97 chevy silverado 5.7l 4x4

cw6292 · 08-11-2008, 08:45 AM

My truck idles rough and blows black smoke which smells like gas when 1st started. The error codes show system too rich on both banks. It also is giving improper switching of the O2 sensors pre-converter. The O2 sensors don't send any info back until they get up to temp, I thought? I have changed the plugs, wires and distrubtor and still the same. I am leaning towards the MAF and/or MAP sensors, but would like to hear someone elses opinion as these are not cheapest things to replace. Easy to get to, but expensive. My thought is the trouble is before compression not after. Any advise will be much appreciated!

**manic** · 08-11-2008, 11:25 AM

You need to pay attention to what codes are being thrown. Plugs and
wires will not throw a code. Not sure about the 97, you may need a
code reader. Most of your part stores like advance auto parts will let
you use there reader in the parking lot. Looking in my crystal ball,
I would go for 02 sensor first, maps would not hurt. Is that throttle
body fuel injection? Might be a injector, codes will tell you alot. If you
have a check engine light its thrown a code. Make sure when you
replace sensors to disconnect the battery, this will clear codes and
make your computer start fresh.

BUDFAN8 · 08-11-2008, 02:47 PM

that truck has the spider injectors. they are known to break but dont think that is the problem here. i would go with the MAP sensor first. make sure the vacuum line is on it and in good shape before you go buy one. if MAP dont work then the O2s are cheaper than the MAF and on that truck i think if the MAF is bad you wouldnt be able to drive it very good at all(unless its stuck all the way open). it would backfire and not get enough rpms to get you very far. another thing it could be is the EGR or fuel pressure regulator.

Good Luck
Bud.

08-11-2008, 08:45 AM	#1 (permalink)
cw6292 Registered User Join Date: Aug 2008 Posts: 1 OS: xp	97 chevy silverado 5.7l 4x4 My truck idles rough and blows black smoke which smells like gas when 1st started. The error codes show system too rich on both banks. It also is giving improper switching of the O2 sensors pre-converter. The O2 sensors don't send any info back until they get up to temp, I thought? I have changed the plugs, wires and distrubtor and still the same. I am leaning towards the MAF and/or MAP sensors, but would like to hear someone elses opinion as these are not cheapest things to replace. Easy to get to, but expensive. My thought is the trouble is before compression not after. Any advise will be much appreciated!

08-11-2008, 11:25 AM	#2 (permalink)
manic Mod Hardware Team Join Date: Aug 2005 Location: Florida Posts: 4,870 OS: xp	Re: 97 chevy silverado 5.7l 4x4 You need to pay attention to what codes are being thrown. Plugs and wires will not throw a code. Not sure about the 97, you may need a code reader. Most of your part stores like advance auto parts will let you use there reader in the parking lot. Looking in my crystal ball, I would go for 02 sensor first, maps would not hurt. Is that throttle body fuel injection? Might be a injector, codes will tell you alot. If you have a check engine light its thrown a code. Make sure when you replace sensors to disconnect the battery, this will clear codes and make your computer start fresh. __________________

08-11-2008, 02:47 PM	#3 (permalink)
BUDFAN8 Registered User Join Date: Apr 2007 Posts: 205 OS: XP	Re: 97 chevy silverado 5.7l 4x4 that truck has the spider injectors. they are known to break but dont think that is the problem here. i would go with the MAP sensor first. make sure the vacuum line is on it and in good shape before you go buy one. if MAP dont work then the O2s are cheaper than the MAF and on that truck i think if the MAF is bad you wouldnt be able to drive it very good at all(unless its stuck all the way open). it would backfire and not get enough rpms to get you very far. another thing it could be is the EGR or fuel pressure regulator. Good Luck Bud.