88 K1500 4X4 Poor Acceleration
 

Just bought an 88 Silverado K1500 4x4 with 5.0l V-8 147k miles. It idles very smoothly, but it is incredibly dogged when trying to accelerate. I changed the plugs , and cleaned out the TBI to no avail. Service Engine light comes on and off, and I got codes 13 & 44 with a scanner which both point to the o2 sensor. I'm wondering if that will actually fix the issue as I've seen many possibilities in this forum. I don't believe it's a tranny problem, she shifts very smoothly and responsively....she just plain doesn't want to get up and go when I push the gas pedal. It struggles keeping highway speeds with even the slightest grade...even when it downshifts it doesn't accelerate much faster...just higher RPM's. And, probably stating the obvious, gas mileage sucks!
Thanks for any assistance.

Replace the o2 sensor and start from there. Also make sure your catalytic converter isn't plugged. Drive the truck till it's at running temp, and carefully feel out your exhaust pipe to see if the exhaust is good and hot after the catalytic converter on the exhaust pipe. If it's plugged, then the exhaust wont be as hot after the cat as before the cat. Watch out, you can definitely burn yourself bad! Wear gloves if you have to, but really you're looking for a temperature difference on the exhaust pipe.

Also, 5.0L engines are just lame ... so don't get your hopes up. It should be plenty driveable, but just know that your 305/5.0l engine doesn't make much power to begin with.

Question: What axle ratio to you have, and is it a 3, 3 overdrive, 4 or 5 speed transmission? The gearing makes a big difference in performance too.

The o2 sensor should really help with gas mileage though.

Hey now, the 305 may not be a monster motor bu they're not thaaaat bad lol. Null is right though, bad O2 and a clogged cat will kill a motor. I'd suggest going with a high flow cat to let the motor breathe a bit better also.

Try The O2 Sensor.
What worked for me though, is replacing the Fuel Filter. I have an 88 Gmc with the 5.7L bored and stroked, with the exact same problem. I had tried everything (new spark plugs, o2 sensor, TBI cleaning, wires, etc....), and the main problem was that the fuel filter had never been changed (it spilled black gasoline out when i emptied it). It runs like a dream now, and is a very violent accelerator.

Oh yeah; for the check engine light, try cleaning the EGR valve. It's located next to the TBI. Use carb cleaner and a toothbrush, there should be a bit of carbon buildup inside it.

Hope this helps/works. Let me know if it does!

Much Appreciated!
 

Thanks for the suggestions guys. I've already got my laundry list for this coming weekend and it includes a lot of what you've mentioned:

02 sensor
Fuel Filter
PCV valve and tubes
Distributor Cap/Rotor
Oil & Filter change

I already changed the plugs, and the wires appear to be an aftermarket Bosch set in very good condition. I also cleaned the TBI with spray and used a container of Rislone Fuel injector cleaner in the last tank.

Also, It doesn't have a catalytc convertor. It simply has a red cherry bomb connected after the crossover pipe (yes....exhaust system is also in the plans very soon) so, I don't think the exhaust is an issue...unless someone thinks NOT having the cat hurts performance. It is the 700R4 tranny. Not sure of the gear ratio. I would suspect it to be stock for all the 4WD 1500's (I thought I read somewhere 3.42:1).

I'll let you know how I make out.

Well my truck's got no cat either, and she runs great. Really, the only performance issue you would encounter from not having a cat is if you have an 02 sensor after the catalytic converter in your exhaust system. But knowing your truck is similar, if not identical, then you only have one or two 02 sensors.

Mine tends to sound like it's "gulping" for air when I stomp on it. Seems perfectly normal for a 305, imo. I got stock intake and stock exhaust and she can pull 1000lbs of weight just fine with my 2.74 axle.

When not running cat(s) your exhaust flows unrestricted, which means exhaust temps. are lower. This affects the upstream O2 sensors for they need to be at least 600 degrees to work efficiently. O2's bounce back and forth from lean to rich very fast to give the comp true readings of the amount of oxygen in the exhaust. Lower temps will make the O2's lazy. The newer O2's with 4 wires have heaters in them, but dont last long being run like this. Im thinkin that 88 is not set up for heated O2's. Which means the only way for the O2's to heat up is the exhaust. Cats create good heat build up. Unless your cammed, not running cats doesn't add power.

Thanks again, guys.

Yeah, I'm not looking for over-the-top horsepower or anything like that.....I just want the thing to respond to the accelerator by speeding up rather than slowing down or having me force it to downshift to pick up any speed at all. I'm sure that part of it is just me needing to get used to the lower HP.....my previous vehicle was a 2000 Crown Vic Police Interceptor. However, there is definitely something NOT right with the way she's performing. Oh well, we'll see after I get done with my list this weekend.

Sounds like it drives exactly the same as mine.