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Followup To
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Followup To
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My LSS is cutting out when I drive 55 plus mph.
As I push the gas it cuts out and if I let off and then push the gas it pushes through. I have replaced the cat, Oxygen sencors, and TPS. The book is leading me towards the EGR valve? Do you think that is right? Have you seen this before? The computer reads no problems, so I am stuck.
Answer -
EGR is a VERY remote and highly unlikely fault.
What BOOK are you using to perform your diagnostics ?.
What engine size is in the vehicle ?.
The engine size is 3.8L the car acts as if it is backfiring in the intake manifold. I am using a Chiltons manual to help me diagnose the car. This problem has been very hard to find with this car. It is very strange. It runs great all the time but you can feel it backfire or stutter around 55. If you let off the gas and then excel the car powers through the problem. It seems like it drives better when the car downshifts when it starts to stutter.
autohelp
Answer -
A Chilton's book is a very POOR example to use as a source of specific information. I have over 100 books in my vast library and NOT ONE is a Chiltons or Haynes as in my professional opinion they are totally useless.
Without actually driving the vehicle the possibilities are ENDLESS.
You could have:
1. An intermittent fault in a spark plug wire when the engine is under LOAD as this kind of fault is most noticeable when the overdrive engages.
2. A hairline crack in a spark plug which can be very difficult to see.
3. A small vacuum leak in any of the many vacuum lines.
4. A partially restricted fuel injector.
5. A problem in the transmission over drive circuit.
6. A small leak in the intake manifold gasket(s).
The list is just plain endless. In order to make an EXACT diagnosis the vehicle will have to be driven by an experienced tech.
Tom,
I have been working on cars for over 20 years. I have even taken this car to other mechs to look at. They all come up with the same thing. They do not know. I am not willing to give up and go with that so I keep troubleshooting and troubleshooting this car. Problem is that I am not the only one to have this problem with Oldsmobiles and I was hoping that you had seen the problem before. If you drove this car you might be able to say that you have felt this before. It almost drives like it has a miss but then it runs terrific the rest of the time. I have put it on several computers but none of them give me any codes to go by. I do agree that Chiltons and Haynes are not the best books but they do give you starting points and basic diagnostics. I am reaching to find this problem. It has stumped me for over two years. The car has passed CA smog and has even been to a dealer to find the problem. So far no one has done it. I know the problem sounds endless but it has to be something that is a sensor because it does not do it all the time. If it was a plug or a wire you would think it would do it anytime. The car seems to only do it when it is under a load like going up a hill and the tranmission stays in over drive and and doesn't shift down then it surges. Once itkicks down it is almost like a backfire in the manifold and then it runs fine.
I know you are telling me what you can and I apreciate it. I was hoping you had run into this before since you have spent you career worling on GM cars mainly.
autohelp
AnswerI have no doubt that we can resolve your problem IF we had the vehicle at our facility here in New Mexico. We do diagnostic repairs for all of the so called CAN'T BE FIXED vehicles and have YET to find the cause once we have personal access to the vehicle.
The one thing that you have to remember is that within the normal torque converter when the over drive is NOT engaged there is a large amount of transmission fluid within the converter that will absorb slight irrigularities in engine performance of which you will NOT usually feel while driving the vehicle.
Once the overdrive engages, you lose this fluid cushion effect and basically have a solid coupling of the engine and drivetrain and especially when under LOAD any slight abnormality such as a slight hairline crack(s) in a sparpk plug, wire, fuel injector spray pattern, EGR system, intermittent fuel pressure regulator variations. o2 sensor(s) intermittent faults WILL be felt due to this solid coupling effect.
I have seen many cases where even a diagnostic scope will NOT pickup the abnormality unless the vehicle is driven with a portable scope sitting on the seat next to you so you can perform different variations in ignition and fuel responses.
Your problem is FIXABLE, Just do NOT overlook the basics of what the cause could normally be, Concentrate on the basics FIRST and disregard the electronics as your last diagnostic procedures.
There is just NOT one item that sticks out that has been a constant cause of this type of problem.
If you have ever had any work performed on the vehicle check and recheck every electrical connection and vacuum hose for faults.
Here is something for you to try:
1. while maintaining the speed at which this fault occurs and while it is occuring, Hold your speed and using your LEFT FOOT slightly step on the brake pedal just enough to light the stop lights at which point the overdrive will disengage and most likely your fault will NO longer be felt as long as the overdrive which is the cause of the engine LOAD is NOT engaged.
On only a few occassions I have found that there was a fault within the torque converter circuitry of the transmission whereas the electronic pressure plate mounted on the valve body was TEMPERATURE SENSITIVE and caused an intermittent fault in the overdrive application. I have also found this to be true with intermittent faults in the torque converter solenoid.
I purchase many vehicles that have been labled as UNFIXABLE and it usually turns out to be something very simple to fix. It is just that everyone is overlooking the BASICS.
Case in point. I just purchased a late model ford that had this type of fault and after talking with the owner of whom I purchased it from, I found out that he is a stickler for oil leaks and several months ago he had the engine removed from the vehicle and had all the seals and gaskets replaced. During this time the vehicle sat outside with all of the OPEN WIRING CONNECTORS exposed to the elements and one of the main electrical connectors builtup some corrosion within the connector that was overlooked and after being plugged back in after the engine was re-installed the corrosion kept building up to the pint where it was causing an INTERMITTENT electrical contact of which just happened to be for the distributor circuit.
After driving the vehicle after i purchased it from the owner due to his disgust that he had it all over and no one took the time to start with the BASICS I soon discovered the corrosion within the connector and after cleaning the corrosion from the contacts, The problem was resolved.
If you can't find you problem, I may be interested in purchasing your vehicle as I have a 1 ton ford dually with a 20' trailer that I travel over several states buying up these UNFIXABLES.
let me know.
autohelp
