dyeager535

Just want to make sure what I've found is right. Hopefully someone can tell me I'm wrong or right here.

I've got an '87 '165 ABWB (305 w/t-5) hooked up to a non-cold start TPI setup. Guess that makes it '88 or '89, correct?

Anyways, I finally finished the new 355 and dropped TPI on top of it.

Lots of problems, but have ruled out things like vacuum leaks, etc.

Mainly, throwing a code 33 2-5 seconds after startup. Went through the troubleshooting manual. Told me there was a broken wire on one of the circuits, there wasn't. (checked continuity)

Trickster was nice enough to post this


in another thread regarding code 34. (MAF low) Although thats the 2.8, it's similar enough in the area where I think I've found my problem. (I used the '88 manual for V8 in my diagnosis though so there is no confusion)

In the above diagram, ckt 528 is the one I'm dealing with. V8 is the same, 5V reference.

Here is what I tried:

Cleared code (verified all steps with autoxray so as not to get false codes)

Disconnected MAF.

Started engine. Code 33 pops up as usual.

Turn engine off. Swap relay between burnoff/MAF.

Clear code.

Start engine. Code 33.

Clear code.

De-pin ckt 528 (in above diagram, different on V8 I believe, dk green wire) from ECM connector, test continuity between it and the MAF connector. Continuity, and no short to ground. Wire is good.

De-pin ckt 528 from ECM connector, and CAREFULLY (pulled ECM fuse before starting this) hooked
the connector back up to the correct pin on the ECM. made sure it wasn't touching any other pins before re-inserting fuse.

Turn key to run, check voltage on that pin. Nothing.

Re-pin connector, re-connect, reinstall in ECM. Stick probe into back, and wiggle wire/connector to see if I can get voltage from bad connection. Nothing.

So....the manual says faulty ECM or wire, but with no voltage on that pin, and continuity in the wire, I have to say ECM. I hate blaming the ECM, too often blamed, too rarely the cause, but this one (was sent to me) had some case damage from shipping, but it appeared to have not touched the board..but was obviously hit pretty hard.

Anyone think that maybe I am missing something, or think I did a fairly thorough job? and should be fairly certain of my theory?

If anyone wants to browse my datalog from winALDL, it's here:
aldl log

I thought MAF seemed to be working correctly, it seems to vary with engine demand, but I'm not really up on reading the chart yet.

Thanks for any help, encouragement, ideas, negativity, whatever.

Trickster

Here is the code 33 chart for the TPI setup and as you can see there is a big difference between the two. Hope this helps and let me know if you need the one for code 34.

Trickster

page 2

dyeager535

#4 on that first page.

As a matter of fact, on the flow chart too.

Isn't ckt 998 supposed to have 5V to it with key on, engine off?

Regardless of everything else that comes before in the chart and in the wiring schematic, isn't one constant the 5V on ckt 998 if the MAF is disconnected? I don't see anything in that chart that indicates something has to happen other than the key being on for that 5V reference signal. Am I interpreting the manual wrong?

The first time I went through the flow chart, where it says test light, I used the voltmeter. Is there some reason they use a test light in certain parts of that chart, and voltmeter in others? If there is a reason a voltmeter won't work for those tests, thats where I went wrong originally.

Trickster

There should be between 4 - 6 volts on that circuit with the key on engine off. The reason they say to use a test light in some area's and a volt meter in others is this. In some of the tests they are just checking to make sure there is voltage present. In other parts of the test, they are looking for a specific voltage to be present. If you can use a voltage meter to determine that voltage is present in these tests that is fine and won't be a problem. It is just the way the manual is written for the mechanics.

dyeager535

If theres one thing I've learned, it's to listen to what others suggest, so I'm going to back and follow the flow chart again. Really not looking forward to it, but the chance always exists that I missed a step or just didn't have a good connection to ground when looking for voltage, etc.

Thanks for your assistance, I will go back out and try again.

dyeager535

Well, turns out I must NOT have had a good ground when testing. Now that my understanding of the MAF setup is better, with it disconnected, the code 33 should be normal.

