" or "short" interminately.
If money is not a problem <alaways is for me lol> Id go ahead and throw a set of injectors in. If you can put them in yourself it will be cheaper than paying a shop to diagnoise the problem, and they will likely be wrong anyway.
I had my doubts about the "fit" of the Bosh111 injectors, but they fit perfectly.
Fuelinjector connection are great folks to talk to, and Im positive that if I had a problem they would help me work it out over the phone, no business does that anymore. Fortinuately I didn't have any problems.
Ohm check may not tell you what you need to know as injectors have "coils" and may "open" or "short" interminately.
If money is not a problem <alaways is for me lol> Id go ahead and throw a set of injectors in. If you can put them in yourself it will be cheaper than paying a shop to diagnoise the problem, and they will likely be wrong anyway.
Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
for the most part you will not pick up cooleant getting into a cyl by means of a leak down test. A leak down test is used to prove there is not excessive leakage past the rings or valves, You relly need to determine if you have cooleant going into a cyl, Mark your level drive it a few days and see if it drops. If you pull your plugs and take a good look at them if you have one that is real clan that indictates a cooleant leak into that cyl, I really think you need to adress this issue first
Melting Slicks
Joined: Feb 2013
Posts: 2,234
Likes: 14
May want to get one of these to check the headgaskets.
http://www.autozone.com/autozone/acc...ester/_/N-25dh
http://www.autozone.com/autozone/acc...ester/_/N-25dh
Burning Brakes
Joined: Dec 2006
Posts: 1,090
Likes: 80
From: Burleson Texas
Thread Starter
Intermediate
Joined: Aug 2013
Posts: 36
Likes: 0
I'm not losing coolant. My exhaust has no sweet smell and all my spark plugs were the same, none cleaner or dirtier than the next. My coolant level has remained constant as well.
larryinalabama I ohm checked all of my injectors and they all posted 014. There are two kinds of injectors on the car. I plan on testing for a bad head gasket the very next time I get time to do it. This will be my first time using a block tester, but from the videos I've watched it should be pretty easy.
jv9999 I ran the car for about 5-10 minutes to let fuel pressure build up. When I unscrewed the schrader valve cap it was already filled with fuel! I pressed the vavle itself and all I got was a drip. Could I possibly be losing fuel pressure at my shrader valve since the cap was already filled before I even did anything? Also I had some trouble locating the break booster, could you point me in the right direction? And It may be paranoia but I think I could smell a hint of fuel on my dipstick.
hooked073 I've taken note of my coolant level and will see what happens as the days go by. May take a while because I've been riding my bike a lot more to avoid any unnecassary damage to my beloved vette until this problem is solved!
larryinalabama I ohm checked all of my injectors and they all posted 014. There are two kinds of injectors on the car. I plan on testing for a bad head gasket the very next time I get time to do it. This will be my first time using a block tester, but from the videos I've watched it should be pretty easy.
jv9999 I ran the car for about 5-10 minutes to let fuel pressure build up. When I unscrewed the schrader valve cap it was already filled with fuel! I pressed the vavle itself and all I got was a drip. Could I possibly be losing fuel pressure at my shrader valve since the cap was already filled before I even did anything? Also I had some trouble locating the break booster, could you point me in the right direction? And It may be paranoia but I think I could smell a hint of fuel on my dipstick.
hooked073 I've taken note of my coolant level and will see what happens as the days go by. May take a while because I've been riding my bike a lot more to avoid any unnecassary damage to my beloved vette until this problem is solved!