still having issues with 92 k1500

[hunter4ever12]

If you lurk around on here many of you know I had an issue with my pickup about a month ago. Well I thought I had fixed it and did, to an extent. The original issue was power loss and hesitation. I finally got that somewhat corrected I figured out that due to having a throttle body spacer, "salad bowl" and injector spacer that my engine was running lean. First I tested fuel pressure was about 11-12 psi, bumped it up because I have an adjustable fuel pressure regulator. I didn't want to hook the pressure gauge back up so I just bumped it up a little bit and put it all back together to test. It improved power but I still wasn't satisfied so I then advanced the base timing to about 4 degrees. Tested again and it ran great. Drove it a couple days and it was like driving a totally different pickup. But one day I was driving it check engine light came on. Checked the code and it was code 42- ignition bypass circuit error and 44- left bank o2 sensor, lean condition indicated. Inspected my timing advance wire and all other ignition related wiring everything checked out, so I then unhooked the battery to clear codes and hooked it back up. Drove a while to make sure code didn't come back and it didn't. Then my problem started. It still runs good but not as good as it did before unhooking the battery. It idles pretty low in the rpm range, idling the engine shakes like when you shut off a diesel and sounds like an engine with a cam that lopes, in other words the idle isn't very smooth. But it is only not smooth once it's warmed up. When it's cold and is in high idle to reach operating temp, it's nice and smooth. Not only that but the exhaust smells very very strong(I don't have a cat on it but it's still way strong) so strong that you can smell it from inside a building if you are parallel parked next to it. It also is getting unbelievably bad fuel mileage. On a 15 mile drive this morning it went from a little under half a tank to a little over a 1/4 of a tank and it's a 30 gal tank. So what should I even start with to correct this problem? I know I didn't bump the fuel pressure up more than a couple psi, but I will get an actual reading of it tonight when I get home. The reason I don't know where to start though is, my truck runs good still now(not as good as it dud when I first made the changes but still better than it originally did) it still has decent amount of power. I even pulled a few plugs and checked and they are a nice burnt chocolate color so it shouldn't be rich. Something has to be causing those issues though. Timing maybe? I have no idea. Help please.

[Schurkey]

Have you checked the distributor cap, rotor, and coil wire/plug wires yet? Do the plug wires glow in the dark? Are the coil and plug wires within normal resistance values?

"Chocolate brown" plugs haven't been common since unleaded gasoline got popular. Might want to replace (or at least clean and re-gap) the plugs while you're in there--how old are they?

[hunter4ever12]

I have not checked them other than looking over the plug wires. I replaced the complete distributor along with cap, rotor, esc module, wires and plugs only about 7-8 months ago so I guess I just assumed it should all still be good especially because I have maybe put only about 5000 miles on that stuff since it was replaced. If you think that's a good starting point I will check them. As far as the plug wires glowing in the dark what do you mean? I've never heard of such a thing.

[Schurkey]

Originally Posted by hunter4ever12

I have not checked them other than looking over the plug wires. I replaced the complete distributor along with cap, rotor, esc module, wires and plugs only about 7-8 months ago so I guess I just assumed it should all still be good especially because I have maybe put only about 5000 miles on that stuff since it was replaced. If you think that's a good starting point I will check them.

Worth a look.

Originally Posted by hunter4ever12

As far as the plug wires glowing in the dark what do you mean? I've never heard of such a thing.

Open the hood at night. If any of the plug wires, or the coil wire glows (corona effect) the wires are leaking energy, and defective.

http://en.wikipedia.org/wiki/Corona_discharge

[hunter4ever12]

I checked all the above things, cap and rotor still look like new, and all wires are good and not glowing. I did order new plugs for it that I will put in tonight. I will say that after I removed the cap and inspected it, then put it back on, initially it ran better that evening when I tested it the exhaust didn't smell as bad and the idle was much more smooth. But when I started it last night idle was back to being on the rough side just like before (had a bit of a lope to it and was shaking the pickup like when you shut off a diesel) I will say tho that the exhaust was still not as strong, it was stronger than before but not as bad as original. Also drove it to the store shut it off went inside started it back up and put it in reverse started backing out and it almost died. It didn't quite die all the way but came pretty close. So with that info where should I look next? Thanks in advance.

[Schurkey]

In MY garage, it'd get an ignition oscilloscope test, along with connecting a scan tool to the computer to analyze the data stream.

