I performed a search using all of the terms of which I could think, and nothing came back "on point." '87 3.2 Mondial Cab.: If running at a steady speed in the range between 3000 - 4000 rpm in a lower gear (seems to be most pronounced in 3rd or 4th gear), the car seems to have a consistent, rhythmic surge. Though it's somewhat slight (maybe 100 or so rpm, back and forth), it's really annoying. Also, I think I remember reading an earlier post in which someone recognized the same problem on another car and offered a solution (now I can't seem to find the &*(^%& thread). The car has recently had a major service, and though it may be all in my head, I don't recall it performing this way before the service. In any event, does this sound familiar to anyone and does anyone know of a solution? Thanks.
Go in the back and disconnect your Caytalitic Converter from the computer...see if that stops the surging... if so your cat is gone, and the "computer" is trying to adjust the air fuel mix... but cant get it right since the cat aint working. this was the issue with my 85 QV.
How is that done? I haven't looked under the car, but the only sensor in the exhaust system is the O2 sensor and it is either before or after the cat, right? Please advise
He's talking about the lambda, and it adjusts based on input from the O2 sensor. The O2 sensor is in front of the cat, and the wires from it run up to a connector in the engine bay. Simply disconnect that connector and see what happens. It's possible the sensor is bad. You can buy a new one at auto parts places for ~$150, or get a generic sensor much cheaper and splice it with the OEM connector
yes, sorry it is the Lamda control... on my 85QV... there is a wire with a connector between the fuel distributor and the airbox ... you may have to remove your airbox to get to yours, but you can just unplug it and see what happens ... you probabbly will not notice it at idle but only when driving...Hope that helps
