Poor performance--bad coil packs?

[usinjin]

Hey all,

So a week ago I noticed I was getting poor engine performance periodically. I first noticed when I pulled onto the highway about the week ago. It was coldish for Austin (about 20). I accelerated firmly to merge, and I found the engine sounded very strained, and the acceleration was very weak. In fact I could put the accelerator almost all the way down and nothing would happen, and no kickdown (automatic tranny). I though it might be the VANOS (no service records came with the car, I assume the only thing ever serviced was the cooling system, as the Carfax states. Car is at 106,xxx). The next day it was warmer, and there was no acceleration issue, it accelerated briskly as normal.

Earlier today, I was on our hwy tx-130 (85mph speed limit), and I noticed the car wouldn't accelerate faster than about 80. Yikes. So I slowed down, and realized it was running quite poorly, like I was getting a misfire. I borrowed a code scanner from an AutoZone and I had the following codes:

P0174 (lean code, already figured I had this)
P0306 (misfire 6)
P0301 (misfire 1)
P0304 (misfire 4)
P0313 (multiple misfires)

So this sounds like bad coil packs. My question is, should I replace all of them, or am I good with just these 3 bad ones? Also, are there any particular ones I need to get? Bosch? Thanks in advance

[Dave1027]

Not coils. Vacuum leak. Do a smoke test to locate the leak and replace/repair offending part. Could be disa or intake boot or any number of other things.

[az3579]

Not coils. Vacuum leak. Do a smoke test to locate the leak and replace/repair offending part. Could be disa or intake boot or any number of other things.

This. It's not that common where you have multiple bad coil packs at the same time.

I have the same issue; multiple misfires (cyl 2+6) and lean bank 1+2, but the car runs fine in my case, just idles a little rough.
I'd put money on it that I have a vacuum leak somewhere.

[usinjin]

Update--so I replaced the 3 coil packs and all the spark plugs (hadn't read this thread yet, oops)--the misfire seems to be fixed for cylinders 4 and 6. But cylinder 1 is still reporting a misfire. On cylinder 1, when I pull the wire, there is no change in engine idle whatsoever. Pulling any other wire results in a pretty noticeable change. AutoZone said they thought I should test the signal to the coil. What gives?

I thought it might be coils because the change happened quite suddenly, while I was driving. The car was idling fine, then after a brief hard acceleration, it immediately started running poorly.

I already suspected a vacuum leak though so I'll definitely do a smoke test. But even though I pulled the wire to the coil on cylinder 1 and it didn't change the engine idle--does this indicate a problem there?

[fredo]

When I had my e90, one of the coil packs failed. The engine ran poorly constantly, not only sometimes like you described it. I replaced the bad coil pack. Fast forward 20,000 miles. Another coil pack failed. I replaced all six at that time.

In summary: if it's bad coil pack(s) the car runs poorly all the time IMHO.

[usinjin]

When I had my e90, one of the coil packs failed. The engine ran poorly constantly, not only sometimes like you described it. I replaced the bad coil pack. Fast forward 20,000 miles. Another coil pack failed. I replaced all six at that time.

In summary: if it's bad coil pack(s) the car runs poorly all the time IMHO.

I know I had at least a few bad coil packs and replaced those, but this last misfire seems to be something else.

[usinjin]

Update. Had a normal and wet compression test done on cylinder 1, no pressure whatsoever. Used a cam to check out the cylinder. No visible damage, piston looked good, no damage. Car does not make make any sounds that would indicate any damage. This video describes the situation and a possible fix: https://youtu.be/_Vo4fm0JDPY

I want to try this tonight, I don't have the upper engine cleaner the guy recommends from GM, but I thought I'd try Seafoam. The video recommends I just pour about an ounce into the cylinder and let it sit overnight, then blow it out and start it, a salesman at Advance thought I should actually remove the valve cover to get it in there properly (or turn the engine over once with it in there). What should I do?

[wertyu78]

Update. Had a normal and wet compression test done on cylinder 1, no pressure whatsoever. Used a cam to check out the cylinder. No visible damage, piston looked good, no damage. Car does not make make any sounds that would indicate any damage. This video describes the situation and a possible fix: https://youtu.be/_Vo4fm0JDPY

I want to try this tonight, I don't have the upper engine cleaner the guy recommends from GM, but I thought I'd try Seafoam. The video recommends I just pour about an ounce into the cylinder and let it sit overnight, then blow it out and start it, a salesman at Advance thought I should actually remove the valve cover to get it in there properly (or turn the engine over once with it in there). What should I do?

Not a good sign, sorry to hear that.... it's time for a leak down test to narrow down where/why you don't have compression.

[Dave1027]

Update. Had a normal and wet compression test done on cylinder 1, no pressure whatsoever. Used a cam to check out the cylinder. No visible damage, piston looked good, no damage. Car does not make make any sounds that would indicate any damage. This video describes the situation and a possible fix: https://youtu.be/_Vo4fm0JDPY

I want to try this tonight, I don't have the upper engine cleaner the guy recommends from GM, but I thought I'd try Seafoam. The video recommends I just pour about an ounce into the cylinder and let it sit overnight, then blow it out and start it, a salesman at Advance thought I should actually remove the valve cover to get it in there properly (or turn the engine over once with it in there). What should I do?

First and foremost, don't listen to the guy at Advance Auto Parts. He doesn't know jack. What would removing the valve cover accomplish?

The part I don't understand is, didn't the compression come up any when doing the wet test? If not then that would point to head gasket or valves. If it did then you are on the right track trying to clean out the rings.

The best way to do the AC Delco cleaner is to remove the plugs and jack up the passenger side of the car to try to get the engine as upright as possible. The pour in 1/6 of the container in each spark plug hole and let it sit overnight. The next day put a towel over the head and turn the engine over to blow out any remaining cleaner. Probably best to do an oil change at that time to get rid of any cleaner that may have drained to the oil.

Another thing you can do is hook up the O2Pilot mod. It will increase vacuum to the crankcase and help seal the rings.

[usinjin]

First and foremost, don't listen to the guy at Advance Auto Parts. He doesn't know jack. What would removing the valve cover accomplish?

The part I don't understand is, didn't the compression come up any when doing the wet test? If not then that would point to head gasket or valves. If it did then you are on the right track trying to clean out the rings.

The best way to do the AC Delco cleaner is to remove the plugs and jack up the passenger side of the car to try to get the engine as upright as possible. The pour in 1/6 of the container in each spark plug hole and let it sit overnight. The next day put a towel over the head and turn the engine over to blow out any remaining cleaner. Probably best to do an oil change at that time to get rid of any cleaner that may have drained to the oil.

Another thing you can do is hook up the O2Pilot mod. It will increase vacuum to the crankcase and help seal the rings.

Yes, I figured the guy didn't really understand the problem.

The mechanic I spoke to said he did not think it was the rings or head gasket--I'll be taking it to an indy BMW shop tomorrow.