For anyone with hollowed cats or testpipes, you will, from time to time, get a check engine light since the rear O2 sensors will detect malfunctioning cats.

I found this site after looking all over at retail solutions which cost anywhere from $40 to $80:

http://www.mkiv.com/techarticles/oxy...sor_simulator/

I got all the parts (minus the wire...i already had that), from Radio Shack for $12. It took about 45minutes to build. I installed it in the car, running the output to both inputs on the ECU (bank 1 and 2).

I watched the voltage through my OBD2 scanner, and it was working perfect...swithcing from .85v - 0v every 3 seconds. I have not had th MIL come on yet!!!

I have a complete Radio Shack parts list for all the components, if anyone is interested. I would also consider making them for people who don't want to...

m

 

Yes, I'm very much interested in the parts list.

Thanks,
Az

 

Skidazzle...since I am electronically challenged, I would be willing to pay you for a complete kit. PM me a fair price.

As a side note...I got my first CEL with the RT cats and the Greddy TT. I have a OBDII scanner, and the code is "system running too rich". Gee...I wonder why?

 

the "too rich" code i think is caused by having the 440's in the car. t32gzz gets these messages also, but I never have. he has the 440's and I don't... we both do have test pipes though.

the codes for having CELs related to no Cats are:
p0138
p0158
p0139
p0159
p1146
p1166
p1147
p1167

and about building these things... i will do it for $25 + $5 shipping. i have some PMs already, and you gq.

i will be posting the parts list next...

 

Here are all the parts you need (minus the soldering equipment).

It is in this layout:
Quantity / Description / Radio Shack Part Number / Individual Price
------------------------------------------------------------------------------------
(2) / 5mm Red Wide-Angle LED / 276-309 / $1.49
(1) / LM555 Precisio Timer / 276-1723 / $1.29
(1) / 8-Pin Retention Contact / 276-1995 / $0.59
(1) / Wire Tap-Ins / 64-3052 / $1.99 (This is optional.. I decided to solder all my connections to ECU, power and ground.)
(1) / UL Recognized Hookup Wire 20AWG / 278-1225 / $4.99
(1) / Project Box & PC Board Combo / 270-283 / $3.99
(1) / 4.7uF 35V 20% Electrolytic Capacitor / $0.99
(1) / 22uF 35V 20% Electrolytic Capacitor / $0.99
(1) 100K ohm 1/4W 5% Resistor pack / 271-1347 / $0.99
(1) 1M ohm 1/4W 5% Resistor pack / 271-1356 / $0.99
(1) 10K ohm 1/4W 5% Resistor pack / 271-1335 / $0.99

This should total to $20.78, then add applicable tax (and shipping if bought online).

michael

 

Is this something that is only if you have FI? I have the test pipes and no lights yet, but I will check the outputs with the scantool to see what they read.

 

what took a long time is making sure I had the right wires on the ECU... It turns out the Factory Service Manual has the correct Pin numbers, but not Wire colors...

Here is that information on which wires to connect to the O2 simulator output to trick the ECU... (Note these colors are wrong, but the pins are correct... not sure if my colors would match yours.. but I will get those later):

bank 1 - pin 74 - W
bank 2 - pin 55 - B/OR

here is an ECU pin diagram to find the wires...

 

Weird, I have had my test-pipes on for over 10k mile and I have NEVER gotten a CEL....

 

wierd.. i wonder if its because i am running FI.... i am way under 12:1 a/f, and i wonder if this is too much for the rear O2s...

also, the info came for a Supra website, so it might be something about FI setups which make rear O2s much more sensitive to not having cats...

either way... the info is here for people who need it... not trying to tell anyone they have to do this all i know is i never get CELs for this anymore, and now can actually put some credit into when it pops on.

m

 

no CEL w/ my pipes

 

Same here, no CEL light and I have test pipes.

 

Must be an FI thing due to rich conditions. ZYRAGO and I both have CEL's with our Greddy TT's. He has test pipes, and I have RT Cats.

Skidazzle, I can't understand why the 440cc injector would cause the CEL. During cruising and idle, the MAF is massaged, so I maintain a perfect 14.7:1 as indicated on my wideband; this should not trigger a CEL. Also, 350Now has the Greddy TT with stock cats and no CEL's. I realliy think its the RT cats and test pipes with a TT that are causing this, rather than the 440 injectors. Now, of course, under WOT, everyone with F/I goes pretty rich..i am in the sub 11:1 range most of the time. I also noticed that the CEL usually comes on after a few dyno runs or several hard pulls at WOT. I think it just overloads the 02 sensor and triggers the CEL. That is my hypothesis.

Either way, I will be buying your kit...thanks for the PM. I have been swamped this week, but I will paypal you shortly.

One last question...is it logical to say that when the CEL comes on for a "too rich" condition, that the ECU would try to lean up the mixture via reduced pulse width or duration? Could this cause a well tuned F/I system to suddently go lean? I haven't observed this..but am justing thinking out loud.

 

the wierd thing is that the "too rich DTCs" are p0172 and p0175. these have to do with the first set of O2 sensors, not the rears. this also means the code comes during closed loop operation, and not when boosting. (even the shop manual states to let the car idle for 10 minutes to get the code...)

this week we will be installing a WBO2 in t32gzz's car so we can get an idea of how it is running in closed and open loop... i will keep you updated.

i think you do not have to worry about the car going lean on you, as i stated before, the DTC comes during closed loop operation. and, the code means the car cannot lean out the mixture enough to make it happy at 14.7... i do find it weird that you are getting 14.7 at idle, though....

hopefully, i will have more findings after we play with tim's car!

m

 

FI w/ test pipes here, light has never come on...

 

Running very rich will consiberely shorten the life of your O2 sensors.

 

How many miles do you have on your straight pipes? It took about 2000 miles for my CEL to come on with the RT cats.

 

update: i have some instructions which include wire colors/locations to wire in a simulator...

http://home.comcast.net/~turbo350z/o2/o2.html

hth,
michael

 

ive had test pipes on for 3 years and no check engine light so far

 

I'm not running F/I and the day i put my TP's in i had the CEL on.

 

Don't the Non-Foulers do the same thing? In other words, they both achieve the same results?