97 hardbody nightmare

[gullymonster]

Hey all, I need some insight regarding my newish 97 hardbody 2wd 5so with 150k
After a distributor, clogged oil screen, some o2 sensor and 5 mechanics I'm still having issues that prevent my truck from passing inspection. But it drove beautifully till this morning when I noticed bit of a seeming vacuum leak.

My issue is that 3 monitors aren't clearing, (cat,o2,egr) only need one cleared to pass inspection. Flipping codes p1400 and p0450. But driving truck 80 miles above 65mph won't clear monitors, turn off for cool down cycle and check engine light appears upon start up.

Nissan tech showed me lowest hose (hi temp vacuum) on egr valve melted, so will replace. My fear is that this won't resolve issue. Truck ran and idled fine with AND without egr clip connected. Could this be an issue with DTM?
Also what symptoms for egr valve failure, solenoid failure. No issues at idle

[califrontya]

if a new fusible link does not get hot or melt when you put the ignition in the ON position (dont try to start the truck), then the issue has to do will the alternator...either the internal regulator is shot or there is a grounding issue.

If the fusible link gets hot with the ignition only in the ON position, then there is a short somewhere. At that point i would start disconnecting all lighting connectors near the engone bay and pull fuses. Then replace the fuses one by one until you find the circuit the is having issues. The fuses themselves are probably okay, but the circuit they are enabling might have a relay shorted or something.

[califrontya]

sorry, ignore the previous message. not sure how to edit posts using the phone formatted website. the message above was in response to another post.

[PapaSmurf2k3]

Really with the EGR removed completely, the truck will still run fine. It will only harm your emissions.
Fixing that blown vacuum line certainly wont hurt, but you ultimately might have to pony up for a catalytic converter too.

[Desert Rat]

are you expecting the codes to self clear after doing work and not resetting the ECU? That could take a while.

If you want to reset the ECU and see if the codes come back, disconnect your negative ground for about an hour, then reconnect and go for a drive.

[gullymonster]

I have reset the ecu. Taken it out on the road. Nissan tech told me all I needed was 30 miles on drive cycle.

Driving it 80+ miles the monitors for egr evap and cat didn't clear. This I believe causes it to throw codes. Turn truck off, cool down, and restart and the check engine light comes on within a couple miles.

Is there any known solution for diagnosing/correcting issues with the monitors (not addressing code issues)

[gullymonster]

Also clearing ecu through the computer, riding through cycle, I can watch that the monitors do not clear, ( I need to get down to 2 monitors) to pass inspection.

[nalz]

If i'm reading this thread correctly, it sounds like you believe that driving about 80 miles is the key to having the on-board emissions diagnostics complete their self-testing. I was a driveability/emissions technician for Ford dealerships for twenty years, and i can tell you that the "drive cycle" that allows the vehicle's system to test itself is more complex than that. There is a minute or so of idling, then accelerating moderately to a typical city driving speed. like 35 mph, then holding that speed for a few miles, then accelerating to highway speeds, like 55 mph or higher, then holding that speed for a few miles. Then decelerating from that speed to a specified lower speed, then more idling. Also, i think the coolant temperature has to achieve a certain minimum degrees to allow testing. I think there are factory service manuals available on this site that should outline the exact procedure. Looks like i found it: http://www.nicoclub.com/FSM/Hardbody/1997_D21_Truck/ . Donwload the ec.pdf folder (engine controls) and go to pages EC39 and EC39. It shows in more detail the specified drive cycle Nissan wants you to drive.

[nalz]

that should state "pages EC38 and EC39"

[zack.]

Don't turn on the AC during the drive cycle and it won't run the EGR diagnostic. If the Egr system is the issue this will prevent a code from popping while clearing the other monitors.

[PapaSmurf2k3]

Whaaaat?
The egr most certainly operates with the AC off.

[zack.]

But the check monitor does not