[Mr_Bowtie]

My wife and I just bought a '92 Astro van. Maintained pretty darn good, but she has a couple issues to be addressed. It starts up just fine and runs great, then after it warms up it starts to miss or hesitate a little. Not bad...usually around town. On the highway you can't notice a problem. Then if you try to start it when the motor is warm you have to hold the gas pedal in to start it???

Its throwing codes 23, 32, & 45 at me...... :dance:

So, using this list of check engine light codes: http://www.gnttype.org/maint/malf.html
Its saying its seeing problems with the MAT sensor, EGR valve, & 02 sensor.

I'm thinking of starting with a new 02 sensor and new plugs cause I'm thinking the bad 02 sensor might have fouled out a plug or two.
I wish I still had my old OTC 2000 scanner......gonna have to pick one of those up again! Been tinkering with Ford for a couple year and got rid of my Chevy stuff. :naughty:

Any suggestions of what a good game plan would be?

Thanks, Nick.

 

[Leeann_93]

Don't replace parts just because it threw a code - it'll get expensive!

It sounds like you have an intermittent small fuel leak under the intake plenum. This causes a rich condition, which carbons up the EGR valve and throws the O2 sensor code for a rich condition. This is how mine started...

You'll need to pull the IMTV at the top of the plenum (under the VORTEC plastic cover) and take a look-see (you'll need a flashlight) - if the passenger side has any washed/clean areas, it's your fuel pressure regulator. If it's the driver's side, it's your fuel pressure and return lines, called the Nut Kit by GM in their infinite wisdom. To pull the IMTV, you will need 2 torx bits: a T-30 for the 2 torx bolts in the plastic cover and a T-25 (I think, might be T-20) for the 2 torx bolts holding the IMTV in place. You might also need a little WD40 to spray around the outside of the IMTV, then gently twist the valve one way and then the other until it's loose enough to remove. Be careful; there is a rubber o-ring that you need intact to reinstall the valve. When you do reinstall, lightly lubricate the o-ring with a little engine oil.

If you do see washing, you will need to get the fuel pressure regulator if it's that (~$40 at autozone, comes with the torx security bit needed for r&r) or the Nut Kit (~$55 at NAPA), the upper intake plenum gasket (~$12), a screened EGR gasket (Dorman/HELP section for less than $10) and a set of AC Delco plugs. And a 10mm deep socket if you don't have it - that's the size of all the nuts on the upper intake plenum.

Once you have replaced the leaking bit and before upper intake reinstallation, pull your EGR valve and clean the pintle and seat very carefully. You'll probably have some chunks of carbon that keep the pintle from fully seating. When you reinstall, use the screened gasket to keep chunks from clogging it up in the future. For that, you will need a 10mm socket and at least a 9" extension (and a little piece of paper towel in the socket to hold the nut securely) for the driver's side bolt. For the passenger side bolt, you'll need a 10mm wrench. Ratcheting, if you have it, is easier.

When you do all this, pull the negative battery cable. After you've got it all back together, put it back on - this will clear the codes and re-set everything. Then start 'er up and get it good and warm, then take it for a test drive.

Oh, and 23 is Intake Air Temperature Sensor or Circuit (Open) . Check to see if it's plugged in (it's on the underside of the rubber intake piece that goes to the throttle body and is easily forgotten).

 

[Mr_Bowtie]

Sounds like a plan to me! Thanks! I did smell fuel when I started it cold, but after that I did smell nothing. Can I get to all this through the doghouse?

Thanks, Nick.

 

[Leeann_93]

I think so, but it's a tight squeeze. I did it on my Bravada, not my Astro.....

 

[Mr_Bowtie]

I didn't see the word VORTEC on any of my components. I got the doghouse off though and I assume your talking about the circle looking thing on the center of the upper plenum? Thats the IMTV???

I did find out that there is no air filter in the airbox. Oil is clean and tranny fluid is super clean. Found a small vacuum leak in the hose that goes from the valve cover to the air box. Fixed that.

