Turbo on 2000 Limited 5.0

Hahaha.
Maybe if your bored you can stop by for a beer and give me someone to talk to while I work. I'm hoping to get it apart tomorrow night, then I'm in no rush for reassembly. I'd think about doing the heads at the same time, but I'm better to just get what I have working before introducing new variables.

:biggthumpDo the heads!!

Crap disturber!
It would be a great thing, but I think I'm better to pull the motor and fix the rear main at the same time.

Dono said:

Crap disturber!
It would be a great thing, but I think I'm better to pull the motor and fix the rear main at the same time.

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I would do it just so one tune can be made.you do it later a new tune would probably need to be made, a rear seal at a later date wouldn't need a tune...:shifty_ey

Come on your 3/4 there and those exhaust bolts are still fresh lol

Your bad.

NOOOO!
get it running now. we still have to deal with other issues, like mr. airfilter.

Also I know you said you did a compression test has a leak down been done??

vroomzoomboom said:

NOOOO!
get it running now. we still have to deal with other issues, like mr. airfilter.

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Heyyy thought we was the bad influences around here..you switching side now!! Haha

lean bank 1

If you have a misfire on cylinder number 1 that means the oxygen and fuel are not being burned in the cylinder so the oxygen and fuel are going into the exhaust. The oxygen sensor only see's the oxygen so it thinks bank 1 is lean and the PCM starts adding fuel with STFT.
Number 1 is the passenger side front cylinder.
If you want to see if you have a lower intake manifold gasket leak take the oil cap off with the engine running and put your hand over the oil cap hole and see if it pulls vacuum on your hand. If you have the oil return from the turbo going through your oil cap you can not do that. Then take the vacuum line that goes to the PCV that was drilled out, off the oil catch can and see if there is vacuum being pulled from the intake side(PCV). If there is vacuum then the lower gasket is bad, if there is no vacuum then the gasket is not bad and you will need to find out what is really going on.
If STFT and/or LTFT are high at Idle and not so bad at higher rpms(2000) then you have a vacuum leak. If STFT and LTFT are adding more fuel at higher rpms and it is not so bad at Idle then it is fuel starvation, contaminated maf, or not finished being tuned. Or you have an exhaust leak pre O2 sensor or the O2 sensor could be defective.
Can you look at STFT and LTFT at Idle and 2000 rpms in park? If so let us know where it is.

I'll get that info for you 4pointslow.
I agree, it's strange that at idle I feel air pushing out in to the catch can. I would have thought I'd feel vacuum also, but I don't.
I changed both o2 sensors yesterday, and still have the same symptoms.

Strange thing is, the truck ran great one night, then the next morning it wouldn't run well at all.

So...it's not the lower intake. There is no exhaust leak. The O2 sensors are new. The tune is good, as on the same tune there was no issue the night before.

Thanks for being the voice of reason.

How about worn valve seats or guides or seals??or even bad rings

It's possible. No leak down was done. I don't have the compression number of that cylinder but the guy looking at it said it was really good. He also found it odd that the engine pulled awesome vacuum and didn't fluctuate
He also couldn't actually see a miss on his test equipment.
I wonder... if I pulled all 4 plugs. I'd think if the trims show a possible fueling issue that one plug would be different than the rest. Ah, I'll start with some logging.

I wouldnt trust a compression test..to do one properly isnt easy..a dry and wet one needs to be done and the block needs to be warm..I bad guide could cause the valve to move around and not seal right occasionally. .or even bad rings could preform great cold or dry but add heat and fuel and could leak..OF COURSE these would be worse case but possibly and reasoning to switch heads..hahah im all for just switching lower intakes but seems very odd he did the spray test and plus you seem to be explaining it as a random..

misfire

Dono said:

It's possible. No leak down was done. I don't have the compression number of that cylinder but the guy looking at it said it was really good. He also found it odd that the engine pulled awesome vacuum and didn't fluctuate
He also couldn't actually see a miss on his test equipment.
I wonder... if I pulled all 4 plugs. I'd think if the trims show a possible fueling issue that one plug would be different than the rest. Ah, I'll start with some logging.

