Trying to help my mechanic - RE: my 1995 Quest...any help out there?!?!

[timothyh]

Hiya ~ If anyone can be of help on this it would be really something. I have been having trouble with my ’95 Quest, and my mechanic is in what might be called the “experimental” phase of mechanic-ing.

Van:
’95 Quest with 160,000 miles.

Trouble:
Check Engine light came on accelerating up hills then would turn off.
Then over a period of about three weeks:
Engine began to slow when accelerating (miss) especially up hills. Check Engine light on all the time. Van would go into overdrive on hills, but then back out of it.
Van VERY sluggish accelerating from a stop, then would sortive “catch on” (after kinfof coaxing the gas pedal and wishing I had a clutch) but then drive OK especially on flat stretches.
Soon no power to climb any kind of hill whatsoever.

At the shop:

Computer showed two error codes: told they were the O2 Sensor and Knock Sensor.

Replaced plugs. Replaced Fuel Filter. Replaced O2 Sensor. Replaced Knock Sensor.

Ground wire to computer looks OK. Timing Belt looks OK and mechanic thinks it was replaced prior to 95,000 miles when I bought it.

Tomorrow morning my mechanic wants to replace the Mass Air Flow Sensor....

Good Grief.

I had the feeling in my gut that it wasn’t the Knock Sensor, but I’m not the car mechanic in this situation. I do, and know, what I can but at this point I’m hoping someone out there might be able to help me help my mechanic....I have no idea what the bill looks like and he says that he will “work with me” on it. I do trust him, and so I’m trying to get him some help.

[timothyh]

I really do appreciate any and all help that anyone can send my direction - if anyone has had similar trouble and the good fortune to figure out what was causing it!! Thank you!!

[tempfixit]

First thing that should have been done is checked the fuel pressure with a fuel pressure tester.

Replacing knock sensor was a waste of time and money. (Knock sensor very rarely fail, the code means that some other problem set the knock sensor code).

Also check the distributor for a bad bearing which will create a brownish dust on the optical sensor causing drivability problems. If bearing is bad the distributor wiil need to be replaced.

Make sure that your mechanic does NOT overtighten any of the drive belts (PS, ALT, A/C) as overtightening with cause stress on the crankshaft and break the snout off.

Let us now what he finds after checking the above.

[timothyh]

Hey there ~ THANK YOU for the reply! And the verdict is....Mass Air Flow Sensor. Replacing it cleared the trouble right up. I thought all along that the Knock Sensor didn't seem like a likely culprit, but I am not a good mechanic....but the van seems to be running a charm and I can pay my friend off in installments - so al in all this van has been completely amazing when it comes to trouble. Bought at 95K and is now 160K with nothing but a Fuel Injector gone bad. So I can't really complain, and I won't. Thank you Tempfix for your time to type, I really appreciate it! Hope all is well - TH