Engine Hiccup
 

Greetings all,

I did a search, and came up empty so I thought I'd ask.

I have a 2000 4dr Blazer, 4x4. Every 8-10 seconds (as near as I can tell), the engine will hiccup, almost like it's gasping (there's even an audible sound). It's EVERY 8-10 seconds, no matter speed, RPMs, temperature, etc. Sometimes it's throwing a code (can't remember the number) for the throttle body position sensor, but sometimes not. I've replaced the TBPS, no help.

My next thought was the fuel pressure, but I haven't had a chance to test it. But even at that, why would it hiccup every 8-10 seconds?

Also, when it throws the code, it's revving all over the place--losing power, speeding up, etc.--like it can't decide how many RPMs it should be running. It's always throwing the same code, every time I've checked it.

Any ideas?

Well, if you can get the codes read and posted back it would be helpful. With the erratic rpms I would look into either a vacuum issue or bad cap and rotor. When was the last time it had a tuneup? You can also spray some brake cleaner or starting fluid around the throttle body with it running and listen for any changes if the idle changes you have found your leak.

It's not actually throwing a code at the moment.

I must confess ignorance--how would a vacuum issue cause the hiccup so regularly? I would think it would be more irregular than it is.

Vacumm leaks can cause all sorts of problems but being that its in time, it makesme think it maybe a bad cap and rotor. The rpm should be at 550 when warm and idling.

Yup. That's just about exactly where it's idling.

It seems like the interval is too long to be cap and rotor. It's only happening once every 8-10 seconds.