AeroNautical Posted September 23, 2015 Share Posted September 23, 2015 These two sensors are very similar, same ohm resistance, thread pitch, almost as if they were the same sensor. My question is, because MAT sensors aren't produced anymore, could a CTS substitute it? It would probably reflect temp change slower because it doesn't have the air ducting built into the tip like the MAT does, but hey, it's better then getting stuck in an open loop. Renix era 4.0 What do you guys think? Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 23, 2015 Share Posted September 23, 2015 Just because the two sensors ohm resistance is the same does not mean they have the same ohm outputs vs. temperature applied. You have to look at the manufacturer's spec charts for both across the low-to-high temperature range to determine if the ohm outputs are the same at all temperatures. I have not seen the charts, but for an example both sensors would need to put out 150 ohms @ 100*F. You also have to determine that both sensors ohm outputs increase (or decrease) equally across the entire applied temperature range. The manufacturer's spec sheets (output ohms vs. temp graphs) will show all that. If it's close, it will probably work in a Renix since the computer doesn't store codes; it's a new adventure every time you start it. :yes: I had to do a similar sensor comparison recently to determine if the 1996 quasi-OBD1 throttle body mounted MAP sensor had the same ohm outputs vs. vacuum applied as the stock firewall mounted MAP. It did, and I swapped one into my 91, and it works great. Link to comment Share on other sites More sharing options...
Crash Posted September 23, 2015 Share Posted September 23, 2015 I believe that HO MAT sensors will bolt-in, just plug is different. Could splice a new connector into your harness. Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 23, 2015 Share Posted September 23, 2015 I believe that HO MAT sensors will bolt-in, just plug is different. Could splice a new connector into your harness. Maybe it will bolt in, but it probably won't work correctly. You have to look at the temp vs. ohm output graphs. As I recall the HO MAT output polarity is 180* out from the Renix, just like the fuel level sensor. Link to comment Share on other sites More sharing options...
AeroNautical Posted September 23, 2015 Author Share Posted September 23, 2015 According to this, they are identical in how they read, but like I said, without the air duct, the MAT will read slower: Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 23, 2015 Share Posted September 23, 2015 ^^ What's the p/n's for the MAT and CTS sensors the above table is referring to? There are many flavors for each with different temp vs. resistance values. Link to comment Share on other sites More sharing options...
AeroNautical Posted September 23, 2015 Author Share Posted September 23, 2015 P/N unknown, but this is the article I pulled the chart from: http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm The first 2 articles refer to the MAT and CTS. Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 23, 2015 Share Posted September 23, 2015 That's an excellent Renix site. Since Renix MAT sensors are now unobtainium, substituting a CTS or HO MAT might be an option if there are close. I'd give it a shot. All it can do is make it run like crap. :yes: Link to comment Share on other sites More sharing options...
Crash Posted September 24, 2015 Share Posted September 24, 2015 I have a couple of renix parts heeps that may have sensors in them... Link to comment Share on other sites More sharing options...
cruiser54 Posted September 25, 2015 Share Posted September 25, 2015 One is made to be immersed in liquid and the other is made to measure air flowing kinda through it. Try an HO one. Or clean the one you have..... Link to comment Share on other sites More sharing options...
AeroNautical Posted September 25, 2015 Author Share Posted September 25, 2015 Cruiser: Do you know for sure an HO MAT will work? Link to comment Share on other sites More sharing options...
cruiser54 Posted September 25, 2015 Share Posted September 25, 2015 No. But someone with a FSM should be able to compare the HO's values to the Renix. Have you cleaned yours yet? Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 25, 2015 Share Posted September 25, 2015 What are the Renix MAT sensor values? I can provide the HO MAT values............. Link to comment Share on other sites More sharing options...
AeroNautical Posted September 25, 2015 Author Share Posted September 25, 2015 No. But someone with a FSM should be able to compare the HO's values to the Renix. Have you cleaned yours yet? I have, as well as the CTS, these two sensors are my last hope to fixing my running rich and rough idle. Before you say it, I've gone through your tips, I'm also convinced my 4.0 doesn't leave open loop. O2, tps, iac, all that good stuff has been replaced, last options are these two sensors. Link to comment Share on other sites More sharing options...
cruiser54 Posted September 25, 2015 Share Posted September 25, 2015 What are the Renix MAT sensor values? I can provide the HO MAT values............. Link to comment Share on other sites More sharing options...
cruiser54 Posted September 25, 2015 Share Posted September 25, 2015 No. But someone with a FSM should be able to compare the HO's values to the Renix. Have you cleaned yours yet? I have, as well as the CTS, these two sensors are my last hope to fixing my running rich and rough idle. Before you say it, I've gone through your tips, I'm also convinced my 4.0 doesn't leave open loop. O2, tps, iac, all that good stuff has been replaced, last options are these two sensors. I'm suspicious of the O2 sensor. Got 12 volts to the O2 heater? Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 25, 2015 Share Posted September 25, 2015 What are the Renix MAT sensor values? I can provide the HO MAT values............. Not close. The MAT Renix is the called the IAT (Intake Air Temp) in the HO and it doesn't look at all compatible. I'll dig all the temps vs. resistance out of the FSM later if needed, but from the HO IAT values I have below it doesn't look like it will work. The Renix junction box probably won't know the difference anyhow..... Link to comment Share on other sites More sharing options...
