Chevy & GMC Vans

ok tech guys, I am new, but I have a problem that maybe someone can help me with. I have a check engine light that is giving me a headache. and I want to fix it, not pull the bulb or put electrical tape over it.. lol
I had on the ODB2 computer, and I had an EGR error, along with "random misfire" (no indication as to where the misfire is taking place) and catalytic converter not working at optimal performance (can't remember the exact wording, but that's the jist of it.. lol). these errors were found using a snap on ODB2 computer.
I replaced the EGR with a new one, my mech cleared the codes. it was great not having that stupid light on for a day.. then it was back. so I took it back to him, he checked it, and told me it was the same 2 codes back again, the misfire and the cat performace problem.
any ideas of what could be causing these problems? he's thinking it's the injection spider, or a bad injector. I talked to a couple of other mechs and they told me it could be a bad cap or coil wire, and maybe a bad cat to go along with everything else.. anyone have this problem before?

EDIT: I've also noticed that my fuel mileage has been very bad. and I'm sure the snow tires wouldn't drop it as bad as it is..

How long has it been since this Astro has had a major tune up? Could be it's time.

The random misfire should be cured with a new GM cap and rotor and new plugs and wires. The P0420 code for the cat converter means that the cat needs to be replaced. Do the tune-up first, clear the codes and drive it. If the cat code comes back it needs replacing.

I did a full tune up, cap, rotor, plugs, wires etc last summer, and the cap has been replaced since then. is there a fuel regulator on the 98? I was reading on another part of the forum that someone had problems including the poor fuel mileage..

Did you use GM cap and rotor? If not, pull the cap and inspect the terminals inside. I bet they are corroded. There is an updated injection system available but I am not familiar with it.

You can also remove the motor cover and watch for leaking spark plug wires at night. Almost everyone here is adamant about using AC Delco ignition parts and I'm not disputing this just adding some more info to the mix. For 30+ years I've used Standard Motor Products ignition pats and never had a failure. The Standard Motor Products distributor cap and rotor have been on my Safari for over 100,000 miles and are showing no signs of giving up. I have a 1968 Chevy pickup that I removed the points and condensor ignition from and replaced it with HEI in 1993. Again Standard Motor Products cap and rotor and they are still on there and working perfectly. Yes, there is a fuel pressure regulator. It resides under the upper manifold plenum and is attached to the CPI unit. They can be rebuilt. It's a very time consuming job but not hard. If it is the cause of your bad fuel mileage then it's worth repairing.

from the flip side of that coin:
I bought brand new cap rotor and wires at Canadian Tire.
I opted for the more economical of the 2 choices they offered. Neihaus brand/cheap or Bosch/not cheap.
Never again.
The cheap wires had bad leakage right out of the box. I returned them stating that as the problem. Got a replacement set that did the exact same thing, and my van had misfiring and poor running issues from the moment of installation, until I bought the higher quality Bosch parts a few months later.

I'm not going so far as to say you should buy only GM parts (I hate buying parts from the thieves at GM).
But I will say don't go cheap on these ignition components, you'll get 'cheap' performance.

I bought a tune up kit a few years ago from Automotive Warehouse (big discount parts counter). kit came with NGK platinum plugs, aftermarket cap, rotor, wires PCV valve, and fram air filter. the only good parts were the plugs PCV and filter. the cap and rotor were both replaced within a few weeks, and the wires kept giving misfire on cylinder 1 and 2 errors. when it was on the hoist getting new front shocks installed, I asked my service guy Cliff to check to make sure the wires were making good contact. after he just touched the #1 plug wire, it literally separated from the boot. good bye new wires, welcome back old Delco wires..

just had the van back at the shop for the CEL. different shop, different ODB2 computer. this one showed misfires on ALL cylinders, so I was told it was a combination of bad wires and coil, and more than likely the cap and rotor too. so I already hit the parts supplier, got coil, rotor, cap and (this was recommended by the mechanic) NGK wires. he told me that he hasn't had the bleeding problem with the NGK's. so I'm going to give them a shot and I'll post back. he also told me that the catalytic code should go away once everything is replaced.
wish me luck..
Mike
aka niagaradood

Good luck, keep us posted...

everything swapped out, let my son crawl under and bust his knuckles getting 1 and 6 plugs in. hehe
so far it's running 100x better, checked for power bleeding from the wires, and not even 1 spark!
but..
the CEL is still on. I'm hoping that after a day or so of driving the cat efficiency code will clear it's self.
if it's doesn't go away by Friday, it's going back in to be checked again, clear the codes, and if it's the cat efficiency code again, then I guess it's going back in to Midas to have a cat installed..

after driving the van for almost a week, the CEL was still on. called Midas Muffler and arranged to have the cat cut out and a new one welded in ($220 CDN + government retirement fund fees..). got there and he decided to clear the codes one last time just to make sure that it is a cat that needs to be replaced. I drove it for over an hour and no light, so I decided to head for home. 2 minutes after getting on the highway the light was back. took back to my friend's shop and the error was:
420: catalytic efficiency low, bank 1.
there were no other codes for the engine, so it looks like the work that we did made a big difference.. engine is running a LOT stronger, my fuel mileage is back up to 16 city/19 highway, so I'm happy with that..
so, it's going in on Saturday to get the cat cut and welded.
Mike
aka niagaradood

no more CEL.. old cat cut out, new cat welded in, new gaskets between the exhaust manifolds and crossover.. now, just wondering how long that CEL will be off.. it likes to come back to haunt me.. lol