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Astro's bad running

4K views 22 replies 5 participants last post by  Cylinder6 
#1 ·
Hey everyone!

I bought my first Chevy about month ago (yeeee!) :driving: And it didn't take long when problems started showing up. :whack: Although i knew these problems existing...

So from the start!

Driving in city (about 40mph) it now runs great after plugging egr. But over 50mph engine starts to shake, and knock.

I opened the throttle body, cleaned it and reinstalled, of course.

All vacuum lines where checked and fixed couple..

Changed parts;

TPS (also adjusted)
IAC (reseted)
CTS
Pickup-coil
Spark plugs & wires (Plugs are original AC-delco made)
Ignition coil
Oxygen sensor

Before plugging the egr, WinAlDl showed error code 44 - Rich, didnt run well etc. BUT after plugging egr, WinAlDl gave me another code; 13 - Oxygen sensor.

Is there possibility for leakage, or is MAP/ECM just going crazy because egr is missing? And what is causing the shaking and knocking?

Please help!
 
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#3 ·
if hyou have plugged the egr, the knock you here is detonation. you need to buy a new egr or it will burn a hole in the piston. i plugged mine when the thing was sticking but pinged and knocked about 45 mph. i changed the egr valve and power came back with no ping or knocks.
 
#4 ·
Cylinder6 said:
Before plugging the egr, WinAlDl showed error code 44 - Rich, didnt run well etc. BUT after plugging egr, WinAlDl gave me another code; 13 - Oxygen sensor.

Is there possibility for leakage, or is MAP/ECM just going crazy because egr is missing? And what is causing the shaking and knocking?

Please help!
No it is not. You have other problems. I have had my EGR blocked for almost a hundred thousand miles it runs great no knocking. Pistons looked perfect when I re-built it. No damage at all.

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#5 ·
ive plugged egr's on other car's and didnt have any problems either, so I dunno why my van did ping and knock. other than the engine was almost worn out. if you think about it, a egr uses exhaust gas to cool the combustion chamber you would think it would do the opposite since exhaust gas is hot. lol... wonder if with the egr blocked off its not removing all the carbon dioxide when it pushes it back into the combustion chamber then it flags it being rich because of it. Alot of people dont know that o2 sensor have use life, just like brake pads, after a certain amount of mile they need to be replaced. it depends on the manufacter on how many miles... more expensive one's doesn't alway mean more mileage life either. ive seen them as low as 10k but none more than 50k. maybe it could be a bit of both causing one problem.... just spitballing here tho....
 
#6 ·
An EGR cools combustion temps because it is introducing burnt gases which are oxygen deprived. Therefore the new mixture can't burn efficiently. Reducing hydrocarbons. After testing they discovered this effect was only at idle. On a dyno pulls running at normal speeds they were worse. Not many people idle, they usually drive their vehicles. This is why they are no longer required in newer vehicle.

Less combustion temps equals less power made. Since heat and pressure what drives the internal combustion engine.

On a older engine carbon build up in the chambers usually the cause of knock or ping. It glows red and causes pre-detonation. So blocking the EGR increased temps and caused this glowing carbon to be worse. Making it feel like it is missing when it is actually pre-detonation. Lucas injector treatment helps clean these deposits out reducing or eliminating ping. I wail the snot out of mine on a regular basis which keeps it clean inside the combustion chambers. The old addage blowing the bugs out was actually this phenomena.

I have been messing with iron headed engines since the dinosaurs roamed the earth. Small block chevies which are identical to these V-6's. 9 to 1 compression is a little high for regular gases octane at the pumps. Once it is tuned . EGR blocked and timing is right, read advanced for power, they will ping causing knock sensors to pull off timing. I run mid grade fuel in mine and it solves that.
 
#7 ·
Thats a good point. maybe he needs to "clean it out" and put mid grade gas in it, or a bottle of octane boost... if they still make that stuff... I reread the post and he changed the o2 sensor already. I knew I was changing the engine so I didnt mess with mine much but he has the same thing I had, and i changed the EGR. Hell, if he gives me his address Ill send him my new EGR valve. its still on the engine that I removed. only has about 2000 miles on it.
 
#8 ·
Hello again!

