But if I wrote a book, then I would have no purpose on the forums.

 

How bout we just hook ya up to something like siri? Auto responses to important questions!

 

Cyborg HeyYou? I gotta admit, that DOES have a certain appeal to it........ I will start practicing my Arnold accent.

 

Making yourself redundant... hmm sounds like half of my work life

 

This is an older thread, but I promised I'd check back in. Unfortunately, so far I have not determined what my issue is. I took the truck to a muffler/exhaust shop, and they checked it out and said the cat actually seemed to be pretty clear (it's not original to the truck). My issue still exists, though it is sporadic.
To give a brief recap on what I've done so far: I've repaired the plenum leak, replaced the fuel injector O-rings, replaced the PCV valve and grommet, replaced the distributor cap and rotor, ignition coil, spark plug wires, and spark plugs (I used the OEM champion copper core plugs). I also did a compression test, and while the numbers weren't GREAT, all cylinders were above 100 psi.

The truck seems sluggish most days, and I was fairly certain the catalytic converter was going to be the culprit. However, now that that seems to have been ruled out, I'm not quite sure what else to check. I don't think it's a transmission issue, because I'm not experiencing slipping (when RPMs increase, speed increases proportionally....just slowly). I haven't changed the 02 sensors...should I try that next? I'm really starting to believe it is some sort of a sensor issue...perhaps 02, or maybe the TPS, or camshaft and/or crankshaft position sensor. I have no check engine codes, and the only symptoms I'm experiencing are sluggish acceleration and hesitancy to shift gears most of the time that I drive. Then randomly I'll get in the truck and it will drive like a dream and accelerate/shift like a brand new vehicle. The truck is certainly driveable, and it will get up to highway speeds...it's just getting annoying because I know something is affecting performance, since it is a sporadic issue.

Anybody have a suggestion on where I should go next? I do have a bluetooth scanner that I've used to do some data logging. If needed, I can post the results here...I'm not very good at interpreting the data on my own.

Thanks again to all who have helped me.

 

Unplug the front O2 sensor, and see how the truck drives. Chances are, that if your sensor is still original, it ain't workin' as well as it should be.

 

You said in a previous post that you had exhaust gas in your coolant, according to the test a shop did on your engine. You either have a cracked head or a blown head gasket.


That will definitely make your truck run bad and be down on power. It seems like its time to pull the heads and have them checked.

 

I haven't had my engine tested, and I haven't discovered any exhaust gas in the coolant, or mixing of the coolant and engine oil. I have been losing coolant, but I believe it is leaking at my thermostat housing, which I have had ongoing issues with (as stated in a separate thread I posted on 12/15/14).

I have been concerned about a possible head/head gasket problem, but have not discovered any definitive signs of that type of problem. Again, my compression test results weren't fantastic, but I didn't have any extremely low readings. I have a suspicion that I probably have valves that are not sealing well (because they are either caked with deposits from the oil that was burning as a result of my blown plenum gasket, or they are just worn), worn piston rings, or both.

If the truck ran consistently poorly ALL the time, I would just chalk it up to it being an older engine with almost 180,000 miles on it and I would just live with it and drive it until it totally gave up. But the fact that it will occasionally run beautifully has me both perplexed and annoyed, because I'd like to get the truck to run that well all the time since I know it's capable of it. This intermittent issue has me thinking that it's not a mechanical problem, but rather a sensor....but, I could be totally wrong about that.

 

Have you put a vac gauge on it? Looked for broken vac lines and loose/cracked fittings? Bottom of the map sensor there is a rubber 90 you might check it.

 

I believe it read about 20 Hg at idle...is that about what it should read?

I have looked for vacuum leaks to no avail, but it's certainly possible there is one. Thanks for the tip about the MAP sensor...I'll have to double check that.