Failed California Smog - CEL 71 - Help (1 Viewer)

[RojoFJ62]

Went to get Rojo smogged today. See attached numbers. The emissions read outs passed but the "functional" test failed. Apparently when its driven under a loan for a while the check engine light comes on and stays on. Once you turn off the rig and start it back up, the CEL goes away.

So seems like the rig is not polluting but there is something I need to fix so the dang light doesn't come on and I can pass smog test.

Any ideas on where I should start given the emissions are low and the CEL code I pulled after the test was 71?

I've checked a few threads, some recommend new cat, some new O2 sensors, others on code 71 say something involving EGR system. On a budget and a time table so would like to figure this out as cheaply and quickly as possible. This is my daily driver.

Cheers.

 

[LAMBCRUSHER]

egr gas temp too low...is the fault. it is caused by the ECU expecting the egr to kick in, but the egr gas temp sensor says the gasses are too cold for the egr to be functioning properly. Most of the time, it is a false code, but it can be real if any of the components in the egr systems aren't working. this code can be bypassed by back-probing a 10k ohm resistor across the 2 wires going to/from the egr temp sensor. put the resistor on the sensor side of the harness and cover the sensors leads and resistor with a piece of shrink tubing- you do not want the smog tech to see a "foreign" object in the harness, so make it look as natural as possible- or invisible would be best. you might also get the FSM from @Trollhole and go thru your smog gear to see if something needs to be fixed. HTH

 

[OSS]

@LAMBCRUSHER is the 62 whisperer. Heed his advice. Although the NO test technically passed within the max limits, the NO is much too high for a 3F-E. High NO is an EGR malfunction- not opening enough.

 

[LAMBCRUSHER]

don't follow me; I am a follower of others...

 

[RojoFJ62]

Thanks guys. Would prefer to Fix what is wrong rather than wire a bypass. Where would you guys start to fix the EGR malfunction? Clean it? Test sensors?

 

[vipergrhd]

Clean the EGR pipe and cooler, there must be a flow issue going to your EGR valve.

 

[morganism]

Start and warm to idle.
Take a spare length of vac tube.
Disconnect the vac to top of EGR top hat, put on spare to that fitting. Suck on end till it stalls.
You should here a 'rock" of carbon fall down to the oil pan.
Drive normally till it starts to buck as you accelerate, then do it again.

 

[LAMBCRUSHER]

I'd start by setting down with a nice frosty bev over my copy of Trollholes FSM... TIP! Also check for similar fixes of 80 series 3fe owners...

 

[RojoFJ62]

@LAMBCRUSHER @vipergrhd , finally getting around to it this weekend. I ordered and EGR gasket off SOR last week and arrived yesterday. Blasted the bolts with PB blaster. If I take off EGR and clean the pipe and the temp sensor, do you think that will be enough to get the NO down and keep the CEL 71 from going off? Or is there something else I should do while it's off? Also, can I clean with anything like throttle body cleaner or simple green? As always. Thanks for your help.

 

[LAMBCRUSHER]

TB cleaner would be OK but only in the large gas pipe inlet and outlet- not into the vacuum tubing or diaphragm area. You might download the FSM and go thru the test procedures for the EGR system. IIRC, there is a VCV near the charcoal can that affects the EGR function...did you ever do any research in the 80 series forum?

 

[OSS]

The best stuff I've found (and read about) to clean out the insides of a carboned up EGR valve is Mr Muscle Oven Cleaner. It's a spray foaming stuff. Let it soak in it over night but be sure not to get it on the rubber diaphragm or plated diaphragm housing. It's super corrosive. Wear thick rubber gloves and have good forced air ventilation (fan) blowing when you're working on it cuz the fumes are deadly.

Use metal bristled pipe cleaning brushes and a small screwdriver to scrap the carbon off. The more you work on it, the cleaner it gets. Kinda a lot of work. You can make it all clean & shiny inside if you keep at it. Use a vaccum pump to actuate the valve up & down while you're cleaning it.

 

[RojoFJ62]

What should I use to clean the EGR temperature sensor? Wire brush? Throttlebody cleaner? Soap and water? Just don't want to damage it. Thanks

 

[vipergrhd]

Soap and water will be fine for sooth.

 

[Desert Dino]

Start and warm to idle.
Take a spare length of vac tube.
Disconnect the vac to top of EGR top hat, put on spare to that fitting. Suck on end till it stalls.
You should here a 'rock" of carbon fall down to the oil pan.
Drive normally till it starts to buck as you accelerate, then do it again.

suck? suck what? rock falling? into oil pan? ?? what?

 

[RojoFJ62]

Thanks at @vipergrhd. Should I use red RTV when re-attaching ERG valve with new gasket or not necessary?

 

[vipergrhd]

suck? suck what? rock falling? into oil pan? ?? what?

^^^ LMAO at this. I think it needs more. sucking.