2004 chevy van 5.7 liter

has a p0102 in memory. and a p0300. hooked up vacuum gauge to check vacuum at idle (runs very poorly) the gauge fluctuates from 0-5 inches at idle. never seen that before. also fuel trims are both around -25. Im thinking the p0102 is a false code caused by how poorly its running. unplugged maf still runs bad. haven't dug into to deep yet

I've got money on a restricted exhaust

is that why the vacuum gauge would fluctuate from 0-5 inches of vacuum at idle? I always thought that when your at around 2500 rpm they vacuum would gradually go down. so I probably will pop the egr valve off and see how it runs.

cheryl hartkorn wrote: is that why the vacuum gauge would fluctuate from 0-5 inches of vacuum at idle? I always thought that when your at around 2500 rpm they vacuum would gradually go down. so I probably will pop the egr valve off and see how it runs.

Maybe? That was just my first guess, don't take it too seriously

Tyler wrote: I've got money on a restricted exhaust

Yeah, sure sounds like a serious breathing problem. Thats crazy low vacuum.

pulled the right valve cover found a rocker arm stud that was pulled out of the cylinder head almost. so going to fix that first then see how she runs after.

cheryl hartkorn wrote: pulled the right valve cover found a rocker arm stud that was pulled out of the cylinder head almost. so going to fix that first then see how she runs after.

Oooooooh, nice, wasn't expecting that. Just curious, what led you to suspect a valve problem?

I've seen MAP engines run like crap due to valve sealing issues, but MAF engines usually tolerate it better... Keep us posted on what you find!

lol the noise coming from the valve cover area.

cheryl hartkorn wrote: lol the noise coming from the valve cover area.

nice, good answer!

cheryl hartkorn wrote: lol the noise coming from the valve cover area.

Hah! Sounds like you caught it before the rocker arm fell off and stopped making noise :lol:

Me thinks you've got a real POS on your hands

well turns out it has a major leaky exhaust valve on cyl #4 did a leak down test air gushed out of the tailpipe

cheryl hartkorn wrote: well turns out it has a major leaky exhaust valve on cyl #4 did a leak down test air gushed out of the tailpipe

Nice. Same cylinder as the pulled out rocker arm stud?

I still say this is just the beginning of the problems for this van. :ohmy:

yes sir. its the same cylinder. its a express 3500 that's been converted to a box truck. so they probably will fix it. I wont be the one doing the work though. keep you posted what I find out happens....