The engine cuts off when reaches 2000 rpm like that when the rpm limiter cut off the engine, I was checking the mass air flow sensor and it is working perfect, I replaced the fuel and air filters and the failure is still present. Some times when the engine is cool works perfect for a couple miles, but some times the failure is present just as the engine start. The check engine lamp doesnt come on, I used a diagnostic computer and the report shows problem with the knock sensor but I do not believe that because the function of this sensor is to delay the spark......please if somebody knows anything let me know. thanks

What year is your Quest?

it's a 2000

i am having the same problem with my 2000 quest.it happens when the engine is at operating temp.it first started out on a hard acceleration over 3000 rpms.i thought i got a bad batch of gas ,the problem stoped for a day but is now back .now it is acting like a missfire it is now doing it at idle.would like to check fuel pressure but cant find the port please help

allright...first of all i recommend you to get a manual of the van(you can buy it in any discount auto parts or any store of that sort....this manual has helped me a lot) in the manual it tells u exactly how to check the fuel pressure and any type of question you have. but to be honest with you i don't think that is the problem at all....because if it was the pressure regulator the engine wouldn't cut at EXACTLY 2000 rpm's or in ur case 3000 rpms.
the problem with our van stopped about 2 wekks ago, but i am pretty sure it might come back, i think it might be an electrical damage or a sensor...or anything like a bad connection. if u need anything else or get any new info plz don't hesitate to reply..thanks

Take fuel sample and check fuel pressure to start..

Hi there - I do have the same problem with my quest 2000. Is with the auto mechanic now. He changed the fuel pump/fuel filter/spark plugs/air filter and also the crank shaft positioning sensor. Now he says the problem might be Knock sensor - and he is still not sure -wants to change the knock sensor. Already spent quite a bit - would like somebody to advise me as what the problem might be. Did David got his van fixed ?

The existing thread is quite old, best to start your own thread.

Have you got any codes?
Does your mechanic have scanner capable of reading live data?
I suggest not changing the knock sensor at this point because they seldom go bad, their main function is to retard timing when somthing is amiss.

Has he checked the ECT (Engine Coolant Temperature Sensor)? This can retard timing if faulty.