Thanks for this many reply's, i didn't even think that i would get this many in 24 hours... I've tried to solve this problem about 2 weeks, posted on my country's forums and it seems that no one is any wiser than me :D Although this Astro is my first one. But anyway, i have some base knowledge about V6 engines already. (although German made)

There are 2 kinds of people who share opinions about blocking egr. I haven't heard ANY of those egr-blocked engines to broke because piston(s) got burn holes. But maybe i give u my address so u can send it to me :D For the other hand, it's gonna cost you, shipments etc... I live in Finland :D But thank you still Fivecoulds! :cool:

And for Chevymaher, i'm gonna try cleaning the system with injector cleaning fluid, but all i can find easily in my country is STP made... Maybe it's the same, i don't know. And the fuel i use, it's 98-octane. We have 95,98, and over 99 octane gas in Finland.

For the compare;

95-oct / 1,64€/L (2.01USD) And it includes 10% ethanol :D Our emission standards are so tight so someone invented that shit.

98-oct / 1,69€/L (2.07USD) This includes only 5% ethanol, is fair priced, so i use this.

Over 99-oct / 1,82€/L (2.23USD) [Only by Shell stations] Not including ethanol.

I checked US prices, and they are HUGE!?!??! Or what is the measure in these? Gallons? If it is, it's cheap as a soap. :2:

But anyway, thanks again, i hope something solves something, gonna clean the system, and change to the 99+ octane gas. :)
 
#9 ·
paintdrying said:
check the fuel pressure and timing. Did you put new base gasket on the throttle body. Wonder what sort of play you have in the dizzy gear.
Fuel pressure was 12.5Psi, timing is adjusted with lamp. I ALWAYS change gaskets, unless it's silicone gasket and in good condition. I noticed, by turning the crankshaft, there where yet big interval when the ignition rotor started turning. I opened the distributor cover, to see what condition the chain is. There weren't any loose, it was, for a suprise, almost new Cloyes double roller heavy duty timing chain. Dizzy gear's play was worn out, so i replaced new one. =) I don't know about camshaft's condition, i didn't want to open the engine in million parts, unless it's the final thing to do.
 
#10 ·
When you first bought the van how did it run? Any problems?
Before you blanked off the egr how did it run?
Did you install an ac delco o2 sensor?
What is the spray pattern of the injectors?
When you set the timing was there a wire to disconnect first?
Did you buy this van from a friend? Someone you trust?
If I was to guess- I would say someone had this problem with your van and a mechanic told him the timing chain is worn out and a new chain will fix your problem. After the chain was replaced it did not fix the problem, so the mechanic went and poured some sort of octane booster in the gas. It solved the problem. So the previous owner poured some more of that octane booster in the fuel and sold it.
A general rule is that when a engine has trouble under load it is ignition related. Another general statement is that when their is an ignition problem it is the distributor for a chevy small block(4.3 V-6)
 
#11 ·
paintdrying said:
When you first bought the van how did it run? Any problems?
Before you blanked off the egr how did it run?
Did you install an ac delco o2 sensor?
What is the spray pattern of the injectors?
When you set the timing was there a wire to disconnect first?
Did you buy this van from a friend? Someone you trust?
If I was to guess- I would say someone had this problem with your van and a mechanic told him the timing chain is worn out and a new chain will fix your problem. After the chain was replaced it did not fix the problem, so the mechanic went and poured some sort of octane booster in the gas. It solved the problem. So the previous owner poured some more of that octane booster in the fuel and sold it.
A general rule is that when a engine has trouble under load it is ignition related. Another general statement is that when their is an ignition problem it is the distributor for a chevy small block(4.3 V-6)
-I knew there was running disorder on light accelerate. It was because vacuum lines in throttle body where plugged, (on purpose or accidentally, i bet accidentally) so i got this van on very low cost. The seller was a kind of goofy..
-Before blanking egr, idle, low and high accelerate where very bad. It sounded like it chokes or doesn't get spark. And after plugging egr, only high accelerate is little shaky. And it sounds like it sparks to CAT.
-No. It's Standard Motor Products O2 sensor.
-Spray pattern looks like ice cream cone's upside down.
-Yes. Disconnected wire -> timing set to 0' -> connected wire -> disconnected battery -> waited 30sec -> connected battery.
-No. To me unknown fellow, kinda goofy.

Dunno is this important, write it here anyway. At the same time when i got the chain on view, i adjusted it to advance 2' (Triangle mark)
 
#12 ·
When you checked the fuel pressure did it hold pressure after shutting off?
I am thinking they may have timed it wrong after install of chain.
start the van up, let it warm up then hold the brake very tightly and push the gas pedal to the floor. Notice how it behaves, any backfiring out of the throttle body?
You may also need to reset the computer, turn the van off, turn key to on, do not start, let set for ten minutes, then turn key to off and start.
The ground wires are very important on chevy small blocks, locate and check all your grounds.
You can also try and tap the computer and wait for a miss or anything unusual.
 
