Help interpreting results

[pappyam]

Hi all
I have been battling with a misfire problem ever since I put in a new engine in my 4x4 97 Jimmy 4.3 vortec last year. I have read all I could find on the subject, with no results. I had done a complete tune up with new ac delco cap, wires plugs etc. with no improvement. I again changed cap and rotor but chose the expensive Accel brand this time with Denso wires and still no improvement. Now this engine has only seen around 1000 miles since last year because of this. I sometimes think I nailed the problem because the truck runs like a champ for a day but, this is rare. A buddy has a scanner that he lent me and it spits out a lot of info. Unfortunately, it does not save dtc and FF data so I had to type it all. I have included 2 files of scans I performed roughly 2 weeks apart. Each time, before the scan, I erased all dtc and FF data. I ran the truck and scanned it. I highlighted what I think is the problem but would need knowledgeable people to help pinpoint what the trouble could be. I must mention that all other scans performed since I have had the scanner (1 month) are similar. As a side note, the second scan was performed after I took out my alarm which I believe was short circuit. The battery was flat within 2 days. With it out, it seems OK. Therefore, the battery was out of the car for over a week. Now the truck really runs like s--t. Oh and,1st scan has no dtc's and cel is off. 2nd has Po147 and 300 and cel is also off.
Now I know what the DTC's mean, but would like opinions of a possible solution based on the scanner results. The fuel filter has been changed, pump pressure within specs, Maf cleaned and checked with scope as well as TPS, IAC etc. I have not opened the intake to check for a spider clog or FPR leak and the distributor gear looks fine. Also based on the same results, how would I adjust distributor timing when it is controlled by the Ecm? Any ideas?
Don

[Markb873]

Your right with the cam retard it should be around -11 or -12 on the 4.3L Also because you have a the highest misfire count on cylinder three and four (although all cylinders are misfiring) accompanied with the cam retard I would check the distributor shaft for back and forth movement Those are the first two cylinders that problem would appear on. When the shaft wears centrifugal force causes the cam to "appear" to retard more because of the movement of the distributor gear.

As far as the timing you can't adjust it at all it's locked in place as you know.

Hope this helps,

Mark

[pappyam]

Thank you. I will check the shaft. I was under the impression that cam retard was suppose to be 0 degrees!! What did you make of bank 1 injectors being on for roughly 1/2 second?
Don

[Markb873]

It's just a consequence of a symptom. All of the cylinders are firing "retarded" or as the pistons are on the way down already. More air/fuel has to be sent to the cylinders to maintain the idle speed. So you see ridiculous injector "on" times.

[pappyam]

Oh I see. Will start with the basic and check for shaft play but I really don't know what I am looking for!!
Don

[MT-2500]

Originally Posted by Markb873

Your right with the cam retard it should be around -11 or -12 on the 4.3L Also because you have a the highest misfire count on cylinder three and four (although all cylinders are misfiring) accompanied with the cam retard I would check the distributor shaft for back and forth movement Those are the first two cylinders that problem would appear on. When the shaft wears centrifugal force causes the cam to "appear" to retard more because of the movement of the distributor gear.

As far as the timing you can't adjust it at all it's locked in place as you know.

Hope this helps,

Mark

Camshaft retard should be 0 degrees or as close to +or - 1-2 degrees as you can get it.

[MT-2500]

Originally Posted by pappyam

Hi all
I have been battling with a misfire problem ever since I put in a new engine in my 4x4 97 Jimmy 4.3 vortec last year. I have read all I could find on the subject, with no results. I had done a complete tune up with new ac delco cap, wires plugs etc. with no improvement. I again changed cap and rotor but chose the expensive Accel brand this time with Denso wires and still no improvement. Now this engine has only seen around 1000 miles since last year because of this. I sometimes think I nailed the problem because the truck runs like a champ for a day but, this is rare. A buddy has a scanner that he lent me and it spits out a lot of info. Unfortunately, it does not save dtc and FF data so I had to type it all. I have included 2 files of scans I performed roughly 2 weeks apart. Each time, before the scan, I erased all dtc and FF data. I ran the truck and scanned it. I highlighted what I think is the problem but would need knowledgeable people to help pinpoint what the trouble could be. I must mention that all other scans performed since I have had the scanner (1 month) are similar. As a side note, the second scan was performed after I took out my alarm which I believe was short circuit. The battery was flat within 2 days. With it out, it seems OK. Therefore, the battery was out of the car for over a week. Now the truck really runs like s--t. Oh and,1st scan has no dtc's and cel is off. 2nd has Po147 and 300 and cel is also off.
Now I know what the DTC's mean, but would like opinions of a possible solution based on the scanner results. The fuel filter has been changed, pump pressure within specs, Maf cleaned and checked with scope as well as TPS, IAC etc. I have not opened the intake to check for a spider clog or FPR leak and the distributor gear looks fine. Also based on the same results, how would I adjust distributor timing when it is controlled by the Ecm? Any ideas?
Don

That far off on cam shaft retard can give you all kinds of miss fires and should be setting a camshaft retard code.
You need to get the camshaft retard to 0 degrees or as close 1 or 2 degrees as you can get it.

