Missing and bad idle??

[DR. EVIL]

Ok, my idle feels like it's missing, and when I hold a constant partial throttle it feels like it's missing as well.... WOT is very good though...

I'm throwing a Cam Sensor Failure code, but my chip has the SM "fast refresh" on it and it may be causing funky codes on the T-Link. I've seen Water Injection Failure before

If my Cam Sensor is actually bad, will it cause this strange problem? WOT is fine, just the idle and partial throttle seem to be missing. It feels like it's surging or something.... no pops, any strange noises. Another strange thing is that sometime the O2's will stay rich and keep rising slowly for a while, and stay in the 800's constant for a few minutes. Eventually the O2 starts reading normal numbers....

I don't have the time to mess with the timing chain right now, so I need to eliminate everything else first. The plug wires are good, but the plugs might not all be good still. Wierd thing is that once in a while it rides fine at partial throttle... then starts with the "missing" again eventually......

 

[The Radius Kid]

FUBAR just went through something similar to this recently[similar symptoms and same code].Turned out it was his ignition module.

 

[DR. EVIL]

The coil pack is only a year or so old, not sure about the ignition module. Where is the ignition module exactly and how can I test to see if it's bad?

 

[V6UnderPressure]

I too am having the same problem to an extent. My car will idle fine and then when i give it just a little gas it runs like its missing or flooding. it will not hold a constant rpm until I get to 3000+ rpms. Basically the thing will not hold constant at 1000-2500 rpms. Would this be the ignition module? Is there a better aftermarket one? Anyone?

Scott

 

[Russ Merritt]

It's under the coil pack, it's what the wide wiring harness plugs into on the drivers side. without a coil pack tester, testing it is rather difficult. Try one from another car or buy one and keep the old one as a spare.

 

[azgn]

pull the cap off your cam sensor (2 screws) and verify the interrupter ring is tight and seated properly....sometimes the screw that holds it comes lose (locktite it!)

and/or unplug the cam sensor (after you start the car) and see if it runs better........if it does, you got some kind of prob with the sensor

 

[DR. EVIL]

Where exactly is the cam sensor? I know it's under the IAC somewhere. Is it the round thing there under the up-pipe with the 2 screws holding it down? (noticed you meantioned 2 screws). Do you have to unscrew it to unplug it, or is there a plug into it?

What bothers me is the inconsistancey of the problem, it sometimes idles pretty normal and doesn't act like it's missing, but then it starts up again.....

 

[DR. EVIL]

Well, I just ordered a Cam Sensor tool from Kirbans, even if it's not all my problems, I'm sure it needs adjusted.

 

[Jeff]

I had a similar problem...check this link

I had a problem that may be related to yours, check this thread...

http://www.turbobuick.com/forums/showthread.php?s=&threadid=47061

Haven't tried the solution yet, most of my problems seem to have been related to the crapped out EGR solenoid I just replaced.
Jeff

 

[DR. EVIL]

UPDATE

I just ran the car around after unplugging the cam sensor..... nothing changed, still missing... it must actually be missing

Just for grins I unplugged the wire boot to the #4 plug off the coil pack for a few seconds... nothing seemed to change in the idle...

I'm putting some new plugs in tonight to eliminate the possibility of it being fouled out plugs.

 

[blackbuick87]

I assume you started the car and then unplugged the cam sensor? I dont think this rules out the cam sensor yet.

As a side note I just changed my module tonight because my car had a miss at part throttle and would stall at lights. Drove about ten miles and have no problems (cross fingers) There are any number of ways a bad module can manifest itself. Some go right away, some die a slow painful death. The problem is they are not cheap. I bought a used one that was guaranteed to work and fixed my problem for $35. Hopefully you can do the same.

 

[DR. EVIL]

yeah, I started it, then unplugged the sensor and nothing changed. We're going to change the plugs and check the resistance on the wires (use a voltmeter?) and not sure how to check the coil pack...

 

[V6UnderPressure]

Hey I posted a bit back about the same problem. However, I am not pulling any codes, and I just calibrated the cam sensor a bit ago. So all is well there, you think its the ignition module? Im thinking of going with a msd dis 40 anyways, will this replace the module/coil packs etc?

Scott

 

[Jeff]

Originally posted by DR. EVIL
yeah, I started it, then unplugged the sensor and nothing changed. We're going to change the plugs and check the resistance on the wires (use a voltmeter?) and not sure how to check the coil pack...

I made up my own little "procedure" when I checked the coil pack on my '87 right after I bought it. I used a multi meter and check for continuity between the packs, which would indicate an internal short, which I did find. I think I also checked restistance with the meter, but I forget exactly how I did that. If your coil pack is _really_ bad, like mine was, you should be able to check it with the multi meter and detect some weird or inconsistent stuff.
That's all I did.
Jeff

 

[DR. EVIL]

Well I have new plugs ready to put in, not new wires though. The wires I have in there now are the Accel 300+ race wires. They tested with the least amount of resistance of any spark plug wire out there, of course they're expensive and you have to cut them yourself too... they are 2 years old though....

can you just test spark plug wires with a multimeter also?

 

[Jeff]

yeah, you can check the resistance of the wires with the multimeter, depending on what settings it has. You should be reading in the mega-ohms of resistance on a short wire, if I remember correctly. Service manuals should have a reference limit for resistance in stock wires.

FYI, I use the 300+ wires on my '74 Corvette, they're nice wires...
Jeff

 

[machinegun]

If you require a 2 step ignition and are running a brake, the MSD DIS 4 box is not needed. Really not needed at all unless going hog wild. The DIS system doesn not replace your stock module. It does however take over after either 1000 or 1500 rpm. Idle is still controlled by the stock module. IE if it is bad your problem will persist. I recommend fixing the stock ignition system, it has been low 9's and faster I beleive.