EGR Code 71 & idle issues. (1 Viewer)

[Roc Doc]

1994 FZJ with 240k on the clock. It runs good but it throwing an EGR code. I plan on sussing out the issue today, but I have noticed some strange stuff going on with the idle as well. Have been reading the various EGR threads and am tempted to remove the EGR and pair system, if nothing else but to clean up and free up some room in the engine compartment.

If I disconnect the + battery lead (to clear codes), it will start up and run without a CEL for a while, then the CEL will come on. I do notice that when the CEL light is not on that it will idle between 5-600RPM or just a little too slow for my taste, and if the CEL is on then it will fast idle 1600 or even faster on startup, and then warm idle at 750 or so.

Also the exhaust stinks when the CEL is tripped, like blowby not getting recycled or something. (Going to check the PCV as well).

Thoughts?

 

[half k cruiser]

How are your o2 sensors ? Not throwing any other codes ? Kinda sounds like the same issues my 94 was just having. A set of factory o2's cured it.

 

[Timpanogos Slim]

I don't know what vegas emissions testing is like, but on 93/94 it seems you can disable EGR invisibly by removing the wire harness from the egr temp sensor, sticking a U of wire in it to short it out, and pushing it back onto the sensor.

No CEL and the valve just never opens. No more hot pipe, no more carbon in the intake plenum.

Deleting PAIR is cheap, and i want to take a gamble with that right after i get this year's emissions certificate. You can get oem blockoff plates, and the hard heater line and throttle cable bracket from an outfit like cruiserparts. As long as nobody actually reads the vacuum diagram or notices the hard vac line across the front of the head with nothing attached, nobody will notice it's not there.

 

[cruiserdan]

Low hot idle after powering down the ECM on a 93-94 is normal. It takes 10-15 ignition cycles for the ECM to recalibrate the hot curb idle. Every start will bring the idle up slightly til it gets where it needs to be.

 

[Roc Doc]

How are your o2 sensors ? Not throwing any other codes ? Kinda sounds like the same issues my 94 was just having. A set of factory o2's cured it.

Don't know their condition, I got zero service records with this thing...what's wrong with people not documenting their vehicles, especially enthusiast vehicles?

I don't know what vegas emissions testing is like, but on 93/94 it seems you can disable EGR invisibly by removing the wire harness from the egr temp sensor, sticking a U of wire in it to short it out, and pushing it back onto the sensor.

No CEL and the valve just never opens. No more hot pipe, no more carbon in the intake plenum.

Deleting PAIR is cheap, and i want to take a gamble with that right after i get this year's emissions certificate. You can get oem blockoff plates, and the hard heater line and throttle cable bracket from an outfit like cruiserparts. As long as nobody actually reads the vacuum diagram or notices the hard vac line across the front of the head with nothing attached, nobody will notice it's not there.

Clark County is much like California, except we have to get a smog check every year. The outlying counties have no such requirement.

I may try the EGR trick.

Low hot idle after powering down the ECM on a 93-94 is normal. It takes 10-15 ignition cycles for the ECM to recalibrate the hot curb idle. Every start will bring the idle up slightly til it gets where it needs to be.

Thanks, good info. I'll be driving it a few times in the next few days around town before hitting the Mojave Road on Sunday.

 

[cruiserdan]

It doesn't have to be long drive cycles. Once it is at operating temp you can shut it down, sit for ~20 seconds, restart and let idle stabilize, shut down and repeat a few times.

 

[Roc Doc]

So I guess the ECM is working fine as the idle does come back to normal over a few run cycles, but as soon as it does the CEL comes on and then the exhaust stink starts all over again. Is blowby getting past the EGR or Pair system?