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5.7 TBI "slightly stinky exhaust" and not as good MPG

Scrap it. I'll give you $1000 for the whole Jeep. :fingerscrossed:
 
mysunnshine said:
You could always TDC the #1 piston to verify the balancer hasn't spun on the rubber-
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I'll check this, too :thumbsup:

Bad Karma said:
Scrap it. I'll give you $1000 for the whole Jeep. :fingerscrossed:
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Deal :wave:

14 psi fuel pressure, dead steady.
24 psi fuel pressure with return line pinched, steady at 24 first 5-10 seconds, then occilates a few psi after youbhold it shut awhile.
 
If your hydrocarbons are that high, then I'd guess you don't have a healthy engine. Does it use oil? How's the compression? Does it run on all 8 cylinders?
 
mysunnshine said:
If your hydrocarbons are that high, then I'd guess you don't have a healthy engine. Does it use oil? How's the compression? Does it run on all 8 cylinders?
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Since I fixed the valve stem seals, it does not burn oil. Runs on all 8 cylinders. I will have to check the compression, but this motor pulls really strong, no power problems, fires up super easy too.
 
mysunnshine said:
What condition do the spark plugs look like? Take a picture-
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All 8 spark plugs look the same.

Right side= Driver side, bottom to top = 1,3,5,7
Left Side= Passenger side, bottom to top = 2,4,6,8

017_zpsoeicoz2b-1.jpg



Close Up:

020_zpsj4hv8p7d-1.jpg



The o2 sensor:

018_zpsw2lszsfi-1.jpg


All the plugs look the same, no oil or funny discoloration/deposits. They all look the same.
But, note #3 and #6, I'll explain in the next post:(
 
Quick re-cap:

No trouble codes
Fuel pressure correct/regulator functioning
Timing correct/computer is controlling the timing
Line on balancer matches up #1 piston TDC

I also tested the EGR system. The valve holds 20in, does not bleed down. The engine vacuum source is fine (front of the throttle body). No codes on the EGR solenoid.

So, I went and bought a compression tester. Here are the results:

Driver side, front to back:

#1=195
#3=120
#5=190
#7=190

Passenger side, front to back:

#2=200
#4=190
#6=60
#8=190

#3 and #6 are low. I added a teaspoon of oil to #3 and # 6 and re-tested:

#3 - Went from 120-150
#6 - Went from 60-90

Only other notes:

The engine does not burn oil at all.
Very little blow by.
The oil does not smell like fuel.

If #3 is low, and #6 is just along for the ride, that probably explains the mpg decrease and the slight smell of fuel/stinky exhaust. I assume #6 is not igniting the mixture and #3 is just a partial ignition.

Only other information I can think of: We changed the valve stem oil seals a good while back, maybe one year/4000 miles ago. At that time, all the valve train appeared to be working, and I was getting good MPG/no stinky exhaust after the seal change. Before changing the seals, the engine would puff right off idle. But, even with the shot valve stem seals, it was getting good MPG, and would only smoke a little bit right off idle. It never burned enough oil to need adding a quart. All the valves were adjusted the same, but maybe I burnt some valves?

So, either heads, bottom end, both:shrug:
 
Now it's time to do a leak down of the engine. Then you'll be able to make an accurate diagnosis of worn or broken parts. By the look of the oil on the spark plug threads, it either was or still does burn oil.

I was assuming that you had a healthy motor to start with with all of the diagnostics earlier.
 
mysunnshine said:
Now it's time to do a leak down of the engine. Then you'll be able to make an accurate diagnosis of worn or broken parts. By the look of the oil on the spark plug threads, it either was or still does burn oil.

I was assuming that you had a healthy motor to start with with all of the diagnostics earlier.
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The engine on this thing was always a "crap shoot". I had no history on it. I am pretty sure, from receipts and other signs, that this motor had not run in at least 10 years before I got the Scrambler. When I first pulled the valve covers, before ever trying to start it, the entire valve train/cylinder head under the rockers was covered in surface rust, like it sat up for a long, long time.

After priming the oil pump, the engine started up fairly easy, even without the O2 sensor hooked up. After that initial start and the miles I put on it, I just assumed the engine was solid. Obviously, that's not the case:shrug:

I will probably pull the valve covers and do a leak down test in the next few days to nail down the problem.

If I have to get a new engine, I will stick with a TBI unit. My throttle body, all the sensors, and all my "front of engine accessories" are new. The 700R4 was just rebuilt, so it kind of make sense to stay with a TBI 350.

I think Summit sells these GM TBI crate engines/long blocks for around $1,500, with free shipping:smokin: I most probably cant rebuild this unit cheaper then that:shrug:

Before I pull the engine, I will nail down the problem.

EDIT:

This is what it looked like before I fired it up for the first time:

IMAG1424_zps299221e8-1.jpg


IMAG1425_zps0825e41c-1.jpg
 
While the valve covers are off, make sure the rocker arms all move about the same amount to make sure you haven't wiped any lobes off of the camshaft.
 
mysunnshine said:
While the valve covers are off, make sure the rocker arms all move about the same amount to make sure you haven't wiped any lobes off of the camshaft.
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mysunnshine said:
You could also back off the rockers on the low cylinders and recheck the compression.
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10-4, thanks for the tips:thumbsup:

I will try to check it out tonight, I will post up my findings.

Thanks for your help:cheers:
 
Apparently 5.7 TBI's don't like it if you pull off a plug wire while they run, or maybe because I dropped it when it shocked the hell out of me :rolleyes::shrug:

Anyway. since I did that, the motor wont idle, acting like the timing is way out :eek:

I am going to re-TDC it, then re-time it, then continue diagnosis :fingerscrossed:
 
A spray bottle of water works wonders finding leaking spark while the engine is running. ;)
 
mysunnshine said:
You may just have bad spark plug wires.
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BRKLYNZ28 said:
Yep cracked plug wires would do it.
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mysunnshine said:
A spray bottle of water works wonders finding leaking spark while the engine is running. ;)
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All the plug wires are good:thumbsup:

I grabbed the end of the wire, off the spark plug, with the engine running, and pulled it off the plug, and it popped the crap out of me, causing me to drop it, it then started firing to ground, on the frame:crazy:

I hope it didn't screw up the ignition module. It fried the MAP sensor:confused:
 
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