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Discussion Starter · #1 ·
Ok so, I have a 99 3800 (automatic) bird and something is up
A while back I had to jump the car and my buddy didn't know how to jump a car so while jumping it I blew a couple of fuses
one of the fuses was the one that controls the speedometer, and for the drive to Walmart for new fuses it kicked like a raging mule when it shifted
Got the fuses fixed for the speedometer and a few others and now I'm left with this
-As the car shifts from 1st gear to 2nd it kicks- not like a bunch of little kicks but one good buck while shifting
-Car has a rough idle- randomly jumping rpm while parked
-Going up hills in lower gears it makes a loping noise where the engine will sound like its under load then quiet then back under load
-Poor fuel economy

For the first week or so after getting the fuses replaced it threw a code and this is what info the scan got me (will post image of paper in response to this post)
Essentially the guys at AutoZone who printed out the paper thought that code was like the funniest thing ever because it says it is either the cat or literally a broken check engine light
But for a while its still been bucking and doing all the things I said above and I'm just wondering this;
Is it a misfire, or is it the trans going out?
I know the automatic transmissions start to show their age in the later parts of the 100k mile range and I'm sitting at 111,000, or do you think it may have something to do with the speed sensor? I sorta just guessed it was a misfire because all those symptoms are really common with misfires but it'd need to be pretty coincidental timing to have it start misfiring right after a jump that knocked out my speedometer.
My current guess is that its a misfire, but I'm mostly asking because it may be something I haven't heard of that could be a fuse or something electrical related to telling the trans when to shift.

Thanks for the help guys and let me know what you think
 

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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Nothing funny at all about those two codes. The fact that those codes exist does not mean they are the cause of the trans (?) or misfire (?) problems. The PCM constantly monitors all the control systems for the engine and trans. It set a code because your SES bulb is either missing or burned out. Nothing to do with the trans or misfires.

The PCM also saw that the after cat O2 sensor was not operating efficiently. It could be plugging up (would cause loss of engine power under load), or the cat has been removed or gutted. Or the after cat O2 sensor is failing. Sounds like someone may have removed the bulb from the SES light to cover up the cat problem. Have the cat checked for plugging. That could account for the engine problems.

If the problem was due to failure of an electronic problem with a trans component, there would be a code set, many of which do not turn on the SES light. If it was a mechanical problem it might not set a code. And there is a code for failure of the vehicle speed sensor (VSS), which is mounted on the trans.

There is no fuse specifically for the speedometer, nor for the VSS. There is a fuse for the instrument panel, and if that blew all the instruments would be dead. Is that what happened?

And to be clear, when the trans shifts from 1st to 2nd, are you saying it appears to slip and then suddenly bangs into 2nd gear?
 

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Discussion Starter · #4 ·
So; with the instrument panel- yes, it was like my whole dash lost power until I fixed that fuse
And when it tries to go from first to second it shifts fine when I go smoothly, but if I'm going up a hill or am giving it too much gas it almost feels like someone slammed on the breaks for just a quick second while it goes from first to second
but this bucking was non existent before I had the car jumped, and has been getting gradually better as time goes by but its still definitely noticeable when I'm getting on the highway- especially in the lower gears, and if i really need to get upto speed quick it will sometimes happen going from 2nd to 3rd but its way softer
Also the check engine light went away after about a week of driving and hasn't came back since but I'm not sure if that info would be related/help
 

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1993 6-spd T/A - 1996 C4
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That stupid "Fix Finder" and it's one-solution fixes... I swear to God.

Get the appropriate Factory Service Manual pinned at the top of the Fourth Generation Forum and look up the DTC for the MIL. I promise there are more possibilities than a simple burned out bulb. While it may be as simple as that, a quick search on Google lists other possibilities as well: MIL wiring problem such as a short or open circuit, poor electrical connection at the bulb/cluster/PCM, failed/faulty PCM, and yes, a burnt out bulb. If the FSM agrees with these possibilities, there will be a flow-chart to walk you through diagnosis of which potential issue is the actual problem. ...there could even be other causes the engineers who wrote the FSM were aware of that you might not see anywhere else.

As you're experiencing drivability issues, maybe it's not as simple as a light bulb failure, and the appropriate flow-chart for the DTC should be followed?

...or not. That's your call. But we do provide a free download of the FSM, and it will step you through resolving ANY code the computer can catch. The "obvious" solution is often the last solution in the FSM. I got a code once that said the O2 Sensor was bad (according to AutoZone/Fix Finder). I followed the FSM flow-chart. Guess what? I had a bad hose under the hood which cost only a couple dollars and a few minutes of my time. Versus $100 for a new O2 Sensor which I obviously didn't need, and all the pain and hassle of trying to change something like that on a 30 year old car with costal exposure that has never seen the inside of a garage. Not looking forward to an actual O2 failure and I'm glad I had the FSM available, that's all I'm sayin'.

Good luck!
 

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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and like maybe 2-3 days ago i scanned it again and it wasn't giving any codes whatsoever
Then it sounds like Auto Zone must have given you a bogus code report to scam you. Apparently you have your own code reader and found the codes no longer exist.

The speedometer is at the very end of the data chain. Failed speedo will not set codes, nor will it affect the way the engine runs. VSS sends the data to the PCM. If the PCM is not getting the data, it sets a code. PCM sends the data to the speedo. If the speedo isn't working, doesn't affect anything in the PCM.

Yes, blowing some fuses could upset the way the engine runs. Hooking up the battery incorrectly to jump the starter could possibly have damaged the PCM.

