98 s10 surging

[booniecars]

I've searched for a couple of weeks, tried some of the tips, and finally broke down to post a new thread. Please help! Here's my problem.

My truck suddenly ditched me when I got outta church. It just turns but doesn't fire. So I left it there for 2 weeks, thinking it's the fuel pump and brought a 2x4 to jam the fuel tank like many suggested. But it started before I got a chance to dent the tank, so it can't be the pump since it started right away. This was the 3rd pump installed, the OE died about a year ago and the 2nd one 4 months ago. Before this happened, it was jerking or surging (might be the same) a little when the engine is cold but runs fine when @ normal op temp. After I got ditched, it surges like crazy when cold but is fine when @ normal op temp. I also need to mention before all of this, that when my friend scanned it, it gave p0440 and p0102 and I changed the paper air filter to one of those fram tough oiled filter about the time I changed the pump. I read somewhere that the oil dislodges and soils the MAF.

A search said p0440 is EVAP and p0102 is MAF. I did what was suggested and cleansed the MAF with carb cleaner then also the idle sensor too. My friend said to clean the throttle body while I'm at it so I sprayed 3/4 of the can into it while gasing it. Now my idle jumped from 600 rpm to 1100 rpm. The surging is the same as before I got ditched.

I should also mention that I disconnected and charged the battery before cleaning all of this since it sat for a while. So the obd2 resetted and the MIL was gone until I was cleaning the throttle body. Once I put everything back together and plugged the MAF sensor back in, the MIL went away, for a while. I haven't scanned it yet since it came back on.

What could be the problem? I read that the EVAP isn't too big of a deal and should still run fine. I cleansed the MAF, plugged it back in and the MIL went away. So the connection is fine and most likely even the sensor.

I searched and didn't find anyone with a cold surging engine. Please help.

Thanks in advance.

[1996LTOwner]

What type of engine? When was the last tune-up? Was the SIS light flashing when it came on? Plugs (NOT BOSCH), wires, DISTRIBUTOR CAP and rotor button are all a MUST. If you do a search on stumbling you should find a lot of info as missfiring, stumbling and surging are common gremlins for the chevy S-10 pick-up and blazer owners. How many miles do you have on it?

[booniecars]

Thanks for replying so quick.

It's 4.3L 'W'. I haven't tuned up yet. I changed the w-pump and the serpintine belt last year. I drowned it at 20,000 miles and had to change the plugs then. I have about 60,000 on it now. Not sure what type of plugs were put in since the mechanic was the one who fixed it under insurance. But it ran fine until recently. what's SIS? No other lights are on other than service engine soon.
I didn't get it tuned up because it's suppose to be "100,000 miles first tune up". But judging by what you are saying and the many posts, that's a bunch of crap.
If I need to change all of these, I rather go performace wires after what I read from Granatelli. They said to have gained about 20hp from replacing stock wires and MAF to theirs and 50hp with cold air intake kit all together. Is this possible?

[1996LTOwner]

Sorry, SES is what I meant. SIS is for Suffer In Silence and I only use that when I want to give my wife a hard time. I don't know about the performance wires, but I do know form experience and many others on this forum that AC Delco wires are the only proven wires. As for the distributor cap, looks can be very decieving. You're better off just buying one. The design I like is the Echlin brand from Napa. The plugs should be a good platinum or AC Delco at a minimum. Bosch works better on more intense ignition systems and foul out easy on the 4.3. Does it always stumble / surge after you start it cold or is it intermittant?

[old_master]

Don't believe it!

Use AC delco platinum plugs ONLY!

Lose the "oiled" air filter. Oiled air filters and MAF sensors don't get along.

A MAF sensor does one thing, no such thing as "high performance". It either works, or it doesn't.

Use good quality ignition wires like AC Delco, Belden, or Autolite, no need to spend mega bucks there.

Cold air intake systems are nothing but media hype. The reasons get quite technical. In a nutshell, engines like warm air, not cold. Example: When you go outside and take a deep breath at 10 below zero you gag, so does an engine.

Use AC Delco distributor cap and rotor.

Check fuel pressure for 60psi MINIMUM when the fuel pump is running and the engine is off. When the pump shuts off, pressure must remain above 55psi for several minutes.

[1996LTOwner]

"Use AC Delco distributor cap and rotor."

