Sick 3.8 G.M. No Power

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  #1  
Old 07-12-03, 03:44 PM
NHT44
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Sick 3.8 G.M. No Power

I have a 94 Buick 3.8, 180K miles ran perfect. Awhile back I experienced a drastic loss of power & #2 wasn't firing possibly #4 also. Compression is fine so no head gasket problem. Problem has consistently gotten worse. Harmonic balancer going bad so replaced that along with new CPS. Had technician pull codes and was told it was showing so many erroneous codes he felt it was the ECM. Changed ECM & still same problem. Installed known good ECM just on chance new one was bad still no change. Car has more (not near normal) power at times then suddenly loses power and will not accelerate over 2500 rpm which equates to about 35mph. I saw some of the codes but know they couldn't be correct as there are no such code #'s. 122, 173, 300 etc. Another strange occurance that has happened is that transmission started shifting prematurely and will not shift into O/D or passing. Sometimes if I shut the car off & restart then I can get enough power to get up to speed albeit very slowly and by shifting manually. You can actually feel the increase of power occasionally as if a plug just started firing a little. Have changed plugs and wires recently. Car is virtually undriveable in it's current condition. Any advise would greatly be appreciated!!
 
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  #2  
Old 07-12-03, 03:55 PM
darrell McCoy
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You could possibly have a couple injectors that are partially clogged. Have the fuel pressure checked to rule out fuel pump or any other fuel related problem.
 
  #3  
Old 07-12-03, 04:05 PM
Joe_F
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When's the last time this thing saw a tuneup?

Has the mass air flow sensor been checked? Go to Autozone and have them pull out the codes for you (they do it free). Post what you find here.
 
  #4  
Old 07-12-03, 04:13 PM
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Another thing to start looking at are the battery cables, and all ground wires/connections. Loose/corroded connections can make a car's computer go totally haywire.. Sounds like your tranny has gone into a "limp mode"..Again this could be related to the same problem...If you can, get a complete list of codes fromt he car..Even the one's "not listed"...
 
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Old 07-12-03, 06:36 PM
NHT44
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Darrell, I just recently had the fuel pump replaced.

Joe, I just changed the plugs and wires, TPS and crank sensor but was thinking in terms of the MAF as it appears that at some point prior to my acquiring this vehicle someone has tapped on it some, nicks and chips.

Msargent, I agree that the whole system is in limp mode and being as how the ECM controls the tranny too this would be a very good assumption. I will check the grounds tomorrow.

codes that I saw were 122, 123, 173 & 300 it read O2 low, throttle position high and engine misfire as if we didn't already know that.
 
  #6  
Old 07-12-03, 06:42 PM
NHT44
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I failed to mention that I have owned this vehicle for almost 3 years and 70,000 miles. Other than items I've mentioned previously, the only trouble with her has been water pump, alternator & Battery new tires and normal maintenance. For 180K it ran like new, no oil consumption, very good oil pressure, quiet smooth & very dependable. Even now with all her problems she still starts exceptional.
 
  #7  
Old 07-12-03, 10:02 PM
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for my own curiosity, how could a 94 (non obdII) car have a misfire code, i thought that wasn't started until 1996.

is the wiring harness possibly laying on or too close to the exhaust crossover pipe, that will cause all kinds of weird stuff to happen(one time i had 36 spark firing spikes on the oscilloscope caused by that on a similiar six cylinder)
 
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Old 07-12-03, 10:11 PM
richyd36
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3.8 gm no power

if it isnt firing on number 2 and 4 you might pull the coilpacks and control module off and take them to autozone or napa they can test these if its 2 and 4 its most likely the coil pack because i think these are on the same coil ive seen this several times or as they said you could have a couple of plugged injectors
 
  #9  
Old 07-13-03, 04:22 AM
NHT44
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mike in NJ, I don't know about the obd II thing. I know it's a 94 and there is a connector under dash they hooked to with a hot lead going out to aux bat connector. I thought 94 used the key and you counted the blinks on the light.

richyd36, the #2 & #4 are on different coils.
 
  #10  
Old 07-13-03, 04:36 AM
Joe_F
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NTH:

That method doesn't always work on 1994, it was a transition year.

Go to Autozone and have them scan the codes for free and tell us what they find. You need a scanner/code reader to do it.
 
  #11  
Old 07-14-03, 12:29 PM
NHT44
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Had Auto Zone pull codes today. Wouldn't work at first but then the counter person said he got it working. Here are the results as were told to me.

O2 sensor
Throttle position sensor
MAP sensor
Idle Air Flow ?? Idle Air something

He said there were 2 other codes that he couldn't determine. When he attempted to scan the codes a second time he couldn't get it to work.

Those are what they told me. Hope you can help point me in the right direction. Hate to waste another couple hundred like I did last week on the ECM. I would hate to just junk it as it's been a great car and I really like it a lot. The tech who first scanned the codes was a GM driveability Tech and it's even got him baffled a bit, of course he hasn't had the opportunity to really dig into it either just scan the codes for me.
 
  #12  
Old 07-14-03, 12:35 PM
NHT44
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One other thing, occasionally I get a smell like burning plastic emitted from under car and there's a strong fuel smell which I just assumed was raw fuel from not firing properly. Thanks in advance for your help.
 
  #13  
Old 07-14-03, 12:45 PM
Joe_F
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The 02 sensor should be changed as a maintenance part anyhow, so scratch that off and change it...

Both the TPS and MAP can be checked with the information in autolibrary, so start there. I would lean toward MAP before TPS.

Have you been using a lot of fuel lately?

The last is probably the "idle air control valve".
 
  #14  
Old 07-14-03, 02:33 PM
NHT44
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Down about 10 mpg to around 15.
The TPS has been changed recently

I just drove the car about 30 miles at full throttle got up to about 60 after 2 or 3 miles then drops off to around 50. When accelerating from a start would be a good close drag race with a tricycle piloted by a 4 year old.

Now if you shut the ignition off momentarily there's a noticeable increase in power from about 20 HP to 35HP
 
  #15  
Old 07-14-03, 02:43 PM
NHT44
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Is it possible that a bad/clogged cat converter could be a culprit? If so how do you check it for proper function or excessive backpressure?
 
  #16  
Old 07-14-03, 02:51 PM
NHT44
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One more question. Does the ECM for this vehicle have to be programmed after replacement?
 
  #17  
Old 07-14-03, 04:02 PM
Joe_F
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Arrow

Whoa Nelley, stop the parts changing ideas.

Catalytic converters rarely go "bad" and when they do, something causes it, i.e. a poorly running/rich running engine. The cause must be found and corrected or the new cat will be lunch in a heartbeat.

Test the MAP sensor (if equipped, my recollection is this vehicle has a mass air flow sensor), and let's go from there.
 
  #18  
Old 07-14-03, 04:53 PM
NHT44
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Checked MAF today operating properly. Just checked all wiring everything seems ok. Checked firing and 2,4 & 6 aren't firing now.These are all on back bank and all on same side of coils.
 
  #19  
Old 07-14-03, 05:22 PM
Joe_F
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Check your coils and module at this time. Also check alldata.com.
 
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