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If the compression was good then there is no need for a leak down test or wet test. But what are the numbers? Usually if you ask someone what their fuel pressure is and they say good then they did not even check fuel pressure. Otherwise they will say 40 psi at idle (or what ever it was). Since the misfire code was on cylinder #1 I would want to know what the compression readings were for that cylinder and a known good one like # 5 which is the first cylinder on the drivers side. I would also like to know what the first compression pulse looked like, it should hit 50 psi if the test is being done right(good battery, open throttle plate, etc.) and if the cylinder's compression is good. Also a running compression test could check for sticking valves or valve spring problems (but a fluctuating vacuum reading would also point that out). To do running compression test pull cylinder #1 spark plug out and install compression tester, start engine and then release the pressure from the compression tester gauge with the little button on it and then let go of the button and see what the compression comes up to. Compare it to cylinder #5 on the other bank. If both compression and running compresion tests pass there can be no leaks so no leak down test or wet test is needed.
If compression test fails and wet test brings up compression significantly more than the good cylinder wet test does then the rings are shot.
If compression test fails and leakdown fails(more than 20%) there will be air escaping from 1. intake 2. exhaust 3.crankcase 4.cooling system 5.side of engine between cylinder and block.
If compression test fails and leakdown passes then it could be a slightly bent connecting rod, worn camshaft lobe, bent pushrod, loose rocker arm etc. Another words the valves would not be opening fully or the piston is not coming up as far as it should.
A misfire on one cylinder is either caused by compression, spark, or A/F mixture problem on one cylinder. You need concrete test results to rule out two of the three and you will know which one it is. Don't assume that new spark plugs are good either, I was thrown off by a defective spark plug once. Check the resistance of the plug from the metal end where the wire attaches to the center electrode and make sure it has some sort of continuity or resistance reading. If you get a reading on the spark plug of OL or what ever your meter reads when the leads are not hooked up to anything means the spark plug is open and is defective. Instead of installing a new spark plug move the one from cyl 1 to another cylinder and see if the misfire changes cylinders. Do that with the wire also. When you change something make sure you disconnect the battery for 10 minutes and then reattach so the PCM's memory is cleared. Then drive it up to 60 and decelerate to 40 without stepping on the brakes three or four times. Then if the engine still runs rough hope a misfire code comes back to let you know if it changed cylinders or not.
And let us know about those STFT's and LTFT's.

Ok, I'll do the compression testing this weekend.
Here is the STFT's and LTFT's. This was with the motor warmed right up, and off of a 20 minute highway drive.

Engine Speed..........739........2004
Analog 2(bank2)....13.72.......13.46 Air/Fuel ratio of wideband O2 on bank 2
STFT Bank 1..........1.03......... .95
STFT Bank 2..........1.03......... .89
LTFT Bank 1..........1.17.........1.27
LTFT Bank 2..........1.05.........1.04

The only way to get correct spacing was with the '.'s added. At least they are in line.

Dont make make me feel to stupid. .but what is#STFT's and LTFT's?? HEYYY im trying to learn still blows my mind a obd2 provides sooo much info...something something FUEL TRIMS??

The oxygen sensors are what drive the fuel trim readings. Changes in o2 sensor voltages cause a direct change in fuel. The short term fuel trim (STFT) refers to immediate changes in fuel occurring several times per second. The long term fuel trims (LTFT) are driven by the short term fuel trims. LTFT refers to changes in STFT but averaged over a longer period of time. A negative fuel trim percentage indicates a taking away of fuel while a positive percentage indicates an adding of fuel.

Its a bit off that my Wideband O2 is reading 13.7 as the commanded value should be 14.7 by the computer. When I look at the logs, this is fluctuating so its just where I took the samples from.

Im guessing it would have been a good thing to disconnect the battery for 10 minutes after changing the O2 sensors. There has been a few drives on the highway since the O2's were changed though, so Id think the fuel trim numbers are reasonably accurate.

Aww thank you sir

I keep going back to what I changed....And that's Injectors and Maf.
So, I really think I should either change all 4 injectors, or move all 4 to the other bank and see if the misfire moves to the other bank.

Id be happy just to change all 4. I doubt Id be able to find 4 of the same locally today. Even if I did, they would be super expensive.

Check compression first Please. Even cold the cylinders should be in range.

Checking the compression is no harder then changing plugs twice in a row. Crank the engine until the gauge jumps 4 times and write down the reading on each cylinder. Do this with all spark plugs removed.