License2ILL

First of all Merry Xmas and happy New Year to all.

It's been another year my friends and I have yet to resolve this shake/shudder just off idle. After she rattles it picks up and just goes hard. But it still sucks.

This year tho I managed to hook up with a data cable, laptop, and TTS data software.

I'm getting code 26 and 44.

Which for awhile I thought I could ignore but have done some research on our CCP and it seems it could have a shudder effect.

I am going to hunt for an Evap purge solenoid which I know for a fact is bad on my motor. I thought that my PCM was bad and was not sending the signal but as I have been looking through my TTS data the PCM IS sending the signal so I don't want to replace it so much anymore.

As for code 44, I am going to pull the plugs on the driver's side and see if someone's not firing for some reason. Or if it's the O2 faulty.

I'm getting better at looking at the data file but I'm still a rookie, can you guys check it out for me?? And tell me your thoughts.

I've replaced a lot of things throughout the years from motor mounts to sensors, I guess I should be tired of the car and want to sell her but I don't, it's just this stupid relentless problem, but it only makes me more relentless towards fixing it, for the record I'm a good mechanic and this has been my biggest "defeat" but isn't official until I give up, so I'm still trying to turn into my biggest victory. 5 years man!!! I have to beat it.

The file is at a yahoo mail account ID: thefilecabin
password: cabin1

Guest47904

Assuming you're posting here for help, we don't know anything about the car. We know it's OBDI but we don't know if it's 93,94 or 95. We also don't know what tranny you have.

As far as your 44 code. That is a lean code. The PCM sees the O2 signal remains below 200mv in closed loop. When the DTC is trigged, the PCM goes into open loop. Looking for a plug not firing is the opposite of the problem. What you want to do is unplug the O2 and put a jumper from the tan/white wire to ground. With the engine warm, check the signal then for a level between .35 and .55 volts. If it's still low, either the other wire, purple/white wire is grounded or the PCM is faulty.

Your shudder problem we would like more info on like how many miles roughly have you put on the car since you discovered the problem (5years ago)? What if any mechanical problems have you eliminated like brakes, tranny, clutch/pressure plate/flywheel if any. etc..... Is there anything that makes the problem worse like temperature outside, temp of the engine, fuel level

License2ILL

woops sorry forgot there was no signature.

1993 M6, 150K now. Bought it at 85K, car came with the problem, was supposed to be fixed by now.

Clutch was replaced little after buying, cuz I thought the pilot bushing was missing but it was there, I swapped it anyway with a roller pilot, and a new lowend spec clutch, but the problem persisted.

O2 Sensor are like 1.5 year old.
MAp is new.
Alternator is new.
Throttle body is new.
TPS is new.
IAC is new.
ICM was replaced awhile ago.
Plugs, coil, and wires new.
I've gone threw 2 different opti's.
Fuel pump is new.
Injectors were swapped for a 96 model year with no difference.
PCMforless chip.
Motor mounts are new.

Wow writing this is not good, cuz in this format it spells IDIOT SELL IT. There might be more but I need to stop tho.

wrd1972

Does it shake or shimmy when reving the engine up with the clutch fully depressed?
Does it only shake when the clutch is between engaged and disengaged?
Does it shake any after the clutch is fully let out?

DrivinSidewayz

sounds like a tranny thats not totally tightened up to the bellhousing, or the bell housing to the motor... orrr a real sticky clutch with a slight mis off idle

License2ILL

Does it shake or shimmy when reving the engine up with the clutch fully depressed? NO
Does it only shake when the clutch is between engaged and disengaged?
Yes but not always.
Does it shake any after the clutch is fully let out?
The shuddering starts at the very last moment of you releasing the pedal then continues past that point, then the engine picks itself up and goes.
I'm guessing this all goes on in milliseconds if not a sec or 2.

ALL bolts are tight.
Yesterday I replaced the EVAP purge solenoid. And CODE 26 is gone my friends!!! Cost me 10 bucks.
And for the first time in a long long time, I drove around with no SES light.
Then it came back on while on the highway, then I stopped and started the car again, and NO SES the whole ride, parked again, NO SES still.
Went back out, NO SES 30 minutes later while on the highway it went back ON.
Parked again, then went back out NO SES, then at a light it came back on.
Got home, put er in DIAG mode, it gave CODE 44.
But it seems intermittent, I thought that was impossible? Once a code is thrown how can it go away on it's own?
This morning the same thing, it was not ON, and I did not clear it last night.
While driving to work on the highway it went back on.

LAst night tho at the light, I was watching closely, and specifically when coming out of the light and getting the shuddering, the voltage dropped and BAMM the SES light came on, so whatever was happening at that light during that launch, triggered CODE 44 which is what I pulled when I got home.

