3-Series (E21, E30)Chat relating to the BMW 3-Series from 1975-1983 and 1984-1991 line. Specific models: BMW 315, BMW 316, BMW 318, BMW 318i, BMW 320/4, BMW 320i, BMW 320/6, BMW 323i, BMW 320i. E30 Family models include: BMW 325e, BMW 325i, BMW 325is, BMW 325ix.
Anyone ever experience this problem, I have a 91 318is, engine runs fine when first started, however once warmed up or hot, when I try to start it it, sputters as if its lacking fuel. I already have changed the fuel pump, fuel pressure reg, cleaned spark plugs, wires, ports etc. Disconnect O2 sensor to see if it is operating properly, car runs like crap without it so I know it works. Kinda feed up, any suggestions.
Thanks for the reply, just want to make sure that the ECT is the sensor located below the fuel rail just back of the oil filter. and that the sensor that operates the gauge is located on the radiator, yes. Also what is meant by AFM? The ckeck engine light is fine and does not illuminate. I'll give it a try. Thanks again
you say fuel pressure regular? i would go ahead and put in a fuel injector cleaner while you at it just to get it running better... do you have an after market air intake? maybe after it warms up it just isnt getting the quality oxygen it needs and isnt igniting as well as it should, hince what starmarvin was comming around to and i double, check to see the quality of the spark... that may be your problem...
I installed a K&N aftermarket cone style air filter and gutted the OEM box style filter. I was experience the problen well before that particular mod. Will add fuel injector cleaner though. Would a faulty coil cause this particular problem and if so how do you determine which of the four coils it is?
Thanks guys, learning big time by read other post as well, managed to fix a few problems by process of elimination with little or no cost.
Well, this is funny because I have the same exact car and it does the same exact thing. It's been doing it forever now. Sometimes it'll even die at stop lights.
Check for an open between the AFM ground and IAT sensor (it's bundled with the AFM). Mine's open and needs a new AFM. While I don't belive this would cause the problem, if you have the same issue, then maybe it is. Normally it would just make the engine run richer all the time, and I have seen this on my O2 sensor.
I've checked my idle control valve, fuel pressure, changed plugs/wires/coils, removed intake manifold and changed gaskets along with all the vacuum hoses etc., checked the TPS sensor, checked my purge valve to make sure it only purges at cruise... Everything checked out fine, 'cept for the AFM's IAT sensor. The only thing I haven't checked is the coolant temperature sensor, mainly because I remember it being in a hard to reach spot. I'm thinking of just buying one and seeing if it helps. However, I know the IAT sensor is shot. Anywho, keep this thread alive please!
There is another thing to check, however to do it correctly you'll need an oscilloscope. I have come across a few barely running motors with no obvious reasion why. And I have found that a bad or cruddy CPS can send a weak, but readable wave form causing the car to run like crap. This is a uncommon condition that should be tested first before throwing money at it. I don't want anyone giving me any greif that they shot out to the parts store and sank $100 for nothing. I do stress that you should search out all other options FIRST, such as build up on the sensor head (gunk, or rust), poor grounds, dirty sensor plug contacts, clogged injectors, weak relays, etc.
Hmmm hadn't thought of that. I don't have a lab scope though =( Any other ideas on how to test it? Wouldn't that cause more of a hard-start condition? It does seem like the engine is missing when it has this "hesitation". I'd say it's more of a stumble. I've hot soaked this car before a couple times and it doesn't fix the problem. I changed the plugs right after too. No help =(
no progress with vehicle thus far, changed the ECT sensor and secured (Clamped) off a couple of hoses to rule out any obvious vaccum leaks, working on researching some of the acronyms that have been thrown my way, I'm probably one that needs it spelled out, getting there though. Once resolved I'll let you know.
what is meant by "bump"? Anyway I tested the AIT sensor and it remains open as you suggested, unfortunately there is no way to replace it as it is in fact bundled with the AFM so the whole unit needs replacing. I also read that as a result of the AIT sensor failure it sends a reading to the ECU and place the car in a "limp home" status, this is probably why I'm still able to drive the car normally once the hestitation ends. Pelican Part want's 180 bucks for a replacement AFM, do you know of any place less expensive, the car is very much drivable just a pain in the ass when starting off on the second leg . Any suggestion on what may fail next so I can be prepared (Common problems you've experienced
You could CAREFULLY try opening the AFM and seeing where the IAT was severed from it's ground. That's about the only thing I can think of. Just make sure you re-seal it very carefully with some silicone or something. I was thinking of just adding a couple resistors to the signal wire and "fool" the computer into thinking the air outside is cooler and making it add fuel to the mixture, but it's prolly a better idea to just buy a new AFM =(
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