[rhandwor]

Originally Posted by hunter4ever12

If you lurk around on here many of you know I had an issue with my pickup about a month ago. Well I thought I had fixed it and did, to an extent. The original issue was power loss and hesitation. I finally got that somewhat corrected I figured out that due to having a throttle body spacer, "salad bowl" and injector spacer that my engine was running lean. First I tested fuel pressure was about 11-12 psi, bumped it up because I have an adjustable fuel pressure regulator. I didn't want to hook the pressure gauge back up so I just bumped it up a little bit and put it all back together to test. It improved power but I still wasn't satisfied so I then advanced the base timing to about 4 degrees. Tested again and it ran great. Drove it a couple days and it was like driving a totally different pickup. But one day I was driving it check engine light came on. Checked the code and it was code 42- ignition bypass circuit error and 44- left bank o2 sensor, lean condition indicated. Inspected my timing advance wire and all other ignition related wiring everything checked out, so I then unhooked the battery to clear codes and hooked it back up. Drove a while to make sure code didn't come back and it didn't. Then my problem started. It still runs good but not as good as it did before unhooking the battery. It idles pretty low in the rpm range, idling the engine shakes like when you shut off a diesel and sounds like an engine with a cam that lopes, in other words the idle isn't very smooth. But it is only not smooth once it's warmed up. When it's cold and is in high idle to reach operating temp, it's nice and smooth. Not only that but the exhaust smells very very strong(I don't have a cat on it but it's still way strong) so strong that you can smell it from inside a building if you are parallel parked next to it. It also is getting unbelievably bad fuel mileage. On a 15 mile drive this morning it went from a little under half a tank to a little over a 1/4 of a tank and it's a 30 gal tank. So what should I even start with to correct this problem? I know I didn't bump the fuel pressure up more than a couple psi, but I will get an actual reading of it tonight when I get home. The reason I don't know where to start though is, my truck runs good still now(not as good as it dud when I first made the changes but still better than it originally did) it still has decent amount of power. I even pulled a few plugs and checked and they are a nice burnt chocolate color so it shouldn't be rich. Something has to be causing those issues though. Timing maybe? I have no idea. Help please.

These trucks have a fuel pressure regulator in the throttle body. http://www.rockauto.com/ sells rebuild kits. Clean and rebuild your throttle body. Adjust your fuel pump pressure to factory specifications. Adjust your timing to factory specifications. Put a pint of injector cleaner in the fuel tank. Ohm your plug wires when cleaning or replacing spark plugs. This should get you going if engine is good.

[Schurkey]

Originally Posted by rhandwor

These trucks have a fuel pressure regulator in the throttle body. http://www.rockauto.com/ sells rebuild kits. Clean and rebuild your throttle body. Adjust your fuel pump pressure to factory specifications

Why? He's already tested the fuel pressure, and it's fine. Spraying some aerosol solvent into the idle air passage isn't a bad idea; and verifying that the throttle shaft isn't wobbly in a worn-out casting is a good idea...but fuel pressure doesn't seem to be an issue. I wouldn't rule out plugged injector(s) although that seems to be a rare condition.

I still stand by "oscilloscope and scan tool".

Originally Posted by rhandwor

. Adjust your timing to factory specifications. Put a pint of injector cleaner in the fuel tank. Ohm your plug wires when cleaning or replacing spark plugs. This should get you going if engine is good.

Not bad ideas. Won't be guaranteed to fix the problem, though.

[hunter4ever12]

Originally Posted by Schurkey

Why? He's already tested the fuel pressure, and it's fine. Spraying some aerosol solvent into the idle air passage isn't a bad idea; and verifying that the throttle shaft isn't wobbly in a worn-out casting is a good idea...but fuel pressure doesn't seem to be an issue. I wouldn't rule out plugged injector(s) although that seems to be a rare condition.

I still stand by "oscilloscope and scan tool".


Not bad ideas. Won't be guaranteed to fix the problem, though.

I agree, fuel pressure is not an issue, in my original post I Stated I have already rebuilt the entire throttle body less than a year ago and installed an adjustable fuel pressure regulator. I also have many throttle body "upgrades" that increase air flow/capacity. My fuel pressure when I started was at stock levels and the engine was running lean hence why I bumped up the fuel pressure and it's still not as high as what some say it should be. Some say with just a throttle body spacer alone and no other upgrades you should be running 15-16 psi. I have a throttle body spacer, injector spacer, a "salad bowl" a more open element filter as well as cleared out the factory intake baffles to increase air flow and with all that I'm still not up that high with my fuel pressure. So with all that being said I am pretty sure it's not a fuel pressure issue. Thanks for the input though I do appreciate that.

[rhandwor]

These units are very prone to problems as there are not pure fuel injected and the air flow goes through the throttle body. They need cleaned like a carburetor. If the diaphragm gets a hole in it they won't idle correctly. I have an oscilloscope but I doubt he does. That was the idea of ohming the plug wires. You may have good fuel pressure but injectors plug up and need cleaned occasionally.