Question About A Slightly Ailing 3100.............

[AMcLeodIII]

Greetings. I'm a noob to 60 degree v6 but not a noob to engines in general. My name is Archie and I just joined the forum tonight. Definitely going to get around to a more proper intro but I need to post this tonight as I plan to work on this tomorrow and drive it out of town the next day........that's the plan.

A brief history........

I've got a 96 Oldsmobile Achieva that purchased in 07 from a church member who brought the car brand new. In 2007, this 3100 suffered (as most have) LIM/headgasket failure. I really think it was more LIM failure but since my mechanic friend is also the transportation dept. supervisor for the school system I work for (can you say BIG YELLOW BUS and FLEET CARS which are mostly 3100 equipped Malibus), he was really familiar with this specific repair. 900 dollars later, he had it running like new.

My daughter went to college in 08 so it began a new life as her daily driver. She did pretty good with it....no major problems.

Segue to 2013. After graduating and working for a year, she decided to leave the fold (we only own GM cars) and bought an 04 Mustang Pony v6. Well wouldn't you know it, the Achieva returned to dad and behold the day before she picked up the Mustang, something went amiss internally on the trusty Acheiva. An awful, loud tapping sound that sounded like the whole block was tapping. Awful miss. Car was actually still drivable...I drove it a few days like it was, anticipating getting a new engine. One day (we're still on summer break here) feeling like I had nothing to loose, I tried to see if i could isolate the tapping. It was slow and countable usually indicating a valve/lifter issue. Opened up the oil cap and looked inside with flashlight and voila', intake valve on 2nd cylinder not moving at all!!!! Pulled the valve cover and found a broken rocker arm on the intake valve. Hmmmmmm.........went to an area machine shop, owner is a friend. Told him I was gonna' try and fix this one myself. He went to a box in the corner of his shop and found four used rocker arm and gave them to me. No charge!!
Go home, install one of the rocker arms and a pushrod, buttoned up everything. (I was lucky and did not have to remove the intake to do this repair !!) Car running perfect in less than 2 hours. Happy Days. Didn't run that good after the 900.00 repair in 07.

Yesterday. After driving the car around locally for most of the day Wednesday, I put it on the highway to the next major town from me about a 45 minute drive on Hwy 95. Car ran like new all the way to Rocky Mount, NC, Got off on an exit road and the car lost power. Wouldn't accelerate and developed a major stumble. I looked out the window and low and behold, there is a massive plume of thick smoke bellowing from the exhaust. I thinking to myself, "this thing did not just blow another gasket set!!!" (back in 07, we replaced the GM crap gaskets with the improved Felpro set converted to good old fashion polyethelene glycol "green" coolant.) Coaxed the car into the parking lot of a Goodwill Store and shut it of. Let it cool off for a minute or two and started to check the obvious things. Coolant level was fine. No noticeable water/coolant in oil. Oil was pretty clean. Fired the car back up and the engine is pluming a thick bluish smoke that smells pretty much like raw fuel. The car ran miserably for about 15 minutes then clears itself completely. Engine is back to running like normal. On the way back home, it did replicate the problem one other time but hasn't done it since then. Help (and some observations)

While working on the engine, I did remove the throttle body and breather assemblies. (Unplugged the two sensors on the airbox and the two connectors on the TB. The loss of power and seemingly rich fuel condition has me thinking something happened in the diss-assembly of Throttle Body. (I didn't replace the TB gasket) OR..........

.....is it possible that it's a computer issue as there was a check engine light on and it flashed off and on when I was driving before the repair running on 5 cylinders. Is it possible that the computer set a trouble code that I did not clear after the repair? I realize this was kinda' long but I hope that maybe this might help troubleshooting for someone else with a 3100 motor or help me track something really obvious. I'm a teacher and the economy won't support me throwing a lot of money at the car. HELP!!!

