Missing(?) at highway speeds

[tex star detail]

1999 Chevy Astro Cargo
2wd
127k miles

Bought the van from my Dad in Missouri and Drove it back to Texas (roughly 11 hours)
The van seemed to "miss" on the hwy at cruising speeds, not when the gas pedal was pushed, just cruising.

What I put in since July:
MAF (threw a code before I bought it)
Battery
Plugs (AC Delco)
Wires
Cap/Rotor (Accel)
Cat
Fuel Filter

Still no change.
Runs smooth all the time except on the hwy at speeds 65-75 cruising.
Gas mileage is ok, no codes at all.

One thing I do notice:
The fuel pump will get a really loud whine every other day it seems. I know what a normal whine is, but when my worker looks at me like my van is going to blow up, then it is loud.

Other than the distributor gear, what else should I look for before I get my hands greasy????

The fuel pump is starting to worry me....

[rev_les]

The first 2 things you need to do, are check the fuel pressure, and check that distributor gear. The gear's only $30-ish; the pump, well...you know. Did you notice any slop in the distributor shaft when you replaced the rotor? ( as in able to turn it clockwise/counter clockwise).

[tex star detail]

Honestly, I don't remember checking. I do however, remember buying a cap for the astro and getting home only to unbox a cap for an 8 cylinder.

I guess I will have to check distributor first. Pull the cap and check for play. Should there be ANY play?

As for the pump, yea, $400 and up for an AC Delco.... Not looking forward to a replacement.

[rev_les]

If you grab the rotor and try to rotate it, there should be zero play. If there is some, you'll notice that the shaft tries to ride up and down as you turn it also ( helical cut gears). It may be that it's just slightly worn, as it progresses, she'll start bucking like a bronc. ( or it may not be the issue)
FWIW, I bought an Airtex pump 4 years ago (before I heard anything bad about them) and it's got over 100K miles on it.I change my filter regularly though, and made sure the ground and connectors were clean. I'd still recommend OEM, having read the horror stories on here.

[webcat]

As for the pump, yea, $400 and up for an AC Delco.... Not looking forward to a replacement.

I just bought a Delphi for right under $200 , its as good as a Ac delco.
http://store.getgmparts.com/fg0127.html

[AstroWill]

1999 Chevy Astro Cargo
2wd
127k miles
The van seemed to "miss" on the hwy at cruising speeds, not when the gas pedal was pushed, just cruising.
Runs smooth all the time except on the hwy at speeds 65-75 cruising.
Gas mileage is ok, no codes at all.

That does sounds exactly like the distributor gear, almost word for word the issues I was having. This is a VERY common issue on the vortec engines, you can find posts all over the chevy sites about it. I actually did a video of the old vs the new one I installed, but I can't seem to find the video.

Are you losing any power?

If you do have play in the dist, you can see what I bought at the following two posts, it was only a little bit more expensive than buying just the gear. viewtopic.php?f=43&t=4333#p29738 and viewtopic.php?f=43&t=4333&start=10#p104833

[Phantom]

In addition to the other things mentioned , the ignition coil may be weak or arcing coil wire, which is easy to check . That distributor for 59 bucks looks like a bargain with a 5 year warranty ,

[Woodweasel]

I had a similar miss. Mine would do it only when cold, but give it 15-20 minutes of street driving to get up to operating temp and it would disappear. did the highway miss also, only when cruising, step on it and it would disappear. I had just replaced the cap and rotor about 6 months before, but checked them both just to be sure. Sure enough the contacts were all burnt. So new Accel cap and rotor and the problem went away.

[alexalexanders]

Mine did the same as woodweasel.. Although you did say it still did that after you changed the cap and rotor. Im kinda thinkin the disributor gear like stated. BTW texs star detail where does your dad live in missouri, im in the springfield area

[paintdrying]

check your fuel presure check your grounds, the one on the t stat housing as well, check the connection to the computer, might be a bad ground on the fuel pump, an worse in wet weather? As said abouve that could be a weak coil.

[tex star detail]

Will have to check everything over Thanksgiving. Too busy to tear into the van. Hate to get into something and then have to cancel an appointment due to me having the van apart.

Alex, (I assume that is your name?) My Dad lives in St. Robert/Waynesville area. About 45 minutes to an hour from Springfield. Right off I-44.
I burn through there everytime I go up there. I lived there for about 8-9 years, split into two different times. I come up to Lebabnon (Bennet Springs) to do a week of camping/fishing with my parents every year. Will have to give you a shout next time I am heading that way.

[alexalexanders]

Ya sounds good let me know when you come to town!

[tex star detail]

Think I fixed this problem with a new distributor. Just as cheap as the new drive gear. Anyways, I pulled the dog house and removed the distributor cap. The dizzy had a ton of play, and lift actually. I marked it an pulled it. Looked used to me. ha. I ordered a new distrib from Advance Auto and installed it. No misses as of yet.

Video uploading of the play I had in the rotor..... Stay tuned.

[tex star detail]

Since I have no idea how to post a vid, click the picture to see it.

[UsedCarTech]

Mine too does the bucking! But no play in the button, on the distributor. I have replaced the cap and rotor button, but with cheap ones. I am very poor right now and cant afford to replace unless have too. I try to test all I can. Can the one coil be tested to see if weak?

[UsedCarTech]

So if I have no play in my button or dist. should I still consider dis. gear? Or do you think that big of a miss fire can come from cheap plugs and cap? No engine light. y94

[Phantom]

If there is no play in the shaft when you try to turn it the gear is likely good , and yes the cap can cause a bad miss ; makes a bad jerk while driving , it can feel like the transmission is going bad when the trans is fine , also make sure the rotor spring is up against the terminals of the cap , the cheap rotors are kinda flimsy and bend easy and may not be making constant contact with the terminals in the cap causing a miss , here is a tech service bulletin about the screens in the dist housing that also cause a bad miss , there is not enough air ventilation in these short caps .

[UsedCarTech]

Thanks I just did those screens a couple of weeks ago. Iam very poor so I am trying to find excat problem and prove it before buying anything

[Phantom]

Can the one coil be tested to see if weak?

Yes , one way is to put a big paper clip in the coil wire and hold/cable tie it close to a ground source and see what color the spark is , should be blue for strong and yellow for weak orange is middle , or use a meter to measure ohms , current and also there is the OBD scanner which is best ,