AeroNautical Posted September 25, 2015 Author Share Posted September 25, 2015 No. But someone with a FSM should be able to compare the HO's values to the Renix. Have you cleaned yours yet? I have, as well as the CTS, these two sensors are my last hope to fixing my running rich and rough idle. Before you say it, I've gone through your tips, I'm also convinced my 4.0 doesn't leave open loop. O2, tps, iac, all that good stuff has been replaced, last options are these two sensors. I'm suspicious of the O2 sensor. Got 12 volts to the O2 heater? You know, it wouldn't surprise me if it was the O2, as this is the third one installed. (had a few lying around to test). All seemed to test OK, but I never tested the engine side of the harness to make sure it's sending/receiving. How would I use the volt meter to test it? Tolerances? Link to comment Share on other sites More sharing options...
AeroNautical Posted September 25, 2015 Author Share Posted September 25, 2015 No. But someone with a FSM should be able to compare the HO's values to the Renix. Have you cleaned yours yet? I have, as well as the CTS, these two sensors are my last hope to fixing my running rich and rough idle. Before you say it, I've gone through your tips, I'm also convinced my 4.0 doesn't leave open loop. O2, tps, iac, all that good stuff has been replaced, last options are these two sensors. I'm suspicious of the O2 sensor. Got 12 volts to the O2 heater? You know, it wouldn't surprise me if it was the O2, as this is the third one installed. (had a few lying around to test). All seemed to test OK, but I never tested the engine side of the harness to make sure it's sending/receiving. How would I use the volt meter to test it? Tolerances? Link to comment Share on other sites More sharing options...
cruiser54 Posted September 25, 2015 Share Posted September 25, 2015 Make sure you've got 12 volts or more to the orange wire at the O2 sensor. You can also test the ohms resistance of the O2 sensor heater. Link to comment Share on other sites More sharing options...
AeroNautical Posted September 30, 2015 Author Share Posted September 30, 2015 Make sure you've got 12 volts or more to the orange wire at the O2 sensor. You can also test the ohms resistance of the O2 sensor heater. Reading 0 volts when the engine is off, key in, but about 14 when running. O2 heater? Link to comment Share on other sites More sharing options...
metrictonner Posted September 30, 2015 Share Posted September 30, 2015 I've done it. I tried a whole bunch of wannabe MAT sensors and even tested a prototype for a St.Louis firm. None were worth a hill of beans. Mileage went way down or there was a lot of backfiring on startup. I think I ruined my catalytic converter playing around with them. According to the RENIX manual the CTS and the MAT have identical temperature responses. So I got my Dremel tool out and cut up a CTS and yanked out the thermistor. Then I gutted one of the many, not the original, MATs I've been experimenting with and epoxied in a CTS themistor. If you fold back the side of the MAT instead of cut it off you will have some compression on the new insert or a lip for the epoxy to hang on. Anyway you will have to experiment with your machining technique so it may take a couple of CTSs and a couple of some other application MATs before you succeed. The Thermistor is not polar. Most of the newer MATs have a female connector built right into the sensor, easier to screw into the manifold, so if you use the new MAT as a mount you'll have to buy a new male connector to replace the Renix one. Rockauto, amongst others, actually sells separate connectors. Don't destroy your old Renix MAT...it probably isn't bad anyway...just buy new parts and work with them. Anyway I ended up with something that seemed to behave identically to the OEM MAT. I will tell you the St. Louis people didn't believe me, they said their thermistor response data didn't reflect the Renix manual data. Indeed, I took the built one out and put the old back in after a year...no difference. Good luck. Link to comment Share on other sites More sharing options...
cruiser54 Posted September 30, 2015 Share Posted September 30, 2015 Make sure you've got 12 volts or more to the orange wire at the O2 sensor. You can also test the ohms resistance of the O2 sensor heater. Reading 0 volts when the engine is off, key in, but about 14 when running. O2 heater? I think between the black wire and orange wire on the O2 sensor you should get an ohm reading and I forget what it is right now. No ohms reading means the O2 heater is shot inside the O2 sensor. Link to comment Share on other sites More sharing options...
AeroNautical Posted October 1, 2015 Author Share Posted October 1, 2015 @metrictonner: Bit much work for me, your probably right, nothing is wrong with my sensor, but I'm using trial and error at this point to track down my problems. Thanks for the info Make sure you've got 12 volts or more to the orange wire at the O2 sensor. You can also test the ohms resistance of the O2 sensor heater. Reading 0 volts when the engine is off, key in, but about 14 when running. O2 heater? I think between the black wire and orange wire on the O2 sensor you should get an ohm reading and I forget what it is right now. No ohms reading means the O2 heater is shot inside the O2 sensor. Ok, so the heater is inside the O2 sensor. I'll test for ohms, thanks cruiser. Link to comment Share on other sites More sharing options...
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