I have a very similar problem with a Briggs & Stratton 17 HP engine. I have put in a new carb overhaul kit. (The float was gunked up pretty bad, but now looks new, checked for leak or holes in it, found no indication that float is damaged.) Put carb back on engine. Engine runs, but poorly. It sounds likes it chugging, noticing black smoke out of exhaust especially at Idle. One thing I didn't notice in all the above posts. Is the adjustment needle on the carb an IDLE adjustment needle or a main needle? What is the initial setting? The engine does have spark. Although one spark plug shows more of an orange spark rather than blue. Both plugs were damp from unburned fuel when I removed them. (They are old plugs.) Engine running: It'll sit and run. I can drive the tractor. However when I slowly engage the mower blades (blades are new, bearings are good, belt is new) the engine dies, unless I quickly disengage the blades and apply full choke. Heading out to store to get new spark plugs this morning. I've already poured quite a bit of money in this beast. I may be the one who has a rolling ball of fire!

Does all of this seem confusing? Opinions everywhere, pieces of facts here and there. Even suggestions of possible fraud in some cases have now surfaced in regards to some of the crashes. From a technicians viewpoint, I have to draw the line at personal experience with these cars and this problem. I have not observed a throttle sticking on one, so therefore I have not had the chance to actually search for the cause on my own. All I can do is rely on the information that basically everyone is getting to hear both from on the news and snippets from techs around the country. Remember all of these are also going to dealers to be fixed under warranty, the aftermarket (independent technicians) are not involved at all with this. One Toyota tech even did a video of how the repair is done and you can find it on YouTube which essentially amounts to removing the pedal assembly. The tech then measures a gap between two portions of the pedal assembly, and then he/she installs a shim to take up that space and that causes more spring return pressure in the pedal assembly. The push for years has always been to have techs that would robotic-ally simply identify a failed (failing) part, remove it and replace it. Remember its all about price, no matter how expensive one may think auto repair labor fee's are, I've said it many times it's under priced by a significant margin. Six months ago, the repair would again have been to replace the part if they found one sticking, and this may well have happened many times. I have never seen information to support or deny how often that may have occurred if it did much at all. The diagnosis and replacement of the pedal assembly likely paid a technician about 1/2 an hour's time for the job. I could very well imagine someone else at another time looking at that pedal assembly, and if they could not prove that it was faulty, they would back flag the dealership for the repair, who would in turn take back the pay that the technician got for doing the repair back off of him/her. Many people would take the position that the tech ultimately not being paid for that repair isn't their problem, and in a direct fashion that would be true on that day. But eventually these actions erode the technician talent pool, and is the fundamental cause of many of the anecdotal stories of poor service you have ever heard of, read or told. Lastly, there have been many times that I have seen people condemn American car manufacturers about quality, and they point to recalls as their proof. It really was just a numbers game before one of the imports suffered a big issue, Toyota's quality hasn't changed because engineering underestimated what appears to be the spring tension required on one specific part. GM and Ford especially were never as bad as consumer reports wanted to make them look. JMHO. Now the Prius brakes issue where there can be a delay under certain circumstances due to a rough road? I can picture what is occurring, the rough road bounces a wheel up and and immediately locks with almost no braking pressure. That would look like a need to begin an anti-lock function to the computer. This isn't something that a dealer technician could fix on his/her own. The fix would have to come in the form of software for the HV, and ABS computers. They could in some cases require a redesign of, or potentially add a yaw sensor if the car didn't come with one. They could even incorporate suspension height sensors to help detect road surface conditions. The wheel speed sensors alone do allow for detection of rough road conditions. There is a resonance to the lock-up that is occurring the system will recognize as not matching the anti-lock systems function, and be scored as road surface, which results in less ABS activation. In Toyota's case that time period must be significantly long which is allowing the drivers to observe it.

Every electrical motor has a maximum rpm that it can turn without sustaining damage. Once that speed is exceeded, centrifugal force will pull the windings from the armature and they will bind into the stator. In the case of the Prius transaxle we are actually talking about a rotor assembly that has permanent magnets attached to it. Exceed the rated speed of that rotor and it will grenade. The engineers are correct. http://eahart.com/prius/psd/ In order for the gas engine to propel the car, MG1 actually has to be a generator and provide resistance for the engine to push against, as well as MG2 being a motor that helps the gas engine push the car. Using the java applets on the site I provided you get to see the normal operation of the motors in the transaxle, and how they work together. Take note there are times that MG1 actually is forced to spin backwards. The Prius has a maximum vehicle speed of 94mph, with the primary reason being risking over-revving the electric motors and causing a catastrophic failure of the transaxle. Here is a link that might be useful: Prius Power Split Device.

If the shop reported that the oxygen sensors are shuting down, this can affect performance, but I not certain just how much. Usually, when an out-of-range reading is sensed from the oxygen sensors, the system automatically reverts to default settings which normally results in increased fuel consumption. Replacing the oxygen sensors should correct this situation (if that is all that is the matter). How many miles do you have on your oxygen sensors? These are supposed to be changed about every 80,000 miles or so. But these can fail before this. So, for example, if you have 50,000 miles on them, they could fail. Could you possibly be experiencing "pinging". The knock sensor, when triggered, retards the timing and that will cause momentary reduction in power. However, as soon as the ping goes away, the system will recover in a short period unless another ping is heard. You may have a temperature related sensor failure. The cam position sensor, or crank position sensor may be failing when hot, but returns to normal upon cooling. Suspect these items if the car starts ok when cold and operates well until fully warmed or under load such as crusing at 65 mph. These parts can heat soak while waiting at a stop light, or in slow traffic. One more unusual thing is faulty plug wires (leads). These are not metallic wires these days, but carbon like resistor materials. The plug leads should measure no more than about 3000 ohms per foot of length. (Consult your repair manual for the recommended ohmic value.) I've had these fail in this manner: Starts ok when cold. Runs ok until the engine get hot, maybe 10 miles of cruising at 50 mph over country roads with stops every 2 miles or so. Then, suddently, on an uphill or when pulling away from a stop, the engine misfires and stumbles and does not run well until the load is reduced (back the foot off the gas pedal). The diagnostic for this condition is that the plug leads will measure too high in resistance particularily when these are hot. This item may not show a trouble diagnostic code. One more item that can cause the problem you descibed is the throttle position sensor. This is a key item for setting the fuel mixture and spark timing.