4.3 missing

4.3 missing Group: alt.trucks.chevy Date: Wed, Oct 8, 2003, 5:28pm (CDT-2) From: snipped-for-privacy@yahoo.com (Michael=A0Rothwell) I have a 93 GMC 4.3 throttle body injected truck. Lately, it has been missing at low to mid RPM. It seems the worse between 1200 and 2000 RPM, but is at a loss of power throughout the entire RPM range. It really struggles pulling a hill that used to be no problem. This truck has 180K miles on it and has treated me right, I just want some of my power back. Any ideas what is causing this? I put a new cap and rotor on recently Plugs are not too old and look good. I'm not sure how the throttle body injection system works (1 or more injectors, etc.) but it seems that it is a fuel problem. Thanks in advance. Michael

I had a similar problem with my 4.3 last spring. A COMPLETE tune up did the trick Spend the extra $50 and change the spark plugs and wires. It is better to change the entire system as a set. Autolite 605 plugs are a $1.24, and Autolite wires 96827 are $42.94 Double check

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It's like changing one shock, or just one pair of brake pads, or changing the oil but not the filter.....wouldn't dream of doing that would you??

THEN...if that doesn't fix it...but I believe it may, then start troubleshooting the fuel system.

No, I do not work in a parts store, but I own stock in the company.

Have fun

8upman

And while your at the parts store buying wires and plugs, get a fuel filter too. Its called preventive maintainance...:)

The reason I changed the cap and rotor was due to the poor running. Also put in a new fuel filter. The wires are not too old, but I gotta say that this engine goes through plug wires, I'm on my 3rd or 4th set. But, before when the wires were bad, It idled poorly and I could see the spark when I open the hood at night. It idles smoothly and I see no spark in the dark.

For the TBI system, is there a single injector, or is there an idle injector, a midrange, and a highrange injector (something like jets in a carberator?)

All I know, is that it cant pull it's own weight up a grade that I used to pull with no problems. (best I can get is 55 mph by the time I hit the top). And just off-idle when cruising on a 50 mph road, it is really rough. Seems to smooth out in higher rpms, but no power.

Thanks for the suggestions so far.

Michael

So, how do I test the EGR valve?? you replaced the EGR and it took care of the problem huh? how much are they?

Michael

yep...forgot about that...that would help too huh?

I got a sweet deal . the blue streak brand was 130 and the junk brand was 80 bucks canadian each.

I got the blue streak premium brand for 80, which was a steal in these parts.

To test it be warned. do this for a short test run >

One more thing on this that I forgot about.

When cold, the truck seems to have better response and power than when warm.

Michael

Eightupman wrote: