Hesitation at 3500 RPM

[Court M3]

Just picked the car up a couple days ago, The issue I'm having is that when the car is warm it revs beautifully up to 3400rpm or so and then stumbles and bucks hesitantly until after driving around 300 miles, the car would hesitate and stumble for 2-3 seconds at time for about 3-4 miles intermittently and then seem to idle fine, go another 30-40 miles does it again and then upon driving further goes away.

Did the same thing today. Don't have any tools, but did a vacuum check with carb cleaner, but found none.

Read somewhere it could be a number of things, from the fuel filter to the regulator. No tools, so will have to take care of those upon arriving home.

Any other ideas? Just want to get this little issue fixed before going back to Japan.

[Cynical 1]

sounds like a fuel delivery problem. filter is cheap and easy.

[greyis89]

Had a similar problem. Stumbling and hesitation at low throttle input no matter the driving condition it was constant. Heavy throttle it was fine. Looked into a few of the things you mentioned, but for me it was a bad maf causing overfueling. Try another maf and rule that out since it's quick and easy enough.

[brenE30]

if it is a vanos motor then it could be the vanos solenoid

[TYBG]

my 87 es does the same thing... i just always give it the ol concrete foot

[M3PO]

I would guess it's the MAF.

[Court M3]

Well it turns out after a little troubleshooting it was just crappy Chevron gas. Found a Shell station and filled up with 91. No hesitation after, tank running low filled up on Chevron again and the hesitation and stumble came back before I could leave the parking lot.

Guess that solves it, Chevron gas is crappy!

[Mr.SWISS]

sounds like a fuel delivery problem. filter is cheap and easy.

+1

FP test while R3Ving?

[woc]

That chevron nitrogen molecule formula or what not is bad for our cars. Shell always. You could also get into consideration that gas is being mixed with alcohol too, they say 10% but I doubt that, it probably more, my fuel tank is old, and the alcohol is peeling out the gasoline residue layers in the tank from all these years, so I got myself a new tank and new lines, filter and should be installing soon. will try to post pics.