Old_master, I agree with everything axcept the above statement, unless AC Delco has changed it's design. I purchased an AC Delco distributor cap a little over a year ago and it left me and my family stranded on I-95. Visual was perfect so I looked elsewhere. After changing the timing chain and sprockets due to the truck backfiring and/or compression locking and still having the same issue, more troubleshooting and common sense told me that the #4 cylinder was firing EVERY time the coil sparked which led me to determine the cap was shorted internally between the center post and the pathway for the #4 pick-up. A resistance check didn't reveal this and I didn't have a megger to verify, but the Echlin cap fixed it. I chose the Echlin because it was designed with a seperation between the center post and the #4 pick-up pathway. The AC Delco cap has the pathway for #4 and the center post molded directly next to eachother. Maybe mine was one in a million, but that was all I needed.

[booniecars]

I didn't know oiled filter sucks with MAF. I'll change it back to paper and change the cap, rotor and plugs and let you know what happens.

"Does it always stumble / surge after you start it cold or is it intermittant?"
It stumbles every time it's cold.

For the pump, I had it pressure tested for the OE and the 2nd one. Both were squirting less than 60. I think OE was squirting 25, can't remember the 2nd. I believe I got genuine ac delco. I ran it down to e on both pumps. Now I know to keep it at least 1/4 tank, better at 1/2. The pump cost me about $120 with warranty. I read some post about how generic pumps sucks. If you're wondering where I got it for $120, global-automotive on ebay. It says it ac delco, if he's lying, then we got some issues we have to take care of.

[1996LTOwner]

Do a search for "intermittant" and look for the site called "intermittant miss at light loads". There is A LOT of useful info in this thread.

[booniecars]

wow! That post does shed a lot of light to my problem. Seems like this is a common thing with the vortecs since 95. Looks like both 534BC and 1996LTOwner did something to the distributor. After checking around for the cap, rotor, wires, & plugs, it adds up quickly. And I can't just slap my wallet on the counter just yet. I'll try changing my cap & rotor 1st. Looking at the cap, it doesn't look like it can be adjusted though. It's not the regular round & tall cylinder shape ones that I'm used to, it's more flat like. Can anyone give me some pointers about this type of distributor. I adjusted the old cylinder ones before, but these are new to me.

On a different note, why haven't GM change their design to fix this & other problems? Like their doors, the rollers to stop the doors from crushing my legs when parked on a hill rusted out & bent & the spring just fell off. I saw the post to change the hinges but not the roller. My point is, the design is so complicated & yet fails so easily but they keep using it. It's logic like this that deters people to our foreign competitors. Or maybe they think we're all rich and should change our vehicles every 3 years.
I'm not opening up a debate, just venting.

[1996LTOwner]

No adjustment on the distributor. From what I've read on this forum, the computer does the fine tuning of the timing. The main thing when replacing the cap is getting the wires in the correct order. Just don't wait too long. The longer you wait the more damage your catalytic converter could be sustaining. Before mine was finished, I needed new O2 sensors and a new cat. Good luck.

[1996LTOwner]

As for the domestic issues, I firmly believe they are designed into the vehicles. Either that or our domestic engineers are inferior, and I just don't buy that. I guess they didn't learn anything from the 70's when they lost a large part of the market share. That is why I am currently looking at a Subaru or a Honda. Gas milage doesn't phase me unless it's grossly bad, but knowing I'm being taken is too much.

[booniecars]

Thanks 1996LTOwner. I'll post the results when I change it.

[booniecars]

Finally changed it. A quick visual showed corroded cap and worn out rotor. As 1996LTOwner said, the #4 is connected to the central post. I got an Echlin and it's all seperated. An insert was included.

NOTICE: Special Technical Bulletin

Per GM Technical Bulletins #03-06-04-041A and #05500, the distributor and rotor may be subject to premature corrosion and ignition system failure due to lack of airflow internal to the cap.

It goes on to recommend corrective actions.

This explains why it won't fire suddenly and after a while it fires right away. The jerking is gone and idle and acceleration is a lot smoother. But my idle is still high at 1100rpm without a/c and 850rpm with a/c. I remember it was 850 without a/c when new. Will it self adjust or do I have to manually do it? Thanks for all the help.

Click here if you want to read about "intermittant miss at light loads".

[1996LTOwner]

Unless you had the battery disconnected for a long time and the computer needed to reset, it should be fine. Even then it only takes a short time of running. Is your throttle sticking a little? I had to pull my "throttle body" and wipe it out real good to remove the build up. Maybe yours needs cleaned. Spraying cleaner in there never worked.