My e30 is shuttering under acceleration. Need advice.

[Rouvld]

First let me tell you what type of e30 I have, I have an 89 325i auto. So, something weird happened justnow with my e30. I left my house to go to the gas station, my car started right up and ran like a top. I filled up with premium like I always do and when I started the car it kind of did a rough idle and cut of, it did this twice. The third time I started it, it idled perfect, so when I drove off I started to accelerate and it started to shutter. By shutter I mean itd accelerate then bog down, almost like I was flooring it then letting off over and over. I pulled over, turned it off then back on and it continued to shutter. I drove it for a bit and it stoped but it did shutter a couple of time again. At first I thought I filled up with diesel because the pump I usually go to is right next to the diesel pump but I looked at my receipt and I filled up with prem. I don't know if it's a vac line, fuel filter or what. I also want to add that before I filled up I was really low on fuel but my light wasn't on. And advice would be greatly appreciated.

[ST1G]

Could be the idle control valve, could be a vacuum leak, could be your fuel pump giving out.

Any whining coming from the pump?

By the way, there is no need to run premium fuel in an m20, it's just a waste of money.

[lambo]

Check your ecu temp sensor as well.

[YosemiteSam]

I had the same problem and it turned out it was my AFM going bad.

[808e30325i]

Check the hose clamps on your fuel filter, I had the same problem found out it was a loose hose clamp on the filter, tightened it and it was fixed. Just a suggestion for you to try.

[barbierij]

I had the same problem and it turned out it was my AFM going bad.

+1 on the AFM. Try to clean the connectors as well as you can and spread some contact grease on the connectors.

[straight6pwr]

the filling of the tank right before it starting running bad is probably a coincidence. this happens more often than you think then people get stuck on that idea and it put blinders on them as to whats really going on. however, it could be bad gas, which is uncommon, but not unheard of, so you could drain the tank just to eliminate the possibility.

To empty the tank using the fuel pump: Fuel pump is simple, undo hose, stick in bucket, remove relay, jump 2 wires and wait. Switch buckets as needed.

Do not run the fuel pump dry, you don't need to get every last little ounce out. As soon as you see it burbling out the hose with air, pull the jumper.

If you run it dry, you can damage the pump in short order, the fuel as cooling for the pump motor.

if its not that, there are a number of avenues to explore, the most likely being fuel or air. if you havent replaced them recently, you might as well change the fuel pump and fuel filter. if it ends up not being the fix, it doesnt matter, now you've got some good preventative maintenance done that wont bite you later. they are both super easy jobs that dont even require you to put the car on stands.

another thought to consider: you can keep throwing parts at the car or go to a car shop and have them diagnose. personally, I do all maintenance on my own cars, but the moment my engines start running funny, I go to the shop and they track down the issue in a single visit, versus me guessing and researching and throwing parts at the car based on hunches. i chased a stumbling running issue once: replaced the MAF, replaced spark plugs, replaced seals, etc but it ended up being the FPR was rusted stuck. no way I would have been able to figure that out without the proper diagnosing tools.

[dnguyen1963]

If you had run the tank to almost empty then it is most likely that you had clogged up your fuel filter. Take the filter out and see how dirty it is. Next, if the filter looks good, tee in a pressure gauge and monitor the fuel pressure when the car stumbles. When all that is done, do yourself a favor and have a smoke test performed. Also, check your CPS.

[e34john]

Sounds like when my c101 had a bad connection, only happened sometimes when it would ground out. Replaced tons of fuel and spark related parts and ECUs until it finally got fixed

[mr2peak]

Either way, save your gas receipt.

[ST1G]

No matter what it's a goose chase.