Engine Missing random multiple misfires

Tiny
HKYPUK6
  • MEMBER
  • 1997 CHEVROLET ASTRO
  • 6 CYL
  • AWD
  • AUTOMATIC
  • 184,615 MILES
First, here's what I have recently done: Changed sparkplugs and sparkplug wires twice, changed distributer cap & rotor, had MAP sensor tested (good), had fuel injectors cleaned, replaced PCV Valve, Fuel filter, new fuel pump (was missing before fuel pump went out), had catalytic converter cleaned out. I have also just purchased a new Ignition Coil, but I have not installed it yet.

Problem: Service engine light is on. Sometimes goes out, sometimes flashes then stays on. Scan code shows "Random multiple misfires" (forgot actual code #). Engine runs really rough (missing) especially when taking off from a stop until it get's into (I believe) 3rd gear. It helps to let off the gas pedal until it shifts. It also sputters or miss big time when traveling at higher speeds (60-75). Some days are worse than others. But it's now missing most of the time.

I'm running out of ideas as to what is causing this problem. The engine has backfired a couple of times, but it hasn't backfired lately. I now also have a muffler leak. I'm sure this is a cause/effect case. The bottom line is that I need to get the engine mis-firing taken care of before this causes any more problems.

Ideas?

Thanks much. Mrb
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Thursday, June 5th, 2008 AT 9:59 AM

10 Replies

Tiny
ASTRO MYSTERY
  • MEMBER
I have the exact same Astro with the same problem and have tried most of the things you did. Every 1 to 6 months the engine starts to stumble. It can be so bad sometimes it can hardly make it up a small hill. When I change the Cap & Rotor it runs fine and I can't see anything wrong with the old ones. I never find moisture in the Cap but I have tried drying it out and cleaning it but this makes no difference. Only when I replace the Cap & Rotor is the problem solved until the next time. Sometimes I think it stumbles after it has been in the rain but for the most part it goes into the dry garage every night. Also, I did buy a bad Cap & Rotor once and had to exchange it. I never figured out what was wrong with it, no visible defects or damage. It just did not work. I have no idea what's eating the Cap & Rotor or what's happening to them that forces me to replace them, but this works for me. It takes me longer to take that damn dog house off to get at the distributor then it takes to change it. I hope this helps somewhat or at least you know you're not alone. I've been trying to get an answer to this for 3 years but know one has a clue. I would appreciate it if you get a more decent answer that you let me know. Thanks!
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Thursday, June 5th, 2008 AT 5:02 PM
Tiny
HKYPUK6
  • MEMBER
Thanks for your response. I also have pretty much done the same as you and had very similar results. As far as the dog house goes.I have forgotten what it's like to have the center console cup holders and small glove box. I only have the firewall cover on. Got tired of continuously taking the other off all the time. Now it's a lot quicker to get to! Whenever I change the cap & rotor out, it definately gets much much better, but I can still feel a bit of missing. Definately not near as bad. I also think this problem is killing my catalytic converter from what I have read in other places (which is fairly spendy). I have seen other's with this problem, but no one really has an answer, the answers all varied. I did see in one location where someone was suggesting that the problem was a bad seal on the Distributer mount and recommended getting a new distributer, but I haven't seen any other similar recommendations and/or results of that, so I have hesitated in spending the $90 for a remanufactured Autozone replacement in "hopes" that it fixes it. If I saw more indication of that being the problem, I might go ahead and try it.I keep putting it off.

Thanks
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Thursday, June 5th, 2008 AT 5:40 PM
Tiny
ASTRO MYSTERY
  • MEMBER
Thanks much for getting back to me. I no longer feel all alone with this mystery. Let me share with you some of the info I have found and perhaps together we can once and for all end this costly / time consuming Astro maintenance nightmare so we can both get our cup holders back. Sorry if this is a bit lengthily but detail matters. This problem started for me at around 110,000 miles. Before that all was fine. The first misfire experience I had was a bad Ignition Coil that was arcing like the 4th of July. I replaced it and about 1 year later it failed too and was arcing again. This one lasted 1 week and vehicle died on the road. That Coil did not arc it shorted out and quit, (off-the-shelf part failure). I replaced it and its been fine ever since. About 8 months later it started misfiring again but it was different. Coil was ok and after a long trouble shooting process I discovered the Distributor Cap was bad. I changed it, it ran great, it made on sense, couldn't figure out why. 8 months later, misfire again, changed Cap and problem solved. 4 months goes by and again misfire. Changed the Cap, misfire was worst. Now it was driving me NUTS. I got another Cap and misfire was gone, again (off-the-shelf part failure). I have gone through 6 or 7 Caps in the last 3 years, expensive and time consuming. I just changed it again 2 days ago. I kept the last 3 bad Caps and tried different things looking for change. I found that each Cap caused a different feeling misfire. Like different cylinders were effected by each Cap. I drilled a 1/2" hole in the side of each Cap so I could see spark when it was running. Sure enough the spark would change color and each Cap had a different spark pattern to it. These Caps are shorting out over time and not the same way. I would always buy the next Cap made by a different manufacturer trying to find a better quality Cap. Have not found one yet. I buy all my parts from reputable auto supply businesses that all the local mechanics use. Their experience like mine is a higher off-the-shelf part failure rate mainly in the last 8 or 10 years and getting worst. I never buy parts from places like Auto Zone or Advanced Auto because they are like Home Depot and Wal-Mart. They buy huge quantities, demand the suppliers to lower the cost because of purchasing power, the manufacturer cuts quality to make up the difference and we the public suffer for it. So, back to the Caps.

