Tn-signal at Engine control module
 

Have been trying to figure out the surging problem on the 320 for awhile now and finally built the code reader and found code 11 showing up. Tn-signal at ECM. OK,,, what is that and is it a repair or replace. Harness has not been replaced AFAIK.

Tn sig is not gotten with the code reader tool ..It is an emmisions DM code and gotten w/built-in LED/SW.

Where did you get the code from???

Got it with the code reader Arthur. No CE light has been on. Got eleven flashes on the Code Reader LED.

Oh..
Well , I guess what I mean is ...if you used the built-in led/sw , you will get the codes from the DM..which would be a TN signal for a code 11.
But......
My question stems from the fact that you said you has built the code reader tool and used that..if that is the case , the tool is to go to the other modules on the Box [ pins 8 or 14] and if that is what you have done , then a code 11 is not a TN sig code.
Just making sure you realize this so you are not going in the wrong direction.

Here are the codes that correspond to both the Tool you made and the built-in led/sw ones ..as you can see , that is why I ask where you got that code from..

http://www.peachparts.com/shopforum/showthread.php?t=107630

If you are already aware of this , please just disregard my post.

OK Arthur,, this is what I did,,,, got 11 flashes off the reader on pin 14, and just went out and checked pin 8 and got 13 flashes. The reader sure is pretty anyhow,,, the flashing lights impressed the crap out of my wife.

Yeah . Flashing Lights always work...I always wanted to build a whole wall of them that did nothing but amaze the observer.. a few wierd audios thrown in there too...


..anyway, as you can see , the tn sig would be a code from the DM module and not related to your problem Those DM codes are gotten from the built-in led [ N59 Emmissioms Module] and that is what brought my attention to your code/module error.

A code 13 on the HFM [ ecu] module means the 02 sensor is running at an upper rich limit, so I would look around for a vac leak ..might want to start at the front plastic vac line running across the front of engine. under the cover..they are notorious on 104s for breaking due to heat fatique.
The othe code from 14 means you have a CTP [ closed throttle position]sw that is not closing all the time ..I would look at the adjustment for this [ you want a little slack in the cable at idle] and I would lube the cable ...this is another common code/problem on 104 HFM/SFI systems ..

I would also go use the built-in reader just to see if any of that info has gotten back to the DM..it can have pending codes in there and not trigger a CE.

Thank you Arthur,,,, will check the areas you mentioned right after din-din.:D

I repaired the plastic vaccum line in the front of the engine a couple of weeks ago and rechecked it to make sure there are no leaks,,, it seems good. There seems to be enough slack on the throttle cable also. A couple of weeks ago I replaced the E-brake cable which required a lot of tearing apart of the console and lower dash,,, are there any vaccum lines inside the car I could have disturbed ? I am going to try to get the car on one of our lifts today and check under the car for lines loose or missing also. Dang thing is still surging pretty bad. Thanks for the help Arthur.

Have examined every vaccum line I can imagine and nothing to be found. I was thinking I could tackle this deal, but it's looking like it's time for the pros $$$$$$. :(

Take the vac hose off the fuel pressure regulator and see if there is any gas leaking out of the port..should be NONE.
If there is any evidence of gas in that line, change the regulator...
You also want to check codes in the DM. That is w/the built-in led/sw combo.

Sorry to be a pain Arthur,,, but where is the Fuel Pressure regulator ?:confused:

On the front of the fuel rail..round, saucer looking device ..thermostat area , a little back and higher...silver metal color

Thanks Arthur,,,, Now I know :dizzy2:

OK

Also, when you check it, hold your finger over that vac line and make sure there is vac there when running.
The regulator had a diaphragm in it and what happens is the dia. leaks and then the gas get sucked into the engine through that vac line, causing your erratic rpm behavior..[ unmetered a/f mixture.] fairly common and easy diyer check/fix.

pete,been reading your thread and had the same prob with customer car several months ago.it wound up being a separate computer/relay on the floor in front of pass feet.i had assumed that main f.i. computer operated the idle but not the case.i went to salvage yard and found the part and fixed the problem.[this client had gone to expense of changing out the electronic accelerator with no effect]

Good vaccum at the regulator Arthur and no gas whatsoever. No codes on the built in reader but code 13 appears on pin 8 with the code reader.

Dave,,,, How did you determine that was the problem.

<<but code 13 appears on pin 8 with the code reader.
>

OK
One more quick thing I would like you to do..

After you get the code 13, I want you to clear it, run the engine after clearing and then turn it off.. Now, go back to same pin [8]and you should get a Single Flash [ code 1] . meaning code is clear..after the single code, wait 2 sec., hold button 6 secs , turn off key for 10 secs on for 50 secs and restart..That will reset the Memory and base line of the HFM module
Take the car for a couple of drives and see what happens..
I still suspect a vac leak [ mat be purge valve] , but do this first, as it a simple thing to do.

with my retriever scanner[mb dedicated] i determined that the e.a. had two or three codes that i couldn't erase and when i tried to access the isc it said error no communication.at that point i dug up the etm and traced the wiring back to idle speed computer.i pulled off plug,opened case and bingo burned smell.went and found another for 150 in salvage yard.[i was lucky enough to have similar car in shop and tried that unit first and it worked]

Thank you David,,,, if Arthurs' solutions don't work I'll start sniffing around for a burnt module.

Did the reset thing when I got home. been driving the SL in this nice weather, and after getting it up to temp, the surge has dissappeared. I am reserving judgement until I get it out tomorrow in hot weather. It never surges when cold and the hotter it gets the worse the surging gets. Thanks for all the help so far.

OK

I doubt you have a ea module problem as mentioned b/c you have/had no communication codes stored...

