jamespwsullivan Posted August 22, 2022 Share Posted August 22, 2022 I am finally getting down to the final phase of resurrecting my 1987 4.0 Renix MJ-at least the motor. One of the things I've been looking for is a MAT sensor. Of course the stock item is no longer available according to my searching and looking at lots of posts in several forums. My brother did find a post: https://www.jeepforum.com/threads/87-90-mat-sensor-discontinued-part-fix-walkthrough-how-to.1549148/ that provides an alternative. The OP's approach involved combining the sensor from one SKU with a pigtail from another SKU. Then someone commented that there was a lower cost way to get to the same solution. Here's the scoop. According to the thread there are two part numbers that will work for the sensor. SU343 and WT3023. I usually buy at NAPA. Searching those two numbers produces two NAPA numbers, TS3004 and TS5014. Which of these part numbers is correct or best? Does anyone have experience with this fix or any other way to approach replacing the MAT sensor? The commenter gave a number for the pigtail - PT778 - that crosses to NAPA TSC300. MORE INFO Nick's (REM) Renix Parts Suggestions page relays a tip from David Groeneveld that GM 213-190 has the correct resistance range. (It does require changing / re-tapping for a larger fitting.) My guy at NAPA says the best cross is TS5100. Does anyone have experience with this part? Link to comment Share on other sites More sharing options...
cruiser54 Posted August 23, 2022 Share Posted August 23, 2022 Why are you replacing it? They can be cleaned and checked. Also, they rarely fail. Link to comment Share on other sites More sharing options...
DirtyComanche Posted August 23, 2022 Share Posted August 23, 2022 9 hours ago, cruiser54 said: Why are you replacing it? They can be cleaned and checked. Also, they rarely fail. Yeah, they're one of the most simple sensors, along with the CTS. Pretty reliable, it's just a thermistor, and it's not being used to limit current, short of mechanical damage or being massively overheated they should just keep doing what they do. The P/Ns I dredged up a few years ago should work with anything that crosses to them, and I believe the AC-Delco (not GM) 213-190 is that P/N. Most of these types of sensors have the same temperature/resistance coefficient as it's a product of the materials used to make them, which is a very standard composition. See this thread: Link to comment Share on other sites More sharing options...
DirtyComanche Posted August 23, 2022 Share Posted August 23, 2022 Also, this sensor is normally called an IAT (Intake Air Temperature) sensor. You will get more results with that. MAT will get search corrected to MAP normally, which is a very different sensor. Link to comment Share on other sites More sharing options...
cruiser54 Posted August 23, 2022 Share Posted August 23, 2022 Link to comment Share on other sites More sharing options...
jamespwsullivan Posted September 1, 2022 Author Share Posted September 1, 2022 Thanks DirtyComanche and Cruser54. Cruiser-apologies for the late responses. I've been raveling and haven't got notifications turned on apparently. I do have the test resistance chart and did the test. For context, my question was really to clarify what the correct replacement part would be if it did need replacement. I'm working hard to get all of the bugs out of my 87 after years of not being on the road and many sensors have shown signs of failure or were at least questionable. And I'm working with a hybrid motor--block is a 93 according to the numbers but Renix is the MPI system. One of the first things I found is that there was no knock sensor. Luckily I was able to fabricate a stud that fit the already threaded hole in the block and allowed a new knock sensor to slip on and be bolted down. At this point we've gone from a lot of stumbling (corrected with new O2 and knock sensors) as well as replacing an injector that did not measure well in terms of resistance )I used a rebuilt, flow-tested set that are working fine.) to an engine that runs pretty well most of the tine. A long test drive last night seemed to allow the ECU to do some learning but there are still some hiccups when under a load (going up a hill from a standing start for instance.) Since I don't know much of the history of this motor it could be the case that the PO did not change the flex plate when it was swapped and it has the part from the 93. That would affect the initial timing. Again, apologies for the late response and thanks for the help. Link to comment Share on other sites More sharing options...
cruiser54 Posted September 1, 2022 Share Posted September 1, 2022 If they hadn't changed the flexplate, it wouldn't even run. Remind me. How many of my Tips have you completed? Link to comment Share on other sites More sharing options...
jamespwsullivan Posted September 2, 2022 Author Share Posted September 2, 2022 @Cruiser54 Renix Ground Refreshing and (Upgrades) - all completed C101 not refreshed or replaced Lighting connector refreshed, not all relay contacts cleaned ICU / coil contact refresh not completed Sensor ground test completed - all grounded points - sensors, firewall, fuel pump, additional ground points in engine compartment - test at .3 ohms or less Sensor Ground Upgrade completed CPS not tested - no cranking or startup issues TPS adjustment completed ECU harness connectors not refreshed TCU connectors in engine bay not refreshed, connector in cab refreshed Throttle body and IAC thoroughly cleaned, new gasket installed Good explanation of finding TDC Distributor indexing procedure not completed but inspection shows that the rotor position in relation to the #1 spark plug wire post is correct. As far as vacuum leaks go, I’m pretty confident that I have chased down all of the bad hoses and connections. I considered using the NAPA / Dorman front and rear vacuum harnesses but they say they fit ‘88-’90 and I have an ‘87. Not sure what might be different. I also replaced the MAP vacuum hose. By the way, the ‘L’ connectors currently available from NAPA using the part number you suggested will not fit onto the MAP. I was able to force one of them onto the throttle body. Perhaps they have changed the material. I used a section of new vacuum hose instead. As always, I appreciate feedback and suggestions from you guys. Link to comment Share on other sites More sharing options...
