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Mystery CEL and Weird Coolant Temp 92 b18a1 and stock ECU in a 90 GS

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  • Mystery CEL and Weird Coolant Temp 92 b18a1 and stock ECU in a 90 GS

    Does anyone know what this CEL is:



    I know this is basic stuff, but I just don't get it lol. Is that a "20" followed by a "7", a "1" followed by a "17", or a "27"?

    20 Electrical load detector
    7 TPS - throttle position sensor
    1 O2A - Oxygen sensor #1
    17 VSS - speed sensor
    27 ??

    Here's a little background on the car:

    90 GS, swapped in 92 b18a1 and matching stock obd-1 ECU by using Rywire OBD0-to-OBD1 adapter. Jump the orange and blue pigtail on the adapter to blink the CEL and get teh codes.

    Extra clues:

    Temp gauge on the dash cluster reads "warm" (1/3 way across left-to-right) even before starting when engine is cool. After running a few minutes reads "hot", 3/4 way to overheating, hotter than I've ever seen a Teg run. Rad fans turn on and engine doesn't seem to be running extra hot. If I unplug the Coolant Temp Sending Unit to the bottom-right of the distributor in the head (one-wire looks like a mini headphone jack), gauge goes all the way back down to cool.

    From what I've read in the manual, CEL 1 is thrown when ECU thinks the engine is warm but the O2 sensor doesn't seem to be working correctly yet. It gets the temperature reading from the Coolant Temp Sending Unit, so that might explain CEL 1?
    Last edited by sloppysleeper; 15 Jun 2017, 23:44:52.

  • #2
    That should be a code 20 and code 7. The long pause between is what separates the different codes.

    It's been a long time since I've done any research regarding the ELD so I'm a bit out of touch there but did find this post: https://honda-tech.com/forums/acura-...ector-2851509/ What ECU are you using? According to that post you could be running into this problem if you're using any ECU other than a 92-93 PR4.

    If this was my car I'd use a multi-meter to check that all the wires are connected properly and that the jumper harness isn't part of the problem. I'd do that first because it may be tough to troubleshoot this if you aren't sure the wiring is as it should be. The temp gauge issue is what leads me to believe there may be a wiring problem. And if that's true it may solve the other issues as well. Regardless, sounds like you just need to spend some time with your multi-meter and Helms manual.
    Track Project DB2 #896
    LeMons Project DA9
    My OG DA9, Wrecked, Stripped, R.I.P

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    • #3
      ok thanks Colin. I was afraid of that, the ELD is a head-scratcher. I'll have to double-check which ECU, but it was the one that came stock with the 92 b18a1 LS. I pulled the engine and ECU from the same car, and it wasn't throwing CELs. Only thing I can think of is putting these in the 90 GS is causing the issue because it doesn't have an ELD?

      Also, the TPS is a bummer, I just installed a used one a buddy gave me, haven't calibrated it yet. Will test it according to the manual. Expensive little bugger.

      May also just swap out the Coolant Sending Unit for a new "ImportDirect" unit from O'Really's for $16 hopefully not a waste of $

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      • #4
        Just to clarify though, the honda-tech link pretty much says our Integras stock don't have ELDs, so it would be normal and nothing to worry about to get CEL 20 with a post-1993 ECU in a pre-93 Teg? If my ECU is pre 93 though like I'm thinking, then CEL 20 shouldn't even happen because that ECU wasn't expecting an ELD. ?

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        • #5
          Originally posted by sloppysleeper View Post
          ok thanks Colin. I was afraid of that, the ELD is a head-scratcher. I'll have to double-check which ECU, but it was the one that came stock with the 92 b18a1 LS. I pulled the engine and ECU from the same car, and it wasn't throwing CELs. Only thing I can think of is putting these in the 90 GS is causing the issue because it doesn't have an ELD?

          Also, the TPS is a bummer, I just installed a used one a buddy gave me, haven't calibrated it yet. Will test it according to the manual. Expensive little bugger.

          May also just swap out the Coolant Sending Unit for a new "ImportDirect" unit from O'Really's for $16 hopefully not a waste of $

          Just to clarify though, the honda-tech link pretty much says our Integras stock don't have ELDs, so it would be normal and nothing to worry about to get CEL 20 with a post-1993 ECU in a pre-93 Teg? If my ECU is pre 93 though like I'm thinking, then CEL 20 shouldn't even happen because that ECU wasn't expecting an ELD. ?
          As mentioned I'm not too familiar with the ELD so I'm likely not much help. I want to say that there was a difference between 90 and 91-93 but I could be mistaken. And obviously you can't take that post at 100% truth (like anything on the internet). I only have a 92-93 manual otherwise I'd be able to look up some of that info. Check the manual for your 90. If you pulled the ecu and engine from the same car and it was all stock then I'd suspect it's a 90 vs 91-93 difference or it could just be a wiring problem. Again, I'd check all ECU/Sensor wires before doing anything else otherwise you may end up chasing your tail.

          I don't see a new ECT sending unit fixing anything. You said that it reads incorrectly whether it's unplugged or plugged in. I can't see why it would read incorrectly when disconnected - how would a bad ECT sending unit send the wrong signal when disconnected? That leads me to believe it could be a wiring problem.

          In terms of the TPS - you should have mentioned it wasn't calibrated previously. That right there could be causing that code. I'd calibrate it after checking all of the wiring and then move on to the ECT sending unit issue assuming the wiring is good and the TPS calibration fixes the code 7.

