On and Off Engine Lope and Check Engine Light
 

This one is a bit of a weird-o problem that I need some help with. First off, the truck:

1997 Chev Blazer
6 cylinder 4.3 litre Vortec
Push-button 2 Hi, 4 Hi, 4 Low (I think that's what most of you will call a 4x4x2, but not sure)

The problem: Only recently started, the engine has an occasional engine lope and the Check Engine light flashes. It was fine Monday morning going from home to work (62km one-way trip); it was fine going from work to home; when I went to pop out for groceries with the wife Monday night, it had a bit of an engine lope, felt like it was hesitating a little bit and the Check Engine light started flashing.

We took it by a friend's place who is a mechanic and we put on his code reader (can't remember what the exact code was) but he recommended changing the Mass Airflow Sensor, so I went last night by an auto wrecker and got one and it ran fine for about 20 minutes after I changed the part. Took it for a drive, and it started doing the same thing only this time it doesn't produce an error code.

Left it overnight thinking it might have been a heat related thing and went to start it this morning to have the same problem but which settled itself out on the drive in to work - in other words, drove it about 20km and it stopped having the lope, no more Check Engine light and all seemed fine.

It's going to come back at some point, so I'd really like to figure this one out and get it fixed. Any thoughts or ideas?

RE: On and Off Engine Lope and Check Engine Light
 

Additional info: truck seemed to settle itself mostly out with the problem happening less frequently, feeling a little more normal but having a very slight hesitation. I put in a new air filter last night and ran through injector cleaner in the last tank of gas and am running through another bottle in this tank.

Just waiting to see if it comes back now.

RE: On and Off Engine Lope and Check Engine Light
 

When was the last time the spark plugs were done?

Mileage?

Your cap + rotor + plug wires might need changing too...

RE: On and Off Engine Lope and Check Engine Light
 

Excellent questions. It has a little over 217,000km on it. I don't know when the last time the plugs, wires, rotor or cap were done.

Slowly over the last few days I've been keeping a close eye on it and it seems to be more and more telling. It seems to be fine when cold or it's only been running for a little while (up to about 30-45 minutes) and happening when the engine is hot.

I was reading in the Haynes manual (I buy one for each car that I own so I can do some basic work myself and save some cash) and I'm starting to wonder if it might be the PCV valve and/or hose, possibly a vacume leak of some form. I haven't checked that out yet, but I'll be doing that in the next day or so (when I get a few free minutes.)

Thanks for the suggestion, I'll definitely schedule myself some time (and budget) to get the plugs done. I usually like to put in some higher performance ones in my vechicles anyways, so that'll be as good an excuse as any. I'll have the wires and the rest all checked out too when I take it in to get that done.

Thanks for the suggestion!

Any others?

(EDIT: I don't know when the plugs, wires et al were last done because I only bought the truck a little over 2 months ago.)

RE: On and Off Engine Lope and Check Engine Light
 

Go for the AC Delco Rapidfires, they seem to work the best...

RE: On and Off Engine Lope and Check Engine Light
 

AC Delco Rapidfire plugs will wear out faster than AC Delco Professional Platinums. Reason being, the Rapidfire Platinum plugs still have a conventional ground strap with a platinum tipped electrode. I recommend the AC Delco Professional Platinums. The extra cost is well worth their expected lifespan. If you feel spendy, the AC Delco Iridium plugs are great as well.

Here's info on AC Delco Plugs(<--CLICK).

RE: On and Off Engine Lope and Check Engine Light
 

Ahhhh, sorry aboot the misinformation there... Last I heard about AC Delco plugs, I still had my Lumina, and rapidfires were the way to go, lol.

I'll keep that in mind, since my plugs are pretty much toasted...

RE: On and Off Engine Lope and Check Engine Light
 

For what it's worth, it seems to have completely gone away now. The engine lope and flashing Check Engine light haven't come back up in about a week, the engine does seem overall better behaved. I haven't done the plugs, wires or distributor yet, but I ran a couple of tanks through with injector cleaner and I did change that MAF sensor, so maybe it was just in need of a little TLC for a bit.

The hot weather is around now too, so I don't know if that's a factor, but I'm going to keep an eye on it over the course of the next couple of months and see if it returns.

Thanks for all of the other input though, I'm definitely going to do the plugs at some point and will keep the suggestions in mind!