howeitsdone Posted September 2, 2022 Share Posted September 2, 2022 For your future reference regarding replacement part since it's no longer made. The GM part 213-190 has the correct resistance range but it's a larger diameter. You'd have to enlarge the manifold port to 3/8″NPT and then replace the connector. Link to comment Share on other sites More sharing options...
cruiser54 Posted September 2, 2022 Share Posted September 2, 2022 1 hour ago, jamespwsullivan said: @Cruiser54 Renix Ground Refreshing and (Upgrades) - all completed C101 not refreshed or replaced Lighting connector refreshed, not all relay contacts cleaned ICU / coil contact refresh not completed Sensor ground test completed - all grounded points - sensors, firewall, fuel pump, additional ground points in engine compartment - test at .3 ohms or less Sensor Ground Upgrade completed CPS not tested - no cranking or startup issues TPS adjustment completed ECU harness connectors not refreshed TCU connectors in engine bay not refreshed, connector in cab refreshed Throttle body and IAC thoroughly cleaned, new gasket installed Good explanation of finding TDC Distributor indexing procedure not completed but inspection shows that the rotor position in relation to the #1 spark plug wire post is correct. As far as vacuum leaks go, I’m pretty confident that I have chased down all of the bad hoses and connections. I considered using the NAPA / Dorman front and rear vacuum harnesses but they say they fit ‘88-’90 and I have an ‘87. Not sure what might be different. I also replaced the MAP vacuum hose. By the way, the ‘L’ connectors currently available from NAPA using the part number you suggested will not fit onto the MAP. I was able to force one of them onto the throttle body. Perhaps they have changed the material. I used a section of new vacuum hose instead. As always, I appreciate feedback and suggestions from you guys. 2) c101 refreshing/eliminating is a big deal and high priority. 3)connector and relay connection refreshing is also a big deal. Take a few minutes and complete it. The vacuum harnesses should fit 87 through 90. Easy way to check for vacuum leaks using carb cleaner at idle. AND, the IAT can be removed and sprayed clean with carb cleaner. Link to comment Share on other sites More sharing options...
jamespwsullivan Posted October 5, 2022 Author Share Posted October 5, 2022 @Cruiser54 sorry to take so long to post an update. I didn't mention that my MJ is in Kirkland WA and I live in Indianapolis, IN. I'm (sort of) retired so I come out to visit my truck (and my brother) about once a month and now I'm back. I just got here and this morning I observed something that I can't explain. My top priority for the day is to delete the C101 connector. There isn't one! I thought that the C101 was the connector through the bulkhead behind the fuse box, bot looking at your video and some other threads make it clear that I am wrong about that. There is a bracket still in place but no connector, and frankly there is no evidence of any splicing in the vicinity of the bracket. There has been an engine swap in the past, but it's still Renix 4.0 and I'm not sure what to do next. I'm looking for advice about next steps. I have considered creating a new wiring harness but that seems to be a lot of work. the truck spent a lot of time sitting in the humidity and heat of south Florida without being started and I have refreshed a bunch of connections - lights and such - so is it time to re-do all of the wiring? I still have occasional issues with bucking and sputtering under load and have done a fair amount of work replacing sensors, working through Cruiser5 tips, etc. Link to comment Share on other sites More sharing options...
cruiser54 Posted October 5, 2022 Share Posted October 5, 2022 89 and 90 had no c101 connector. Link to comment Share on other sites More sharing options...
jamespwsullivan Posted October 5, 2022 Author Share Posted October 5, 2022 @cruiser54 Yes I understand. I should have said that I have a 1987 and it's verified by the VIN. Link to comment Share on other sites More sharing options...
cruiser54 Posted October 5, 2022 Share Posted October 5, 2022 H is the 10th digit in the VIN? Link to comment Share on other sites More sharing options...
jamespwsullivan Posted October 6, 2022 Author Share Posted October 6, 2022 Tenth character is "H" Link to comment Share on other sites More sharing options...
DirtyComanche Posted October 6, 2022 Share Posted October 6, 2022 Harness was probably swapped. Welcome to owning something that's 30+ years old. I'd check your fuel pressure. Do you have a ballast resistor? You shouldn't, sorta, maybe, hard to say if they swapped the harness and put one in or not. I guess there was also a recall to add one. If you have one, bypass it and take it for a boot and see if the issue goes away. If it does, failing fuel pump, plugged filter, or corroding connectors/wiring are the issue. Failing that, get an actual fuel pressure tester. I hear you can borrow/rent them from lots of parts stores. Link to comment Share on other sites More sharing options...
jamespwsullivan Posted October 7, 2022 Author Share Posted October 7, 2022 Yes it has a ballast resistor. Haven’t tried the bypass but did test fuel pressure and it’s well within spec. Link to comment Share on other sites More sharing options...
cruiser54 Posted October 7, 2022 Share Posted October 7, 2022 bypass it. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now