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99 chevy Astro Van anybody know how to test a fuel injector to see if it is causing a misfire? 6 cyl eng runs rough. P0301 code.
 

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P0301 is cylinder 1 misfire. Check the secondary ignition first (wire, coil tower, spark plug). You can measure the resistance of #1 injector and compare to others. All should be ± 10% of each other. To go further, you will need specialized tools.
 

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99 chevy Astro Van anybody know how to test a fuel injector to see if it is causing a misfire? 6 cyl eng runs rough. P0301 code.
This is a spider aray under the intake and the resistance will not tell you if the injector is clogged. I am looking for a way to activate the number one injector. Wire, coil, spark plug good and plug fires.
 

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You can install a fuel pressure gage and manually PWM the injector with a tester, measuring and comparing the fuel pressure drop between injectors. You can also use a noid lite to check the ECM output and wiring to the injector.
 

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Those spider injector assemblies have poppet valves on each hose that are common to plug. There isn't much that works to clean them without an injector flush machine that will pulse the fuel psi and that only works half the time. Gm has an updated assy. that gets rid of the poppets and uses regular injector tips on the hoses.
 

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Those spider injector assemblies have poppet valves on each hose that are common to plug. There isn't much that works to clean them without an injector flush machine that will pulse the fuel psi and that only works half the time. Gm has an updated assy. that gets rid of the poppets and uses regular injector tips on the hoses.
cjm94 so is there a way to acess the injector to check it with out taking the intake off? I should have never taken it in for repair. I should have bought a few test items. Because they replaced the MAF, Computer, fuel pump, cap, rotor and then some. damaged the gas cap, the air box. Needless to say they are done.:mad: I have since purchased my own OBD scanner, Fuel pump pressure gauge. I have It narrowed dow to number one fuel injector. Cold here now and no garage.:wink:
 

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No way to get to them with the intake on. It's not a very DIY friendly set up. I know people think dealers are a rip off but for about a hundred bucks you would have had a good diagnosis instead of a couple thousand dollar mistake. I hope they stood behind there mistakes. I'm not saying dealers don't make mistakes but good ones would not have charged for the stuff they misdiagnosed.
 

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No way to get to them with the intake on. It's not a very DIY friendly set up. I know people think dealers are a rip off but for about a hundred bucks you would have had a good diagnosis instead of a couple thousand dollar mistake. I hope they stood behind there mistakes. I'm not saying dealers don't make mistakes but good ones would not have charged for the stuff they misdiagnosed.
Taking the intake off is not an issue, just wanted to make sure it is an injector. This all started out at the dealers, they went out of business. From what I understand $1,500.00 to replace the injectors. I can do it my self. I should have bought a few test items and did the trouble shooting my self. :(
 

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Taking the intake off is the hardest part of that job. You should be able to find the injector assy for 200-500 depending if you go with the old style or the updated ones
 

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Taking the intake off is the hardest part of that job. You should be able to find the injector assy for 200-500 depending if you go with the old style or the updated ones

$250.00 online

P0301 code is a misfire on number 1 cylinder so would I be wrong assuming the problem is something dedicated to cylinder number one?



I still have to check compression.
 

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If you have spark and compression you are pretty safe with the injector. A cylinder leakage test would rule out a burnt valve but injector poppets are very common on those
 

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If you have spark and compression you are pretty safe with the injector. A cylinder leakage test would rule out a burnt valve but injector poppets are very common on those
That is what I am thinking, bad injector.
 

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Discussion Starter #16
Injectors

Ok thanks for all the info, I will research replacing the injectors before I start. I will take pix so if I forget where something goes. It is just a matter of starting the process.:thumbsup:
 

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Update, done nothing so far. But now it is running so smoothe, can't tell it is running idling at a red light. Check eng light has not came back on yet. So I don't know.
 

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Dude, do not get into that spider system. On an astro it is able to be done but is very tight. You should take it in for a fuel injection cleaning, you have a poppet stuck. If the dealer did not use ac delco parts than pull all those off. Also replace the wires. I can not stress enough that you need to use ac delco parts on that van.
 

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I had one of them in our shop awhile back for a misfire that would come and go (P0307 - Cyl 7 Misfire). The owner had it another shop and they replaced a ton of parts. All that was left was the injector spider. I have worked on so many Chevy 4.3/5.0/5.7's that I have boxes of spare parts. I threw on a distributor cap that I knew was good and that took care of the intermittent misfire. It had been replaced already. And it was an ACDelco part. Those caps were a terrible design to begin with (they cross conductor paths in the cap so that the wires come neatly off each side). Maybe a defect in the cap, maybe the guy who put it in dropped it, maybe the box got dropped during shipping, etc, it doesn't take much.

In my experience once the spider poppets plug up they don't usually come back on their own. I've had 50/50 luck using a high pressure injector cleaning tool. But replacing the spider assembly isn't very difficult. I'd use the new design if at all possible...much better design (no poppets).

I had a 99 Astro AWD for 2 years. It was awesome in the snow, I'll say that. And I'm not a Chevy guy. But finally sold it off as the gas mileage was rotten and the wife wanted a sliding door on both sides (we had just had twins).
 

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Discussion Starter #20
I had one of them in our shop awhile back for a misfire that would come and go (P0307 - Cyl 7 Misfire). The owner had it another shop and they replaced a ton of parts. All that was left was the injector spider. I have worked on so many Chevy 4.3/5.0/5.7's that I have boxes of spare parts. I threw on a distributor cap that I knew was good and that took care of the intermittent misfire. It had been replaced already. And it was an ACDelco part. Those caps were a terrible design to begin with (they cross conductor paths in the cap so that the wires come neatly off each side). Maybe a defect in the cap, maybe the guy who put it in dropped it, maybe the box got dropped during shipping, etc, it doesn't take much.

In my experience once the spider poppets plug up they don't usually come back on their own. I've had 50/50 luck using a high pressure injector cleaning tool. But replacing the spider assembly isn't very difficult. I'd use the new design if at all possible...much better design (no poppets).

I had a 99 Astro AWD for 2 years. It was awesome in the snow, I'll say that. And I'm not a Chevy guy. But finally sold it off as the gas mileage was rotten and the wife wanted a sliding door on both sides (we had just had twins).

Have not had the P0301 code or any code since my last post. I agree with you that a plugged injector is not going clear up and the reappear. I also have read several articles on the after market caps. Still runs rough at idle thou. Who sells Delco caps?
 
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