Author Topic: Hesitation on acceleration! (Read 8582 times)

wenbeaver · « **on:** October 09, 2011, 11:51:45 PM »

Hi i got a 91 m42 that runs great but under load when you accelerate it pull good but then kinda hesitates then kicks in again! Just wondering if there is any input. Fuel pump?

Ryann · « **Reply #1 on:** October 11, 2011, 10:18:48 PM »

Are you getting a check engine light? If so, Google and perform the Motronic stomp test and tell us what codes you're getting. If not it sounds to me like you've probably got a vacuum leak or fuel delivery issue.

wazzu70 · « **Reply #2 on:** October 12, 2011, 01:24:16 AM »

Vacuum leak, or possibly old plug wires/plugs.

DesktopDave · « **Reply #3 on:** October 12, 2011, 07:03:06 AM »

Gret suggestions...I'd check for a sticky AFM flap as well.

wenbeaver · « **Reply #4 on:** October 15, 2011, 08:53:54 PM »

Ok Thanks guys! I dont have a check engine light on an also it seems to do it mostly after its warm! When its cold it doesn't really do it much!

Nelson_40 · « **Reply #5 on:** October 15, 2011, 10:15:51 PM »

That sounds like it could a cracked hose somewhere that is being warmed and expanding. Also check to see that your intake boot is fully seated and not cracked around the edges on both sides.

anthonymax007 · « **Reply #6 on:** October 16, 2011, 11:45:40 AM »

Have you checked this? It's probably an issue already mentioned but I did this yesterday and it was helping me with my warm start issues:

http://www.m42club.com/forums/showthread.php?t=7757&highlight=figure+out

wenbeaver · « **Reply #7 on:** October 26, 2011, 04:34:28 PM »

Checked all the hoses all seem good! Checked the wire from the thread an its not plugged in! new fuel pump wasn't that! Not really sure what else to try!

wenbeaver · « **Reply #8 on:** October 26, 2011, 04:38:11 PM »

Also if i let up a little bit on the gas it clears up an pulls good then does it again!

Ryann · « **Reply #9 on:** October 26, 2011, 10:52:44 PM »

Did you remove the upper half of the intake manifold and check all your ccv/icv hoses?

wenbeaver · « **Reply #10 on:** November 04, 2011, 10:21:36 PM »

Checked all the hoses i could find all seem good replaced a few an still does it! The gas tank has been replaced lately wondering if a fuel vacuum line could be messed up?

wenbeaver · « **Reply #11 on:** November 14, 2011, 09:05:03 PM »

Removed the intake manifold an checked all the hoses under there all seems to be fine. AFM meter seems fine too!?

?

Ryann · « **Reply #12 on:** November 14, 2011, 10:46:35 PM »

Did you check closely for cracks in the rubber intake boot? It's pretty common for them to split on the AFM end along the ridge where the hose clamp sits. Also check the port and plastic elbow on the bottom. Does it start hard when warm?

wenbeaver · « **Reply #13 on:** November 15, 2011, 04:45:04 PM »

checked all the afm hoses an stuff! Doesn't really start hard when warm either!

Ryann · « **Reply #14 on:** November 15, 2011, 09:05:47 PM »

Pull the vacuum line off of your fuel pressure regulator while the car idles. The idle speed should kick up a bit and no fuel should be present in the vacuum line.