Well I've determined that I'm going to need to do an engine upgrade soon, either a rebuild or replace with a newer version. I believe a newer version would be sufficient for now and a little cheaper than a complete rebuild.

I have a '97 Chevrolet Suburban 2500 series with a 5.7 L vortec engine. I've been experiencing some power loss and it has been setting codes. I went by auto zone today and the reader showed it had set 8 different codes recently: P0171, P0102, P0131, P0134, P0137, P0151, P0154 and P0157.

After researching all the symptoms I ran a fuel pressure check -- it held at 50 psi for over 15 minutes so the fuel pressure regulator is not malfunctioning. I followed up with a cylinder pressure test while the engine was warm and found that cylinder # 8 tops out at 120 psi, all the rest are between 150 and 160 psi.

I know that an engine rebuild will cost approximately $1500.00 to $2000.00, I believe I can find a newer running engine with lower miles for at least half that cost and just do a simple swap.

My question is, how new of a 5.7 L engine can I upgrade to with just a simple swap and without having to change or upgrade the computer in my suburban?

just do a simple swap? In a Suburban?

2002 is the last year of the 5.7 Vortec. Find another engine, and just swap over what few sensors there are. While you are at it, install the upgraded fuel injector assembly, drop the oil pan, change out both front and rear seals. Everything else can be replaced once the engine is in. Lucky you, shoehorn a 5.7 into a Suburban. I'm dredging up flashbacks of putting a 5.7 in an S10.

Basically, there are no "newer versions". This engine stayed basically the same from yours up to 1999. Model year 2000 saw this engine in 3500-series pickups, and it too was unchanged. Let'* see more what is going on here . . .

What does your odometer say about it?

How often do you change oil?

How many miles since your last set of spark plugs?

What make/model spark plugs are they?

P0171 Bank 1 lean
P0102 MAF unexpectedly low
P0131 O2 sensor voltage low (bank 1 forward sensor)
P0134 O2 sensor inactive (bank 1 forward sensor)
P0137 O2 sensor voltage low (bank 1 rearward sensor)
P0151 O2 sensor voltage low (bank 2 forward sensor)
P0154 O2 sensor inactive (bank 2 forward sensor)
P0157 O2 sensor voltage low (bank 2 rearward sensor)

. . . so all related to oxygen sensors, and one showing a lean condition while half of the others show that sensor can't tell anyways. Nothing of these codes tells me "engine swap".

Almost agreed here, then I asked myself: running or ignition on engine stopped?

This would create a bit of a limp, but depending on how the vehicle is used this would not be very noticeable if noticeable at all. In my opinion not worth a complete engine swap or rebuild unless you need it to be perfect.

. . . or sometimes less for a rebuilt in a crate, depending on who you go to.

Here'* where it becomes concerning: The newer running example is either (a) out of another Suburban much like yours so why not just trade into that car or (b) is out of a pickup or a Suburban worse than yours so more likely to have a harder life or (c) is a "good running just-pulled" unit from a boneyard where you are stuck trusting someone'* biased word on condition. Either way unknown past and at about 20 years of age I'd call it a crap shoot.

1997, 1998, 1999, and 2000 from a C3500 that is probably in worse shape than yours. I think a 1996 might work but am always hesitant to go backwards . . . or change years at all for that matter.

My $0.02: It seems like this engine isn't in that bad of shape, just likely needs O2 sensors and/or troubleshooting of wiring etc. and maybe a few other parts depending on answers above. Unless there is something else about it not presented here such as [dangerously low oil pressure] or [loud knocking sound] or etc. Then, if you did swap or overhaul, you'd be left with the same codes etc. with the new engine as an engine overhaul doesn't normally replace electronics.

My vote: keep what you have and fix the codes. Maybe you need catalytic converters AND oxygen sensors. Would be the same with the replacement/overhauled engine.

What does your odometer say about it? The engine currently have 391,000 miles on it.

How often do you change oil? I generally change oil every 3000 miles, but over the course of the past 15 - 18 months it has begun to use oil more rapidly. I am currently adding a quart of oil every 200 - 250 miles. I have changed the pcv valve and that did no good. So through discussions with mechanics from my work I ran the compression test, the results seem to suggest that the rings are weak on cylinder # 8 causing excess pressures in the engine which forces the oil through the breather and the engine is burning it...hence causing some of the O2 codes.

How many miles since your last set of spark plugs? I have changed spark plugs twice since April when the rough idle issue began, neither set of plugs seems to help the situation. The original set was champion copper core; the second set was champion platinum (the parts store was out of the champion copper core); the third set I put in was champion copper core.

What make/model spark plugs are they? See answer above -- I didn't record the plug model #


. . . so all related to oxygen sensors, and one showing a lean condition while half of the others show that sensor can't tell anyways. Nothing of these codes tells me "engine swap".
I believe all of the O2 sensor issues would be cleared up if I can resolve the burning engine oil issue. I read up on the MAP sensor and it will cause the engine to rough idle. I pulled it out and changed it with one from a 98 model engine and the rough idle issue has gone away. However, it is still sluggish at times and slow to accelerate. I looked through the throat of the intake and could see oil sludge and buildup, the MAP sensor had some oil sludge/build up on it when I took it out.

Almost agreed here, then I asked myself: running or ignition on engine stopped? I fired the engine up and brought the pump to full pressure then shut the engine off and let it set for over 15 minutes and it didn't lose pressure.

Here'* where it becomes concerning: The newer running example is either (a) out of another Suburban much like yours so why not just trade into that car or (b) is out of a pickup or a Suburban worse than yours so more likely to have a harder life or (c) is a "good running just-pulled" unit from a boneyard where you are stuck trusting someone'* biased word on condition. Either way unknown past and at about 20 years of age I'd call it a crap shoot. I'm really in no big rush to make the purchase of a used engine...I can take my time to look around and find a decent one in a similar 3/4 ton truck with fewer miles. I will have to see it run before purchasing it and I'll be there to assist pulling it out or no deal. I don't buy junk yard promises.

I really appreciate everyone'* feedback and helpful ideas.

Consider yourself blessed if you got that many miles out of the Vortec 5.7. Some people rave about them, but me not so much. The engine has never been smooth and quiet. My 1997 Silverado'* engine always had a cold start bearing knock-I cringe at engine noises- that got worse with the higher mileage. Then it developed a new noise that sounded like a rod bearing on the rear passenger side. Installed a new long block and the engine made MORE knocking noises that before. These engines were built with difference main bearing specs that caused the noise, thanks GM. In my quest for a better deal I chose a suspect rebuilt long block from a "mechanic" who assured that he had no problems with his engine supplier. Engine runs good, just noisy. Have one built to spec or GM, Pace, Summit, Jegs sell new engines for affordable prices, only buy used if you can hear it run and know the history. Hindsight, eh?

Well I'm going to chalk this one up to a lesson learned. It seems all my troubles were caused by plugged up catalytic converters. I had new ones installed as recommended by a friend and 5 of the 7 codes went away within 2 hours. Now I just have a P0171 and P0174 code to deal with...lean fuel mixture...so I'm looking for a vacuum leak now.

Good luck with your upgrade!