95 QuestTiming mark

[medusa]

I have a 95 Quest with about 160000 miles and I failed emissions for a high Ox reading.

The check engine light is on and the codes I read are code 32 (EGR control solenoid and or curcuit fault) and a code 34 (Knock sensorand or circuit fault).Some vacumn lines were crack and I relplaced about 5 lines going to and form the solinoid and EGR valve.EGR solenoid opens and closes and I can blow air through the two ajacent ports when I apply 12 volts to it.I went through the procedure to erase the codes but I still read the same two codes.I now going to check my timing but I can't see any "YELLOW" in any of the timing notches which is suppose to indicate TDC, which mark is suppose to be the "YELLOW" TDC mark?I went to check the fuction of the EGR valve per Haynes book .... it says that the I should see movement of the EGR valve stem but the stem is enclosed/hidden inside the EGR valve. Am I suppose to remove the EGR valve for this test?Can type gasoline or spark plug type affect operating tempurture and prodcued Ox? ... currently using regular gas.

I read up on the knock sensor and have not ivestigated it yet .... looks like a big job to replace it. Is it normal for the knock sensor to go bad? What else can cause the code 34 for the knock sensor?

Please advise on what else I can check to solve high Ox reading.

Thanks in advace for your help.

[offtheline]

This probably isn't your problem, but I once had a knock sensor code thrown when my coolant level was extremely low (though I'm not sure why that would be the case). You might want to check the coolant level just to rule that out as a possible problem.

[medusa]

Thanks for the coolant level advise... matter of fact I did add about 1/2 gallon of coolant last night after I read the codes .... I should now try clearing the codes again and see if the knock sensor codes comes back. Any suggestions EGR code or the failure of emissions because of high Ox reading? Thanks.

[NISTECH]

The knock sensor will not cause NOx. You egr code is the cause. The egr is not opening because there is a hole burnt through you bpt hose. The knock sensor wont even turn on your check engine light. The only complaint I have ever had related to a knock sensor was lack of power on a steep incline.

On your EGR there is a metal straw size tube at its base. Follow that tube till you feel a rubber hose where the rubber hose bends you should feel a small hole toward the passenger side of the hose.It is a special hose so be sure to replace it with a factory one. they are about 5 bucks at the dealer. After you replace it take the van out for a drive. The light should shut of by itself after a couple stop signs or so.

I wouldnt worry to much about the knock sensor unless you are looking for absolute optimum performance. It is a real pain to replace on the Quest. It is under the intake manifold directly under the 2 steel hoses running through the valley of the block.