Need Help Getting 99 3.8 running properly - Misfire/Running Rough

[mrd05d]

Running super rough sounds terrible.

P0171
P0135
P0131
P0300

I will be looking at it more tonight and through the weekend. Its my sons car and I really hope I can get it fixed before next week so he can get to and from work. Any help would be appreciated greatly.

[mrd05d]

When I got home i was planning on looking at the 02 sensors however car wouldn't start now. I was getting 12.4v at the battery but at the alternator i was getting 3.5v and at the positive post (drivers side) I was seeing 3.5v. When I wiggled the main Positive wire coming from the battery Positive to the positive post on the Drivers side voltage jumped to 12.4v.

Even when it jumped to 12.4 volts. The Starter just gives one loud click and the entire electrical system goes out again. I have to move the wire to get it to come back...

I am hoping to get the electrical fixed so i can then fix the other stuff. Or maybe this was the cause of everything the entire time? Just a little agitated seems I always get the difficult troubleshooting smh.

[ssms5411]

Sounds like you first need a new positive battery cable, then I think your on the right track with new O2 sensors.

[mrd05d]

Is this a common problem for these cars? I have never had a thick cable like this go bad.

[ssms5411]

Don't know, ive had mine for 22years and no problems, but im the first owner of mine so dont have to worry what other people might have done.

[LETZRIDE]

Alright let's start with decoding your codes first:

P0171 - System too lean, bank 1
P0135 - O2 Sensor Heater Circuit Bank 1 Sensor 1
P0131 - O2 Sensor Circuit Low Voltage Bank 1 Sensor 1
P0300 - Random multiple cylinder misfire detected

So the first thing on this is they all appear to be fuel / lean related except for the cylinder misfire - which could occur due to lean conditions. These can all also be attributed to low voltage conditions in some cases.

You've then gone on to mention that you checked the battery voltage at 12.4v - is this with the engine on or off? If this is with engine off your battery is good, if this is with engine on you have a problem.

When you said you were getting 3.5v and wiggled the wire and got 12.4 - where were you checking? How does the cable look like that is running from the battery "+" to the alternator "+" to the starter "+" ? Sometimes (and I had this happen on my LS1, the wire gets corroded real bad inside, mine was holding on with 2 copper strands when I managed to pull the plastic off).

Even when it jumped to 12.4 volts. The Starter just gives one loud click and the entire electrical system goes out again. I have to move the wire to get it to come back...

What do you mean by this? Which wire?

What is the voltage of the battery on an ohm meter in the morning key/engine off? It should be 12.xx or the battery is bad. (may not be your only issue, but is one of them)

Once we get passed these answers I'll have several more questions I can narrow down.

[mrd05d]

Thanks for the response. 12.4v is with the engine off. And I was getting 3.5v when on the positive post (on driver side) and neg battery until I wiggled the positive battery cable going to the positive post it then hits battery voltage.

I also did this with a jump pack on the battery with same results. When I send battery voltage to the starter all electric cuts out then turns on but relays etc goes crazy clicking etc. and the voltage at the post and at the alternator etc drops to 3.5v/4v if I wiggle the positive battery cable bundle going across the fans to the driver side it jumps back to battery voltage.

So to make things worse today I was concerned that maybe the starter just can't move the engine and is pulling too much current for the wire causing issues of some kind. I put the car in Neutral and couldn't budge the crank at all (using long breaker bar) with belt on or off. I expect that the 3800s should free turn like this as other engines do unless there is something mechanically wrong with the engine ?

Voltage in the morning is 12.4v also its a newer battery less than 6 months old.

[ssms5411]

Yeah the engine should turn with a breaker bar, even in park, did it with mine about a year ago. Just used a regular ratchet with the belt on.

[LETZRIDE]

Ok what are you getting these voltage results with? Are you using an ohm meter or going off of the cars gauges?