I'm thinking a stinking misfire that if it's not the plugs or wires, could be the damm distributor cap+rotor.
I'm watching closely and I want to see this repeat, I want to be at a light, shudder, and note the voltage, and see if the SES comes on at that precise moment. My thoughts are the shuddering is somehow related to Code 44. I think the voltage may be dropping cuz of the Code 44 and not the other way around, (you know the Alternator being bad and not giving proper voltage).
I'm at fix Code 44. And take it from there at this point. I might be able to get into her again this Saturday. What do you suggest?? and thoughts.

wrd1972

From what you are describing it does not sound like a mechanical issue which leaves either fuel or electrical.
If you have had two optis I dont see how it could be the cap and rotor.
I wonder if the ignition module can cause this, I had seeing you having to throw parts at it but it sounds like thats what it is going to take to fix it.
I hope someone has the answer!

License2ILL

Cap and rotor was re-used all times.
ICM was replaced awhiles back with same results.

wrd1972

I once had a RPM surging problem that was fixed with plug wires.
I guess its conceivable that the rotor and cap can cause this. I would try this to eliminate it.

Guest47904

O2 faults are like that. ON and OFF. Even quicker than the test I mentioned earlier, you can put a multi meter across the battery with the engine running and confirm the alternator is putting out by observing about 14 volts on the DC scale. If it's lower, the cause could be a few things and not necessarily the alternator.

That's not your problem cause a "brown out" will cause several random problems not to mention you would see it in the lights. Remember, letting the clutch out with engine speed low will pull the voltage low and cause a shudder at the same time.

If you bother to confirm the alternator voltage then take another 10 seconds and confirm the diodes in the alternator are ok. Change the multimeter to AC and check from the Neg terminal of the battery to the output post of the alternator. Confirm the reading is no higher than 0.03V AC. This is the only time you check it for AC.

After you confirm its ok, then try the test I mentioned earlier. If all that checks out, swap O2s reset and drive it. Remember, O2 faults take a while to register. If the problem follows the O2, it would then be a DTC 64.

There are very few causes for lean codes assuming the PCM is ok. The most likely is wiring. The next most likely is a bad O2 and you would see that if you swap them. The least likely reason is a clogged injector. If that were the case, you would have a cylinder causing a definate misfire you couldn't miss. This all assumes you do have a definate lean problem. This is what you would look for if you swap O2s and the problem (DTC44) remains. At that point, you would remove injector clips one at a time until you find the one that doesn't change the running condition of the engine.

Taken one step further. If you had a dead hole causing the engine to bog down more than usual when you go to take off from a light, maybe causing your shudder problem.

to recap:
DC voltage across the battery ----- 14 volts DC or higher
AC voltage batt to alternator -------0.03 volts AC max.
swap O2's -------------------------If DTC44 then pull injector clips or check the
wiring like I suggested before.
-----------------------------------If DTC 64 replace O2

License2ILL

Speedy that's awesome.
I'm gonna run through all of this on Sat. morning.

The only thing I'm doing slightly different is after checking the alternator,
I'm gonna just pull the injectors like you said to see which cylinder comes up suspicious and if one does im gonna pull the plug to look at it.

If they all don't show a misfire then I know that's not the problem. And will get under the car and swap the 02's and hope for DTC 64.
And at the same time remove and scrape up all the grounds on the engine while down there. Thanks bud.

License2ILL

DC voltage across the battery - 14.01 volts.
AC voltage batt to alternator - 30 hV is this right??
Swapped 02's -- CODE 64!!!

O2 sensor is bad. I'm going with AC Delco replacements this time rather than these Bosch's. Is stepping up to the later warmed O2's worth the hassle?? Just how much more work is it? 2 wires right?? We have to run an additional to each?

I pulled the injectors(the PCM signal) on the driver's side one by one. They all made the engine limp slightly the 2 rear cylinders gave the most, the first cylinder gave very minor limp tho. But slight enough to see.

I haven't driven her yet, but I don't think the O2's are going to resolve the shudder. But in the least the SES service light will be gone for good. Which is a big deal for me.

I checked a few grounds, but could not get to G103(above the starter-O2's ground) or the big battery one on the motor mount loose, both are on the passenger side.
I was able to get G102(under the ignition coil) and the smaller brother that leads to the chassis, I scrapped all the faces up real good with sand paper. Then bolted them back down.

shoebox

Try the Delco O2's. Boschs don't seem to be real dependable in the LT1 realm.

Guest47904

Once you get the O2 problem resolved, try taking off from a stand still at say 2K RPM's and try to not let the engine speed drop and see what that does. Then try it at say 1500 RPMs same way. Last, go down a little lower and try it one last time.

You may want to also try it at 2k rpms while it's cold and still in open loop before doing the above test at temperature for comparison.

License2ILL

Speedy will do, I have to order the heated O2's first.
So far tho the after having cleaned the bad O2 the SES light only comes on intermittently sometimes not at all and it still shudders altho a little less.
I'm going to replace the O2s either way cuz I keep wondering how it might be with AC delcos.

Unfortunately my beater Toyota is giving me problems and I have to get that car back on the road in order to try and get around to my "rebuild engine+M6".
It took me a week to find a carb rebuild kit for this Aisan 2 bbl carb, so im waiting for it to see if that puts that damm car back on the road it's had an idling problem for awhile and it finally just gave out.