Calling all mechanics

Discussion in 'Vintage Topic Archive (Sept - 2009)' started by Oldgeek, Dec 12, 2007.

  1. I've got a great looking 1995 Silverado with the 5.7 litre with about 95,000 miles on it. The truck runs great for a while and then gets a miss in it. I think it is a dirty/ worn fuel injector. It may miss for a day or a month and then smooth out. I've changed all the engine wiring, new dist cap, new plugs, cleaned the throttle body (that helped a little) and the PVC and EGR sensor. Before I throw myself on the mercy of the local mechanic, does anyone have any ideas. I'm a marginal mechanic so be gentle. Thanks
  2. pills

    pills Guest

    fuel pump? fuel filter?

  3. Funny you mention that cause I have a 1999 Malibu and experiece the same problem. When I start it up its misses, sometimes even the check engine light turns on but after I gun it a couple of times its evens out. This problem happens even if the engine is warm. Done the same, changed plugs, wire harness, but also changed the fuel filter (fearing it was clogged)... has not fixed the problem.

    Also, it wont happen all the time, like right now, its running "great".
  4. azhipoint

    azhipoint Member

    Had a 93 Toyota fuel injected that did this in the cooler times of the year.
    I used a product called seafoam injector cleaner
    start car let her warm up... while motor is running spray seafoam in the intake about a 2 second shot wait a few seconds and repeat.
    cost about 6 bucks at the time worth a try for the cost.
  5. urotu

    urotu Member

    Seafoam is a great product, use it.

    You can either put it in the tank and let it run through the fuel system (works well), or you can do as it explains on the back of the can (works better).

    To properly run it through the manifold you have to run it through a vaccuum line, I'lll walk you through it.

    1 Get the vehicle all nice and warmed up to normal operating temperature.

    2 Find a good vaccuum route to your manifold. The big vaccuum line off of your brake booster works best.

    3 Unhook the vaccuum line from the booster, not the other side.

    You'll need two people to do this properly.

    4 Get someone in the cockpit and have them feather the gas while you pour the Seafoam into the vaccuum line. Once it get's going, the vaccuum will suck it right up. You'll need to feather the gas to kep it running though.

    5 Do this until you see smoke coming from the tailpipe. Once you see the smoke from the tailpipe, quit feathering the gas and let the vehicle die.

    6 let it sit for about 20 - 30 minutes then fire it up and drive it until it quits smoking.

    For carburated or TBI injected motors you can do the same thing except through the carb or TBI unit.

    Once you fire it back up it will smoke like a train, literally. Some motors smoke longer than others, depending on what's in there to clean up. I have had some smoke for about 10 minutes, others lasted as long as 45 minutes. One thing for sure is it will make a difference in how your car runs.

    It will take anywhere from about 1/2 a can to a full can to do this. I generally run a can through the intake and use another can in the tank to follow up and get anything from the lines themselves.

    Good luck man, and don't freak out on the smoke, it goes away.
  6. Go to the auto parts store and buy a automotive steathscope. Looks like the one the Dr uses but has a long prob on the end instead of the flat piece. With the engine running put the tip of the rod on each injector and listen to how the injector is ticking, you can easily identify a weak/clogged injector and will know for sure that's what the problem is.

    Then you can either use Seafoam, quickest method, or add a quality injector cleaner to each tank of gas till it smooths out. If this does not work your next option is replace the bad injector, but chances are they will clean right up and save you a good bit in the long run.

  7. urotu

    urotu Member

    If you have one, you can also use a long screwdriver instead of the stethoscope. It's an old trick, really, but effective.

    Simply use the tip of the screwdriver for locating the noise, and the butt end to listen with. It works very well and will save you the cost of the stethoscope.

    To locate the sound, listen to the other end of the screwdriver as you move the tip around from injector to injector. You can also use this for locatig valve noise, rod noise, just about anything internal.
  8. z71silverado98

    z71silverado98 Member

    SeaFoam it first.

    Could also be the Fuel pressure regulator sending erratic fuel amounts to your injectors mine's been going out for a while.

    Instead of taking it to a mechanic, try swapping injectors yourself. easily done in a weekend alone. even quicker w/ help.

