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Discussion Starter · #61 ·
Cats were checked by an exhaust shop and determined to be OK. The guy there said he owned a similar vintage GM with similar issues, and ended up needed the CPS. So, I brought to my normal mechanic, had him do the CPS, and also a Delphi brand MAF.

CPS was cracked, came out in 2 pieces. After replacing the MAF (again) and CPS, it ran worse than ever, and got a CPS error 0335 (not to mention, a MAF 0101 again). Replaced the CPS again, still not running great. Do I need to do a CPK relearn? If so, is there some place locally I can buy the device needed for this?
 

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Discussion Starter · #62 ·
Found a GM specialist this morning, did the CKP relearn. Also, tested the back pressure of the cats, only seeing 1psi. Headed to work after the relearn, got on the highway, instant loss of power, SEL started flashing, P0101 and P0300, (MAF and misfire). The GM specialist noted my timing was being retarded by 7 degrees.

I don't think there is much more for me to try at this point. One of the only things left I can think of is the distributor. Is the worn distributor gear fixed by replacing the distributor, or does it need something additional replaced? Any other ideas greatly appreciated. At this point, I can't even make it into work, and there's not really any way for me to get to work, so am anticipating losing my job due to this.
 

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Discussion Starter · #63 ·
Problem persists. Replaced the distributor, did not fix. P0101 and P0300 (P0306 is most common specific cylinder atm). To summarize what has been replaced or checked:

Dist cap and rotor (twice if you count it being included in new distributor below)
Distributor
Spark plugs and wires
Coil checked
MAF (twice)
CPS (twice)
Air filter
Fuel filter (twice)
Spider assembly
Fuel pump
Cat checked 3 times (twice visually, and twice measuring pressure)
Drilling a 1/4" hole in front of cat seemed to help, but after a 2nd hole it ran bad as ever

Loss of power accelerating to get onto highway as well as any uphill sections of the highway. Have to slow down to 30-40mph sometimes on the highway. Slowest vehicle on the highway on every uphill. Drives fine on side roads. Can get up to 70-80mph on often when level or slight decline. No issues starting. Will sometimes rev up and down after getting off the highway and sometimes stall in this situation. Starts right back up.

Again, thanks for any help.
 

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Discussion Starter · #64 ·
The 2 wires for the alternator right at the connector were deteriorated insulation wise. I don't think they were shorting, but if they were, could that create the symptoms I am experiencing? I will find out in a couple hours if taping it off goes well. I broke my heater control valve working on that connector, so, bypassing that right now.

Not being familiar with astrosafaris specifically, here are some things I personally think could be my issue (assuming taping off the alternator wires doesn't fix it), please let me know your thoughts:

Again, these are only *thoughts*:
New fuel pump went bad. Maybe from excess restriction in the spider assembly? Maybe it just was a dud? Maybe it's the wiring? The van ran marvelously for a month after it was replaced the first time.
Sticking valves. Not that familiar with valves, but I have read that the valves on these engines stick on high mileage motors.
Random electrical short or vacuum leak.
Considering P0101 is a common error for me, maybe it's wiring for the MAF system. Any advice on where to check this circuit?
 

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Discussion Starter · #65 ·
Yesterday I replaced 2 deteriorated vacuum hoses (I don't think they were leaking though). I also removed my heater control valve (plugged the hoses going to it into each other), and plugged the vacuum line that went to it. Also removed the heater-core hoses, and the extra space freed up from doing that is very nice. I think I have ensured that the wires at the connector on the distributor are not shorting.

Basically, nothing changed drive-ability wise. The issue definitely seems to come and go. The van will be driving fine and something will click (figuratively) and it will be running poorly; happens so fast it's almost like a jerking motion. Turning off the A/C makes it run better, turning it on makes it run worse.

Here's where things get pretty interesting though; About 15 miles from home, at the start of about a 4 mile uphill stretch, I was slowing down to about 40mph, so I gave it a little more gas, it down-shifted, and unsurprisingly, the SES light started flashing (P0300/P0306). About half way up this uphill stretch there is a very short portion where it levels out, and I let off the gas, and the SES stopped flashing. And the van ran perfectly the rest of the ride home. I struggled to keep it *under* 85mph. It really is a nice ride when running properly.