          Track Project DB2 #896
          LeMons Project DA9
          My OG DA9, Wrecked, Stripped, R.I.P

          Comment


          • #6
            Went and checked the ECU, it's a 37820-P75-A01, looks like it was in "1994-1995 non-vtec Integra"?

            https://www.oemacuraparts.com/oem-pa...ne-37820p75a01

            Interestingly, the ECU had the fluorescent marker writing on it they use at wrecking yards, and I'm not the first owner of that car so guessing this is a replacement ECU not the original. Also Colin think you're right about there being a difference between 90 and 91-93 with the ELD. I see nothing about an ELD in the 1990 shop manual, but I have 90-91 vs 92-93 schematics in my other manual so gonna check those also. From the honda-tech link sounds like my only choices for extinguishing the CEL might be grabbing a used ELD from a wrecker and wiring it up (under the fuse panel?) or chipping the ECU and turning off the ELD check. This is looking like a chassis version issue (90 vs 92), I doubt it's wiring because I don't have weird electrical issues yet (relays flipping, etc,..) but you never know. Also I'm lazy to do full elec inspection.

            With the ECT, the gauge seems to work correctly. If I unplug the sender, temperature goes all the way down to Cold. Unfortunately my multimeter is too finicky to reliably tell the difference between 100 and 400 Ohms so I can't tell if the sender is defective. I am yet to try the test where you very quickly ground the wire to the gauge to see if the needle goes up to Full Hot (manual says you're supposed to stop grounding before it does to avoid damaging the gauge).

            Ahhh,... and I thought was gonna smog and sell this Bad Boy.


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            • #7
              Sounds like you're on the right track. And I think I misunderstood what the temp gauge was doing, now it does sound less likely to be a wiring problem and more likely to do with the sending unit.
              Track Project DB2 #896
              LeMons Project DA9
              My OG DA9, Wrecked, Stripped, R.I.P

              Comment


              • #8
                Yes I just replaced the ECT sender this morning and voila! Reads Cool when it's cool then seems to warm up normally. Did reach Super Hot idling again today though, but I had the exhaust mani heat shield off. I hope that was it? Main part that bothered me was the rad fan did not turn on this time

                Colin you were right about calibrating the TPS,.. supposed to read about 0.5 volts throttle fully-closed, was reading about 0.2v probably explains immediate CEL upon starting to idle. Calibrated it, now no CEL!!


                In fact, the ELD does not seem to be considered a show-stopper by the ECU or I dunno why, but no CEL at all. I think I've read if you jump the service connector though, the CEL will still be displayed as it is being stored.

                Next steps -- make sure it's not going to overheat, figure out where the smoking oil leak is when it gets hot (hoping just valve cover), and pass the stooopide Arizona "Rebuilt Title" inspection which is $50 hehe. Well better than hauling it to the wrecker, and then I can finally smog & sell.

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                • #9
                  The exhaust manifold heat shield shouldn't have any significant effect on engine coolant temp unless there's something else funky going on here. Looks like it's time to check your fan switch and relays.
                  Track Project DB2 #896
                  LeMons Project DA9
                  My OG DA9, Wrecked, Stripped, R.I.P

                  Comment


                  • #10
                    Back to an old post after several months in a Land Far, Far Away.. I am now in AZ and had a chance to try and get Old Betsy running again to be ready to be sold @ market to the 1st competent bidder. She Runs Good(tm) but Hot :'(

                    Replaced the thermostat and radiator cap but still no dice. My remaining guesses include:
                    1. the stock muffler is backed-up and giving the motor more work to-do than necessary
                    2. the O'Reilly coolant-temp sending unit is a Chi-Comm piece of Sh*t and was reporting the wrong temp since day juan
                    3. Colin is Right (tm) about the fans not turning on/off @ the right time (although I thought I heard them flip on&off)
                    4. the 2-year-old coolant is useless
                    5. water pump is MIA, time to do a T-Belt-Jawb, sorry, Bud (tm)

                    Comment


                    • #11
                      In case anyone is still reading this thread, I will try to keep the smilies under control...

                      Still trying to cool this Teggy down. Today poked around the radiator fan with a manual, and found that it doesn't seem to be going on & off right. Looked underneath the car and could not find the engine coolant temp switch which is supposed to screw in to the head on the intake side. Decided to just quickly wire-up a switch I ran into the cabin to turn the fan on & off manually for S&G's. Thought for sure if I manually ran that fan, the engine would run cool. No Dice. Driving around for 10 minutes I pulled over 3 or 4 times and had to turn the engine off and let the fan run because it seemed to be running so damn hot (needle almost all the way to "H" but not quite in the red). It also seems to warm up super quick after starting compared to my other Teg.

                      Water pump?

                      Plugged-up muffler?

                      Bad radiator?

                      The only thing that's changed since last time that engine was running fine is the exhaust, I grabbed a cheap rusty Teg muffler (with accompanying pipes and tips) from a Pick and Pull and just slapped it on. Gonna try running without the muffler and see if that changes anything, preferably next to a library at 3am.

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                      • #12
                        Heater started blowing cool instead of hot. Don't feel nuthin' flowing through the upper hose or see flow in the radiator even though it's hot. Don't see any milkshake in the oil or coolant. Must be the water pump. Sold it to the highest bidder, gonna focus on my other Teg, let the lucky buyer figure it out -- hey no guilt, full disclosure on the car's issue. Thanks for everyone's help especially in the last month..

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