Happened to the sisters car only that one involved coil packs instead of a distributor set up.
Everytime it was raining, humid, or whatever just moisture in the air it would run like crap and it gave no codes.
Changed coils, wires, plugs everything to do with the ignition. The thing that only really seemed to fix it was loading everything up with di-electric lube.
We bought a big *** tube and put it in every end of the spark plug wires and the prongs under the coil packs...been runnin fine since all that.
Now I dont know if this will help you at all if the problem is happening from rotor to cap, but it would hurt to hit all the plug wires

 

You might consider the injector poppets sticking, a VERY common failure we see almost daily. There is a bulletin to replace the original SCPI system with a MPI system that cures that problem. For California vehicles there was a Special Policy Bulletin from GM.

The GM Bulletin is 00-06-04-003B.

It's a bolt-in fix.

 

Yeah Deathrattle I dielectric greased everything I could think of and more. After that did not do it.. In an act of frustration I sprayed the ignition components with WD 40. Nothing helped at all. BTW. Where are those pics of your Dyna you promised?

Retrowill I am not sure what an injector popit is. Could you enlighten me? How would humidity affect them?

 

Yeah Deathrattle I dielectric greased everything I could think of and more. After that did not do it.. In an act of frustration I sprayed the ignition components with WD 40. Nothing helped at all. BTW. Where are those pics of your Dyna you promised?

Retrowill I am not sure what an injector popit is. Could you enlighten me? How would humidity affect them?

Wow...didnt think i was old enough to outright forget things like that...but it happens..ill try tomorrow

 

The fuel injectors on that vehicle are what GM called "SCPI"....or Sequential Central Port Injection". It has a main block of fuel injectors in the inside the center of the lower intake manifold with small plastic tubes running to each intake port. At the end of these tubes is a small metal spring loaded "poppet valve" that waits for the system to send a high pressure wave of fuel to each injector, at the specified pressure the little poppet valve is opened allowing a squirt of fuel to that port. These worked pretty well but as mileage increased these little poppets have a tendancy to stick....either open or closed, usually closed. Of course that causes a missfire. Engineering redesigned the system a couple years ago, made a "retrofit" kit to replace this entire injector package with true port injectors.....small electronic port injectors that do not rely on poppet valves. It cures all those sticky fuel related problems. In California they had a GM Special Policy to upgrade these systems because they were causing emissions problems. The new system is much MUCH more precise and runs better than the original design. It all bolts right in to the engine nicely.

 

That is interesting to know.. Might me something to think about on this high mileage motor.
I don't see a relation to these (popets) malfunctioning due to humidity though..

I have been dealing with this problem for some time and it has not changed other than depending on how humid or wet it is outside.

 

.....yeah, these things really don't care how humid it is.

 

Pop the hood on one of those mornings in the dark, probably the plug wire's are bad.
You can mist some water on them at night to duplicate the condition.

 

Have some one put a good scan tool on it and see what altitude it thinks it is at. We had a similar issue on a vehicle here and it turned out the altitude reading was 2000 ft above sea level. The humidity can effect this as I believe it is determined by the MAF.

Chet

 

Yeah Onebad80 I did all that and did not see any lightning. I replaced my new wires with better ones anyway just to make sure and did the plugs too.
No change at all.

Tbucket was it a malfunctioning MAF that cause the weird reading? I had it scanned but I still have not found a good guy. I will not take it to a dealer. I worked at a dealer!

 

Yeah Onebad80 I did all that and did not see any lightning. I replaced my new wires with better ones anyway just to make sure and did the plugs too.
No change at all.

Tbucket was it a malfunctioning MAF that cause the weird reading? I had it scanned but I still have not found a good guy. I will not take it to a dealer. I worked at a dealer!

I believe that was the fix, we chased it for a while, it missed and pinged a lot. It was either a maf or a map, and there were no codes either.

 

Most likely it is the MAP sensor. This might be part of the MAF, but on your vehicle I doubt it.

Moist damp air, leads me to believe, it has an HO2' sensor problem. One that is "lazy" before the catalytic converter.

If you have an aftermarket (oil based) intake air filtration filter, this can also cause this drivability problem.

