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Engine Specific Info and Questions => IDI Engine => Topic started by: silvertdi on April 04, 2009, 06:08:23 am

Title: Weird pulsing problem
Post by: silvertdi on April 04, 2009, 06:08:23 am

My 1.6 NA is doing something weird at 55 mph.  At precisely 55 mph the engine starts to "pulse" or "shudder" rapidly.  I can tell its the engine because its been "pulling" funny.  It seems like it has a 2-stroke power band where it will pull then fall on its face.  Once I get up to 55 the engine shudders.  It has new tires and alignment and overall is as smooth as glass.  Any suggestions?  Thanks.

Title: Weird pulsing problem
Post by: hamradio on April 04, 2009, 06:25:21 am

What gear is this in?

Title: Weird pulsing problem
Post by: 8v-of-fury on April 04, 2009, 06:57:48 am

did it happen after you added the new tires? Maybe they are out of balance?

Title: Weird pulsing problem
Post by: LoneWolf on April 04, 2009, 02:25:28 pm

like a juddering through the pedal at certain revs?

Title: Weird pulsing problem
Post by: silvertdi on April 04, 2009, 02:39:20 pm

Quote from: "LoneWolf"

like a juddering through the pedal at certain revs?

Yes, like a juddering in the pedal at a certain rev.  The whole car shakes.  I can tell the engine is shaking in its mounts.

It's in 4th gear.  The tires aren't out of balance.  This feels way different.

Title: Weird pulsing problem
Post by: maxfax on April 04, 2009, 07:23:00 pm

Would it feel anything similar to a gasser with bad plug wires????

Title: Weird pulsing problem
Post by: silvertdi on April 05, 2009, 05:31:21 am

Yeah, like a gasser with a cylinder down but only at a certain RPM.

Title: Weird pulsing problem
Post by: clbanman on April 05, 2009, 06:00:09 am

Does it do it in 3rd gear at the same rpm?   If it's engine related it should.  If it's actually only speed related it's something between 4th gear in your trans and where the rubber meets the road.

Title: Weird pulsing problem
Post by: Jettage1 on April 05, 2009, 05:15:56 pm

Make sure your IP bolts are all present & accounted for, and all are tight.

Title: Weird pulsing problem
Post by: vanbcguy on April 05, 2009, 05:35:27 pm

The one at the bottom of the pump just below the injector lines can cause some REALLY weird behavior when it's missing.  My car didn't have one there when I got it and it would do some totally nutbar surging at certain RPM ranges.

Just got back from a road trip and that bolt had come loose on me - started noticing a vibration that wasn't there before.  Once I fixed it the motor was smooth as butter.