EGR Resistor Revisited

by **akora12** » Wed Jul 22, 2009 5:57 am

It's been a while since this was last discussed, so I'm hopping that someone has made some progress on this effort.

Has anyone ever found a resistor that will fix the CEL commonly associated with deleting the EGR on a gen 1-1.5 solara? I've tried a 1/2W 10k, 12k, and 16k ohm resistor with no luck. Just to confirm, I've been wiring these into the harness for the EGR temp sensor.

Here's the original discussion about this topic from almost a year ago.
http://www.solaraguy.com/viewtopic.php? ... r+resistor

Honestly, having a CEL for this is driving me nuts. I have no other problems associated with my car, so I hate having to explain the light to every passenger who rides in my car. I'm half tempted to throw the TRD EGR tube back on, but I like the performance gains of having it removed.

by **SolaraPete** » Wed Jul 22, 2009 3:41 pm

^^bump

Anyone have any ideas on this? I'm also tired of this CEL staring at me all the time. I know there's tons of knowledge here - someone has to have a solution....

by **lilm** » Wed Jul 22, 2009 3:56 pm

there is a performance increase when you do this?

by **NRDriver** » Wed Jul 22, 2009 4:07 pm

i dont really think that using a transistor will work in place of the temp sensor. i think that the temp sensor reads close to zero while there is no flow and reads from .5v to 1v or something to that affect while fully open. a transistor is going to have a constant range(not changing). therefore you will get a code for insufficient flow or a code for too much flow.

i was thinking of another approach.

Disconnect the egr from the intake plenum and route is straight to the exhaust intead of intake. this seems like a more simle and straight forward way to do it unless i am missing something in the equation

by **akora12** » Wed Jul 22, 2009 4:50 pm

lilm wrote:there is a performance increase when you do this?

I don't know about any hp gains, but it seems like a good idea to keep as much hot air out of the s/c as possible.

NRDriver wrote:i dont really think that using a transistor will work in place of the temp sensor. i think that the temp sensor reads close to zero while there is no flow and reads from .5v to 1v or something to that affect while fully open. a transistor is going to have a constant range(not changing). therefore you will get a code for insufficient flow or a code for too much flow.

i was thinking of another approach.

Disconnect the egr from the intake plenum and route is straight to the exhaust intead of intake. this seems like a more simle and straight forward way to do it unless i am missing something in the equation

I've also pondered how a fixed resistor would work for the egr's variable voltage, but I know people have had luck with a 10k resistor on the older supras and even camrys.

If you removed the egr unit from the plenum, how would you run the flow back into the exhaust system? I'd love to dump the entire egr system all together, but I don't know how you'd keep away all the CEL's.

by **JamesT** » Wed Jul 22, 2009 5:23 pm

The reason you guys can't just use a resistor is that the ECU reads the changes in the resistance of the EGR, not just whether it is working or not.

The only thing I could think of to attempt to bypass it would be to figure out the resistance increments coming from another sensor and tap that wire. From there, send the info to something that can adjust the resistance to what the EGR should be reading at that time.

Example (purely hypothetical - the values are all made up)

Coolant temp sensor Resistance:
4k at startup (coolant cold)
20K at 100F

EGR Resistance:
2.5K at 0F (EGR Closed)
100K at 300F(EGR Open)

If you were to, lets say, Tap the Coolant temp wire and run the new wire to the EGR pin on the ECU (and somehow adjust the Ohms), than it would tell the ECU that the EGR is closed when the car is cold and open when the car is warm.

I have no idea if this makes sense but I figured I'd give a guess.

by **JamesT** » Wed Jul 22, 2009 5:44 pm

Bahh.....

I just read through a factory service manual for your EGR system...

Alright, it looks like you would need to tap the Coolant temp sensor, TPS, IAC, and somwhere to get your RPMs.

You would need to figure out what the values are for each of those when:
Engine is cold: Coolant Temp
Throttle is closed, or slightly open: TPS
Car is Idling: IAC
RPMS above 4000: RPM

When these situations (any of them) occur, you would need to signal the ECU (via the EGR wire) that the Valve is closed.

I'll make a list of the Resistance coming from each of these wires in these situations in a bit.

Website · by **99BlackSandv6** » Wed Jul 22, 2009 7:00 pm

Sounds like James is off to a good start. Someone needs to make a plug and play black box for you guys. I'll try some stuff in my spare time and sell it to you for a couple grand when I get it figured out.

by **JamesT** » Wed Jul 22, 2009 9:23 pm

Alright, here is what I have so far:

Coolant temp:
10k-20k = -4F
4k-7k = 32F
2k-3k = 68F
0.9k-1.3k = 104F
0.4k-0.7k = 140F
0.2k-0.4k = 176F

TPS:
0.2k-5.7k = Closed
2k-10.2k = Open

IAC:
17-24Ohms (Cold)
21.5-28.5ohms (hot)

by **akora12** » Thu Jul 23, 2009 5:21 am

James, thanks for you help.

When you reference the EGR wire, are you referring to the wire leading to the ECU from the temp sensor or one from the pressure sensor?

Would we also need a given set of values to signal the ECU when the valve is open? Sorry if I'm a bit slow on this concept, I'm trying to keep up

.

by **trd4life** » Thu Jul 23, 2009 5:56 am

james, can you make a black box with all the resistors ready to go so we can completely bypass the egr with no CEL's?

by **JamesT** » Thu Jul 23, 2009 8:16 am

akora12 wrote:James, thanks for you help.

When you reference the EGR wire, are you referring to the wire leading to the ECU from the temp sensor or one from the pressure sensor?

Would we also need a given set of values to signal the ECU when the valve is open? Sorry if I'm a bit slow on this concept, I'm trying to keep up .

I'm referring to both.

The reason is that the ECU will throw a CEL if both sensors don't read correctly given the measurements from the other sensors.

I'll definately get the values for those as well.

Gabe,
I'll see what I can do - the problem is I don't have a car with this type of EGR setup so I can't test it here. I know you guys have been dealing with this issue forever so I'll definately try making something to help you guys out.

by **JamesT** » Thu Jul 23, 2009 8:52 am

Damn you guys! (j/k)

I just spent the last hour reading up on logic gates, diodes, etc...

This should be do-able.

by **akora12** » Thu Jul 23, 2009 9:06 am

JamesT wrote:Damn you guys! (j/k)

I just spent the last hour reading up on logic gates, diodes, etc...

This should be do-able.

I'm glad you know what you're talking about, b/c I'm having troubles keeping up. Thanks for you help on this, I would be exctatic if we can finally put this problem to rest.

If you need help testing this, we can use my car as a test bed unless someone closer want to jump in.

by **JamesT** » Thu Jul 23, 2009 9:37 am

akora12 wrote:
JamesT wrote:Damn you guys! (j/k)

I just spent the last hour reading up on logic gates, diodes, etc...

This should be do-able.

I'm glad you know what you're talking about, b/c I'm having troubles keeping up. Thanks for you help on this, I would be exctatic if we can finally put this problem to rest.

If you need help testing this, we can use my car as a test bed unless someone closer want to jump in.

I hope I know what I'm talking about... :wink:

That would be great if you could test this out! I'm really hoping I can get this idea into something tangable.

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