[Leeann_93]

Awesome. Unfortunately, sometimes you do get what you pay for...

 

[tonydobbs]

So the actual delco check valve solved the vent issue. I think that dorman was either defective or just useless. Not sure, but would not recommend. Luckily only a few dollars lost. Replaced the PCV hose with 1/2 ID Mishimoto "universal catch can hose" it was a bit tricky to get to slide on as it's a bit stiffer than what was on there, but it seems like it should hold up well. Thanks for all the help everyone, that one is solved. :cheers:

What's the part number on that delco check valve? I want to pick up a spare for when mine dies.

 

[pmou]

So the actual delco check valve solved the vent issue. I think that dorman was either defective or just useless. Not sure, but would not recommend. Luckily only a few dollars lost. Replaced the PCV hose with 1/2 ID Mishimoto "universal catch can hose" it was a bit tricky to get to slide on as it's a bit stiffer than what was on there, but it seems like it should hold up well. Thanks for all the help everyone, that one is solved. :cheers:

What's the part number on that delco check valve? I want to pick up a spare for when mine dies.

I actually prime'd it here: https://www.amazon.com/dp/B0016I0E42/re ... mFb54E3Q9X

Looks like GM part number is 15-50568 / 15733271 according to that

 

[tonydobbs]

Thanks, saved it to my list of crap to buy later.

 

[pmou]

well, it's baaaaaaaack...

have a lift & bigger wheels on now (30.5) so i think the engine is under a little more stress. Took a drive across the rockies and back over the weekend. Climbing out of denver on i70 got a code, it first read P0101 & P0135, P0132 (B1S1 lean / heater circuit). as i knew there were a lot more hills to come, i let that settle for a minute and then reset. Later in the drive, got a P0101 and a P0132 (heater circuit B1s1).

Hung out for the weekend on the far side of the divide, eventually this turned to a solid SES light for the P0132 just driving around. I had recently done my coolant and felt concerned that I dumped coolant onto that B1 o2 sensor. Stopped into a LAPS on the way home before any big hills and changed the o2 sensor quick with a bosch and the sockets they lent me. cleared codes and continued on. pretty late into the hills to get back over the rockies i got a P0101, no o2 codes this time. cleared it and it came back later in the drive.

I've double checked the connections at the filter box, maf, the snorkel thing on the throttle body (as these all came apart to do the lift) and they all looked good. I got a tip that the little plastic snout on the throttle body can leak where it meets the throttle body. I took this apart and i would say that orange o ring in there didn't look great. I tried spraying that whole intake area up to the snout and the base of the snout with MAF cleaner (not carb cleaner, but seemed equally flammable in my quick test).. i got no changes in idle. so i think that means there is likely not any leaks along there. I can double check the vacuum ball for cracks.. but I'm 99% sure that is fine. I also double checked the heater vent / blows on the windshield under load test while driving and that did not have any issue (kept blowing at my feet under heavy loads).

I'm once again stumped. I have gotten another tip that this could be early LIM gasket.. however i haven't been losing any coolant that I can tell, and oil had no coolant in it when i changed. Anyone else want to toss some ideas out there? I'm thinking it could _possibly_ be the MAF.. however i tried unplugging it -- got a quick dip in RPM and then it bounced right back. Idle seemed about the same. Is the idea with disconnecting it to go out and do some heavy driving?

 

[Leeann_93]

Several guys have had the MAF go bad. At least one more has had the MAF wiring harness go bad. Quickie test is to disconnect the MAF and see if the van runs better in regular driving. If it does, the MAF probably has outlived its useful life.

I got P0101 when my cat was plugged. As soon as I got ignition and fuel straightened out and replaced the cat, all was well.

 

[pmou]

Thanks Leeann,

I did test the wiring for the MAF at one point, and my memory is that it seemed OK enough. I think it was in the first post of this thread that I spec'd out what I had found. I'll be helping a buddy with his lift (aka drinking beer and watching) this weekend. I will try to get my hands on some O2 sockets again, pull the MAF and drive, and also see what happens if i pull the O2 sensor while running -- see if that changes the idle at all, indicating a clogged cat. I should have a new MAF ( with free return) showing up sometime this week, so that will give me something else to possibly try. It's just tricky to test -- it seems to only happen above ~40-50mph or so, on a big hill, with WOT.

edit: regarding your fixes.. I think i should have ignition sorted with a new dist, wires, plugs. I have not touched the ignition coil at this point, however. Fuel I have done filter and new delphi pump. Have not tested pressure at all.

