Help deciphering CEL codes + Exhaust Issue

[Boddie]

So in the past I had barometric sensor issues (Only the shop could get this code... I never have), and just for fun I decided to through in a third MAF sensor that the seller assured me worked great. Anyways my issues are getting progressively worse. This car is my daily driver, and I am now to the point I just want it running.

Anyways... I followed the directions here and attempted to check the codes. I seem to be no good at deciphering the codes, so I recorded them.

They can be found at the link below:
1991 Plymouth Laser RS Turbo - YouTube

I think I get:
L-S-S-L
S-L-L-L-L
L-S-S-L
S-L-L-L-L
L-S-S-L
S-L-L-L-L
L-L-S-L
S-S-L-L-L
L-S-S-L
S-L-L-L-L

With lines 7, 8, 9 it looks like L-L-S-L-S-S-L-L-L-L-S-S-L (12 (MAF) and 42 (Fuel Pump)??)
...I know the car has some crazy wiring going on with the fuel pump through a relay and stuff. It was like that when I got the car. I am not sure if that has anything to do with it. I also noticed the lower honey combs were taken out of this new maf.

Here is a picture of the relay under the hood (red wire goes to battery, and blue goes back through harness or something):

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Here is the mess that is going on in the trunk:

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On this car there is no catalytic converter, and the muffler was replaced with a fart can as you can see in the video. He had a MBC on the car that is set to 15 PSI. It dropped to 7 for a long time and fixed it with a combination of getting the wastegate unstuck and fixing the boost leaks. Now it is back to where the previous owner had it.

In the last 10 seconds or so of the video I recorded black stuff that is coming out of my exhaust at an alarming rate. Any help on any of this would be great. I have thrown in an unbelievable amount of money now just to get this thing up to par...

UPDATE: Just swapped in the old MAF sensor just in case -> Disconnected the battery for about 15 minutes -> started the car and let it run for 10 minutes -> check engine light came on -> turned off and checked codes -> got the same above pretty much:

L-S-S-L
S-L-L-L-L
L-S-S-L
S-L-L-L-L
L-S-S-L
S-L-L-L-L
L-S-S-L
S-L-L-L-L

...the five long buzzes in a row really throw me off.

ANOTHER UPDATE: So I decided to check all the voltages at the ECU again. Here is what I got:

PIN 13 (Fuel pump) 13.57V cold, 12.49V idle (450-550 rpms?? seems low)
PIN 24 and 17 (Sensor ground) 0.45V AKA GND
PIN 10 (MAF) 2.8V at idle (No idea what this should be)
PIN 23 (MAF Power Supply) is at 5V exactly which is what it should be

I may try to set the BISS using this strategy in case that low idle is causing issues.

UPDATE: Got the BISS screw set properly. It idles at 750 RPMs when fully warmed up. After a short drive the black crap stopped coming out of the exhaust. I am going to run some seafoam through it tomorrow to see if that helps.

 

[Boddie]

Since that night the black out of the exhaust has not happened again, but the codes still remain an unresolved irritating issue...

 

[DSM1G90]

Dang, that poor Laser is all but effed up pretty bad with band-aid wiring going everywhere.

It's good that you made the buzzer trick.

L-S-S-L
S-L-L-L-L
L-S-S-L
S-L-L-L-L
L-S-S-L
S-L-L-L-L
L-S-S-L
S-L-L-L-L

LSS=12 MAF sensor
LS=11 O2 Sensor


Above using the best sequence of your code display. the "LLLL" has no code assigned to it.

EDIT: There is a code that uses the four "LLLL",but also has four "SSSS" to make it 44=ignition coil, ignition power transisitor unit.

There must be a short buzz added to the long buzz pulse to make a legit code.

These are the only two codes that makes sense in these above posted strings - if using the "L" at the beginning of the code.
Quite simple in what VFAQ presents in reading codes.

Codes always begin with the long buzz, then the short buzz

1st number is the number of long buzzes. short pause
2nd number is the number of short buzzes. short pause
Then, a long pause, and the buzzes begins all over again for the code.

If you have more that one code, there should be a long pause inbetween codes

Common one is the coolant temp sensor (code 21): two long buzzes, short pause, one short buzz, then long pause and then it repeats.

You need a long pause inbetween the set of swings since there is only a two digit number per incident and can tell you're including the pause in your count.

For starters, there is no beginning short buzz - always a long buzz - to begin the code outside of the first one that shows normal ECU operation where then you get a sequence of short buzzes then long pause, then the short buzzes repeats again.


Good luck - DSM

 

[Boddie]

The video is still up and after the first set is does a break and then starts with a short buzz.

Well thank you very much for your help, but it appears I just found my biggest culprit... The ecu definitely appears to have problems. It is a shame and a huge burden to, because I just got it back form ECMTuning two months ago to get new caps and be tested.