BTW, I only paid $250.00 for the car from the previous owner. She was told that the motor was toast by a trusty GM dealer who was "willing" to take the damaged car in trade for an 06 Impala

[robertisaar]

kind of sounds like the ignition is failing. coils would be a pretty common cause. ICM too. i would definitely change the plugs after that event in any case, and since you're that far in, plug wires as well.

[fat rabbit]

"the engine is pluming a thick bluish smoke"

Bluish smoke from the tail pipe generally means your burning oil. As for the ECM, it'll flash on and off when the engine gets random multiple miss fires that can damage the catalytic converter. It doesn't seem like GM cares if your engine blows up as long as it happened emitting the least amount of emissions possible and not damaging the cat.

[AMcLeodIII]

"the engine is pluming a thick bluish smoke"

Bluish smoke from the tail pipe generally means your burning oil. As for the ECM, it'll flash on and off when the engine gets random multiple miss fires that can damage the catalytic converter. It doesn't seem like GM cares if your engine blows up as long as it happened emitting the least amount of emissions possible and not damaging the cat.

Blue it was (and it looked a whole lot like Jimmy Johnson"s blow up last week at Michigan) yet it smelled like a combination of raw fuel and pellet type cat converter on cars from the late 70's-early 80's when the cat was going bad. Oddly enough, it hasn't done it since and when it did do it, the motor felt as though it lost all power. Pressing the accelerator to the floor actually caused it to clear and return to normal operation. Further, I had noticed that as I was working on the engine, replacing the broken rocker arm, I replaced all the bypass hoses to the throttle body, actually removed the throttle body, gave it a good cleaning. Noticed some oil residue in the throttle body and also in the EGR housing. I even pulled the air box assembly, replaced the filter and cleaned the mesh in the maf sensor (it's 3 am here and I think I'm calling it the right thing) It was after all this that the problem started. Also if i remember correctly, you could hear the engine actually change it's note running idle with the with the broken rocker as if the timing was changing back and forth. (from rough to smooth running; still missing but smoother) I've reset the codes/ecm and as i've said, the problem has not replicated itself. Just got back in from a 3 hour drive to DC and back and the car ran flawlessly. I AM FRUSTRATED AND PUZZLED CAUSE I CAN'T FIGURE OUT WHAT CAUSE THE INCIDENT IN THE FIRST PLACE!!!! I PERSONALLY LONG FOR THE 70'S THROUGH EARLY EIGHTIES! Inline 250 sixes with 2 barrel carbs, (or small block Chevy V8's) with lots of torque........ systems that made logical sense (even those aggrevating dual point ignition systems like the one I had in an LT1 equipped Camaro back in the day) and those engines liked running the ragged, highly imperfect edge. Ahh, frosty white exhaust tips at hi rpm and 108 octane fuels.......used to call that stuff "Hi-Test" Those were the days.

[trotterlg]

Wonder if one of your injectors is sticking full open. That would put a lot of raw gas into the system, and would also explain why wide open throttel would hlep clear it out. I would pull the plugs, look for the black one and change out that injector. Larry

[AMcLeodIII]

Wonder if one of your injectors is sticking full open. That would put a lot of raw gas into the system, and would also explain why wide open throttel would hlep clear it out. I would pull the plugs, look for the black one and change out that injector. Larry

Larry, I seriously contemplated exactly what you just suggested but not being as knowledgeable at testing modern tech engines, I wasn't sure if that made sense. (Had several "mechanics" attempt to tell me that wasn't possible.) This 3100 does have 220,000 miles on it I'm certain that the original owner ever had that checked before. Those of us senior hot rodders can surely remember faulty Q-Jets or big bore Holleys with stuck floats and secondaries flooding the cylinders.........blowing a bluish-black smoke out of the exhaust.

[trotterlg]

The injectors are either on or off, how long they are on makes how much fuel is delivered. If one is stuck on, it delivers lots and lots of fuel, but only to one cylinder, so it floods out badly and dumps a lot of raw fuel right out the exhaust. I would check for sure. P.S. if you like Q jets you will like my 3100. http://www.youtube.com/watch?v=ES4mJ...ature=youtu.be Larry