3100 miss / sputter after udp install

[bobgagt]

Hey guys, I just found out about this place so I figured it would be appropriate for me to post here. I have a 98 Grand Am GT with the 3100... you can see pics in my sig.

Anyways yesterday I installed the ffp underdrive pulley and rksport engine mounts (the lower dogbone and upper insert). We did everything as the directions told... started it up it was all good. Revved up fine, etc. So after I left I had to get on it of course. The car runs smooth, but now at WOT it will accelerate fine to like 4-4500 rpm then sputter sputter then keep climbing, then sputter, then 5500 then shift. It doesn't do this all the time. Sometimes it will just be one lil sputter that feels like wheelspin... but again this is only at WOT... and when its not sputtering it feels like the shit made a difference... but it sucks because this is happening.

Anyways, the crank sensor ring is pressed into the new pulley, it wasn't bent at all by the holes and its epoxy'd into place. I also have no codes being thrown (or at least no check engine light). It has been raining these last few days, so MAYBE that has something to do with it... I'm guessing its not related to the crank pulley (and hoping). My other mods are cai, 180 tstat, straight pipes where stock mufflers were. So is this a spark problem? What should I check first?

Thanks guys
-Bob

[bobgagt]

So something is probably messed up with my crank sensor. Just a thought. I can tell you all that removing the stock sensor ring and putting in the new pulley is not fun, and I wasn't too impressed with how far it sticks out of the new pulley.

Anyways, the udp made my car slower... this sucks

Can anyone help me?
thanks
-Bob

[robby1870]

Before you go messing with the crank sensor, check your coils first

[bobgagt]

Yea I'm going to change the plugs and wires first. I did notice a slight miss before I did this stuff and I think that now its worse because of the new mod (maybe) and the fact that it has been raining for the last few days... so its always wet under there and yeah...

I have stock plugs / wires and 92k miles so I think theyre in need of changing. I was told by my bud who is a mechanic that if something was rubbing the crank sensor that the car would prolly not stay running.

SO... in a day or so I'll change the plugs and wires and see if that helps. If anyone else has ideas let me know.

Thanks
-Bob

[robby1870]

On my old 92 GP (old crank sensor that goes into the block, not on the pulley), the wire was rubbing the block and grounding the sensor out and the car wouldnt run. Im not familiar with the new style crank sensors, but if there are wires, they maybe rubbing. But, if you said it was missing a little before, the very slight loss in alternator output b/c of the UD pulley might cause the miss to get worse. Im just throwing out ideas here, trying to think of something that makes sense

[bobgagt]

Yea its hard to make sense of this. The newer style crank pulleys have a sensor ring that has to be pressed into the pulley, then the actual sensor on the block. But the car starts, drives and idles perfect (aside from the TINY miss that has always been at idle)... its WOT that the problems happen. And the alternator should be putting out damn near the same voltage at wot now as it did before... at least at high rpms... at idle I know theres a bit less power.

But again, I never really drive my car hard when its raining, and the weather has been very odd lately... half snow half rain. I don't know... this is just crappy and I don't want to have to mess with the crank pulley again but we'll see I guess.

-Bob

[bszopi]

The reluctance ring has no effect at WOT. It is only used for a more accurate crank position as low RPMs for a smoother idle. Therefore, the UDP isn't causing your problems. The 3x00s still maintain the in-block 7x crank position sensor.

[bobgagt]

So its gonna be related to something else then... thats good to hear I guess

[vsop4me3.1]

I had the same problem I changed my wires and plugs but the problem was still there so I let it go untill it got really bad. It turns out that the sensor ring in the crank pulley came loose which caused it to slip and "sputter". I would take the pully off and make sure you tighten the ring down with the 2 or 3 screws used to hold it in place

[bobgagt]

I have the pulley with no screw holes... the ring is pressed in there evenly and epoxy'd into place but I guess it could be that if you had the same problem. I'm off to autozone to get new plugs and wires.

-Bob

[bszopi]

Even though I already talked to Bob about it, here is a description of the 24x sensor for everyone else....

PURPOSE
The 24X crankshaft position sensor is used to improve idle spark control at engine speeds up to approximately 1250 RPM. A concentric interrupter ring mounted to the rear of the crankshaft balancer has blades and windows that, with crankshaft rotation, either block the magnetic field or allow it to reach the 24X crankshaft position sensor. The 24X crankshaft position sensor contains a hall-effect switch. The interrupter ring has 24 evenly-spaced same-width blades and windows and the 24X crankshaft sensor produces 24 "ON-OFF" pulses per crankshaft revolution. The 24X and the 3X crankshaft position sensors react similarly. The 24X signal is used for better resolution at a calibrated RPM.

OPERATION
The magnet and Hall-effect switch are separated by an air gap. A Hall-effect switch reacts like a solid-state switch, grounding a low-current signal voltage when a magnetic field is present. When the magnetic field is shielded from the switch by a piece of steel placed in the air gap between the magnet and the switch, the signal voltage is not grounded. If the piece of steel (called an interrupter) is repeatedly moved in and out of the air gap, the signal voltage will appear to go "ON-OFF-ON-OFF-ON-OFF." Compared to a conventional mechanical distributor, this "ON-OFF" signal is similar to the signal that a set of breaker points in the distributor would generate as the distributor shaft turned and the points opened and closed.

[bobgagt]

Good information Brad

Well today I changed the plugs and wires and the problem is gone. Also though, the weather was dry... so its one of those things. But yeah, udp + mounts = good combination.

SO, SO FAR the problem is solved... lets hope it doesnt re-appear when it rains. But the back three plugs were terrible, and the car idles better now too... so thank you for your help all!

-Bob