OK Arthur,,, what in the heck did we do ? Have been driving the car in the heat today and so far,,, I'm knocking on wood here,,, NO surging or missing at all. Does this eliminate the vaccum leak, or has the engine recalibrated itself to compensate ? I mean this thing is running real smooth today. Thanks again.

Good

Either you fixed a leak or the ECU was border-line adapting.

Anyway , you are now running proper base line , BUT, you now have to watch to see if the adaptations start to creep up again..That will mean you still have a leak and if it is large enough, the adap will not be able to handle it.
The suspect I have would be a purge valve . You may want to take the lines off of it and squirt some WD40 in there..that will clean it and stop it from sticking.. I would do that regardless now. Just cuz they get crapped up .
Keep an eye on codes , even if you do not have a CE, as you may catch one before a bunch start coming up.. Just monitor it for a while..as you now have the tool.
Another thing I would do is get on the gas up a few hills , [dropping down to 3rd gear to keep the rpms up and so you don't get busted for speeding.]
That will clean up the 02 sensor a bit..
Lastly, I have had some luck with these new MAF sensors cleaners ..easy enough to do and can't hurt to give it a quick squirt [ CRC MAF cleaner]
The MAF is detrimental to all these a/f mix adaptations.........

Arthur,,,, Purge valve ? Sorry, but don't have a clue as to where to find it, but you will only have to tell me once,,, I take notes.

Left , inner fender well..says "MOT" on top
One larger vac line from engine manifold going into it, one coming out that goes to the emmissions canister.
It is fed a 12 PULSING sig when car is warm to get the gas fumes from the tank back into the engine for burning..if you place the valve in your hand, it will have a rapid beat to it [ closing/opening] about 6-7 htz.
It purges [ regenerates ]the fumes and does not do it in one gulp b/c if it did , it would effect fuel mix and give you your idle problems. So, a trick is to squirt the WD into the valve out port, let it sit for a while , and then run the engine ..that sucks the crap out of the valve and clears it up so it oscillates again..it is just an emmissions device , but when they stick open, they raise hell with the adaptations parameters of the a/f mixture.
So, I clean them , regardless , just cuz it is easy, cheap, known fault,... and doing so takes that possible out of the a/f mix equation.
Another test guys do when they have adaptation codes pop, is they just unplug the vac line to the purge and cap it..then run the car a few days and see if the adap gets back to norm..that verifies internal leak at purge..only problem w/that technique is you will bring on a purge code..but you know why, so you just clear it later..

Took the valve completely off the fenderwell Arthur and the inlet line was plugged with a ton of tiny carbon like particles that came out,,,, probably a teaspoon full. should I just get a new valve or do you think cleaning it will suffice ?

If you have it off, get some power to it [I think that is only 6v]. Put a hose on the inlet port and blow through it with a few psi while you rapidly on/off the power . That should clear it good and also tell you if it is open/closing as it should..you can even just blow through it w/lung pressure by mouth..give it the mouth job....

Gave it a good cleaning Arthur,,,, I'm beginning to feel real good about this.:D I am assumming that if the valve is bad or not working properly, it will throw a code ? On the built in reader or use your code reader ?

Purge can come back in the DM or pin 8 of HFM module.
It will come back as a purge code , but if it is causing MAF adaptations , it can come back as a rich/lean fuel trim code..so check both.

The car ran beautifully on the way home tonite and there were no codes on the built in reader,,,, code 13 on the 8 pin on your reader though. :eek:

Ok
That's an indication we have not solved it..
What we are looking for is unmetered air ..Here is another common possible. The cross over pipe from the MAF.. it should have good connections at the MAF, a little further up the line you will see an Air Temp sensor..make sure that is tight , and finally . [ and this is common] where the hose finally clamps to the intake there is a round clamp about 3" in diam..this has to be tight and you can only tighten it by sneeking in there with a long screwdriver from the front of the engine..try that..
You may also want to cap that purge and try a few trips w/o it.
Did you do the CRC MAF cleaning I mentioned..???

...and , check you do not have a dirty air filter.

Will clean the MAF today and check all the connections. Read Jim F's tutorial on cleaning the MAF,,,, pretty thorough piece.

Unlike the 400E, which is a thin wire, the MAF seems to be a little plate,,, looks clean but I got a can of the CRC MAF cleaner. The air filter is clean and all the connections are tight. I even took the short accordion hose out and inspected for cracks,,, none.

<<the MAF seems to be a little plate>>

Yes . You have HFM system..that stands Hot Film Mass. So ,this is not Hot Wire like the older LH systems.
But , that plate gets an oil/dirt film on it that effects the sensitivity and ablity to read air mass... more so than the hot wire ones do [ they burn it off]
Anyway, you know the deal..reset and drive it, watch for the change. Might also want to cap the vac line going into the purge for a few drive cycles at the same time ..that way , if all turns out OK , you can return to purge and if comes back then, you know the MOT is not closing .if that is the case, seeing that you have cleaned it, I would replace it..but not until you have verified where you are at.
An Indie/dealer would be looking at these adaptation numbers, but it can be done diyer this way, just takes some patience/time and monitoring.
Try and get that 02 sens cleaned up with the hill trip too..you know it is carboned up b/c of the past condition of a/f mix..you want that to be clean so it can work fast to help keep the trim in place..

Disconnected and plugged the purge valve, cleaned the MAF, beat it like a rented mule on the longest hill we have around here, brought it back and the surging is about as bad as it's been. I recently had a new EGR tube put on,,,, I wonder if the bolts for the intake have worked loose ? I'm going out to check.:confused:

Did yu clear te memory after cleaning the MAF and capping the purge..that has to be done just like before .