Chart lead me to bad MAF this time, so I'm on the hunt for one of the Wells units. Not many places around here carry Wells, but at $60, (compared to $160 for cardone locally) I'm willing to work on finding one. Still need to buy one locally so I can return it if for some reason diagnosis was wrong and it's not the cause of the 33, but I will be sure to follow up whether it solves the problem or not.

Trickster

Here is a suggestion that you could also try. Get a can of electrical contact cleaner and spray the inside of the MAF sensor. They sometimes get dirty from the air being sucked through them and sometimes give a false code.

dyeager535

I have a feeling this was all because of an oversight on my part.

Needed to use a section of tubing from a Volvo to hook the air cleaner to the MAF. Turbo Volvo, there was oil in the ducting, and with the ridges, no way to get it out.

When I pulled the MAF the other day, I noticed oil on the bend in the tubing BEHIND the MAF. "Whats that from?" was my dumb question.

I popped the screen off the MAF, and it appears there is oil (or something) caked onto the wire in MAF, as well as the thin blade up front.

Used some rubbing alcohol on a q-tip (very gently) and tried cleaning it up. Definitely a lot of junk came off on the q-tip, but there still seem to be "bumps" on the wire from foreign matter, and the code is still there. Cleared codes, went for drive with MAF disconnected, got both 33 and 36(? Burnoff Relay code if thats not the right number) do I believe that is another indication that the wiring itself isn't suspect, still a MAF problem.

I believe it was pretty banged up in shipment, so no clue what really caused it to not work, but we'll see.

Amazingly enough, guy at an Autozone (quite a ways unfortunately) suggested cleaning the MAF instead of outright replacement as well. Thanks for the tip, it hadn't occurred to me on my own to spend time actually making sure it was clean...wish it would have been the answer though!

Trickster

Your code 36 was set because the MAF Sensor was disconnected during your drive, that is all. There is not a problem with the MAF burn-off relay.

dyeager535

Yeah don't know why I wrote what I wrote...I meant that disconnecting ithe MAF completely seems to indicate that at least some of the other wiring associated with it works correctly, as it throws codes like it should.

In other words, when it's hooked up, the other components work correctly.

dyeager535

Just to "close out" this thread, got my hands on a known good MAF, swapped it in, code gone, engine runs like a top.

Appreciate the assistance. Always pays to go back and double check your work, and your posting reminded me of that, and saved me more hassle and expense.

dyeager535

Talk about going back in time.

On top of my intermittent (becoming less intermittent now) no start issue, the code 33 came back yesterday. lol

This is probably going to be of help to very few people, but this is another "goes to show you" instances. This could apply to any electrical issue though. Thought I'd post it partially because I see code 33 issues coming up pretty often, and its general applicability to troubleshooting.

Followed the troubleshooting flow chart for the code 33, but I kept coming up with the ECM being bad. Checked continuity on the wire in question, etc., no voltage when it should have.

In a split second of intelligence, I decided that I needed to check the connection between the ECM and the wiring connector. There was nothing wrong with the wire, and if there was no voltage, it had to be the ECM, right? No.

Turns out, the metal tab that "locks" the pin into the connector had been broken in the past. Not all the way, the pin was still captured in the connector, BUT with the end of the tab gone, there was enough movement away from the ECM that once it vibrated back, it lost contact with the ECM pin.

Couldn't fix the pin (correct thing to do would have been to get another female pin from the wrecking yard that wasn't broken, and solder it in place, or at least get a new female pin and wire it up right, but not going to happen today!) so I wedged it in place with the connector lock until I can get the right piece.

Definitely one of those things that can come back to bite you in the future for not taking care of problems (both the broken tab and my "repair") the right way in the first place.

And a further edit: swapped out my injectors, took the vehicle for a drive, got a code 36. (MAF burnoff) Pulled the ECM fuse for aboiut 3 seconds, re-seated the MAF connector, problem gone.