Ugh...clogged cat?
#21
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#25
Update - still trying to find my gremlin...
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.
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.
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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.
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.
#28
Hmm...I think you may have me confused with another poster.
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.
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 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.
#30
I did put a vac gauge on it right after fixing the plenum...
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.