JMO

 

I replaced the MAP sensor this afternoon after seeing yalls posts. Five minutes of install and a $50 dollar part. I figured it is absolutely worth a shot.
I will not know if it was or was not until tomorrow morning. I have learned not to get my hopes up with this thing.

As always I appreciate all the help and suggestions from you fellas.

 

Dang! I had a feeling it would not be that easy..

Any other ideas?

 

I have been dealing with this problem for over a year now.
I start the truck up in the morning and if it is humid out then I will get a bad misfire after about a mile of driving but not before. It takes a about a mile before it will start. Even if it is raining. The mis is directly proportional with how humid it is outside. Around here its always humid until things start to cool off. Then The mis is gone on those dry days.
What could cause such a weird problem? Nobody knows!
I get no codes.


I replaced the coil, dizzy cap and rotor, plugs and wires twice, ignition module. Went crazy and did the O2 sensors.
Nothing has make a difference.

If you can figure this out I will buy you some beer!

pull the dizzy out ad take a good look at the gear.
the vortecs eat 'em for some reason...
if you had a scanner, you wouldn't have to pull it to see it but not everybody has one.
not saying it's your problem but....

dist caps die on these too with no visual
problems BUT it still sounds like a cracked plug or bad wires to me...

 

Yeah I had thought about the distributor gear, But in dry weather it runs perfect.. So that could not be it..

It sounds like a bad wire or cracked insulator on a plug to me also!
But after changing them twice and still having the same problem how could that possibly be?
Thats why I am really going crazy over this thing. :smash:

 

well, you MIGHT want to try replacing the crank sensor (bottom of the timing cover, usually leaking oil )


any way you can get it scanned?

 

Its fixed.....


I decided since I had only replaced the dizzy cap and rotor once I would just do it again for good measure.

I noticed that one of the hold down screws on the distributor cap was loose. It looks like the hole for it on the distributor was broken. glued all that back together and filled the new cap with dielectric grease.

I am mis free for the first time in a year! It feels good but I was beaten by this problem. I still don't understand it!

The way it would not happen until I drove for a mile.. And why it would go away after 10 miles or so... How the humidaty and tempature effected it...
Man I just don't know. I am glad that its over. ain:
I have never had my butt kicked by a vehicle like this before. :boxing:

 

Don't get too excited, i had a 97 and for a year i delt with a misfire code, changed plugs, wires , cap , turned out the intake gasket was bad, (common prodlem) and was causeing a lean condition in the affected cyl. changed the gaskets and it ran perfect for another few years till i sold it.

 

Its fixed.....


I decided since I had only replaced the dizzy cap and rotor once I would just do it again for good measure.

I noticed that one of the hold down screws on the distributor cap was loose. It looks like the hole for it on the distributor was broken. glued all that back together and filled the new cap with dielectric grease.

I am mis free for the first time in a year! It feels good but I was beaten by this problem. I still don't understand it!

The way it would not happen until I drove for a mile.. And why it would go away after 10 miles or so... How the humidaty and tempature effected it...
Man I just don't know. I am glad that its over. ain:
I have never had my butt kicked by a vehicle like this before. :boxing:

I now understand which distributor you have, it's that plastic piece of junk GM put out for only a few years. Sorry I did not pick up on this earlier on this thread.

I have had to replace only 2 of these, one for a broken housing at the hold down clamp, and the other one was for the 2 cracked distributor cap mounting holes.

Both of these were towed in, and had obvious problems for no starting. The one with the cracked cap hold down bolt holes was towed in on a rainy day. The cap and rotor had damage to it, and I just figured that to be the problem. I just replaced everything and it cured the no start problem.

:thumbup:

 

I now understand which distributor you have, it's that plastic piece of junk GM put out for only a few years.

:thumbup:

Why do they do this to us? It makes me sick.

 

Don't get too excited, i had a 97 and for a year i delt with a misfire code, changed plugs, wires , cap , turned out the intake gasket was bad, (common prodlem) and was causeing a lean condition in the affected cyl. changed the gaskets and it ran perfect for another few years till i sold it.

Heck I would have been glad to do the intake gaskets after all I have been through. It passed my leak test.