#13 ·
The v6 is on its last legs, time to install a small block! lol! (joking)! Our gas by the way is in u.s gallons. its around $2.39 per gallon here in kansas.... vacuum diagrams are available at www.autozone.com if you wanted to correct the loose or pluged lines. on a 89 tbi 4.3 there isnt many at all! what is your fuel pressure when running under a load? fuel pressure regulator may have a weak spring or a hole in the diaphram. paintdrying is correct about chevy's and the grounds, the ecm has issue's on an engine that has a bad ground or even a poor one. yours, if its like my 88 4.3 v6 is on the back of the drivers cylinder head, and then another on the passanger side on the egr soleniod, esc, map bracket stud. when I want to clear the codes on my van, i just pull the fuse to the ecm. then I dont have to reset my radio clock... it does sound more like an ignition or timing related issue tho, I would try power braking it and see it if knocks, pings or front/back fires. keep us posted...
 
#16 ·
Reply for everyone.

Got the timing chain adjusted back to factory settings. Adjusted the spark timing at 0' without the est wire. Worked better when adjusted by ear, but with timing lamp, it got worse. Did the gas/brake thing, it didn't backfire, but engine almost died and started running bad. Idle is good on P or N, but under load, sounds and feels like 1 cylinder is missing. After engine shutdown, fuel pressure drops to zero. There is no vacuum leak externally atleast. Tryied to reset the ecm with power on for 10 minutes, didn't work.

Need seriously good ideas... Mine are sold out. :banghead:
 
#17 ·
Running poorly under load and leaking down to zero after a few minutes are your clues.

Either the fuel pressure regulator is leaking badly or your fuel pump check valve is toast. To test, take fuel pressure at the fuel filter. If it holds, it's the FPR. If it drops instantly, it's your fuel pump.
 
#18 ·
Leeann_93 said:
Running poorly under load and leaking down to zero after a few minutes are your clues.

Either the fuel pressure regulator is leaking badly or your fuel pump check valve is toast. To test, take fuel pressure at the fuel filter. If it holds, it's the FPR. If it drops instantly, it's your fuel pump.
Seriously, i've been thinking this and bang'n heads together with my buddy.. Regulator isn't leaking, cause we increased fuel pressure not a long ago, and the regulator was new! Hope this solves the problem for sure! I'm sick and tired thinking and fixing and thinking again what the *beeb* is wrong with my astro.

THANK YOU FOR GREAT IDEA!!! :rolling:
 
#19 ·
Drop the tank carefully, pull out the fuel hanger assembly and I'm sure you'll find the problem.

Only get AC Delco or Delphi on the pump unless you want to do this again soon. Check the fuel pump wiring harness when you do this.
 
#20 ·
Leeann_93 said:
Drop the tank carefully, pull out the fuel hanger assembly and I'm sure you'll find the problem.

Only get AC Delco or Delphi on the pump unless you want to do this again soon. Check the fuel pump wiring harness when you do this.
I sure will. :ty:
 
#21 ·
Hi everyone!

The Astro project is on ice for now, haven't had time to do anything yet but to drop the tank down, change the pump (and it was in average condition, i shaked it a bit and it sounded like something is loose.) It takes time when i have a change to test that. Little welding on frame etc. I will post here when i get those things done. :)
 
#22 ·
Hello! "Little welding" seemed to me like the project is going to last forever.

However! I've done this and that, and finally my Astro is running nicely! Fuel pump change did the trick.

Thanks to everyone who helped me to solve this problem!
 
#23 ·
Should not lick ur lips before the apple falls - said somebody wise.

I have had rough times with my astro.. Months of work seemed to go to waste. After hours of work nothing seemed to help.

Finally i got tired of this s**t and i opened the intake manifold. Former owner have sealed intake manifold with glue?!!?! No caskets, nothing. :rofl: I just laughed my *** off. Suprisingly, no glygol have gone to oilpan. Wonder how lucky i am. However, i changed the whole intake manifold to new, put REAL caskets there, started testing and almost crapped my pants. It runned. For a while. After engine warmed up, idle changed from rapidly to almost none. Seems to leak air from somewhere. Oxygen sensor is still going crazy. And winter is right in the backdoor.... Time's almost up.
 
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