When you say:

I was getting 3.5v when on the positive post (on driver side) and neg battery until I wiggled the positive battery cable going to the positive post it then hits battery voltage.

Are you touching one wire to the positive post on the battery and the other wire to negative on the battery? I am having a hard time following which post - some cars 98+ I believe had and additional "accessories" post that was separate from the battery that power wires ran to. If this is the case have your tried cleaning your connections?

The good thing is, if wiggling the wire causes you to jump back up to 12.4 volts that you have your work cutout for you. It appears you have located the faulty connection in the harness somewhere in that location across the the fans area. Open the harness area and inspect the wiring in this area. The big power cables aren't hard to trace. If you have to replace the power cables they run from the batter to the starter/alternator. You can pickup a hydraulic crimper from harbor freight for $15-$20 and buy 4-8gauge wire for pennies on the dollar by the foot. Open the harness and take a look at the wiring, continue to wiggle and monitor voltage in small increments across the wire, you may find you figure the break out rather quickly in the harness.

So to make things worse today I was concerned that maybe the starter just can't move the engine and is pulling too much current for the wire causing issues of some kind. I put the car in Neutral and couldn't budge the crank at all (using long breaker bar) with belt on or off. I expect that the 3800s should free turn like this as other engines do unless there is something mechanically wrong with the engine ?

This is odd, is there metal in the oil? Aside from the car running rough was it knocking? The crank should turn with a ratchet on the crank bolt without much effort. I question whether or not your electrical issues to your started have caused the starter gear to pop out and remain stuck in it's "crank" position thereby holding the flywheel in place. If there was no indication that the motor seized/locked itself up when it was running, nothing should have changed.

Let's focus on the electrical issue first and see what that corrects.

What initially caused the engine to begin running rough? Was the car running fine and then all of a sudden it began running rough and throwing the low voltage codes on the O2 sensors?

[mrd05d]

I was talking about the accessory Post on the drivers side of the car next to the fuses/relays. And yes I was using a multimeter to test. DCV Black on Ground (either battery ground itself or body ground) and Red on Accessory Post or Alternator.

The night before it wouldnt turn on i heard him pull in the drive and only got to hear it for a couple seconds before he turned it off. To my recollection it was knocking/clanking and and running rough.

Id sort of rather see if the starter is jammed into the flywheel before spending any more time and money. If the engine is seized/wont crank because of internal issues likely not worth my time or money to fix.

Initially the car was idling a little rough and had a lifter tick but other than that sounded fine. The 02 sensors had thrown codes and i was getting around to check the lean condition/misfire but this happened prior to me being able to look at it.

Thanks for the response

[mrd05d]

Took the starter off. Was able to get the crank to move backwards but not forwards past the sticking point... There is discoloration 6 inches down the positive battery cable. Other than that no physical signs. At this point i'm not sure if its worth fixing.

[LETZRIDE]

How far backwards is it rotating? Are you able to turn the motor over and over while going backwards?

If the motor really is fubar'd then you can always snag a motor out of any 3800 series II vehicle from the junk yard - this site searches all junkyards in north america: http://car-part.com/

It's where I got my 3800 from a buick lucerne with 5k on it for $400 - unfortunately the decision to fix the car is your decision. I would take into consideration the shape of the rest of the vehicle - if the body / frame / interior is all in great shape - I would say fix it...if it is rotting and in real rough shape, then you need to weigh the costs.

[mrd05d]

Engine rotated at least 2 or so rotations backwards then 2 forwards and stopped again. This car is pretty old and rickety. steering column keeps binding the ignition linkage, the interior is hosed, etc.

And if i remember correctly you cant come through the top with these 'maro motors you have to drop them then jack up the frame to clear them right? Sounds like a serious pain considering im doing all this in the street atm.

[LETZRIDE]

I have gone both out the top and out the bottom- I actually preferred out the top myself- I felt I had to get the car up too high to go out the bottom and it didnt feel as safe at the time.

I did both mine in the driveway outside