Fed up with my car. Hesitation and poor fuel economy.
My car is running like total sh*t, with no CEL or codes. It's a 1995 325is which I bought in November, at that time it was running great. Now, I'm getting about 450 kilometers per tank, not even in city driving, and the car has no guts to accelerate at all. The car itself is very, very clean (or so I thought), which is why I bought it in the first place. It has just over 225000km.
I have put a lot of money into solving this issue. It has got all new spark plugs, a new MAF which I just put in today (which I was hoping would solve it, since it didn't I'm here venting/asking for advice), all new fluids for everything, checked for any and all vacuum leaks, all of which were found were fixed, still runs like crap.
I have a brand new o2 sensor on the way which I'm hoping will boost my fuel economy.
The exhaust seems to be shaking a lot, as is the engine itself, like an occasional knock every 1/2 second. I've also noticed the car heats up much quicker than before. The car has no guts whilst accelerating, and at WOT you can feel the shaking in the pedal a bit.
If the o2 sensor doesn't fix it, any idea what might? What comes to mind is clogged/fucky injectors, bad cat, bad crankshaft sensor(?), bad coils (one of which was replaced a few months ago because the car was misfiring).
Any and all input is appreciated, I'm very flustered with this car and I want to love it but it's making things very hard for me.
After letting the engine cool down with the new MAF in, there is a notable increase in fuel economy. The engine now also struggles much less to reach higher revs, and the torque and power of the car is a bit easier to feel. Before it would take me about 12 seconds from a stop to reach 100km/h, now it seems to take 2-3 seconds less, quite the improvement. The fuel economy gauge now reads about 7-8l/100km when I'm just cruising at 50km/h in 3rd as opposed to the 11-13l/100km it used to read. The fuel economy needle was buried all of the time when in 1st gear, now it reads about 15l/100km when reving up until about 2000 where shortly afterwards it disappears.
This is good news, I will post the results of the o2 sensor change in a week. Let's say the o2 sensor didn't change a thing, all things considered (new fluids, plugs, tire pressure is good) what else could be done to improve my fuel economy? Injectors? Coils? Let me know. The knocking problem with the exhaust also still persists, so if you have any input please feel free to voice your opinion.
Last edited by Minsc; 06-20-2011 at 08:19 PM.
Reason: 2 hours later, not 4
Well, I'm not sure if changing the MAF is supposed to make a sudden difference, but it seems as though the more I drive it the better everything feels. Could the ECU be adjusting itself bit by bit as it realizes there's more air going into the engine after all this time? If so, could I just unplug the battery for 30 minutes to reset the ECU and see if it's like back to factory spec?
I checked the air filter and its practically brand new. I should have an update next week on the o2 sensor. I've got a full bottle of Lucas Oil I'm going to put into my gas tank on Thursday (when I get paid, gas is too damn expensive). I can't check the fuel filter as I don't have access to a lift. It was, however, replaced no more than 1200km ago, so it cant be THAT dirty.
Last edited by Minsc; 06-21-2011 at 09:46 PM.
Reason: can't check the fuel filter
Well, since Canada Post is on strike I have to wait longer for the o2 sensor to come in, as well as my credit card which I was just approved for to pay for all this damn work.
Here's the deal... I think the o2 sensor is fine. After replacing the MAF and driving it since then, the symptoms have gotten worse. I am now lead to believe the cat is clogged. It certainly seems like the engine has the power to rev high and actually move but can't because there's nowhere for the exhausted power to go, so it makes its way out of (what my guess is) a likely straw sized hole in the cat. Mileage is a bit worse, and the engine warms up much quicker than when I hadn't had any symptoms. The engine also shakes quite hard when idling after being driven for a while.
First thing Monday morning I'm going to my nearest muffler shops, having them check the cat out, and I'm going to aim for a $600 to $900 estimate. The o2 sensor itself is still on the way so I figure I'll replace it along with the cat as a maintenance item.
I think this might be the real culprit, as I am experiencing all of the symptoms of a failed or soon-to-be failed cat. No CEL though. I also noticed while driving at decent speeds (50-90km) and listening closely it sounds like I can hear a cheese grater lightly grinding against metal... So I think the cat is toast.
Keep your fingers crossed, I'll update once I can get into a muffler shop.
hey dude what you might try is taking the o2 sensor thats before the cat and driving it like that if you see a considerable increase in performance than its most likely the cat..
also you might check that the intake hose after the maf sensor is not ripped.. although if you changed it u probably already checked but check anyways..
