obd2 link error/misfire

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Sep 26, 2020 | 07:33 PM

nachahmer

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obd2 link error/misfire

Ok, so I have a 00 civic, completely stock. Took out engine and trans to rebuild seals. Ran tip top before. obd2 read fine. After putting everything back together I now have a misfire mainly at idle, and can’t get obd2 to read codes.

here’s what I’ve done
-checked all fuses. 0 blown
-obd2 has power
-timing is set and checked twice
-spark plugs gapped correctly
-new wires new plugs new cap and button
-distributor is in time

im at a loss. I can’t wrap my head around it.

Sep 27, 2020 | 04:52 AM

nachahmer

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Re: obd2 link error/misfire

Bump. Anyone?

Sep 27, 2020 | 06:03 AM

muellersfan

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Re: obd2 link error/misfire

Can you read CEL codes by jumping the 2P service connector above the ECU?

Sep 27, 2020 | 08:43 AM

nachahmer

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Re: obd2 link error/misfire

Quote:

Originally Posted by muellersfan

Can you read CEL codes by jumping the 2P service connector above the ECU?

I have done this, I’m getting 1 short flash, pause 6 long flashes, 5 short flashes, repeat. Which if I deciphered correctly comes back to O2 sensors. Unplugged them car runs a little smoother, but still misfire.

earlier in the day I got misfire codes on 1 and 2, took spark plugs out checked gap and put back in reset ECU and they haven’t come back.

Sep 27, 2020 | 09:03 AM

muellersfan

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Re: obd2 link error/misfire

The hood fuse for the data link connector may be blown. Locate and test it.

Ohm test the coil.

Is the engine idle set correctly?

Sep 27, 2020 | 09:13 AM

nachahmer

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Re: obd2 link error/misfire

Quote:

Originally Posted by muellersfan

The hood fuse for the data link connector may be blown. Locate and test it.

Ohm test the coil.

Is the engine idle set correctly?

I did check the fuse it’s good, also just for giggles looked at every fuse in the vehicle they are all good.

Im on my way to check the ohms now.

How would I know if the engine idle is correct?

Sep 27, 2020 | 09:19 AM

muellersfan

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Re: obd2 link error/misfire

Quote:

Originally Posted by nachahmer

I did check the fuse it’s good, also just for giggles looked at every fuse in the vehicle they are all good.

Does the installed DLC fuse show battery voltage on both test tabs?

Quote:

Im on my way to check the ohms now.

Read the Ohms on your multimeter while touching the two probes together. Subtract the reading from the reading you get on the primary coil winding.

Quote:

How would I know if the engine idle is correct?

What Civic engine do you have? Use an external tachometer or code reader to read the rpms of the fully warmed up idling engine. Post the rpm reading.

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Sep 27, 2020 | 09:44 AM

nachahmer

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Re: obd2 link error/misfire

Quote:

Originally Posted by muellersfan

Does the installed DLC fuse show battery voltage on both test tabs?

Yes tested with a test light on both sides.

Read the Ohms on your multimeter while touching the two probes together. Subtract the reading from the reading you get on the primary coil winding.

Ok, I am on my way to the vehicle I should be there in about 45 min.

What Civic engine do you have? Use an external tachometer or code reader to read the rpms of the fully warmed up idling engine. Post the rpm reading.

d16y7

I will do this also.

Sep 28, 2020 | 06:36 AM

muellersfan

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Re: obd2 link error/misfire

Quote:

Originally Posted by nachahmer

Yes tested with a test light on both sides.

Did you verify that your code reader works in a different car? If so, use your multimeter to check whether (1) DLC pin 8 gets battery voltage and (2) DLC pins 12 and 13 have continuity to body ground.

Sep 28, 2020 | 06:42 AM

#10

tony_2018

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Re: obd2 link error/misfire

Anything you want to say about the ecu?

Sep 28, 2020 | 07:07 AM

#11

muellersfan

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Re: obd2 link error/misfire

Quote:

Originally Posted by tony_2018

Anything you want to say about the ecu?

Quote:

Ok, so I have a 00 civic, completely stock. Took out engine and trans to rebuild seals. Ran tip top before. obd2 read fine.

Sep 28, 2020 | 03:24 PM

#12

nachahmer

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Re: obd2 link error/misfire

Ok so update. The misfire was caused by a simple mistake. When I rebuilt the seals I tossed the old air filter and forgot to put in a new one. Caused the air to fuel ratio to go whacky I guess. Not sure what caused o2 sensors to trip, but they seem to be in working order now.

