Saved from scrap

[Dan2002]

This past weekend I saved a 2003 Cadillac Escalade from being scrapped.


It did cost me a lot because I bought it from the scrap guy. He was going to part it out.

But I had to save it because it's one of the cleanest Escalade I have seen. And 0 rust,

The guy just told me that the engine had a skip. After checking it out for a couple of days, I managed to pull a code p0300 which is random misfire

Which is about 5 cylinders that have misfire when its running.

Today I checked fuel pressure and it's at 49-50 psi with the engine running, is that normal or does it need to be higher

 

[Fless]

That's normal for running fuel pressure. I think that year had a choice between the 5.3 and the 6.0 engine -- tell us more about what's in it, how many miles, etc. What's the 8th digit of the VIN?

 

[rockola1971]

How much is "alot"? Which cylinders are misfiring? Do a compression check of all cylinders. And like said before, which engine?(8th letter of vin). We need pics or it didnt happen!!!!

 

[TollKeeper]

At least its an 03, so no AFM/DOD to worry about.

8th digit?
Miles?

Who knows, you might get lucky and its a coil, or a shorted out plug wire on the manifold.

 

[Dan2002]

Yes sorry.

It's ,2003 Cadillac Escalade with 256,000 miles 2WD 5.3 engine vin "T"

I bought it because I have a GMC Yukon Denali with a 6.0 that has a rusty body and frame, but If this 5.3 is repairable I can keep it.

Misfiring cylinders are.

2, 6, 7 and 8

 

[TollKeeper]

If you had said 2, 4, 6, and 8... I would have said the wiring harness, or plug, for that bank...

But you had to go and say 7 instead of 4!

I personally would start with a compression test, after verifying spark, plugs, and coils.

 

[Fless]

And in addition to that, a fuel injector balance test might show a thing or two.

 

[Dan2002]

How much is "alot"? Which cylinders are misfiring? Do a compression check of all cylinders. And like said before, which engine?(8th letter of vin). We need pics or it didnt happen!!!!

How much psi compression should It be ok? With vehicle cranking or vehicle running?

 

[TollKeeper]

From memory, so my numbers may be off..

170-185 Is optimal
With the miles it has, 150 would be OK. Lower than that, and you might have issues

Edit: A quick google search shows that as low as 135 might also be acceptable, but power is starting to suffer.

 

[Bigburb3500]

Here for the party!

Give us all the break down what you replace/check. Plugs, coils and wires would be a good refresh to see if it’s a sparking issue. That can be a bit of $$$ tho if it has low compression

 

[Fless]

Besides the absolute compression value, all should be within about 15% or so of each other. Maybe even as much as 20%, but that's getting borderline.

 

[Alex_M]

I'd check spark plugs first - I've changed many a factory set at 250-280k miles and it makes a world of difference. My next guess is fuel injectors. I've had 2 or 3 with misses like that I had trouble tracking down and it was clogged fuel injectors. I'd swap coils around cylinder to cylinder before springing for injectors though, assuming spark plugs and wires are not the culprit.

 

[Fless]

So, ("T") an LM7 non-Flex engine. I was going to suggest running some E85 (or E30-50) but that's out.

If you get to the point of thinking it's an injector issue, I would recommend an injector balance test. If you pull the injectors to clean them, be sure to use new o-rings when reinstalling them.

 

[Alex_M]

And pay the premium for injectors from the parts store. There are fake "AC Delco" injectors floating around. I had one stick open and kill a motor.

 

[Dan2002]

Besides the absolute compression value, a

Besides the absolute compression value, all should be within about 15% or so of each other. Maybe even as much as 20%, but that's getting borderline.

Did compression check on one side of the engine,

Cylinder 8 == 90 psi
Cylinder 6 == 100 psi
Cylinder 4 == 110 psi
Cylinder 2 = 90 psi

 

[TollKeeper]

And thats the harder side of the engine to do. I would say you have some blow by going on by those numbers. Its within spec cylinder to cylinder (barely), but those are some pretty low numbers.

 

[Dan2002]

And thats the harder side of the engine to do. I would say you have some blow by going on by those numbers. Its within spec cylinder to cylinder (barely), but those are some pretty low numbers.

got all cylinders tested.

with engine running

Cylinder 8 == 90 psi Cylinder 7 == 90 psi
Cylinder 6 == 100 psi Cylinder 5 == 100 psi
Cylinder 4 == 110 psi Cylinder 3 == 95 psi
Cylinder 2 = 90 psi Cylinder 1 == 105 psi

thats with the engine running. i watched a couple of videos and they did a compression test but with the engine just craking. not running, so i removed the fuel pump relay
and re checked all cylinders again, they avarage from 135 PSI to 150 PSI,

so its safe to say compression is not an issue

 

[rockola1971]

Compression checks are done with engine cold, not running and throttle wide open. (Pull fuel pump relay to disable engine start).

 

[Dan2002]

Update..!!

Got a set of injectors on Amazon (prime) so I could get them quick,and cheap and installed them today.

Most of the misfiring cylinders are not misfiring anymore, I have my scanner which shows each cylinder, how many misfires it generates. I have only 2 cylinders on bank2 that are misfiring a little bit. And one cylinder on bank1 that is also misfiring a little. Bit

I believe those little misfires are due to the bad spark plugs because they were dark when I checked compression.

Now im about to order, new coils ,new cables,new spark plugs and new injectors, maybe a good name brand

 

[Tonyrodz]

Update..!!

Got a set of injectors on Amazon (prime) so I could get them quick,and cheap and installed them today.

Most of the misfiring cylinders are not misfiring anymore, I have my scanner which shows each cylinder, how many misfires it generates. I have only 2 cylinders on bank2 that are misfiring a little bit. And one cylinder on bank1 that is also misfiring a little. Bit

I believe those little misfires are due to the bad spark plugs because they were dark when I checked compression.

Now im about to order, new coils ,new cables,new spark plugs and new injectors, maybe a good name brand

Hopefully you got genuine AC Delco injectors. Amazon is notorious for selling knock off/bogus car parts, especially spark plugs. You really should make sure--as stated above--you buy genuine parts.