 

[WinnieVan]

While you're "helping" you buddy do a lift --- take his MAF sensor and plug it into your car. Go find that huge hill and send it. On your way over to his house -- unplug the MAF, go find that hill and send it!

Remember -- the engine bay gets hot and that can exacerbate wire resistance -- sometimes everything specs out fine -- althought I suppose a live reading of the MAF would give that away.

Is your airbox cracked? How is your air filter? What about the flex hose from the airbox to the intake? Are you sure there aren't any holes? It could be that the MAF is/was getting caked in dirty stuff and now it is beyond repair.

How do your fuel trims look? Have an exhust backpressure reading? I don't think it could cause your MAF code -- but maybe a bad injector or plugged exhaust could be messing up the intake side on WOT pulls -- seems that would be more "repeatable".

Also -- I'd go with Leeann on this -- but after tracking down a misfire code myself -- I thought my van was missing a PCV valve... I've spoken with a few differen parts guys and it doesn't appear the Gen-III Astro has a PCV valve. :shrug:

It sure does fit in that receptacle on the valve cover -- but apparently there isn't supposed to be a PCV valve in there! I didn't have one in when I first looked and then I put one in... then I took it out again once I discovered it isn't really supposed to be there (I think).

I think this is detailed in my build thread somewhere -- but most of that thread is me being neurotic. I've learned to shut up and drive since then

 

[Leeann_93]

The old-style PCV valve isn't supposed to be in there. That's the new-style valve that doesn't need to be replaced.

 

[pmou]

While you're "helping" you buddy do a lift --- take his MAF sensor and plug it into your car. Go find that huge hill and send it. On your way over to his house -- unplug the MAF, go find that hill and send it!

This is a very good idea. I'll see if i can convince them to lend me their MAF real quick haha. (also i will be actually lending a hand :lol: )

Remember -- the engine bay gets hot and that can exacerbate wire resistance -- sometimes everything specs out fine -- althought I suppose a live reading of the MAF would give that away.

I had wondered about this -- as the issue seemed to go away.. however, now that i completed the lift I have noticed that the upper radiator hose is directly below (being squished by) the MAF.. I think this was less so when the engine was sitting higher relative to the radiator, but don't have a great way to go back in time and compare. I had wondered if this could overheat the MAF or something.. cause incorrect readings? I sorta threw that idea aside as I figured this would not be the first time this happened. Also, the calculated g/s that i get on the OBDII seems to have not changed, I have not tried to do any sort of live voltage reading.

Is your airbox cracked? How is your air filter? What about the flex hose from the airbox to the intake? Are you sure there aren't any holes? It could be that the MAF is/was getting caked in dirty stuff and now it is beyond repair.

I double checked the air box, the rubber flex hose (bent it around as well watching for cracks)... those all looked good. double checked all the connections. Air filter is new as of July (<3k miles) and looked a little dusty.

How do your fuel trims look? Have an exhust backpressure reading? I don't think it could cause your MAF code -- but maybe a bad injector or plugged exhaust could be messing up the intake side on WOT pulls -- seems that would be more "repeatable".

Fuel trims have been what I would call minimal.. no live graphs to share at this point but in my random watching, almost always <5%, never above 10%. Have not tried to see what backpressure is looking like, I will pul the O2 this weekend and see how it runs. Is there a LAPS tool to borrow that would give a number here?

Also -- I'd go with Leeann on this -- but after tracking down a misfire code myself -- I thought my van was missing a PCV valve... I've spoken with a few differen parts guys and it doesn't appear the Gen-III Astro has a PCV valve. :shrug:

It sure does fit in that receptacle on the valve cover -- but apparently there isn't supposed to be a PCV valve in there! I didn't have one in when I first looked and then I put one in... then I took it out again once I discovered it isn't really supposed to be there (I think).

I think this is detailed in my build thread somewhere -- but most of that thread is me being neurotic. I've learned to shut up and drive since then

So i replaced my PCV.. When i went to replace it, there was what appeared to be an identical valve already in there. Whether or not it should be, is another question entirely but mine definitely had one.

 

[pmou]

Is there any reference to what a new or old style PCV looks like? i replaced mine with what rockauto listed as the part.. and it seemed to be a direct replacement for what was already in there.

 

[pmou]

well, TIL that i had some random aftermarket MAF (i think) in there. Delco one showed up today (reman) and i pulled the old one and looked at them side by side. Unless Delco seriouslychanged what their MAFs looked like in the last 17 years, including new tooling and molds.. this is likely some Autozone crap. That said, with the new MAF in there i didn't notice any immediate differences in idle or performance.. but who knows, could just be in those extreme stress situations that there's the difference. I decided to just go for it as I feel like removing glaring question marks is always a step in the right direction (yes, i know people have gotten fault MAFs before).

Here's a few shots of the 2 side by side, Delco is on the right.

Notice the much crappier molding on the left one, and the "AC" text on the one on the right.

Below, you can see the cheap one appears to have the honeycomb pressed in and it's almost crunched around the edge. The delco looks to be molded in or otherwise undamaged by the install process.

The inside, it's obvious the surface differences -- the delco is nice and even while the other has weird molding marks

whether this translates to anything actually working differently, i have no idea. mainly just sharing in case anyone else finds this useful.

 

[pmou]

took some graphs of the fuel trim, but ofc the export from torque is useless. This was with new MAF. Summary: long term hit about 6% on very high loads (80-100%) and then dropped back to zero. Both banks within about .5% of each other. Short term would hit -2-3% on those high loads as well. when foot went off the gas, there was a bit of a rebound period and then they would both settle a bit closer to 0.

 

[MechBob]

From 96 up(95?) this is the pcv valve.Yes,they can go bad and cause problems--
https://www.autozone.com/emission-contr ... 3_923740_0

 

[pmou]

Thanks Bob!

I replaced the metal bit that sits in the valve cover and connects to that via a little hard plastic hose.. I'm not sure what you would call that then. I should probably at least check what you shared as well. I may also put a new ignition coil in, since i never did that as a part of the "tune up" when i first got the vehicle (at this point I've done dist, wires, plugs, pump, fuel filter, air filter, oil, coolant).

Also, for the sake of housekeeping -- I looked at my friends astro and he had a very similar looking MAF under his hood, the barcode on the side etc and all. His is a 2000. Looks like that is what they came from the factory with and have since changed? dunno.

 

[pmou]

Still haven't done anything with that PCV valve, but did the ignition coil yesterday. Happy to report that it's possible to replace with about 24" of extensions, a wobble, a 10mm deep socket, 10mm box wrench and some swearing without removing the doghouse as long as you have at least a 2" body lift. That seems to have gained a little power, the old one was rattling around inside the coil although it still seemed to work well enough. I'll look into the PCV next as that can't hurt and is cheap.

followup: Well, whether or not it will help the code I can't say but I do feel like the van gained some power.. mainly under heavy throttle or off the line.

 

[pmou]

Have done a few stressful drives with highway mountain passes (close to same drive as before) and have not had the code pop up! i think it's likely that the ignition coil was at least a part of the issue, and probably should have just been done with the dist/wires/plugs

 

[Mmusicman]

Have done a few stressful drives with highway mountain passes (close to same drive as before) and have not had the code pop up! i think it's likely that the ignition coil was at least a part of the issue, and probably should have just been done with the dist/wires/plugs

Well after 57 posts and 3-4 months trying so many different things.. congrats on the hopeful fix!
Have I mentioned lately how much I love my 92's carbureted one-wire engine? lol
But my 2000 is still factory stock.. so good information to know!

 

[sixsix]

No, nothing like that - just wondering why just now - the coil was mentioned...

 

[pmou]

Hey @sixsix, my mom had a saying.. maybe yours did too.. about not having anything nice to say. Know the one?

If not, I'll just add you to my foes since I've only seen not-nice and backhanded racist comments from you since I joined the site.