Like this picture.
http://files.automotiveforums.com/ga...hp?photo=51302
Some times with a dist replace or engine replacent.
And.
If you can not bring it in to the 6 on dist by turning dist you may have to remove dist gear and give it a half turn.
Let us know how setting the camshaft retard goes.

[pappyam]

Thanks for the help guys. I posted a pic of how I got it in last year and that is the closest I could get it to the 6. I took the dist. out tonight to check shaft end play but before I did, I played with the rotor to see how much it would move. I can move it back and fourth around 3/8". I don't know if this is OK. Up and down play of the shaft is .045". Checking the gear once more, I can definitely see worn teeth. No chipping but the wear pattern from one side to the other is not even. Some of the teeth at 12 O'clock are .020" thicker than at the 6 O'Clock position but, I don't know what is acceptable.
Don

[Markb873]

Originally Posted by MT-2500

Camshaft retard should be 0 degrees or as close to +or - 1-2 degrees as you can get it.

That's for the Vortec V-8. The V-6 has a much larger tolerance it will run fine within 12 degrees. Agreed though that 0 would be ideal. It actually wont set the DTC until over 20 degrees on the 4.3L and 14 degrees on the 5.7

[Markb873]

Originally Posted by pappyam

Thanks for the help guys. I posted a pic of how I got it in last year and that is the closest I could get it to the 6. I took the dist. out tonight to check shaft end play but before I did, I played with the rotor to see how much it would move. I can move it back and fourth around 3/8". I don't know if this is OK. Up and down play of the shaft is .045". Checking the gear once more, I can definitely see worn teeth. No chipping but the wear pattern from one side to the other is not even. Some of the teeth at 12 O'clock are .020" thicker than at the 6 O'Clock position but, I don't know what is acceptable.
Don

Yeah Don, she's a worn....

[pappyam]

Yeah Don, she's a worn....

Markb873
Are you saying that the whole distributor is worn out or just the gear?
Don

[MT-2500]

Originally Posted by pappyam

Thanks for the help guys. I posted a pic of how I got it in last year and that is the closest I could get it to the 6. I took the dist. out tonight to check shaft end play but before I did, I played with the rotor to see how much it would move. I can move it back and fourth around 3/8". I don't know if this is OK. Up and down play of the shaft is .045". Checking the gear once more, I can definitely see worn teeth. No chipping but the wear pattern from one side to the other is not even. Some of the teeth at 12 O'clock are .020" thicker than at the 6 O'Clock position but, I don't know what is acceptable.
Don

If the gear has any wear replace it with a good GM gear.
A Worn gear can also damage camshaft.

On bring it on in to center up with the 6 I have had to file out or drill out the notch in dist hold down plate.

And if it is way off over 15 degrees I turn the dist gear 1/2 turn on dist shaft.

You need to get the camshaft retard setting as close to 0 degrees as you can.
Remember the more degrees off the farther the rotor pointer is from the plug wire terminal on cap.
The wider gap on higher degrees off cause a lot hoter spark from having to jump that far.
Causes miss fires and burns up caps and rotors and plugs and plug wires and can even burn up pistons.
Good Luck and let us know how it goes.

[pappyam]

Thank you for the help. I am ordering a gear now and will let you know how it goes when I receive the gear.
Don

[pappyam]

Well, I would like to thank you both. Before ordering the gear, I made a test. I elongated my distributor hold down clam so I could play with the distributor. On the first try, I got it to -7.5 deg. The truck ran like a charm. On the second try, I got it to +0.5. The truck now pulls a lot better, fuel mileage has improved dramatically and it is now all around fun to drive. I drove it a few hundred miles since yesterday in all sorts of traffic and on the highway before posting back, just in case. I scanned it again and not a single hiccup although bank 1 injector open time still shows 400 mS. I am ordering the new gear this instant and, "THIS IS A GREAT FORUM"

[MT-2500]

Originally Posted by pappyam

Well, I would like to thank you both. Before ordering the gear, I made a test. I elongated my distributor hold down clam so I could play with the distributor. On the first try, I got it to -7.5 deg. The truck ran like a charm. On the second try, I got it to +0.5. The truck now pulls a lot better, fuel mileage has improved dramatically and it is now all around fun to drive. I drove it a few hundred miles since yesterday in all sorts of traffic and on the highway before posting back, just in case. I scanned it again and not a single hiccup although bank 1 injector open time still shows 400 mS. I am ordering the new gear this instant and, "THIS IS A GREAT FORUM"

You are welcome and thanks for posting back how it is going.
After new gear out on dist.
Put it on tdc compression and line the pointer up with the 6 on dist base.
Remenber if it does not come out the same with new gear or if new gear throws it way off turn the new gear a 1/2 turn on dist shaft.
Good Luck