Questions For jtgh And Other Readers...

[sluhbmet]

jtgh,

First I want to thank you for all of your write ups especially regarding the dreaded 51 code and also the one explaining how to set the fine timing on the Geo Trackers.

With that being said, I do have a few questions. I spent most of Saturday this weekend disassembling, cleaning and troubleshooting the egr system in my 1994 Geo Tracker 8V 4x4. Man, I looked and felt like Dick Van Dyke in "Mary Poppins" when he was playing the chimney sweeper covered in soot. Regardless, I did make alot of progress introubleshooting and repairing the 51 code I was getting. After cleaning all the soot out of every possible hiding place from the rear throttle body port to the egr valve and manifold passages, I started troubleshooting the system. I didn't get very far before I found that my vacuum solenoid valve for the egr system was defective. I found a wrecked 92 tracker with a donor solenoid assembly that tested good, so I purchased and installed it in my 94. I was certain that would solve my code 51, but after disconnecting and reconnecting the battery, the "CEL" came back on within about 10 minutes of driving down the road. So I was back under the hood working my way down the egr system testing the egr modulator and the egr valve itself; and everything tested good according to the procedures in your write-up and the pages copied from a service manual you made available as a download. I was stumped for just a few seconds, but then I noticed a wire pigtail assembly coming from the egr valve itself. The diagrams I had, listed this component as an egr temperature switch. I removed it from vehicle and tried to check both resistance and continuity through it while it was at ambient temp (60 degrees) and also while the tip was being held in the flame of a cigarette lighter, in an effort to mimick the heat of exhaust gases. To my suprise it read "open" on my digital multi meter during all of these tests. I then measured the voltage at the connector on the firewall that this temp switch plugs into. With the engine running it was about 4.75 volts. Lastly, since my Tracker was already at operating temp, I reset the "CEL" and placed a jumper wire across the connector that the egr temp switch plugs into. I started my Tracker and ran around town the rest of the day without the "CEL" coming on, which is unusual because in the past the "CEL" would come on within about 10-15minutes of driving.

Question #1: What is the recommended testing procedure for the egr temperature switch? My troubleshooting guides had zero information on how to test this little part.

Question #2: Is jumpering the connector that goes to the ecm from this temperature switch a bad thing, until I can get a replacement temperature switch installed?

Final Question: Does anyone have any recommendations for used parts/salvage yards for Trackers/Sidekicks that might have this temperature sensor? I'm not excited about having to pay $100 for a pigtailed temperature sensor that is almost lighter than a sheet of paper.

Thanks for everyones help and advice.

sluhbmet

[jtgh]

gawd love yah,
no ones tried that! cool.

ok, that is the CAlifornia EGR test. on CAL cars ( or newer cars that adopted this bs ) the
the sensor is monitored full time ( well hot and cruise, etc)

yours is for sure Bad. i have the scale for it my shop manual.

page 6E98 in my sidekick fsm
there are only 5 data points.
214-313kohms = 68f
90-125k ohms =104f
42-55k ohms = 140f
21-26k ohms = 176F
11-13k ohms = 212 F

so shorting it , says red hot all the time.
if worried try a 10k ohm resistor
i checked my ecu (a naked one) it has a 20k ohm input protection resistor on this pin.
so it is safe a short to ground or 12v.

thanks for the trick!

the silly thing , just might open the EGR and look for HOT , yours says hot, and
it is happy as clam, dumb is good.
cheers.

[jtgh]

keep watching ebay for used egr, one will pop up.

[sluhbmet]

jtgh,

Thanks for the data points and specified values. I'll keep my eyes peeled for an egr assembly on ebay that hopefully has the same temp sensor attached to it.

Thanks again,
sluhbmet

[TheZuke!]

I can check to see if the 97 Tracker at the salvage yard
still has the EGR and temp sensor...

Do you still need one?

Where are you located (country?)

[sluhbmet]

TheZuke!

I would be very interested if you could obtain at least a price for just the egr temp sensor itself from the 97 tracker at your salvage yard. I really don't need the egr valve as mine is in pristine condition, but would consider the whole assembly if the price happened to fit into my budget (which is really tight; married-college student). Don't go out of your way for it though. If you happen to be at the salvage yard already or can make a phone call to see if it's still available, I would greatly appreciate it. I'm still searching the yards high and low here in Little Rock. However, every one that still has an engine in it has the egr system that doesn't use the egr temp sensor. Thanks for any effort Zuke at getting me pricing; I just don't want to make any guarantees I can afford it. On the other hand, with gas prices the way they are, how can I not afford to have this running at it's optimal mpg's.

Thanks in advance,
sluhbmet

[jtgh]

they will say all or none,
removing (attempted) breaks most of them

i will see if my spare is around, tomorrow, it is good and if i can find it its yours free.
i dont need it, mines federal model.

cheers.

[jtgh]

OK , I FOund my spare

252k ohms at 68F. so it is good.

plunges to 1k ohm with match applied
no corrosion, white 2 pin connector on end.
can send HR photo
you pay postage, its free.

[TheZuke!]

Dang Jerry!
The only way I can beat your price is to give it to him AND pay
the postage!

Okay, you win...

TheZuke!

[jtgh]

sorry ,but mine is useless to me,

good to a good home.

cheers