Obvious leak or very bad solder mess...

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Seem to have some solder issues underneath as well...

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I don't know if it is there fault or what, but I do not know if I should risk it and just do it myself. At least that way I will not have to wait...

 

[DSM1G90]

If you know how to do desoldering with either a vacuum or copper braid wick, it would be a good attempt to try to remove the excess that has obviously bled over to neighboring traces shorting out a good section of the momboard .. and hopefully, all of this shortage hasn't destroyed the momboard in itself.

The solder job on the bottom of the board looks like a cold soldering job (which causes resistance issues) which can be vacuumed or wicked up, then redone, but not let the solder get cooled too quickly.

But, get some acetone to scrub off any excess rosin residue off the momboard before doing the desoldering.

This is prob why you were blowing out black smoke on that one day. I had the same issue with my Laser and found some ground traces blown openon the momboard - why I had a CEL and numerous codes to read off the ECU.

The traces were blown due to the 5vdc jumping straight to ground from one of my sensors that gets the 5vdc to operate from the ECU. It was my fault since I still had motor running while fiddling with some sensors. Now, I learned that when fiddling with sensors, either have key OFF, or disconnect negative cable from the battery.

Good luck, once again - DSM

 

[Boddie]

Well it looks like it was sanded or something there like an attempt to fix a broke trace.

Well I made sure their sloppy job didn't jump over any traces. It appears everything in that spot where the solder is located is at an electrically equivalent spot. I redid the solder joints underneath to assure they are not cold solder joints. To no avail it still throws same codes...

All in total so far I changed all the piping out, changed blow off valve, boost leak tested after building homeade tester, changed gaskets, tried three different mafs, put in new spark plugs, new wires, rebuilt the throttle body, calibrated tps, calibrated BISS, tested the voltage from the lines to ecu, tested ecu voltage, had the ecu redone by ECMtuning, and to no avail more things keep going wrong and getting the same problems I got when first got the damn car. In neutral it will not rev past 4k rpms (Doing it for testing not for fun), whole car bogs down sometimes when driving, still throwing same code patterns. I have taken it to three local shops here and none of them could get it (although fortunately I still had to pay for labor costing overall over $800 in total for testing). I really do not have any faith that these issues can be resoled. I have seen no progress in the year I have owned the vehicle and put in literally thousands of dollars.

Anyways now that im done venting... I noticed two connectors that are not connected to anything. Anyone know what they are or where they go?

First comes out of the line for the MAF sensor:

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The next is on the driver side of the intake manifold by the spark plug wires:

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[DSM1G90]

Upper one looks like the connector for the stock Boost Controller. The lower one is for the AC compresor. They both can be forgotten.

Gonna throw a dumb one here: tried to switch out ECU's?

Find a MD128625 ECU - same as mine even though I'm a year older.

Wonder if ECMTuning did something to that ECU where some drivers are shorted out on the momboard (that's those long flat black units on the momboard that drives the sensors .. and these drivers can be toasted quite easily with very little excess current, esp if something gets shorted out to ground) since you're getting the same code results no matter what you do since you've 'condemned' everything else in the CEL string.

Good luck. DSM

 

[Boddie]

DSM1G90 Thank you for all your help so far! I just purchased a ECU and a logger from a member on this forum, so hopefully that will help these issues resolve. I will update when I get it put in and can do some testing.

 

[DSM1G90]

Always glad to help a fellow vehicle owner no matter what make of vehicle they own. You're welcome and always at your service as needed.

On these two possible codes that I posted previously: To eliminate the sensors themselves is to do the VOM tests of these two items.

Temp sensor gives out resistance information pertaining to water temp and the O2 sensor gives out voltage information. If you got the shop manuals on sensor testing, please follow these instructions to determine sensor functionality. At least, this will 'comdemn' this section of the equation where it could be the ECU at fault

 

[SrKegler]

Went thru similar problems with my laser. Found out my problem was the plug for the MAF. Cleaned up the connections and haven't had any problems since. Might be worth a try since nothing else has solved your problem.

 

[Boddie]

Just put the new ECU in. Right after I start it up, and it is suddenly idling at about 3k rpms and throws instant CEL... Kind of lost for words right now... Any ideas?

The guy from ECMTuning said "I don't think that the buzzer is working right. The pattern of beeps in
the video is nonsensical."

So I just went out there with a voltmeter instead of the buzzer and it gave a different code that made sense kind of. Consistently code 25. Which is what the shop got. Unfortunately the same code as the last three MAF sensors threw. I will try SrKegler's advice and clean the connectors.

Figured out the issue. The plug connecting to the ECU was not hugging the pins on the board close enough. Tightened and cleaned them and got everything to work. A voltmeter and logger really helped to troubleshoot this problem!

Thank you for the help!