Well I brought my car into a local Speedy Auto place today, had them jack the car up and take a look at the cat. It appears to be fine, a little rusted and succumb to wear and tear but by appearance the exhaust system seems okay. The front left strut also needs replacing (I replaced the front right about 5 months ago.) I asked how much it would cost to have the cat replaced (found out then and there that I had TWO cats, god damn it), and he quoted me $1,626,51. That ain't gonna happen. He suggested I take it to the BMW dealership to do a back pressure test to see if the cats are truly to blame.
While at the dealership I had a talk with the manager/supervisor guy for the maintenance bay, and he ended up taking my car for a drive after I described to him the situation, the symptoms Ive been having, and no CEL. He said that it seems to be running fine, but if you give it quick acceleration it buckles or hesitates. Just with my luck, when he had been driving it with myself in the passenger seat the car was driving much better than normal.
He said its definitely NOT the catalytic converters, and that there would most definitely be an o2 sensor code or catalytic converter code thrown. He thinks that its a spark issue, and asked me what I had done to the car in terms of maintenance. I had the MAF replaced, all new NGK plugs, new fluids for everything, a new ignition coil as the car had been misfiring a few months back, a few vacuum leaks fixed, the usual maintenance stuff. He said he thinks it could be the other 5 ignition coils which might be starting to die, or maybe one or two of the plugs aren't torqued right or something.
I have the car booked for July 11th at the BMW dealership to have this diagnosed, as well as have a new left front strut put on, a new o2 sensor which I'm supplying will be put in, have squeaky brakes fixed, and have a squeak coming from my front right tire as I turn right fixed. For $150/hr they better wax and buff the damn car while they're at it.
I'll keep you all posted. Lets hope I can get another solution added to the gigantic list of "hesitation/bogging/stuttering" car problems that e36's have.
Last edited by Minsc; 06-28-2011 at 01:12 PM.
Reason: He thinks that he thinks that
Well, 4 hours and $450 later the results were inconclusive. They managed to put the o2 sensor in, put new retrofit body moldings on, and give me a list of things they see need replacing. Both front struts, left tie rod end and left ball joint. They also said the e-brake expanders appear to be stuck? They said there was no "spark" problem, but I can still feel it as I drive, even with the new o2 sensor. Hesitation in acceleration from idle.
Welp, I'm stumped. One last thing I can think of is the other 5 ignition coils I haven't replaced yet, but they said they appear to be fine.
I called up my mechanic, who has known I've had this problem for the past 6 or so months, and gave him the OK to order new coils and coil boots. On top of that, I'm going to get all new pads and rotors, new e-brake parts to fix supposedly stuck expanders, new front struts, a new tie rod assembly and ball joint (driver side), and a new driver side door microswitch because the car thinks the door is open when its closed.
I had mentioned before that ignition coil 2 had failed previous to this, and was replaced by him, but the boot itself was not, so I've got 5 brand new coils and 6 boots on the way, to go along with the fresh plugs already in the car. If this doesn't fix it I don't know what will. Bad DME/ECU? Some sort of short somewhere?
Here's some further information for anybody with any input. There is no CEL. I took it to the BMW dealership, had them replace the o2 sensor with a new one which I supplied because I figured it might make a difference, (which it really didn't), and they said the ignition system seemed fine, but I know for a fact it is not. In regular mosey-around city driving the car performs alright. Coming off the highway today where I had been doing about 120-140km/h for about 20 minutes I noticed something. The harder I put the car under load, the lesser it performs once it calms down. I illustrated this by coming to a stop sign after coming off the highway, the car had been accelerating seemingly fine, maybe a hiccup here or there, I was in fifth gear revving at about 3.5k+.
Once I came to a full stop and tried to start moving again I had to give it much more gas before the car pulled forward. At this same time the engine had been shaking, and I could feel it a little bit. When holding the shifter during my launch from a stop you could really feel the engine struggling to output power and push the car forward. I know the clutch isn't slipping because the revs don't go up when I floor it, the car just doesn't want to push itself. I tried driving it home after this as though I was driving my normal commute from work. Every hill I encountered proved to be a struggle, I was always in the proper gear at the right time, with minivans and oldschool land yachts ahead of me speeding off, and when I floored it I just couldn't keep up, it's embarrassing. As the revs climbed higher, the car was certainly more responsive. I could accelerate with few hiccups when revving at about 4.5k+ in first or second gear.
I finally arrived home and parked the car. I opened the hood, and the engine was shuttering, shaking quite hard. There was a deep, somewhat subtle "thudthudthudthud" noise coming from the engine, and the exhaust was making the same thudthudthud noise, but when I held my hand behind the exhaust you could feel bursts of exhaust emissions coming out with every thud.
Any and all input is appreciated, I have been browsing any and every forum I can find for e36 hesitation and bogging problems with no real definitive answer.
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.