Maf replaced but still a bad miss

Post by **Q_SHIP** » Tue Apr 12, 2005 5:30 am

I scanned the car before the maf. The car gave me a bad knock sensor code. What I think is happening is the sensors are throwing false knock and pulling more timing? Does this sound correct?

Post by **Q451990** » Tue Apr 12, 2005 5:43 am

Assuming we're talking about the 1993, you should not experience a miss from kock sensors. The typical symptom is that the car "just doesn't feel right" and you may notice some jerking under a load (e.g. OD at 40MPH up an incline right before a downshift).

A dead miss is more likely an injector, injector o-ring, or (rarely) a coil pack or Bosch spark plug. Have you ohmed the injectors? Even if they Ohm OK it's still very possible that one is clogged.

Heath

Post by **Q_SHIP** » Tue Apr 12, 2005 6:04 am

Im speaking of the 99 actually. You hit it right on the head. it is only when under load (lugging the car up a hill) or even at the top of the RPM range. It almost feels as if somthing is holding the car back.

Post by **Q45tech** » Tue Apr 12, 2005 6:21 am

Think globally, in that the knock sensors affect all cylinders whereas an injector is local and at rpms a single cylinder loss is barely feelable in WOT........1/8 power loss.........32 lb/ft loss would change quarter mile by 0.3---0.5 seconds.

Post by **Q_SHIP** » Tue Apr 12, 2005 6:30 am

It feels like it's more than that.

Post by **Q45tech** » Tue Apr 12, 2005 9:38 am

That's why I said think [globally] timing [affects all cylinders] a 8-10 degree retard can cut power in half.

Data log the ignition advance in various modes: light, medium, and full throttle acceleration to report the advance vs. rpm.

Post by **Q_SHIP** » Tue Apr 12, 2005 10:17 am

Thats why I was thinking it could be the knock sensor.

Can you tell me how to do that? or is it a hard thing to do?

Thanks for the help
Modified by Q_SHIP at 1:28 PM 4/12/2005

Post by **Q45tech** » Tue Apr 12, 2005 12:11 pm

An experienced master tech with a Consult II will eventually figure out how to data log. Cheap obd2 scanner don't record data fast enough.

Post by **Q_SHIP** » Wed Apr 13, 2005 5:10 am

This problem is taking every bit of enjoyment out of driving this car. I feel like I am driving a big P.O.S. Maybe I should drive it into a wall.

Post by **maxnix** » Wed Apr 13, 2005 5:35 am

The Consult II readout will help alot. Maybe Squeefoo can give you an informed opinion. It is solvable, once you obtain the dorrect diagnosis.

Maf replaced but still a bad miss

Maf replaced but still a bad miss

Re: (Q_SHIP)

Re: (Q_SHIP)

Re: (Q_SHIP)

Re: (Q_SHIP)

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