Any ideas what's going on? Did the computer realize I fixed stuff and it's supposed to run better now? Did the computer decide to ignore sensors and go into closed-loop mode and that made it run better? Something else? I am guessing it will run well for a while and the issue will come back, but it really was running especially well that last part of my trip home. Also, thankfully, work has been understanding about the days I am missing.
 

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Discussion Starter · #66 ·
Well, ran well enough today to not be a stressful ride, but still less power than it should have, and did get a misfire code up a hill again. I think my theory of the learned computer parameters like long term fuel trim not being appropriate for new parts/repairs is probably not valid, since when I worked on it 2 days ago, the battery was unplugged for like 10 hours, and I assume that would clear such things. Will look for electrical shorts and vacuum leaks this weekend probably. Is it a good idea to drive 100 miles with the MAF unplugged?
 

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Unplugging the battery doesn't clear these things in a Gen 2 van.
 

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Discussion Starter · #68 ·
Right now P0306 is the error coming up most often. What should I look for here? Seems odd for a specific cylinder to misfire after all the new ignition components. Will come up every day multiple times a day. Today there was a portion of the highway I could only do about 25mph on. My scanner also shows P0172, P0175, and P0455. Could the P0455 be related or is that just a separate issue?
 

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WOW, this seems like a mess, reading the whole thread made my head hurt and gave my wallet sympathy pains.

Ignition component issues are not the only thing that will cause misfires. Keep driving with that light flashing and it's going to trash/accelerate wear on your engine and destroy your cats.
What are your fuel pressures KOEO, 1min after, 10min after, while driving, while driving up the hill. Compression test values for all cylinders? LTFTs and STFTs?
 

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I just read the last page and the top of 1st page - to see if it was bought this way.
2 things stood out - I'm just mentioning for folks trying to help. (not to be confused with advice.)
Saw CPS was done 2x - maybe didn't get a shim.
Original dizzy could have been off a tooth and replacement installed the same (7 degrees was mentioned.)
I don't know anything compared to the other folks helping nor do I think the above would be misfire causes.
But as a whole the stuff above may or may not be worth mentioning.
I'm out of this one and not coming back - WAY over my head. Good luck!
 

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Discussion Starter · #71 ·
The light doesn't stay on usually, it flashes then turns off. I've been managing by I think feeling it misfire, and limiting speed/throttle. I drive 100 miles a day getting to and from work. When I say I can't go over X speed, what I mean is I can feel it stumbling, vibrating, and losing power, so I let off before the SEL comes on. Unfortunately I don't have fuel pressure numbers at the moment.

My mechanic finally took it for a freeway ride, and this is what he messaged me:

"your van had Mechanical problems like camshaft worn out, intake valve do not open enough air, during your driving not enough power when I driving your timing advance enough but the intake air stroke not enough to general power to the engine sometime cause your car misfiring on the engine and engine knocking sound so I considering the engine need to be rebuilt your transmission and shifting ok.And all so about cost a problem throw a lot of code code misfiring code, mass air flowe sensor, sometime random miss firing an engine knock sensors come on"

Any thoughts on his evaluation?
 

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Yes, those things can cause issues, with all you have replaced/tested I was leaning towards something mechanical. I would still borrow a pressure tester and check those fuel pressures, also borrow/buy a compression tester and get the values for each cyl dry, and then with a squirt of oil to see if anything there needs work, if you are low enough miles and the bottom end is fine, might be worth working on the top end. Rebuilt heads/camshaft/etc can be had relatively cheaply, I wouldn't want to pay the labor but it all comes down to personal decisions.

Another thing that I would be looking at with your scanner is live data to see if the TPS is fully functioning. Maybe swapping the knock sensor, an overly active knock sensor can really mess with things, not sure if that is the issue of course, but they can be had pretty cheap and are easy to swap, just don't over-tighten it.
 

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Discussion Starter · #73 ·
Figure it's worth mentioning, the severity of the issue is intermittent; changes from "barely drivable" to "just be happy with 60mph sometimes".
 

