My brains are oozing out of my ears or I am getting confused.

I have a nasty misfire issue that started after I changed the timing cover and timing chain.

I took it to a mechanic who had trouble doing the CASE relearn due to a P0300 code being set. At this time cylinder 6 seemed to be culprit but then if shifted to cylinder 1. So we agreed to change the ignition coil and cap and rotor. also found the number cylinder on the header.

This straightened out the misfire code and cleared it. A CASE relearn was done. he suggested that I replace the number one wire and plug so I did.

Seemed to be fine but had some intermittent misfires on cylinders 1,4 and 6.

I drove on my vacation and it seemed to run fine until a cold Montana morning and tank full of 85 octane fuel. it set the P0300 code. noticed a high number of misfires on on #1.

So I cleared the code and refilled with mid grade mountain fuel i.e. 87 or 88 octane.

Drove it home 1510 miles and 91 gallons of fuel getting 16.6 mpg.

It set the P0300 code so I checked the misfire history

Cylinder 1 18,136
Cylinder 2 5
Cylinder 3 97
Cylinder 4 5,886
Cylinder 5 2
Cylinder 6 858

I was worried about a hot trans but the misfire might be the source of the issue. It didn't have a misfire until I changed the cover and change.

Is the CMP retard a symptom or a cause?

 

Why did you change the timing chain, what was the truck doing at that time?

Have you had the distr out? If so, was the gear worn?

Did you change anything else?

Do you know what CMP retard was before these changes?

Any other codes?

With CMP retard that far out and random misfires flopping around you most likely have a timing problem and are getting arching and carbon traces in the distr cap. Do you see carbon traces from the posts under the cap? Do you see arching in the engine compartment around the cap or wires in the dark?

67 1/2 Camaro. Nice!


George

 

The cover was leaking at the crank position sensor as the bolt had been over tightened prior to me getting it., Since I dug into the the engine that far and it had 230k miles figured a new timing chain was a bit more time and wouldn't hurt. .

Just learned today what the CMP retard was on the truck because I learned that Dash Command could read it. so no idea what it was before.

When I did the LIM gaskets 20k miles and 2 years ago the distributor gear wasn't worn.

Yes one other code but it's a C0265 for the ABS system which I don't think is related.

The old cap had corrosion and no arcing around the wires did that inspection earlier tonight.

Before I fire the parts cannon trying to determine if the CMP retard is a problem or a symptom.

Fuel trims are decent so I am not worried about the fuel system and MPG was the same as it always has been on the truck so I don't it's dumping fuel. Previous to me buying it it had the upgrade spider installed.

Fuel system held pressure for over 10 minutes with only losing 1-2 pounds as I tested twice.,

If I decide to adjust the CMP reatrd should I turn the distributor clockwise or counter clock to get closer to zero? .

 

I believe that you rotate the distr CC to bring a negative reading closer to zero. Its simple though because you do it while the truck is running and watch the value on scanner live data. These distributors are not meant to be adjusted so you will need to either bore out the hold down hole to an oval shape or buy a new hold down that is adjustable. I did the latter:


Are you confident in the timing chain alignment? Did the distr come out this time?

George

 

I had to rotate the engine as the 1st time I brought the #1 piston up it was 180 out. The two marks on the sprockets were pointing to each on the set removed and the one installed.

 

Tonight two discoveries were made.

First the bad one even though I tried to be careful there is a small crack in the front ear of the distributor housing. So my hope of getting a billet distributor has moved closer. The cap is on and doesn't move but the next time I take it off it will probably be the last. Any recommendations?

The truck runs much better after I loosened the distributor hold down bolt and moved the unit CCW.. Number 1 doesn't really show any more misfires but number shows a few. 6 and 4 aren't as bad. The CMP retard went from 9.7 to 6.2.

I will have to see if I can enlarge the hole and bring it closer to zero.

 

Meticulously clean and then epoxy the ear with JB Weld. Just epoxy on outside if it hasn't broken off yet. Inspect the distributor gear for wear. This is a common cause for negative Cam Sensor readings. If the gear is worn out, go for one of the cheapo billet distributors you can find for the Vortec V6 ($40-$50). Save your old distributor for the cam sensor and cap/rotor in case you need one.

 

Thanks Les had to read it on my computer not my phone to actually see this.

I think Skip White was selling the SW Performance units made of the finest Chinesium. Seen people have great results and others have issues with the assembly not being right.

Summit sells one they have an answered question that they are made in El Paso

Found a burned wire on cylinder 2 which never increased it's count but number 1 showed no current misfires but the historical count was increasing. Changed out the wire on #2 in the 10 minutes between vital meetings today.

Reduced the misfires but #2 is still showing a misfire but at about 1/10 the rate as before. Number 4 and 6 seemed to still be increasing but again at a reduced rate.

 

I've got almost 50K miles on my Skip White Chinesium distributor. But he doesn't seem to sell them any more.

 

I have over 70k miles on the Skip White dizzy. Cam retard sitting at -0.2°.