That is my thought too, that I have the back coil pack bracket against the intake. It makes sense to me, the whole time I was putting it back together I was thinking that I was going to do exactly that. The throttle cables are good, clear of obstructions. I ended up replacing the spark plug wires, did not swap the coils. When I pulled #5 off the coil pack it looked like it was broken inside and came off more easily than it should have. Hopefully it is just a matter of loosening it up again. I got a endo camera from temu a while ago. Works really well to see what is behind the engine, $10 well spent, it plugs into a phone or tablet.

Hopefully I can get it sorted tomorrow, its not nearly as intimidating as one may think. Also, the wire loom they sell at Harbor Freight is junk, I used it for my fog lights and it literally is crumbling into pieces after about 2 years. The OEM stuff is fine after 20 years.

 

New coil packs, New leads,10k miles on plugs. When I started it up, ran great at idle. Drove ot 20 ft and the misfire started. First a blinking ses, then on solid.

From what I have read, the blinking ses js bad sign. Something is wrong that will destroy the cats? Any suggestions on what that is?

I swapped the 3 and 5 plug, the misfire is still at 5. I triple checked my wiring, if one was misplaced i would have 2 misfires.

Saw that a bad injector could be the issue, anything else i should look at while it is apart for the third time?

Would scoping the cylinder show me anything of value?

What else causes a misfire?

Thanks again

 

Did you check compression? Like I said before, anything under about 90 psi will set off a cel for a misfire.

Just takes a little carbon and pitting and and exhaust valve will leak. These engines have some very weak valve springs to boot.

 

I have not had one done in a while. I can pick up a kit and see what it it finds. If there is low compression, short of pulling the heads and getting them re-done, is there an easier solution?

I thought it is meaningful that it idles beautifully, but as soon as it is in gear it stumbles and the SES flashes Sounds like it may point to low compression?

I picked up a compression gauge, will try it tonight.
Thanks for the direction, I hope its not the compression.

 

If it's valve issues or leaky head gaskets pulling the head is the fix.

But I wouldn't worry about that until you've completed the test.

Pull all 8 plugs and the fuel pump relay, then test them all. One low cylinder won't show up much at idle on a V8.

 

I pulled all the plugs except 7 and 8, when I crank it, it seems to only get to about 30psi. It will hold 30 psi, at least around 15 minutes, but not get above 30 psi, I cranked until the battery almost died.

I got the same result when I only pulled #5. Left the other plugs in place. Does it matter to pull 7 and 8? As low my readings are.

I had the engine tested several years ago and it was high and uniform, I forget the actual numbers.

It is worth doing a wet test, I am sure it would not get the psi up 100?

I noticed a few drops of oil in the throttle body, could that be related? At idle it sounds perfect, quiet, smooth.

How would I determine if it is the head gasket or the valves? Pressure test the cooling system? It does not lose coolant, at least not enough to measure really. Or worse? If its the heads, I can manage that, if it is related to the cylinder, I would probably need to take it to shop.

Any thoughts?

 

I would pull 7&8. It will help your starter crank the engine a little faster. And then test all your cylinders. If you don’t test at least a few of them you won’t even know if your test gauge is accurate. 30 psi is very low.

 

Wet test it, if the compression comes up then it is the rings. You can also use a blowby tester to determine if it is the rings or the valves or something else. Or if the kit has a quick connect just connect your air compressor to it. If it is intake valve will blow out the intake, if exhaust valve it will out the exhaust. Either way with 30psi the head has to come off. Good idea to check some of the otehr cylinders and make sure the gauge is working properly. Also good to pull the fuel pump relay while cranking and open the throttle wide open.

 

I'm not sure I'm following, was cyl five 30 lbs or all the cylinders?

The idea is test all cylinders and compare numbers.

If all are reading 30 except 7 and 8, try another gauge and try 7 and 8. Also make sure you're holding the throttle open while doing this.

 

I have a thread in here from a couple of months ago where I was chasing a misfire that didn't go away with coils, plugs, wires, or injectors. Finally, I did a compression test and had zero pounds. Was a blown head gasket. Mine was not intermittent, but I had a massive blow. Yours may be a much smaller failure, causing it to be less consistent and have some pressure built up rather than 0 psi, but 30 is super low. Also, I had a small amount of oil in the intake too.

I hate to say it but it sounds like its probably a blow between the head and valley, your symptoms are really similar to what mine were. Like the others said, pull 7&8 and test the other cylinders, but it sounds like HG.