Chevy & GMC Vans

Ok this is a 92 astro with a 4.3 TBI motor . it idles fine but when you put it in gear it stumbles & runs like crap & dies when you step on the gas peddle . fuel pump & filter have all been recently changed . its shows a code for the ESC (electronic spark control ) we have replaced the ESC twice now with new ones & still does the same thing . my cousin put it on his scan tool & it shows a bad ESC so we figured maybe computer or chip . both have been replaced with a same # computer & chip , it won't even idle with a different computer . we've tried every different combination of compuers & chips you could think of . we have 3 computers & 4 chips . reset the computer each & every time . it will only run & idle with the original computer & aftermarket chip that was in it when bought from lockdoc . i also need to say that this happened once before with the esc oing bad & when it was replaced everything was fine untill it happened again 2 weeks ago . today we'r replacing the ICM just for hopes sake as we have a good used one here & checking all the wires for broken or burnt wires or contacts , other than that i'm at a loss . if anybody has any suggestions we're open to anything right now . this van needs to be up & running soon .
thanx guys i'm sure someone will have an idea we didn't think of .

Replace the Ign. module and or Distributor.

we did replace the ICM with no difference
.

Have you checked the coil at all? Does it rev at idle OK? How does the fuel injector spray pattern look? What about the pick up? you can deck that with the ohms setting on a multimeter. What about your coil wire? I'd check it too, I had a major idle issue with my van, and the coil wire had some silly high resistance to it.

Runs great at idle , spray pattern is perfect , wires cap & rotor all check out ok . coil i have one here i can replace it with , maybe i'll try that . i'll try anything right about now .

thanx alex , gonna replace the pickup in the dizzy & the coil , will let ya know how we made out .

that kinda makes sence cuz one other symptom we have is that it starts hard , by that i mean it has to crank about 15 to 20 seconds before it will start .

question , it has a blaster coil on it now that was given to him , would that maybe burn out the pick up in the dizzy ?& cause these problems .

Coil & pickup replaced with no difference . played with the timing a little by turning the dizzy back & forth ,it only makes it run worse .

i have no idea here !!!

the code we keep getting is a code 42 for electronic spark timing . if this helps anybody .

if the van has jumped time , would it still idle & run like it should during idle ? its only whenits put in gear (under load ) that it falls on its face . it spits sputs & won't go anywhere without dieing . .

bump , lookin for clues here guys .

would a small vaccum leak from the intake make it run like crap under load and good during idle ?
theres a hose that goes from the intake to a tee then to the cruise control tank & one side of the tee is open , no hose connected . can't find where it would go , but the idle picks up a little when you block it off .

Skippy,

I don't know if it will help your problem, but I had a 94 Astro that did about the same thing. On the distributor under the rotor where the pickup coil is. The magnet that is splined to the shaft would move. I could move it with a pocket screwdriver. It should not move. Drove me nuts. Somebody on AS helped me with it, I hope they will forgive me I can't remember who it was like a year ago.

*EDIT* Drat! Now I see that the van has a V8! Dunno if it was a problem for the V8.

Man if YOU'RE stumped you got real trouble... you really know what you're doing! Doesn't look like Monday is your day for an answer.

Thinking outside the box, which is all I can do in an infantile way, is the assumption that it requires more gas flow to move than to idle... can you be sure the fuel pump continues to do it's job in gear and there is no flow obstruction? Any other electrical symptoms, dash or otherwise when you shift from park to D?

You can get it to rev HIGH in idle? A good 4-5000 rpms?

I would check fuel pressure as PharmAstrocist suggested. It is also possible to have good pressure but poor volume, but since your pump and filter are recently replaced this may not be the problem. The only other thing I can think of is an EGR valve sticking open. Engines generally don't like EGR flow at idle.

Hope this helps...

bump, getting a pressure tester tonight but i'm still not convinced its a fuel problem cuz we're still getting a code 42 which is an EST malfunction . in this van the EST (electronic spark timing module ) is part of the ignition control module which we have replaced . all wires & connectors check out fine the grounds check out fine . as of now the only part of that system that hasn't been checked or replaced with a knowingly good part is the dizzy itself . even the electronic parts in the dizzy have been replaced . the ICM the pickup etc.....

i'm soooo confused !!!lol

oh & brandon this is not my v8 van its my brothers 92 AWD astro with the 4.3 TBI

Try replacing the scan tool

Skippy, I'm working from memory here, the vacuum hose routing goes from the throttle body to the T where the cruise control hose ties in, as you mentioned. I believe the hose from the third leg of the T routes down to the vacuum reservoir. It's buried on the passenger side towards the front of the engine compartment. It's one of those hose connections you can see with a flashlight, or you can touch it, but you can't do both at the same time.
If there's no hose on this it would introduce a pretty good sized vacuum leak.