Chevy Astro and GMC Safari Forum banner
21 - 40 of 78 Posts

·
Banned
1992 Astro - Silver / Gray / 4 Wheels
Joined
·
5,327 Posts
Birdshake said:
That broken vacuum line you have is the red line in the diagram in this thread. Its easiest to get to with the doghouse removed.
I do not think that is true.
The line plugs in at the bottom of the intake plenum throat, right ?
 

·
Super Moderator
05 Astro AWD
Joined
·
14,097 Posts
No. It plugs into the front of the canister that the PCV hose plugs into.

The barb pointed up, here:


Which goes in the big, round empty hole at the driver's side front of the intake plenum
 

·
Registered
Joined
·
224 Posts
Discussion Starter · #23 ·
Oh nice, those pics will be really helpful. seems like it may actually be easier access from the front. but now it also has me wondering if I should double check that lead to the PCV while looking into vacuum leaks. Parts are all on order, and I'll be getting to this hopefully next week or two.

Edit: also, it looked like in my case it's 6mm internal from check valve to firewall, 4mm internal everywhere else. ( 1/8" and 1/4" for English speaking folks)
 

·
Registered
Joined
·
318 Posts
pmou said:
tonydobbs said:
pmou said:
It then read what seemed quite low (4.5g/s). Before this, it was reading between 8.5 - 11.5 at low/high (cold) idle.
If my memory serves the last time I measured my MAF it was 4.6 at idle, so that doesn't seem too unusual. It's going to measure higher when it's cold and the RPM is higher. If I take a drive today I will check the MAF data and post it here.
that would be great! the reason i thought this was low was because in the factory manual under P0101 it states that the MAF should read " 7-12g/s at ide to 150g/s or more at the time of the 1-2 shift"

lol and now that i'm reading this closer it also states that

a high resistance of 15 ohms or more on the ignition 1 voltage circuit may cause this DTC to set. A high resistance may cause a drivability concern before this DTC sets
I'm assuming the ignition 1 circuit is the red lead? i verified resistance from that pin to + terminal. So perhaps this could be the problem? I will double check that resistance (this was KOEO) edit -- err, key on engine off.. i realized i have no idea how to differentiate the O's for off/on in those abbreviations.
I checked mine today, and in-gear at idle I measured 5.67 g/s but I can't say if this is normal or not.
 

·
Registered
Joined
·
224 Posts
Discussion Starter · #25 ·
Ok -- got all the vac line stuff at home. I order 4mm & 6mm, looks like there is in fact no need for the 6mm on my van. I used about 14" of 4mm for the "yellow" lines in the image shared earlier. Confirmed I do not have the purple lines. The orange line is a hard plastic that goes into the firewall, and looks like its a part of a larger assembly. In fine shape for now. Going to replace the main vacuum source (plastic line) in "red" in a minute here and then we will see how the MAF reads.
 

·
Registered
Joined
·
224 Posts
Discussion Starter · #26 ·
Also, I was worried about that hard plastic cracking again, so I encased it in a vac line. 4mm fit over it nicely. might make inspection a little more tricky, but I'm hoping it insulates it. I had the thought that I could just use the 6mm vac line in its place, but I was concerned about oil breakdown which is why I'm guessing the plastic is there in the first place. anyhow, we will see how this holds up long run.

IMG_20200729_081307.jpg
 

Attachments

·
Registered
Joined
·
224 Posts
Discussion Starter · #28 ·
So got everything buttoned back up. cleaned up the tstat ground a little while in there, that looked ok to begin with though.

The previous HVAC line was resting essentially "behind" the elbow of the coolant line going into the tstat, between the bracket that the throttle cable is held in place by. I have no idea if this is the normal routing, or if it fell in there when I crumbled to pieces. either way, with this extra vac line on it, it no longer fit back there. now it just rests more on top of that elbow. still plenty to work with for length. dunno, seems fine for now anyway. Did notice another line coming off the intake, PS, looks to be 18mm internal that seemed to be crumbling apart. gonna replace that as well as I think it could be acting like Swiss cheese. Initial fire up, got around 5.1 g/s at the MAF at about 620 rpm. a bit more it seems, closer to yours Tony, but not the manual. Gonna do a decent test ride and hit WOT and see if the code pops and what the #s look like all warmed up. will report back in a bit.
 

·
Registered
Joined
·
224 Posts
Discussion Starter · #29 ·
Seems to still be reading more or less the same at the MAF. couldn't get the code to throw on a shorter drive, but we shall see. I'm gonna have the doghouse off soon as a slight detour while doing radio stuff, so I'm gonna put some eyes on the MAP and PCV.

I can't find anything about this hose in my manual... anyone know what it is or what it does? it seems to hook into the hard plastic part of the intake and a rigid metal hose on the other side. It's pretty toasted so I'm thinking I'll replace it if possible.
 

Attachments

·
Registered
Joined
·
224 Posts
Discussion Starter · #31 ·
Interesting.. I still can't seem to find much information about this, or the crankcase ventilation system in general. Is this rubber hose a specific part for these vehicles? Is it pulling a vacuum? venting to the intake?
 

·
Registered
Joined
·
224 Posts
Discussion Starter · #33 ·
Anyway, following up on the P0101 -- took a longer drive and still no code (not pending either) so that seems promising. None of the MAF numbers appear to have changed though. My manual says 7-12.5 g/s is a normal reading for MAF at idle, however when searching for P0101 and looking at what other people have copy/pasted as the trouble code description, some site 3-10 g/s as the proper range. Perhaps this is a different model year? I have no idea. I'm going to plan to replace that crumbling PCV line with something and then see what I see as far as the PCV system soon when I have the doghouse off. For now, calling the P0101 "Fixed"
 

·
Registered
Joined
·
318 Posts
pmou said:
Anyway, following up on the P0101 -- took a longer drive and still no code (not pending either) so that seems promising. None of the MAF numbers appear to have changed though. My manual says 7-12.5 g/s is a normal reading for MAF at idle, however when searching for P0101 and looking at what other people have copy/pasted as the trouble code description, some site 3-10 g/s as the proper range. Perhaps this is a different model year? I have no idea. I'm going to plan to replace that crumbling PCV line with something and then see what I see as far as the PCV system soon when I have the doghouse off. For now, calling the P0101 "Fixed"
Definitely replace the crumbling line, but it sounds like your issue is fixed. I wouldn't stress to much about the MAF reading.
 

·
Registered
Joined
·
224 Posts
Discussion Starter · #35 ·
The saga continues -- still no code, however under heavier load, it looks like the air ends up getting re-directed to the windshield defroster. I had it on feet, low. that worked fine, but once accelerating it would start coming out the top of the dash.

I looked at the check valve i have, I just bought a dorman one as it's what was on rockauto (no delco). Testing it, it seems there is no checking or valving in this POS. not literally, but i can't see that it stops flow in any direction... so I ordered a delco that'll be here in a few days and hopefully that's all that it is. any other thoughts are welcome.
 

·
Banned
1992 Astro - Silver / Gray / 4 Wheels
Joined
·
5,327 Posts
One member is using an aquarium piece - 2-3 bucks if that.
Years later he says it still works.
The CPI motor has 2 check valves in the vacuum circuits.
 

·
Registered
Joined
·
224 Posts
Discussion Starter · #37 ·
sixsix said:
One member is using an aquarium piece - 2-3 bucks if that.
Years later he says it still works.
The CPI motor has 2 check valves in the vacuum circuits.
I'm not sure I'm totally following.. you are saying there is another vaccum check valve I need to look at? I have a 2003 w/ rear AC, no rear heat.

Is this under the dash? I didn't see anything else under the hood.
 

·
Registered
Joined
·
224 Posts
Discussion Starter · #40 ·
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:
 
21 - 40 of 78 Posts
Top