I would really like to keep a dialog with you about this if that's ok and perhaps get off this forum. My name is Tony and my e-mail address is tlea2nd-1@yahoo. Com You are the first person I've found with this identical problem and I really want to end this nightmare. Thanks, Tony. The guy desperately in search of a quality manufactured Distributor Cap.
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Friday, June 6th, 2008 AT 1:43 PM
Tiny
HKYPUK6
  • MEMBER
Sounds good to me! I'll email you directly. Looking throughout this forum, I see a lot of lookers but I don't see a lot of help. There are many questions that folks have with no replies. Just a lot of lookers!

Thanks
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Friday, June 6th, 2008 AT 4:34 PM
Tiny
SECURITY101
  • MEMBER
VERY INTERESTING! I have the same issue exactly! Only mine finally backfired and died last winter. I had replaced the cap (again) just prior to the "backfire event" and just figured it couldn't be another cap.

I had a certified mechanic come by and he said the backfiring could only happen with timing chain issues, that the deposits and constant replacing of the rotor/cap was from the chain allowing slack which altered the spark.

So it's sat until now as I tried to sell a "no start" for 5-700 bucks!

By the way it's a 97 Astro v6.

I would also like to email you and see what your finding out, wow - wouldn't it be cool if I could solve it with just a "better Brass" cap and some filter cleaning.

Jim
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Wednesday, June 18th, 2008 AT 8:58 AM
Tiny
HKYPUK6
  • MEMBER
Jim, I'm sorry to hear that you are having a lot of the same issues. It's interesting that it seems that there are many vans out there with the same issue, but no one has yet to find a solution. At least that I'm aware of.

I am currently still troubleshooting my van's problems. I have just purchased "another" dist. Cap (AC Delco) that I'm about to install. The word on the street, that I keep hearing, is that the AC Delco dist. Caps appear to have the best and longest results with these vans.

I'd be happy to hear some of your results of troubleshooting also. Please drop me an email at the following address: mrbjunkbox1 at gmail. Com

Mike
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Thursday, June 19th, 2008 AT 4:19 PM
Tiny
SECURITY101
  • MEMBER
Hi Mike,

I have tried everything everyone else has to no avail - 6th cap (many have been AC Delco as this was recommended a ways back) and still have issues.

I had all but givin up and was in the process of selling the van (97 Astro) for $700 bucks (well below KBB) as it is clean, everything else works (except the rear door latch) and I gave up on it (and everybody had an opinion like: "fuel pump" which I'm on my 3rd probably for no good reason) - when I came across this thread on a related Google search!

I had researched this heavily and found no similar threads or explanation for the problem. So about 5 mos ago, the day after my daughter bought her first new (junker) car - I, as the "bad Dad", commandeered it, and have drivin it since (don't worry I still take her everywhere she has to go!). She's told me to vacate it as she's turnin 18 and I'm looking for something for me to drive.

SO sell the Astro add 1k and go by me a junker - right?

Nope, I found you good folks chattin about "my issues" and it looks like I better revisit the old Astro before some "wiz kid" straight out of mechanics class buys my van, throws a new distributor/cap/rotor in it and squeezes the last 20,000 miles out of it!

ANYWAY.

I called the local dealer service dept this morning and spoke with "Darrell" and you wouldn't believe it but he said he knows about this issue. He has "fixed a bunch of them" and it's easy.

Replace the distributor, bottom line!

He said the "vent issue" is prominent (I explained I didn't think that was MY issue - but I dunno) and he also said there was mechanical issues with the "old style" yet he wasn't clear exactly what physically is different. He's just been replacing them and all is well.

One other note, the last time it "pooped out" it also backfired when I was trying to start it and when we tried the old cap replacement, and could never get it to go again (I could get it to idle, but just touch the pedal and it died). Hopefully the timing chain didn't go (anyone with an astro knows that is a "more major" job than on most vehicle's) cause I'll just sell it as a "no start" before I put that kinda effort back into it!

Anybody got a cheeeep Kia?

Jim
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Thursday, June 19th, 2008 AT 5:26 PM
Tiny
RIFLEMAN
  • MEMBER
Hey you all. I was just looking for a solution for my van and read all of the cap problems. I have an idea which is the problem. I saw it on Well's garage. These distributors have a high out put and generate a lot of heat. So condensation builds up causing arching. This is your Missfire. The solution is to remove the distributor and clean the air vents in the base with compressed air this will allow the temperature to cool down inside the cap and expell the heat. I hope this helps anyone out there.
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Saturday, September 10th, 2016 AT 6:16 PM
Tiny
1ST RASTRO
  • MEMBER
Same issues. 98 Astro awd, 142,000. New to me. Random misfire code. Replaced plugs, wires, rotor, cap twice (second time to ac Delco), upstream o2 sensor on passenger side, fuel filter (2x), cleaned mass airflow sensor with sensitive electronic spray, cleaned and reattached fuel pump ground, checked for tdc and rotor alignment (good). Took for diagnostics for spider, poppets seemed to be functioning normally (equal pressure drop for all). No shorts in the wire harness that I can find. Ran some sea foam through it.

No backfires, occasionally runs fine. Like every 20th time I drive it.

List of things still to try:
Replace distributor
Clean or replace egr valve
Ignition coil
Timing chain
Fuel pressure/pump

Other ideas?
I m getting desperate, bought this for a band van but don t feel comfortable taking it for long trips, can t be good for the engine to have this problem long term.

Thanks in advance for any tips or advice.
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Monday, November 26th, 2018 AT 3:18 PM
Tiny
ASEMASTER6371
  • EXPERT
Good evening,

The most common cause for this issue is the fuel pump.

Did you check the pressure? if so, what was the result?

Roy

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

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Monday, November 26th, 2018 AT 6:29 PM

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