Bad Ignition Coil?

kcjones · Post by **kcjones** » 04 Apr 2011, 10:51

I've been trying to work my way down the preverbial checklist, but to no avail. To simplify, I will list the issue(s) I am dealing with, things I have tried that didn't work, and some more questions....

1997 850 GLT Auto 160,000

I have been getting misfires in cylinders 1,2,4, and 5, but never 3. It began about a month ago. I haven't received any other codes during this time.

I have:
Replaced and triple checked spark plug gap. Using NGK coppers.
Replaced plug wires with bougicord.
Cap and Rotor are 9 months old, bosch.
MAF is original, but doesn't throw codes and I have cleaned it with approved MAF cleaner.
Checked for vacuum leaks, found none.
Replaced bad fuel pump 2 months prior with OEM from junker. Filter was done as well.
Cleared codes via OBDII and battery drain.

So, why hasn't cylinder 3 thrown a code?

My only ideas are:
Ignition Coil?
Slight possibility that injector O-rings are failing simultaneously?
Or maybe ECU is freaking out?

Recently, the codes have gotten more frequent. I have noticed a trend. After becoming warm, and running around 2200 rpm in fourth, if I keep a steady throttle position, the CEL flashes. Great. More codes.

I've tried testing MAF by pulling the plug, the car dies. This does mean it's working, right? Closed loop vs ECU?

When my plugs were bad, I could really feel the misfires. This is nothing like that. It seems to run just fine. My MPG is around 21-22, better than before plugs were done.

Let my know what you guys think or if you've experienced anything similar.

I plan on picking up used MAF and coil from Junker within a few days to test.

*Edit: I replaced BCS recently, works great.

Post by **JDS60R** » 04 Apr 2011, 10:58

Multiple misfire usually refer to a component that effects all cylinders such as oxygen sensor, MAP sensor, Boost sensor, MAF sensor, fuel filter, fuel pressure regulator, fuel pump, cam sensor, crank sensor or ignition coil.

kcjones · Post by **kcjones** » 04 Apr 2011, 16:45

Thanks for the quick reply. However, most of these components would throw codes individually, wouldn't they? If it were air related wouldn't I get faulty signal codes? Or even crank/cam sensor? I feel so lost, I have been troubleshooting for weeks..... Just doesn't seem to add up.

Post by **vjaneczko** » 04 Apr 2011, 19:04

I'd first swap the ignition coil - especially if it's original - and then take a look at the cam sensor.

Post by **Glencoeteen** » 04 Apr 2011, 19:22

Doesn't always throw codes, Honestly could be the injectors are clogged, i mean honestly if it was the coil then you should have misfire on all 5, I mean the coil feeds the cap which feeds all 5 plugs, so that can not be the issue. so that leaves faulty cap. may only be 9 months old but that's still enough for some to fail, they are not perfect. but it has always been my experience like i said first I would check the injectors, I mean a quick way to check is full the fuel rail and swap #1 with #3 and see what it does, if #3 starts missing then you will know

kcjones · Post by **kcjones** » 04 Apr 2011, 22:14

I'm doubting injector problems. Usually MPG will suffer and my misfiring would be more noticable physically. I will make sure to give them a try if the coil + MAF don't do the trick.

Post by **Glencoeteen** » 04 Apr 2011, 22:29

well doesn't make any sense to be the coil, I mean if it was the 99+ where it had individual coils then yes. just think, you have one coil feeding to the Distributor cap where its divided up to 5 cylinders, 4 of the 5 are having a misfire. so how is that possible if there is only one coil?? i mean honestly if it was the Coil then all 5 would have a misfire code not 4 out of 5, just not plausible. MAF and Cam Sensor are a suspect, Because they help the ECU know how much air is coming in, and where the Cam is at so it knows when to inject the fuel in to the cylinder to match where the cam that turns the rotor in the distributor cap which in turns sends the spark thru the wire to the spark plug giving ignition, so if he has spark, which he does, then look at next in line, the plug? if that is good then fuel. Injector, ect just like Member JDS60R mentioned.

20-21 is not really that good if its hwy driving, my T5 will average 30-32mpg at 60 with pure hwy driving 27mpg with some light traffic and then 15-17mpg with pure city driving. my xc70 is sightly lower on the hwy mpg due to the AWD system. it only has 122k on it and i had to replace 3 injectors on it at 112k they just crapped out. he loses nothing by keeping that as a strong possibility.

Post by **pkc303** » 05 Apr 2011, 08:21

+1 on the cam sensor.

C704me · Post by **C704me** » 05 Apr 2011, 15:22

pkc303 wrote:+1 on the cam sensor.

Hi, New member here.. (Doing quite a bit of research).

Wouldn't the Cam Sensor throw a code??

I've had them go bad on my BMW 540 and a few of our old Mercedes' and I used to actually get a code "almost before" I even noticed any symptoms.

I'm actually getting ready to type a new post regarding a "misfire type of symptom" I've been fighting with on our 2001 C-70. (Doesn't really seem to fit the ETM symptoms).

Post by **Glencoeteen** » 05 Apr 2011, 18:13

no it would NOT always throw a code.