    I'd guess parts and labor would run ya around $1500 at a shop prolly $300 if done at home. w/ the money saved go out and buy yourself a gun ;)
  9. 69burbon

    69burbon Well-Known Member

    Just to make sure, is the engine throttle body (basically looks like a carb with two injectors in it) or Port Fuel Injection (one injector for each cylinder). I know GM started introducing port fuel about that time but can't recall if it was available on that series truck for that model year.
    Port fuel has fewer problems because it is less exposed to the elements. On a Throttle body engine you can watch the spray pattern since the injectors are right on top of the engine. The pattern should be almost a clear mist. If it looks like either injector is "dripping" replace the injector.

    +1 on using Seafoam. You may have carbon build up around the valves. I have used Seafoam on customer vehicles with great success. What I do is add half the can to the fuel tank. I then connect a vacuum hose to one of the unused ports on the vacuum tree on the intake manifold. Pinch the hose off and insert the other end into the can with the rest of the Seafoam. Start the engine and then draw a small amount of the Seafoam into the intake (engine will start to bog down). After engine has recovered do it again and continue in this manner until all the cleaner has been used.

    DO NOT run the engine and keep feathering the gas until the entire can is empty. You must only draw small amount in at a time or you risk engine or Catalytic Converter damage.

    I am an ASE certified mechanic and work for General Motors Technical Assistance.

    The other thing to consider is how long this has been going on. Did you recently change where you fuel the vehicle? We constantly get calls on driveability issues related to poor fuel quality. A lot of fuel suppliers would have recently changed to what is referred to as "winter blend" fuel. It is "oxygenated" to reduce emissions. This also may cause the perceived misfire. Using "top tier" fuels from name brand gas stations instead of the local Quicky-mart may make a difference too.
  10. Thanks for all the ideas, I need this thing to run another 3 years. I probably should have mentioned that it gets a lot of short trips (6 miles) back and forth to work. Since it only gets about 12-14 mpg when it is running good, I don't drive it much for fun. The rpm's don't get much over 2200 so I can see it carbon up. I have noticed that it starts running bad right after I've pushed it up to 3500 rpms passing a car. Could it be some carbon breaking loose and clogging up something? I'll try the Seafoam this weekend and let you all know.

    PS: I learned that the cheapest gas isn't the best. Around here it is all the same price except for Shell and they are 20 cents more than everyone else.
  11. I would definately run some seafoam. For injector cleaner(ie: in gas) I like the lucas stuff.

    Just dont' scare the neighbors with all the white sea-foam smoke. Friend of mine did it in public(car wash) to his 89 supra and drew the attention of a cop...

    SHOOTER Z Well-Known Member

    After you get whatever is wrong straightend out once a month if you live near an interstate get on it and run the tar out of the engine. Short trips and carbon buildup are a major killer of engines. [you'll also get better mileage on your short trips :wink: ] Also note this yes gas may be better the more you pay for it but evry once in a while get some octane boost and put it in a tankfull of gas. It will also help with carbon build up. A few months ago I had problems with the ecort running rough Everything else checked out I got 2 gallons of racing fuel 105 octane at $6 per gallon and pumped it in the car. That car ran so much better it cleaned the injectors and the car ran like a charm til it's demise
  13. Sakdog

    Sakdog Member

    +1 on seafoam, I know it sounds crazy But I usually do a good dose of sea foam (Usually smokes like all get out when you directly inject it to the intake) after it clears I let the engine ingest a quart of water (VERY SLOWLY) It sounds crazy but the water turns to steam in the combustion chambers and helps loose any other carbon buildup that is left behind after the sea-foam loosens it up. Putting water down the intake of a running engine does not hurt it whatsoever (By hand you will have to feather the throttle) Some people actually adapt water injection systems on turbo or high compression aplications because it will retard pre-ignition due to high temperature...

    Anyhow that should help you out a bit. I am not 100% familiar with a 95chevys I would suppose that if its an early 95 its prob. OBD1 So if it has an ignition module outside from the distributor I would check that. (Worked a 97 Z71 that had the same problem as you describe) It wound up being that ignition module (Mounted near the distributor its a little unit with an aluminum finned heat sink.

