Engine Bogging Down, Misfiring

[thunderpanda]

I have a 98 bonneville ssei and its symptoms have kind of been getting worse, to the point where i can no longer drive it on the freeway :(

It seems fine at idle, but bogs down a lot when more gas is applied and misfires a lot. It even will backfire frequently. It's difficult to get it moving without flooring it, and that sometimes leads to the engine dying (maybe flooded??)

OBD codes confirm random/multiple cylinder misfire.

I have no idea where to begin to pinpoint the problem... Clogged injectors? Bad spark plug? timing off? I have no idea. There is also a separate (but probably somewhat related) fuel pressure problem, but I am sure that is not the only thing going on here. I think the backfiring suggests that a cylinder IS accepting gas but IS NOT igniting it properly.

Any help would be appreciated, thank you!

[LeSabre in Buffalo]

We need 00Beast and his tuneup list.

Give it a very thorough tuneup (plugs, wires, PCV, clean the MAF sensor, clean the throttle body) first, and see where you're at. I'd bet the car's due for it anyhow.

[renchjeep]

Don't forget the fuel filter. Sounds like it's clogged.

[00Beast]

We need 00Beast and his tuneup list.

Give it a very thorough tuneup (plugs, wires, PCV, clean the MAF sensor, clean the throttle body) first, and see where you're at. I'd bet the car's due for it anyhow.

Boom Goes the Dynamite!!

• 1987-2005 Bonneville / Buick 3800 Maintenance List
  
  Run Seafoam through gasoline and intake every 5,000 miles. One pint of Seafoam in a half tank of fuel is a good mix. The intake is optional, but recommended.
  
  Grease: Ball Joints, Tie Rods Every 8-10k ( Green Grease recommended)
  Air Filter Every 15k (Amsoil EaA, Purolator PureONE)
  PCV Valve Every 30k
  MAF Sensor Element Cleaning/TB Cleaning Every 50k viewtopic.php?f=48&t=1661
  Fuel Filter Every 15-25k (Purolator, AC Delco, WIX)
  Spark Plugs Every 30-50k (NGK TR55 or Autolite 605) (Never Bosch)
  Ignition Wires Every 30-50k (Napa Belden, AC Delco, Autolite Pro, NGK) (Never Taylor or Bosch)
  Oil & Filter Every 5-6k or Every 6 months (Mobil1 or Amsoil)(Mobil1, Purolator PureONE, Amsoil EaO or WIX) (Never Fram) viewtopic.php?f=45&t=214
  *Conventional Oil Every 3k/3 months(Pennzoil with a WIX (Napa), Delco or Purolator filter)
  Transmission Flush or Pan Drop Every 15-20k (Always make sure filter is changed when flushed) http://www.pontiacbonnevilleclub.com/fo ... 45&t=10193
  Cooling System Flush Every 25-50k or 3-5 Years (Peak or Prestone Green Coolant Only) (Never Dexcool)
  Oxygen Sensor Every 80-100k (30k for non-heated) (AC Delco or Denso) (Absolutely never Bosch) viewtopic.php?f=48&t=794
  Accessory Belt Inspect every 15k, replace every 100k, or as needed
  Cabin Air Filter Inspect and Replace every 15k, or as needed in dusty conditions. (Note: 00+ Only)
  Evap Core Cleaning Whenever Needed (Note: 99 and older only) viewtopic.php?f=45&t=2432
  
  *Special Considerations*
  All 3800s, LG3, LN3, L27, L36, L26, L67 & L32, especially important on vehicles factory installed with orange Havoline Dexcool Antifreeze/Coolant: http://www.dex-cool.net/
  Lower Intake Manifold Gasket Replacement, every 80-100k (ignorance of this can allow coolant to enter your engine oil, this happening can cause irreversible lower engine damage, requiring replacement of subject engine)
  
  Series II, Naturally Aspirated, RPO:L36:
  Upper Intake Manifold Plenum Replacement, Every 80-100k (ignorance of this can allow coolant to enter your intake manifold, possible damage to occur can be hydrolock, irreversible damage to emissions devices, misfires, etc. Most times, engine replacement is required if ignored long enough.) viewtopic.php?f=53&t=1061
  
  Series I, II, III RPO Code L67 & L32:
  Change Supercharger Oil; Every 30-50k. (Intense Racing or GM Dealer) viewtopic.php?f=56&t=1690
  Supercharger Belt; Inspect Every 15k, Replace Every 100k or as needed.

11/6/2010 by 00Beast

[Bob Dillon]

Don't forget the fuel filter. Sounds like it's clogged.

Yup. Got to be the most ignored item on this forum.

Amazing.

[thunderpanda]

Thanks for your help guys!

Two of you have mentioned the fuel filter, and that was kind of something I wanted to check out too, so I think I will start by seeing what I can do with that. If that doesn't fix the problem I will get started on most of those tune-ups right away, or at least take a look at which ones are most likely to be causing my main problem for now. I will let you all know how it goes, thanks again!

[00Beast]

Do it all. That way you KNOW what is good, not just guesstimating.

[thunderpanda]

Okay so I got some interesting results. I replaced the fuel filter, which helped a tiny bit. Then I replaced all six spark plugs. Interestingly things actually got a little different, but not any better. The backfiring stopped but the car still ran awfully.

