removing the egr and pair vsv's

[CruiseOrlando]

Yes, it's at the very back of the motor. If you take the upper intake manifold off, you can see where it originates.

I've been told you can take the nuts off of the pipe header without removing the lower intake manifold, but I didn't have much luck when I tried it, so that's why I did what I did.

 

[dannyp]

You need to have the heater lines and valve off and the wiring harness disconnected and pulled back from the firewall to get back there with a ratcheting wrench and its one click at a time so it sucks.

 

[bsmart82]

I used a small plate made from aluminum to block off the egr port on the head. I also bolted it on when the head was off for head gasket. I peeked int the intake via the throttle body after about 5-6k miles, and it was spotless other than a light coat of oil.

 

[landtoy80]

Has anyone got a lean or rich CEL code from removing or disabling the EGR?

 

[CruiseOrlando]

I got those, but my problem, I believe, was due to the wires in the connector. They were toast, and when I shorted out the temp sensor, I was getting 25/26's. then I went back in there and noticed the wires were falling apart at the connector so I cut it off and just butt spliced the two wires together then taped it all up. No more CELs since doing that on mine - but keep in mind everything changes after OBD-II trucks come into the picture.

 

[landtoy80]

I have been getting Code 25 26 on my 94 OBDI ever sense I messed disabling the EGR. This info helps me as I have been testing other sources for my 25 26 problem. I was at Toyota Dealer yesterday and he said EGR could be a cause to 25 26 (lean rich) problem so hopefully its the cause of my problem.

I cut the temp sensor wire and ran them together and got code 71 EGR problem. I tried the resistor and started getting 25 26. Removed the resistor and put plug connector on the wires (so that I could unplug if necessary) and still get 25 26.

I tried to read the Ohms from the EGR temp sensor with a Radio Shack multimeter and didn't get any reading with the Radio Shack meter. I tried heading with water and mini torch with no reading.

Maybe I damaged the EGR temp sensor with torch and its not working anymore. The EGR is working. My IR temp sensor shows the EGR part of the intake plenum is hotter than the rest of the plenum after driving. When I disabled the EGR, it was not hotter than the rest of the plenum.

I am just wondering if not having a EGR temp sensor causes messes with the ECU and thus causing a CEL 25 26?

 

[CruiseOrlando]

I am just wondering if not having a EGR temp sensor causes messes with the ECU and thus causing a CEL 25 26?

I don't know for certain, but my experience shows that an open circuit gives these errors. Perhaps your wiring harness is broken somewhere between the temp sensor connector and the ECU?

Maybe you could leave the connector open and try shorting at the ECU connection? Although I have no idea where that connection comes in...

 

[landtoy80]

I have the ECU out right now checking wires to the O2. I will check wires from the ECU harness plug to the EGR temp sensor plug.

 

[xjaz]

I used a small plate made from aluminum to block off the egr port on the head.

I was able to get it off without removing the upper intake manifold. I used the side access port in the wheelwell and used a long extension with a universal joint on the end. It wasn't easy and I had to use several different positions to get the bolts out and back in with the block-off plate.

 

[mandinga]

Did anyone ever post the "plug" pt# for the egr temp sensor?

 

[UWdave]

I'm just trying to understand the operation of the PAIR system.

Here is what I've read:
The ECU turns on the PAIR system during deceleration and cold startup by actuating a vacuum valve. The PAIR system introduces air directly into the exhaust (before oxygen sensors).

So these leads me to a few questions:
- If the ECU engages PAIR during a cold start, this would introduce air into the exhaust & o2 sensors. This would make the engine working in closed-loop appear lean. Does the ECU just adjust the desired A/F ratio or does it operate in open-loop?
- If the PAIR system is removed, and the ECU does adjust the desired A/F ratio (first question), wouldn't this result in a true lean condition during startup/deceleration?

 

[Timpanogos Slim]

Cold starts generally imply a rich condition, no?

PAIR is also active during deceleration.

 

[bsmart82]

Cold start will be open loop until the O2 sensors are up to operating temp and or coolant temp reaches the set point for closed loop. The pair will likely only operate during open loop and deceleration during fuel cut.

 

[bruja blanca]

subscribed !

I'm looking for more info on doing this to a 96 tho !

x2

 

[johnalex]

Keep the knowledge coming. I will get around to this some day.

 

[silverhorse]

found out some good info today. i bought a new engine harmess(94')(82121-60341) It has the OEM CONNECTOR/PLUG(82824-35020) already installed. I believe, because (93-94.5) have same harness and same ECM. Since some 93' have no EGR temp sensor but have same ECM as 94' this tells be the 94' is just as easy to convert at least electronically, to NON temp sensor and NON EGR...

 

[landtoy80]

How much is a new harness?

On my 94 I disabled the egr and shorted the temp sensor back to its self. No CEL.
Now in emission testing area I hooked up EGR leaving the temp sensor shorted. The EGR works with no CEL.

 

[CruiseOrlando]

List on the harness is $463 but you should be able to get it for $340-ish with a Mud discount.

 

[OGBeno]

How much is a new harness?

On my 94 I disabled the egr and shorted the temp sensor back to its self. No CEL.
Now in emission testing area I hooked up EGR leaving the temp sensor shorted. The EGR works with no CEL.

5/1993-5/1994 engine harness is still available.

5/1994-1/1995 engine harness is discontinued.

 

[landtoy80]

What does the engine harness service? That is, is it for the whole engine or just one section? All I would like to change is the left and right O2 sensors and fuel injectors harness wires.
Not that it matters as I think mine is discontinued.