Reset ECU again, drove around 75 miles no CEL no codes. But still no OBD2 functionality. Will be taking the multimeter to it tomorrow afternoon.

Sep 28, 2020 | 03:29 PM

#13

nachahmer

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Re: obd2 link error/misfire

Quote:

Originally Posted by muellersfan

Yes tried multiple scanners that work in other vehicles. (3 different brands) I will be doing multimeter test tomorrow. Thanks for all the help! Will update with any finds.

Sep 29, 2020 | 01:45 PM

#14

nachahmer

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Re: obd2 link error/misfire

Quote:

Originally Posted by muellersfan

ok update, I am getting 12 volts on pin 8, continuity is reading 0.00 on both 12 & 13

Sep 29, 2020 | 01:51 PM

#15

muellersfan

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Re: obd2 link error/misfire

Quote:

Originally Posted by nachahmer

ok update, I am getting 12 volts on pin 8, continuity is reading 0.00 on both 12 & 13

The next step is to test the data line at pin 15. The wire at pin 15 runs to ECU pin A21. Check the Blu/Yel wire for a lack of continuity and for a short to ground.

Sep 29, 2020 | 02:08 PM

#16

nachahmer

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Re: obd2 link error/misfire

Quote:

Originally Posted by muellersfan

The next step is to test the data line at pin 15. The wire at pin 15 runs to ECU pin A21. Check the Blu/Yel wire for a lack of continuity and for a short to ground.

ok pin 15 reads 0.00 when black wire is ran to it and red wire is ran to a ground. But read 3 volts when the red is touching the pin and ran to a ground.

Sep 29, 2020 | 03:16 PM

#17

muellersfan

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Re: obd2 link error/misfire

Quote:

Originally Posted by nachahmer

ok pin 15 reads 0.00 when black wire is ran to it and red wire is ran to a ground.

You may have a short to ground on the Blu/Yel wire.

Unplug ECU connector A and repeat the short to ground test on ECU connector pin A21 with key OFF. Do you still get a continuity to body ground reading on pin A21?

Sep 29, 2020 | 04:50 PM

#18

tony_2018

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Re: obd2 link error/misfire

Quote:

Originally Posted by muellersfan

Then I would check the wires behind the DLC, or look directly at the DLC and check to see if there are any burnt marks.

Sep 29, 2020 | 04:59 PM

#19

nachahmer

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Re: obd2 link error/misfire

Quote:

Originally Posted by muellersfan

A21 reads at 147.2 ohms. Does this indicate a short?

Sep 29, 2020 | 05:18 PM

#20

nachahmer

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Re: obd2 link error/misfire

Quote:

Originally Posted by muellersfan

update, the reading may be incorrect I’m just getting OL now.

Sep 29, 2020 | 05:28 PM

#21

nachahmer

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Re: obd2 link error/misfire

Quote:

Originally Posted by tony_2018

Then I would check the wires behind the DLC, or look directly at the DLC and check to see if there are any burnt marks.

nothing visible out of the ordinary

Sep 29, 2020 | 05:43 PM

#22

muellersfan

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Re: obd2 link error/misfire

Quote:

Originally Posted by nachahmer

update, the reading may be incorrect I’m just getting OL now.

Did you test the Blu/Yel wire for continuity between DLC pin 15 and ECU pin A21?

If the Blu/Yel wire is fine, then the ECU would be the prime suspect.

Sep 29, 2020 | 06:05 PM

#23

nachahmer

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Re: obd2 link error/misfire

Quote:

Originally Posted by muellersfan

Did you test the Blu/Yel wire for continuity between DLC pin 15 and ECU pin A21?

If the Blu/Yel wire is fine, then the ECU would be the prime suspect.

Sorry a bit confused are you saying put one end of the meter on DLC Pin 15 and the other end at A21?

Sep 29, 2020 | 06:32 PM

#24

muellersfan

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Re: obd2 link error/misfire

Quote:

Originally Posted by nachahmer

Sorry a bit confused are you saying put one end of the meter on DLC Pin 15 and the other end at A21?

That's one way to do it.

Sep 30, 2020 | 10:51 AM

#25

nachahmer

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Re: obd2 link error/misfire

Quote:

Originally Posted by muellersfan

That's one way to do it.

ok with multimeter set to ohms key off black wire ran to pin 15 from multimeter red wire ran to a21 from multimeter it reads 30.0 with the ECU plugged in. Read OL with unplugged.

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