Now here is where things get weird.

My information said that the spark plug wires corresponded to the spark plugs in the following order: (This is also the order physically listed on my car itself, labeled right on the coils)

6
3

2
5

4
1

The three groups you see here corresponding to a coil each. So we have had them set up like this. I found this conflicting diagram online, however, which has the order within each individual coil to be swapped, resulting in the following order:

3
6

5
2

1
4

I was working on this with my dad, and he was saying that the order of the two within each coil should not matter, because it fires for both at the same time, one of the times it ignites at the correct time for one cylinder, and the next at the right time for the other. He says switching them would not make a difference.

I switch them. The car drives a lot better. Especially when lots of gas is given. I switch how the spark plug wires are set up back and forth 3 times, and it is confirmed without a doubt. Switching it to this supposedly incorrect configuration makes the car run better.

Can anybody tell me why???

[harofreak00]

This is how it should be, end of story.

[thunderpanda]

This is how it should be, end of story.

Lol well that is how I had it and it ran like a POS. I switched it and it runs probably 5 times better. And the cords are definitely run properly.

I believe there is still some misfiring going on, and maybe what happened is that one of coil nipple things is bad, and that bad one HAD been running to a GOOD cylinder, causing it to not fire, whereas now, the BAD coil nipple could be running to a cylinder that is BAD for some other reason.

I am just trying to come up with an explanation for the performance change that I am seeing, other than you are wrong and so is the label on the car. I am definitely not switching them back to the "proper" way though until I can figure out what else is wrong. I like being able to use the freeway

[enslow]

Don't forget the fuel filter. Sounds like it's clogged.

Yup. Got to be the most ignored item on this forum.

Amazing.

Dang, gotta remember to do mine...

I'd bet plugs and wires will solve the problem, but the other items should be done too.

[enslow]

I believe there is still some misfiring going on, and maybe what happened is that one of coil nipple things is bad, and that bad one HAD been running to a GOOD cylinder, causing it to not fire, whereas now, the BAD coil nipple could be running to a cylinder that is BAD for some other reason.

Did you do both plugs and wires? Also, are you certain you seated the wires properly on the plugs? I find it tough to get the rear 3 wires on the plugs properly. Also, the use of dielectric grease inside the boots can help keep moisture out and prevent arcing.

[thunderpanda]

Did you do both plugs and wires? Also, are you certain you seated the wires properly on the plugs? I find it tough to get the rear 3 wires on the plugs properly. Also, the use of dielectric grease inside the boots can help keep moisture out and prevent arcing.

Ya I had just replaced all the spark plug wires like a month ago because a squirrel had chewed on them... so they are all still new. And I am pretty sure I have them all plugged in properly, i may double check tomorrow though. I haven't had too much trouble getting them on though, given that they are new and the dielectric grease is a good lubricant so they slide right on.

I think the two most likely REMAINING problems are possible bad fuel pump and possibly some bad fuel injectors still. I had replaced all of them, but i replaced them with junkyard ones which I guess may not have worked. Unfortunately since multiple cylinders are misfiring according to my OBD, i can't pinpoint it to a specific cylinder that needs help.

[LeSabre in Buffalo]

Have you tried running a large dose of fuel system cleaner? Buy 2 bottles of Gumout Regane, or Chevron Techron, run your gas tank down to half, and pour both of the bottles in. Then run the car as close to empty as you feel safe. That should clean out any junk in the injectors.

[thunderpanda]

Have you tried running a large dose of fuel system cleaner? Buy 2 bottles of Gumout Regane, or Chevron Techron, run your gas tank down to half, and pour both of the bottles in. Then run the car as close to empty as you feel safe. That should clean out any junk in the injectors.

I haven't tried that with these new injectors yet, though I did use several bottles with the last injectors to no avail. And running the gas until empty is not a new concept to me.... The gas gauge is broken and I get random mileage so I run out all the time lol... An extra can of gas and I'm good to go. I will probably try that though and see if I can't help it out a little

[00Beast]

You might have had some corrosion on a post that got knocked off? It does not matter which post on a coil the wire is on.

[thunderpanda]

You might have had some corrosion on a post that got knocked off? It does not matter which post on a coil the wire is on.

They all look like they are fine, I haven't noticed any corrosion at all. I suppose there could be some internal corrosion somewhere that I can't see though, causing one of the posts not to work

[00Beast]

Might not hurt to remove the coils and ICM and make sure the ICM and grounds are all clean. The coils use a 5.5mm or 7/32 socket (They're the same).

[enslow]

I haven't tried that with these new injectors yet, though I did use several bottles with the last injectors to no avail.

You could try taking your old injectors in to have them flushed and tested. You should be able to find a place that will flush them out of the car. Then you will know that your injectors are good and that your problem is not injector related.

[thunderpanda]

I think I am going to test each spark plug one at a time by plugging in a working spark plug and wire into each post and turning on the car, and seeing which ones spark and which don't. If they all spark, then I know its not that. And ya I might have to do that with the injectors... I will probably try the gumout first and see if that takes care of it. If not I will get a little more serious with them.