SOLVED: Another misfire chasing threads (2008 express van)

[Tonyv__]

The wires definitely fixed the morning misfire issue. But I noticed as I was trying to pass someone on the highway (pretty aggressively) my CEL was flashing and detected random misfires. The code is gone for now as long as I take it easy on her.

I’m fairly convinced I’m just running on borrowed time since I had to open the engine up at 60k ish Miles last year.

 

[Rocket Man]

I don’t remember, but have you had the cats checked for restriction? That’s exactly what mine was doing
, the cats were 60% restricted.

 

[Tonyv__]

I don’t remember, but have you had the cats checked for restriction? That’s exactly what mine was doing
, the cats were 60% restricted.

so before I tore the engine apart last year I definitely borrowed a cheapy tool like this pressure tester and it showed nothing significant to make me think there was a clog.. however that was a year ago. And earlier this year I definitely put a cheater bung extender on my downstream 02 sensor because it was throwing codes. The codes stopped after that.

I can order a tester for myself and try again. Or would 1 get significantly hotter than the other like if I used a temp gun?

 

[OR VietVet]

so before I tore the engine apart last year I definitely borrowed a cheapy tool like this pressure tester and it showed nothing significant to make me think there was a clog.. however that was a year ago. And earlier this year I definitely put a cheater bung extender on my downstream 02 sensor because it was throwing codes. The codes stopped after that.

I can order a tester for myself and try again. Or would 1 get significantly hotter than the other like if I used a temp gun?

View attachment 379770

You want the cat to show close to the same temp at front middle and back.

 

[Tonyrodz]

The wires definitely fixed the morning misfire issue. But I noticed as I was trying to pass someone on the highway (pretty aggressively) my CEL was flashing and detected random misfires. The code is gone for now as long as I take it easy on her.

I’m fairly convinced I’m just running on borrowed time since I had to open the engine up at 60k ish Miles last year.

I'm starting to think Express Van's are pieces of shit. Mine has been nothing but problems, and I think the motor is going. I had that flashing cel before too. 1 of the cats was more restricted then the other, so I gutted it. I also had a hv Melling oil pump installed maybe 2 years ago because0 oil pressure. Also did the O ring, cleaned the pickup and cleaned all the sludge out of the oil pan. Cold idle was almost 80 psi, and warm idle was around 60 psi after that. Now at idle it's 0, and when I rev it, it's maybe 10-20 psi. Only has 161,000 miles too. I'll never buy another one!

 

[Tonyv__]

I'm starting to think Express Van's are pieces of shit. Mine has been nothing but problems, and I think the motor is going. I had that flashing cel before too. 1 of the cats was more restricted then the other, so I gutted it. I also had a hv Melling oil pump installed maybe 2 years ago because0 oil pressure. Also did the O ring, cleaned the pickup and cleaned all the sludge out of the oil pan. Cold idle was almost 80 psi, and warm idle was around 60 psi after that. Now at idle it's 0, and when I rev it, it's maybe 10-20 psi. Only has 161,000 miles too. I'll never buy another one!

I really only bought it because I’ve had good experiences with all my Gm trucks in the past. But this one is really a pain in the ass.

I also couldn’t afford any of the newer vans on the market lol


My oil pressure never improved after new pump, o ring , and rebuild on the top end. I still idle at like 10psi

 

[Tonyrodz]

I really only bought it because I’ve had good experiences with all my Gm trucks in the past. But this one is really a pain in the ass.

I also couldn’t afford any of the newer vans on the market lol


My oil pressure never improved after new pump, o ring , and rebuild on the top end. I still idle at like 10psi

I think the root of my issue is one of the 862 heads might be cracked.

 

[Tonyv__]

I think the root of my issue is one of the 862 heads might be cracked.

How does that even happen? Overheated in the past?

 

[Tonyrodz]

How does that even happen? Overheated in the past?

No idea. It has the 4.8 which has the 862 heads. I read somewhere the 862's are also prone to cracking like the Castech heads. I'd have to add coolant maybe once a month to the overflow bottle. It would just be empty. Actually I had the same issue with my 03 Tahoe, which also had the 4.8 with the 862 heads.
I think it's just a lemon. Bought it with 110k, driving it home the water pump went. This summer I replaced the trans--160k--and it already had a GM reman trans in it. If I keep it I already know I'm gonna need to replace the motor. Should've got a ferd lol.

 

[Rocket Man]

so before I tore the engine apart last year I definitely borrowed a cheapy tool like this pressure tester and it showed nothing significant to make me think there was a clog.. however that was a year ago. And earlier this year I definitely put a cheater bung extender on my downstream 02 sensor because it was throwing codes. The codes stopped after that.

I can order a tester for myself and try again. Or would 1 get significantly hotter than the other like if I used a temp gun?

View attachment 379770

IDK. I paid a shop to test mine, cost me $60 or something.