Help? sputtering and popping terribly

[Tre36]

First things first I have a 1995 325i vert. Okay so I left for school this morning, car was going “just fine” started up no problem (with my usual bog in Rpms). As I was leaving school, I noticed my car had a different tone at idle... sounded deeper (it seemed to be slightly more rough but I have solid motor and trans mounts and thought it was my vac problem), but I disregarded it and originally thought it might have been a bad exhaust leak from bottoming out on a torn up piece of road. However shortly after I pulled out of my parking spot I realized that it wasn’t a leak and the car was sputtering and popping terribly... I made it home but almost the whole way it sputtered and sounded pathetic. Under heavy acceleration, the car would seemingly cut off power and hesitate terribly. First thing that came to mind was crank/cam angle sensor as it was a problem on my brothers 300zx and had the same issues (minus the random power cut outs), I don’t exactly remember which it was though... My question is, would the crank or cam angle sensor be the culprit? I tested the coil packs and they all seem to be working, I replaced the spark plugs about 2-3k miles ago, there are no visible cracks in the intake elbow, and I cleaned the maf just to be sure (and for the most part it fixed my pulsing idle) .

If anyone has any information on this please help me out, I don’t know what I should do... I just want me car back mane.

[Tre36]

Any help would be appreciated! Did it again this morning... pulled out of my driveway and got half a mile up the road before it started sputtering again...

[Thomas525]

Firstly, pull the codes from your car. Please do some research on how to do this on your ride. I'm not sure if you need simple equipment for this. That's always the first place to start.

Failing that, try the sensor disconnect test. Basically the car has a couple of driveability sensors which help the ecu manage the engine perfectly. If any are damaged, the engine could produce bad behavior while still connected. Disconnect it and the ecu uses factory safe default values in place of that sensor/ ignores that sensor's input. Wait till your car starts spluttering. Then pull the maf plug. See if that fixes it. If not, replace it, and pull the coolant temp sensor (on the cylinder head) plug. See if it fixes that. And so on and so forth for the following devices : icv, air temp sensor, o2 sensors.

Third (maybe try this first), see if there's a problem with your ignition coils while the spluttering is going on. Put a long screwdriver or wooden stick onto each coil while the engine is spluttering, and hold the other end against your ear. Note how it sounds. Then go coil by coil. Identify the one that sounds different. Stop the engine and exchange that coil with its neighbour. Start the engine, wait for the spluttering. Listen again with the stick (you can also use a mechanic's stethoscope) and see if the different sound moved with the coil. If it did, the coil is the problem. If it didn't, the plug or the wiring to that coil, is the problem.

You can also do this when you first start up when there are no symptoms, to better familiarise yourself with how it should sound.

If you use a screwdriver, don't put it directly on top of the coil. You might damage it if you apply too much pressure. Put it on the bolt that holds it in place.

Another tool you can use for this that's perfect is the magnetic pickup tube.

[Nanniepoo]

A '95 requires the stomp test to read codes.

Also please don't touch the ignition coil bolt with a screwdriver. That's part of the ground path. It's one of those it's probably fine but if not....

[Tre36]

Thank you! The only code I could pull was 1215, which is maf. Looking further into this, I’ve seen that a bad pre cat o2 could also somewhat create a problem like this.. I’ll try the disconnect method today thank you!

[Tre36]

Got a code for maf, not too sure if a bad maf would create problems like this though... I could be wrong!

[Thomas525]

Its possible. The ecu is dumb enough to accept wonky readings. Just disconnect the maf alone, then check the coils in the method suggested above ( you can use a long rubber hose too - get creative, anything that can channel sound and vibration will do). If no joy with listening to the coils directly, then go onto the rest of the disconnect test with the rest of the sensors. Spluttering is usually either a bad vacuum leak or something ignition related. If its such a bad vacuum leak, it should be there right from startup. So its probably ignition.

Please be patient when doing this. It may take longer than it sounds over here. Doesn't matter, do it patiently and you will track down the problem.

Forgot one of the sensors in the disconnect test earlier - cam sensor.

[shogun]

Put a long screwdriver or wooden stick onto each coil while the engine is spluttering, and hold the other end against your ear.

That is dangerous! be careful, because the amount of electricity generated by the ignition system can be dangerous. If they are bad, problem. Ignition Coil High Voltage Display https://www.instructables.com/id/Ign...ltage-Display/

[Thomas525]

Voltages are high, but the current is very low and it is the volume of current - quantity of electrons which actually move through you - that does the damage not the voltage. The current involved in sparking is incredibly small - because that's all that's needed for spark plugs. If you look at the stove ignitor you have in your kitchen, its basically a spark plug just the same. They just say 'voltage' colloquially.

And if i'm not mistaken, aren't all the coils already directly voltage grounded grounded through the metallic portion of the valve cover and the ground straps down to the cylinder head through the valve cover bolts ?

Regardless, it is easy to take extra precautions in this case so why not. OP, the other end of your screwdriver is either made of plastic or wood, both of which are known good insulators. So wear a glove or wrap cloth around for added protection. When you put the screwdriver on top of a ignition coil's bolt or anywhere near the coil, if you see sparks, then you know that this coil is badly screwed so you can stop your diagnosis there, switch coils, and check again If you don't see sparks then put the other end to your ear and listen to each in turn as described earlier.

In fact first touch all the 12 bolts to check for arcs. Move the screwdriver around the edge of each coil as well. You can lightly tap on them as well. Just make sure that no other part of screwdriver is in contact with any other metallic part of the car. This would be VERY important.

Or use a tube of wood or a small diameter rubber hose (about the size of a fuel hose) and you'll have good sound transmission too. results. WIth the hose, use a gloved hand to to hold the hose down flat on the surface of the bolt properly if not sound will not be transmitted well.

If you have inpa, a computer software that can read the engine,. there is something called engine roughness which you can use to essentially check this as well.

[shogun]

There problem starts when the ignition system is damaged and you test with a screwdriver, sparks are then there and they go a long way. And there are many screwdrivers with metal end. The TO still goes to school and does not have too much experience so far, and also many other DIYers are beginners. So we have to be especially careful with our advice. Safety first!

As Nanniepoo mentions above

Also please don't touch the ignition coil bolt with a screwdriver. That's part of the ground path. It's one of those it's probably fine but if not....

[Thomas525]

The TO still goes to school and does not have too much experience so far, and also many other DIYers are beginners. So we have to be especially careful with our advice. Safety first!

Ok fair enough.

There problem starts when the ignition system is damaged and you test with a screwdriver, sparks are then there and they go a long way.

What do you think of my suggestion above, to hold a screwdriver with a glove and tapping it on all the ignition coil bolts and the coils themselves, (provided the metal part of the screwdriver is not touching any other part of the car) to see if there's an arc. This would be a fast way to check for some types of extreme coil failure. I just thought of that while writing that post. How do you feel about that?

[shogun]

Hella has very good info with pics: "Ignition coil — checking, measuring, faults , Here you will find useful basic information and important tips relating to ignition coils in vehicles." https://www.hella.com/techworld/us/T...ion-coil-2886/

When someone is experienced he can do it as per your idea of course. We have on the forum beginners, experienced people, pro's, people with certificates and so on. So we have to adjust our DIY help hints accordingly and always try to make sure that nothing dangerous can happen.