neal64ss

iTrader: (1)

Finally got my 5.3l/4l60e installed and running in my 64 chevelle. It has some issues. Long term fuel trims are maxxed at +25% and tailpipes show black as would be expected since it is running rich.

It is runs very rough, as if it is missing a cylinder, but runs fairly good above 2500 rpm.

Pulled the plugs and all had oil on the threads except number 7 cylinder and the number 8 cylinder was not as oily as the rest.

Compression test shows 162, 168, 155, 174, 164, 170, 162, 154.

Leak down test shows 28%, 24%, 38%, 22%, 24%, 24%, 22%, 18%.

The thing that really has me puzzled is the cylinder with the lowest compression shows the least amount of leakage????

Anyone have advice as to what my problem is. Picture of plugs and test numbers attached below. You can see the difference in the number 7 & 8 plugs.

speedtigger

iTrader: (16)

It is possible that you have fuel washed the cylinders with the rich tune. That would give you bogus cranking compression and leakdown numbers. You could try turning the fuel pump off, spraying some wd 40 in the intake while cranking the motor and then testing again.

oldgoat69

How long did the engine sit while the swap was being undertaken? It is highly likely that a rust ring has been created on the valve faces or seats. It is also possible that the lifters have bled down some, it can take a while for them to fully pump up again. Having owned a machine shop I have seen these symptoms before.
When you did the leak down did you back off the rockers? If not you can get false readings.
I would suggest that you refire the engine and let it run for 15-20 minutes at idle. Let it fully come up to temp, then slowly raise and lower the engine speed similar to doing an flat tappet cam break in. I expect that this will make a big difference. If not go back and repeat the leak test. Leak percentage hot and cold will be different, as will compression (this is really cylinder pressure not actual compression).

BanditDave

iTrader: (11)

What type of injectors are you running? Also what is the PCM you are running the injectors with? It is posssible a couple of your tables are way off...one coming to mind, the table that distinguishes the Flow Rate v. KPA.

What was done to the motor? Stock? Is it oil or gas on the plugs?

nascarnate326

iTrader: (1)

Possible the tune is wack?

pdsq98gt

If the engine and tune are stock you need to scan the PCM to see if all of your sensors are reading correctly. For example, if the coolant temp is open it will read -40 and dump fuel. Check fuel pressure. You should have about 60psi. Also if you have the injector harnesses one the o2 sensor harnesses on the wrong banks it would cause one bank to be full lean and the other full rich.
If the engine is modified then you may just need a good tune.

garys 68

iTrader: (1)

Any codes? Any chance you have the MAF in backwards?

neal64ss

iTrader: (1)

Car is driveable, and I have put several miles at speeds up to about 70 mph.

neal64ss

iTrader: (1)

All stock 5.3l, stand alone tune by lt1swap.com, definitely oil on plugs. Stock PCM and injectors (non flex fuel).

neal64ss

iTrader: (1)

MAF is installed correctly. Getting the code for motor running lean. Was getting an O2 heater resistance code but replaced both O2 sensors and that code is gone.

neal64ss

iTrader: (1)

I have "scanned" the PCM using OBDWiz software hooked up to my laptop and all the sensors are responding as expected, except the LTFT's on both banks are maxxed high.

aknovaman

iTrader: (7)

If the engine has set for a while without running there are sticking injectors. Run some sea foam through it or better then, remove and soak the injectors in some kerosene for a couple hours and then wask in coleman camping fuel.

garys 68

iTrader: (1)

You're getting a lean code, both banks, and your plugs are wet and you're running rich. There's your problem. An air leak after the MAF will affect both banks. Other than that, a clogged injector in both banks will look lean, so the ecu will compensate by richening up the others. Or at least that's my understanding.

BLK02WS6

iTrader: (2)

Are you sure your O2's are pinned, wired and hooked up correctly? Check to see what the fronts are reading vs the rears... and bank 1 vs bank 2... unplug one O2 at a time and see which one goes to .450mv - does it correspond to the one you unplugged? It is reporting lean on the O2s and commanding the maxed LTFTs, resulting in an overly rich condition that is then not being seen by the O2s - that's where your problem is - in the O2 sensors/wiring...

neal64ss

iTrader: (1)

Don't have rear O2's, programmed out. Yes, first thing I did after getting it running was change to new plugs, then a pair of new O2 sensors, then triple checked O2 sensors wires. I removed the fuse(s) for coils and injectors when performing the compression and leak down testing. I have tried to find a vacuum leak without success, so I am going to try cleaning the injectors. The engine did sit for several years before I started it up.

At this point I feel fairly confident that the problem is either sticking injectors or a vacuum leak after the MAF.

Thanks everyone for the advice. I had overlooked the possibility that a sticking injector would look like a lean condition to the PCM.

neal64ss

iTrader: (1)

Update:

I pulled the fuel injectors and tried testing them using a 9V battery. Only 6 of the eight will operate. I guess that 2 of them are stuck closed and will not function. This also explains what I saw with the spark plugs and the other indications I was getting. I had a stuck injector on each side of the engine.

So, how do you "un-stick" an injector. These are the Delphi multec 2 non-flex fuel type injectors. I have tried soaking them in kerosene for about 3 hours with no luck.

BLK02WS6

iTrader: (2)

I would replace them or send them off to someone reputable for a rebuild...

neal64ss

iTrader: (1)

After some more research (I am learning more about injectors than I want to know) I went and checked resistance on all 8 injectors, and all 8 measures about 13 ohms, which is specification for these injectors. So I am back to trying to figure out why 2 of the 8 will not actuate. I guess they are stuck mechanically, but still haven't been able to get them unstuck. Anyone know of something other than soaking them in kerosene that might dissolve whatever is causing them to stick.

neal64ss

iTrader: (1)

Sure enough, it was 2 frozen injectors. I tried and could not get them un-froze. Two salvage yard injectors later and engine runs smooth as silk.

Thanks to aknovaman for the advice. I had totally missed that possibility.