Your description of the trans shift from 1st to 2nd is not clear enough to the point I can't understand it:

As the car shifts from 1st gear to 2nd it kicks- not like a bunch of little kicks but one good buck while shifting
when it tries to go from first to second it shifts fine when I go smoothly, but if I'm going up a hill or am giving it too much gas it almost feels like someone slammed on the breaks (sic) for just a quick second while it goes from first to second
At this point seems like you're not interested in my input at face value, so maybe someone else who's smarter can help you figure it out.
 

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Discussion Starter · #8 · (Edited)
At this point seems like you're not interested in my input at face value, so maybe someone else who's smarter can help you figure it out.
No- I really do appreciate your help and time- I'm sorry I just don't really know how to describe it is all, I've never really seen or felt what a car does when it slips so its hard for me to say whether or not the car is slipping and then banging into 2nd gear. The best way I can really describe exactly what it does is right before when my car should be shifting into 2nd gear it almost feels like a really quick but hard tap of the brakes, it causes me and anyone else riding in the car to sorta jerk forward. It kind of feels like how it feels to ride as a passenger with someone whos fairly new to driving a manual behind the wheel. Every time I look at videos of actual transmission slip it mostly focuses on the RPM and how it lines up to the speed of the car- which my car doesn't show, which is why I'm hesitant to say that it is slipping. And I know that a really bad misfire can cause a bunch of little jerks/ kicking when accelerating or when its under load which it also doesn't do.

I'm not completely sure if that check engine light is even related to the issue, you had mentioned that it could be signs of a clogged cat which could be the case, but wouldn't that lead to a broadband lack of power, and shifting issues across the board? I genuinely don't know, and I don't want that to come across as me dismissing/refuting what your saying but that's just my train of logic- though I could be completely wrong, I'm just bouncing ideas is all. The issue I'm having is nearly exclusive to first and second gear, so would that rule out the possibility of the cat being the cause of the rough shifting? Would VSS having issues maybe send incorrect data to the PCM and cause the transmission to be off on its shift timing? I don't know if any that previous line would make sense, again, i greatly appreciate your help, you are a lot more knowledgeable about all of this than I am.

And also I think your point about AutoZone giving me a bogus code report may have some credibility to it because I didn't have my own scanner tool I used the second time around, I scanned it at AutoZone maybe a week after this all started, and then maybe a week ago from today I scanned it again at AutoZone. so unless the issue fixed itself I think your right about AutoZone giving me a bogus code report to try to sell me on some cat cleaner.

I'm sorry again if I'm just going on incoherent tangents here, I really appreciate your help and especially your patience, I'm just really having a hard time describing my issue with proper terminology, because it seems that a lot of the common issues like misfiring or slipping are just slightly off, maybe it is one of the two and the finer details just differ on a case to case basis and I'm getting hung up on the smaller details.
 

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Discussion Starter · #9 ·
That stupid "Fix Finder" and it's one-solution fixes... I swear to God.

Get the appropriate Factory Service Manual pinned at the top of the Fourth Generation Forum and look up the DTC for the MIL.
And ZumpTA, I actually didn't know there were Service manuals pinned, thanks for the tip- I've been scouring it for the past half hour or so and ill let you know what I find
 

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Discussion Starter · #11 ·
Ok so; update, after some tweaking and busted knuckled I think I have it figured out.
I had multiple misfires, and some slipping gears.

So for starts I spent some time working on the ignition system and there was quite a few broken links; misfires in cylinders 4 and 5 due to some old spark plugs at the forefront but also quite a few other broken links.

Apparently the previous owner had noticed it too because they had to of put an entire tube of dielectric grease in each of the plug wire boots in a attempt to either fix the misfire or fix the fact he had annihilated the metal inside of the boots.
But that's just one of the issues that I found in the ignition system because one of my ignition coils was cracked and not working properly.

Did an overhaul of the entire ignition system, went with NGK iridium plugs, got some duralast spark plug wires since the old ones were greased to high hell and the metal inside was bent out of shape from the previous owner, and replaced the ignition coil that was giving me trouble.
After fixing all of that the car stopped misfiring and has much improved fuel economy(literally id burn nearly a 6th of a tank just driving like 5 miles to work), but still left me with what I described as a really rough bucking while shifting gears

So after driving it for a while, I was certain I could check off the possibility of what I was physically feeling while driving being because of the ignition system and I can say for a fact that Injuneer hit the nail right on the head with it being slipping gears and banging into 2nd gear.

So essentially I said screw it lets just check Scotty Kilmer, and he had a video recommending Lucas Transmission Fix. Expecting absolutely nothing I added some.
You know how those snake oil 1 bottle cure all products usually go.
But I added it, and from the time I last responded until now I've been driving it and usually those miracle additives don't do squat but its already getting a lot better, and every time I drive it gets smoother and smoother. I thought for sure I was going crazy or it was placebo, so to check if it was I took my girlfriend for a drive and she was well acquainted with the bucking. So I drove her without saying I had done anything and previously in passing id jokingly say id get the transmission rebuilt or just manual swap it to fix it and she was basically convinced I had the transmission rebuilt after driving.
So color me surprised, because this just sounds like a Lucas Trans Fix promotion now but its actually working

For now ill just see if this stuff holds up- if it does and the issue disappears- by golly it was worth it- ill keep you guys updated
 

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Dang, I wish I saw this post earlier because I bought my 2002 v6 firebird about 5 months ago and I had to do a full tune up recently because my car was kicking really bad out of no where. It would do it when I was at a stop and was starting to accelerate, as well as when I was in idle. Turned out my tensioner pully, ignition coils/ wires, and spark plugs had to be replaced. Now she runs good as new. As I was reading your issues it just sounded a lot like what I was dealing with so if I saw it earlier I could've helped a little but i hope you get everything else figured out.
 
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