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started skimming, this thread just keeps going like the energizer bunny. now reading of random and intermentanty but, mostly ignition issues like this. i can tell you it would be on the 2 post lift getting the grounds remade top and bottom, no matter how good they look, likley being tied back in to the loom/harness, with an additional body to engine and body to battery ground straps along with a battery to engine ground strap to complete the "trifecta" on top of redoing existing grounds.

THEN there's still no guarantee there isn't an issue in the loom/harness somewhere. a power probe with some experience can help. i managed to find a bad ground for my windshield washer on my VW and it fixed the washer pump AND the blinkers at the same time. ...how in the hell that's wired up.....
 

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Figure it's worth mentioning, the severity of the issue is intermittent; changes from "barely drivable" to "just be happy with 60mph sometimes".
Does it only happen in closed loop mode? Once the engine warms up?
 

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Discussion Starter · #76 ·
Several months ago I would have said it ran great at below operating temp, but now it pretty consistently runs bad as soon as it's started. This morning, I felt like I was lucky to make it to work. On lunch, it felt horrendous. On the way home, it started out bad, but went to pretty good. The 1st hill I was limited to 50, and the 2nd bigger one I was able to hold 60, and the rest of the ride home I could throttle it pretty heavy and not have the power die off. What it was doing was stumbling (misfiring?) when I let off the throttle after having given it a lot of throttle. Also did the thing where it idled up and down coming off the highway, and almost stalled.

This cycle of driving good enough sometimes and barely driving at other times is maddening.

I think a bad ground sounds plausible, and I haven't checked much there. As for the TPS, I did look at live data on my scanner, and it seemed fine. I'm still trying to find a knock sensor locally since that seems like an easy install. Haven't had my SEL come on since my mechanic reset everything, I do tend to purposely drive in such a way that it doesn't trigger the SEL, because normally it stays driving bad after it comes on. I am curious if further misfires will show as cylinder 6.
 

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Discussion Starter · #77 ·
Drove about as good as it does on the ride in this morning, but was able to get the SEL to flash on heavy throttle; P0306. Anyone else think the valve assembly on cylinder 6 is likely bad?
 

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Discussion Starter · #78 · (Edited)
Well, my mechanic is basically done trying to figure it out. Brought it to the GM specialist, told him I took the whole week off to figure this out, and would be happy just figuring out the problem, not even necessarily getting it fixed this week. He just finished spending a week figuring out a cylinder 6 misfire on another Astro, and ended up being a piston ring, so, he all but declined to look at it. Both mechanics saying due to the 255k miles, the van is basically abut dead.

So, I'll give a quick look at wiring, see if there's anything I can find that might cause this, but I am expecting I'll be getting rid of this van this week. I'll probably be posting it up for sale this week, unless a dealer will give me something reasonable as a trade in.

To all who have given advice in this thread, thank you.
 

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A compression test as I mentioned above would tell you if it's the rings. Owning an older vehicle you probably want to learn how to do this yourself otherwise the cost of paying a mechanic gets crazy expensive.

But even if the engine is toast it may be cheaper to replace the engine and keep the van rather than buy another vehicle with other possible issues. Depends on if it suits your purposes or not. I know I like the idea of having an engine with 0 miles, if it lasts another 255k miles that would be a heck of a return on investment.
 

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Discussion Starter · #80 ·
Well, I do know how to do a compression test, it's more a matter of having the energy, space, and desired/needed tools to do it. My budget to get this thing fixed does not allow for a motor swap, or an upper end rebuild. At best I could maybe afford 1 rebuilt head + labor. Unless some place allows a payment plan for the repair, but shops around here are all very busy it seems. The vehicle does suit me very well, I like the interior space, the solid axle, RWD, the renowned truck motor, the ground clearance, but, I can't continue spending money on this thing without some guarantee that it will truly be fixed. I've known 1 person with 375k miles on his still running 4.3, and another with 325k, so I think it's a good motor. Another person I've known with one went through what I am going through now, fixing one thing after the other, draining the bank account. So, it's a tough choice, but, working 50 miles away, with no viable public transit to get there, I'm kind of forced into a corner.
 
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