    Also is your truck throttle body injected or does it have the CSFI (central sequential fuel injection) system? ? Throttle body injection will have a manifold mounted carburetor looking thing (If its TBI check with stethoscope as previously mentioned)I think it has 2 big injectors and CSFI will have on the top of the manifold in the middle a big wire plug about 3x5 inches that screws down and has 2 fuel lines leading up to it. if it is the latter type of injection you might have a bad spider. the actual injectors would be where the wire harness plugs in and the nozzles are near the intake ports and the whole unit in the intake manifold looks like a spider with plastic tubing to each injection nozzle... Well these things have a real bad tendency to go bad and clog and stick open and crack in the plastic tubing etc... You might have problems with that spider assy... NO FUN!
  14. My dad used to put water into the carbs of engines to break carbon free. Used a pop bottle and had his finger over the end and let it trickle into the carb.

    Dont let too much go in to fast because water will not compress like air will and you can bust the top out of a piston or something similar with too much of any liquid

    I have also seen people do the same with auto tranny fluid. Smokes like crazy. I think they did that for stuck rings if I remember correctly.

    This was in the old days before lucas and all of the stuff they have out now.
  15. Mine has the throttle body and it did help when I cleaned it with "throttle body cleaner" That lasted a couple months and now the problems is back.
    I thought it was a bad valve for a long time because the back two plugs on the drivers side would carbon up. Changing the plugs made a little difference for a while. I've used Seafoam on outboards and older cars before. Is there any danger of it loosing up crap in the gas tank? Is it better to run it through the throttle body instead? Everyone that I talk to said that the 5.7 motor should last 200,000 miles if I take care of it.
  16. Back in my younger crazy days we'd go to the airport and put avaition gas (half regular and half aviation) in our cars. My old Firebird ran great, but at $1.50 a gallon a guy couldn't afford it. :lol:
    Yeah, I've been doggin this truck to keep the mileage up...hell, I'm driving like an old woman. Time change.
  17. Why has no one mentioned the use of a shotgun? Everyother help with my car thread has had a reference to using a shotgun, seems like it'd do the trick. I hit a tire tread and did some damage to my car, thinking about using some buckshot to clean that up.

    SHOOTER Z Well-Known Member

    Might also help to runa hotter plug.Years ago [mid 80's] I put a set of Accell split plugs in my old Valient and that car ran like a dream till the body rusted away. Late on I hace a 92 Eagle Summit that I had trouble with the plugs. My friend [a mechanic and ran a garage] installed Bosch Platinums in it and it LOVED them I got 48 MPG with them. They were designed to run hotter in slow traffic but run cooler in fast traffic. I also would gas it up and throw in injector cleaner and run up I 95 about 2 or 3 am when there was only 1 Trooper on duty. [ I knew him and he would meet me at a rest stop at a certain point he would head North and I drive about 75 to 8o south and really blow all the crap out of it :wink: ]
  19. I love sea-foam i use it in evry thing from snow-mobile -to bassboat-to cars i love the stuff
  20. urotu

    urotu Member

    Not to be rude, but I am an ASE certified Master Mechanic myself, and have been doing this for years myself.

    The feathering of the throttle is from Seafoam themself, as I've worked with them personally. As I said, many years under the hood myself.

    As far as plugging up a catalytic converter, that's an old wives (or mechanics as it applies here) tale. There is not now, nor has there ever been any cases of plugging up a cat from using Seafoam.

    As I mentoned in a previous post, you can run it through the TBI unit the same way.

    The problem with runing it just through the manifold is you miss the injectors. That's why I suggest also adding a can to the gas tank. 1/2 a can will work, but a full can will work better. I know many people who use it every other tank or so just for preventative maintenance.

    I would not suggest running hotter plugs. If you have to run a hotter plug to get it to work right you are only bypassing the real problem, and not fixing it. Your motor was designed to work around the plug you have and should have no issues doing so with the proper troubleshooting and repair.

    Again, I am just giving you the many years of experience I have working on cars, as I'm sure most otehrs here are trying to do also.

    Seafoam is an inexpensive alternative to spending a lot of money on mechanics who may or may not be up to the task. For about $10 you can Seafoam your vehicle, if it works, then your golden, if it doesn't work you're out a few dollars. No harm, no foul.