Its definatly running rich as its spitting raw fuel out the tailpipe if I rev it in park. :rockon:

 

[Mr_Bowtie]

OK.........stuck my head in as far as I could and bent the AC lines up a little to see down in that hole. Looks like the passenger side is much cleaner then the driver's side of the plenum. The driver's side also looks to have fuel sitting in it??? Like a little puddle maybe??? Hard to see with my big-azz head!

Whatcha think? Fuel pressure regulator? And thats located inside the plenum? Thats weird that everything is inside there. This is my first 4.3L with this type of fuel injection on it. :dance:

Thanks, Nick. :mrgreen:

 

[Leeann_93]

Sounds like someone removed your Vortec cover, just like the one on my Astro.

Good job on finding the vacuum leak.

Yep, the round thing in the center is the IMTV.

Sounds like you might have both things leaking (fuel pressure regulator AND nut kit)...but now the thing to do is to pull the upper plenum and take a closer look. Once you pull it, you can turn the key on (but engine off) to energize the pump so you can see any obvious leaks. While you have the upper plenum off, clean out all the passages as they're likely carboned up pretty good.

 

[Mr_Bowtie]

Alright I'll pull that upper plenum cover off tommorrow and see what I got. Thanks for all the help!

 

[Leeann_93]

Good luck!

 

[Mr_Bowtie]

So, I was in the process of pulling everything off the front of the plenum so I could just unbolt it and pull it off through the doghouse. I found the MAF tube not hooked up to the TB at all.....just sitting in front of it? Also found a huge vacuum leak(second one) on the back passenger side of motor off the valve cover going to the plenum. So, I fixed that crap and threw that sensor back in the plenum to start it up. Also disconnected the battery to clear the ECM codes.

So, with the Van just idling it didn't throw a code and seemed to be running less rich, but I still think its too rich or bad plugs. I'm gonna go for a ride later tonight & see how she is. She starts easier too, but could still use some improvement. Probably end up having to open that plenum up, but its worth a shot to see if any of that helped. ray:

Nick.

 

[Leeann_93]

Hey, it's worth a shot. Let us know what happens.

 

[Mr_Bowtie]

Still running rich and get code 45 still. 02 sensor too rich. So, my buddy and I pulled the plenum off and looks like the fuel lines or whatever on driver's side is leaking and the regulator on the passenger side is leaking too.
So, looks like a good way to spend $100 on my $700 Van. But, after that she should run like a top. :dance:
The vacuum leak before was the EGR valve & the air tube that was loose must have been throwing the other code too.
While I'm foolin' around I'm going to pull all my AC crap out beside the compresser...just to get some crap out of the way so its easier to work on in the future.

 

[Leeann_93]

Great! Glad you found it. Just be careful on reassembly and everything'll be cool

And don't forget to replace your spark plugs and change your oil before you start 'er up again.

 

[Mr_Bowtie]

Thanks again for pointing me in the right direction. Gotta work the next few days, so no time to work on the Van until next Saturday.....hopefully.

 

[Leeann_93]

No problem - let us know how it goes when you can get to it!

 

[Mr_Bowtie]

Ok, got the fuel lines and regulator in and everything back together. Started the beast up and no black crap out the tailpipe. Its running pretty clean now. I didn't have time to go for a drive. Gotta change the oil yet. Hopefully my hard start ups once warmed up are gone and gas mileage is back to normal. Time will tell.
Next order of business is to fix both my power window motors. ugh!
-Nick. :mrgreen:

 

[Matrixx]

Thanks for the updates P71CVMAN.

 

[Leeann_93]

Great!

The window motors aren't too bad once you've done one. The first one's a PITA. After you figure out what works on the dang rivets, the next one's a breeze...sorta

 

[Mr_Bowtie]

Thanks for the updates P71CVMAN.

No prob man! :thumbup:

 

[Mr_Bowtie]

Hey hows about another quick update? :lol:

Finally drove the Van on a 2.5 hr round trip cruise today. Shut it off a few times and she restarted without any problems. SO GLAD that hard start problem is gone! No more check engine light either. Gas gauge moves slower too!

Thanks again Leeann93! I would have been chasing my azz all over the place trying to get it to run right if I would have never signed up for this forum and simply asked a question. :mrgreen: