dealership can't fix problem
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Instructor
Joined: Sep 2004
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From: peoria il
dealership can't fix problem
91 coupe stock 103k miles. my car has been hesitating or, bogging down so i took it to jim mccomb chevy here in peoria because i haven't found a good shop. they checked the car only thing they found was it was running lean. they checked the cat (its good), checked fuel pressure(good), checked injectors(good ohms.) checked codes(none) fuel filter new, only use shell 93 oct. gas, they said the spark plugs may be it because they are not the eom (put in delco) new wires already, they also said maybe clean the injectors, but couldn't be sure of anything except that it was running lean. shouldn't the dealership know alot about the cars they make? does anyone have any suggestions about my problem? 
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From: Exit 89 GSP,Lakewood,NJ The Land Of Mojo
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Remember, the dealerships don't make the car, they only sell them.
But I agree they should know how to fix it, that's what the techs go to school for and they get updated training all the time.
But I agree they should know how to fix it, that's what the techs go to school for and they get updated training all the time.
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From: Almost all Skyline Cruises Vettes at Waterside 1-5
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Originally Posted by Mr Mojo
Remember, the dealerships don't make the car, they only sell them.
But I agree they should know how to fix it, that's what the techs go to school for and they get updated training all the time.
But I agree they should know how to fix it, that's what the techs go to school for and they get updated training all the time.
But the training on 91 C4's probably ended ten years ago and those that were trained are probably gone!Probably best to try to look for a shop that specializes in Vettes, particularly C4's.
Several things can contribute to "lean" conditions and i wouldn't want to suggest that you start replacing parts in hopes of finding the problem, but there are several "cheap" things you might try
1) is the Oxygen sensor(s). This sensor tells the ECM when to richen or lean out the mixture. Easy to replace and should cost less than $50.00 As with all the electronics, the sensors could be at their limit but still within tolerance and not throwing any codes
2) and maybe you mentioned this, is the fuel filter. A new filter is under $ 15.00 and depending under what conditions the shop checked fuel pressure a dirty filter may not show up
Hey Frank
Are you coming to Skyline?
seeya
Last edited by jackdaroofer; Oct 5, 2004 at 07:54 PM.
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From: SE NY
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Well they can put a scan tool onto the ALDL and see if the coolant temp sensor and O2 sensors are functioning ok.
If the O2 sensor is ok and fuel pressure if fine a lean condition is due to an air leak before the O2 sensor.
You could measure the voltage at the TPS to assure that is moves smoothly with throttle position change.
Also, bump base timing a few degrees for crisper throttle response.
When you hit the throttle the ECM looks at throttle position, manifold pressure and temp to determine timing and fuel enrichment. If the above don't eliminate the bog look to these areas.
If the O2 sensor is ok and fuel pressure if fine a lean condition is due to an air leak before the O2 sensor.
You could measure the voltage at the TPS to assure that is moves smoothly with throttle position change.
Also, bump base timing a few degrees for crisper throttle response.
When you hit the throttle the ECM looks at throttle position, manifold pressure and temp to determine timing and fuel enrichment. If the above don't eliminate the bog look to these areas.
Melting Slicks
Joined: Jun 2004
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my opinions of dealerships cannot be stated here due to language restrictions... Anyway, I agree with whoever mentioned find a corvette mechanic. In fact you probably dont even need to find a corvette specialist, a good independent chevy shop (that knows SBC's) could help you just as much.
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Is it intermittent? Or, can you duplicate it at will, for instance at a certain throttle position, rpm, load condition(uphill/downhill), light/moderate/hard acceleration. This info would be very helpful.
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From: El Paso Texas
How many pounds of vacuum is it holding at idle? I suspect a vacuum leak is causing your lean condition. It may not be severe enough to throw a code, but enough to cause the hesitation you mention.
If you get a low vacuum reading, say under 16 pounds, get a hand vacuum pump with a gauge and start testing vacuum lines, connectors, actuators, cruise servo, etc.
If you get a low vacuum reading, say under 16 pounds, get a hand vacuum pump with a gauge and start testing vacuum lines, connectors, actuators, cruise servo, etc.
Thread Starter
Instructor
Joined: Sep 2004
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From: peoria il
1st, thanks for all the info. the dealership kept the car overnight and in the morning it wouldn't start. they checked the fuel pressure and found intermittion fuel pressure. they put in a new fuel pump. i took the car out tonight, and for the 1st time scene i bought it the tires spun. yyyyyeeeeeeessssssss, it ran great and now i have a good vette.
jeff
jeff
