OP
OP
SOLVED: Another misfire chasing threads (2008 express van)
- Thread starter Tonyv__
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
OP
OP
Tonyv__
Full Access Member
Months of headache may of finally come to an end. Replaced the intake manifold gasket on a whim. Then drove it for a day or so. Code reader picking up misfire 7 again and now a new code evap leak…. At this point WHAT THE F***!!! I was so close to throwing in the towel. I even called 2 local mechanics to try to schedule my van. Weirdly enough. Neither one called me back…. I popped the hood a few days later and noticed the evap hose was not connected to the purge cylinder thing! Hooked it up nice and secure. Cleared the codes and were we are about 2 weeks later nice smoooth idle. Hope I don’t jinx myself
Tonyrodz
Resident Resident
Can you post a pic what/where you're talking about.
OP
OP
Tonyv__
Full Access Member
So directly behind the alternator is this vapor purge thing. I think. It’s mounted on the intake manifold. The hose wasn’t clicked in all the way and fell off. So I had to secure it.
Attachments
Tonyrodz
Resident Resident
Thx. I'm still chasing my low idle issue. Idles around 425-450 rpms. My P0300 went away when I swapped out my plugs--I also gutted one of my cats. They're both clogged some, but the gutted one was the worst. Strange because when I bought it at 110k, driving it home the P0300 popped up--did plugs and wires, and that damn code was still there. I did buy the plugs--1st time--on Amazon. Might've been bootlegs. 2nd set I got from Advance, at changed it at 152k. Has 153k on it now. Low idle is going on 2 yrs now. Annoying.
OP
OP
Tonyv__
Full Access Member
I’m sitting in mine right now. Mine idles at 500 consistently. Which I think is a tad low. I cleaned the throttle body. Fuel injector cleaner. I think a few other things about a year ago. And I just let it go. I was more concerned about the misfire
I do know that replacing the throttle body on my Tahoe fixed the low idle issue I had on that… I bought new sensors and cleaned the TB. Didn’t fix the problem. So I wen to junkyard and pulled one off a Yukon and slapped it on my Tahoe just like that with the used sensors and all fixed the problem
Last edited:
Tonyrodz
Resident Resident
So far I've done the map, maf sensors and swapped a known good throttle body. Intake gaskets were done maybe 3 years ago. I tried spraying around the intake with brake clean with no results. Really ****** me off. I saw on yt a supposed common issue for a messed up idle is broken internal wires that plug into the maf sensor--just like on the Tahoes.
OP
OP
Tonyv__
Full Access Member
That spray with carb cleaner didn’t work for me either. I even smoke tested it. Couldn’t find the leak on the intake
OP
OP
Tonyv__
Full Access Member
Back again…. I really really thought the intake manifold did it but 3 solid days of running then BAM misfire is more noticeable than ever. Truck shakes at idle. Never did this before just minor rumbling…. I’ve read here and there that sometimes gunk from the fuel rail seems to settle at the number 7 injector area so I’m probably gonna pull the rail and the injectors out to see if it’s clogged? If nothing there I think I have no choice but to pull the heads and inspect the valves, lifters, and cam. I find it hard to believe that it would be mechanical because it’s still only at idle. But i feel like I’ve explored all avenues and no results.
One more question about vacuum… is the valley cover under vacuum? So when I pulled the intake I stupidly used the valley cover as leverage to pry the intake off and dented the cover… i don’t know if this cover is crucial to the function of engines performance or to just keep crud out of the internals…. The worsened misfire did not happen right after this. It ran perfectly fine for a few days (which I thought was fixed) then the worsen misfire occurred in the same cylinder. So I’m wondering if I caused a leak there
One more question about vacuum… is the valley cover under vacuum? So when I pulled the intake I stupidly used the valley cover as leverage to pry the intake off and dented the cover… i don’t know if this cover is crucial to the function of engines performance or to just keep crud out of the internals…. The worsened misfire did not happen right after this. It ran perfectly fine for a few days (which I thought was fixed) then the worsen misfire occurred in the same cylinder. So I’m wondering if I caused a leak there
OP
OP
Tonyv__
Full Access Member
FINALLY HAVE SOME ANSWERS!!!
Caved in and tore the cylinder head off. I have an eaten up lifter on cylinder 7… so now I have to weigh my options.
Do I rebuild the top end while in the truck? Need some opinions on the valves? Do I just get the heads rebuilt since I have them off the truck anyway? Assuming the dead lifter is gonna cost me a cam? While I’m in there do I do the timing chain as well? Planning on doing a high output melling oil pump while in there since I have low oil pressure.. after I price this all out I need to consider if it makes sense to fix the top end and freshen up a few other things or do I just spend the money on a long block and replace the whole thing
Opinions and advice please.
The lifter pictured is the 2nd lifter from the back of the engine on cylinder 7. The valves pictured are cylinder 7 and the picture of the cam doesn’t show much
Caved in and tore the cylinder head off. I have an eaten up lifter on cylinder 7… so now I have to weigh my options.
Do I rebuild the top end while in the truck? Need some opinions on the valves? Do I just get the heads rebuilt since I have them off the truck anyway? Assuming the dead lifter is gonna cost me a cam? While I’m in there do I do the timing chain as well? Planning on doing a high output melling oil pump while in there since I have low oil pressure.. after I price this all out I need to consider if it makes sense to fix the top end and freshen up a few other things or do I just spend the money on a long block and replace the whole thing
Opinions and advice please.
The lifter pictured is the 2nd lifter from the back of the engine on cylinder 7. The valves pictured are cylinder 7 and the picture of the cam doesn’t show much
