Frustrating 5.7L TBI problem(s)

[colbystephens]

@4X4HIGH @Russell and at all you other TBI gurus.....

I recently replaced my engine with a crate long block. Freshened everything up under the hood too, though I didn't replace my distributor (probably could use it though...)

It runs great, but I'm having an ongoing problem that it blows a huge plume of white smoke shortly after start up. It does so until I get on the throttle under load, at which point it clears up permanently. The colder the engine, the bigger the problem. If I idle for a long time, the smoke comes back. I think this indicates that the cat had cooled.

I had the intake gasket replaced to confirm no coolant leaking into the combustion chamber. Tested it for a bad head gasket. All came out OK.

Timing mark bounces around a fair amount when timing.

The smoke smells like I'm running rich, and I think the smoke clears up because the cat is getting hot and burning the unused fuel. I did have some terrible passing smog because I was running rich.

Then I started getting a code 43 on the SES light every so often. Sometimes I lose power suddenly when hitting the gas for a down shift, which triggers that. A little reading suggested that it could be a knock sensor problem. I replaced mine, no improvement.

But I'm wondering if this has to do with timing and fuel delivery problems leading to an excessively rich mixture.

Please help. :-)

 

[blazinzuk]

If your timing mark is bouncing around when you have a timing light on it, that needs fixed first. Timing should not be jumping around

 

[Russell]

Fix your timing to start. White smoke is usually coolant though (it isn't just condensation because it's chilly outside eh?). You should have your coolant tested for hydrocarbons and pull your plugs out to see if one looks cleaner than the rest. Especially if it is running rich.

 

[Big6ft6]

If it is any consolation, I've had two TBI trucks and they always had lots of white exhaust when starting on cold days and the exhaust smells rich. In warm weather it isn't as noticeable. I've always assumed it was just condensing water vapor. Both trucks also had black soot inside the tailpipe, and if I revved the engine while in the driveway it would spit out black soot leaving some on the driveway. I don't have any SES lights associated with this, they run great, get good mileage and have good power. I've just lived with it. Hard to know if you're seeing same amount of white exhaust as me...but thought I'd share for what it is worth.

 

[colbystephens]

Fix your timing to start. White smoke is usually coolant though (it isn't just condensation because it's chilly outside eh?). You should have your coolant tested for hydrocarbons and pull your plugs out to see if one looks cleaner than the rest. Especially if it is running rich.

It's a thick cloud big enough to engulf other vehicles. And it just sits there - doesn't dissipate quickly. You'd think I was firing up a 6.2 in Northern AK in the winter on 3 glow plugs.... ;-) I'll video it for ya.

How do I fix a bouncing timing light?

I had the coolant tested and it was fine.

I'll check the spark plugs.

 

[Kay86K5]

If it is any consolation, I've had two TBI trucks and they always had lots of white exhaust when starting on cold days and the exhaust smells rich.

This is usually indicating of the typical TBI bad valve seats. With the oil pooling in the heads while the motor is off around the valves, since the seats start to wear over time they leak small amounts of oil down into the cylinders and once you start the motor up it burns that oil out the exhaust.

For what it's worth (don't really think this is your overall problem, but maybe something to check) when I did my TBI motor swap, I finally got everything running good but it would periodically smoke like crazy out just the passenger bank (I have true duals so I could tell if it was just one bank or both) and then once it would warm up it was intermittent where it would smoke, then go away, then smoke again....all white smoke and it was the same thing where I thought it was smelling rich.

I finally found a thread where a guy said he was having a similar problem and pulled the valve cover off and found one of the drain ports on the head (not sure their technical name) was plugged a little bit. He cleared it out and the smoking went away. I did the same however didn't find any glaring problem with the drain ports so decided to change the oil with the valve cover on the passenger side off. That must have done the trick to clear whatever was plugged out cause ever since then, no smoke whatsoever.

Like I said, not sure if this is really your overall problem, but something really easy to check to try and help the smoking problem

 

[colbystephens]

This is usually indicating of the typical TBI bad valve seats. With the oil pooling in the heads while the motor is off around the valves, since the seats start to wear over time they leak small amounts of oil down into the cylinders and once you start the motor up it burns that oil out the exhaust.

For what it's worth (don't really think this is your overall problem, but maybe something to check) when I did my TBI motor swap, I finally got everything running good but it would periodically smoke like crazy out just the passenger bank (I have true duals so I could tell if it was just one bank or both) and then once it would warm up it was intermittent where it would smoke, then go away, then smoke again....all white smoke and it was the same thing where I thought it was smelling rich.

I finally found a thread where a guy said he was having a similar problem and pulled the valve cover off and found one of the drain ports on the head (not sure their technical name) was plugged a little bit. He cleared it out and the smoking went away. I did the same however didn't find any glaring problem with the drain ports so decided to change the oil with the valve cover on the passenger side off. That must have done the trick to clear whatever was plugged out cause ever since then, no smoke whatsoever.

Like I said, not sure if this is really your overall problem, but something really easy to check to try and help the smoking problem

I have a TBI rebuild kit with all the seals. Haven't done a complete overhaul on it. It's got 210,000 miles on it. Thoughts?

 

[Cucv_M1008]

Would not hurt to rebuild it.

 

[sreidmx]

when you are checking the timing are you pulling the spout plug? if not thats why your timing is jumping around. I just had a bad dizzy in my tbi truck and found that by accident. The smoke deal is same over here, if its cold itll puff some but I attribute that to the age and it sitting so the valve guides or seals are toast. but the issue with power tells me one or two things, you have an issue with fuel pressure, or your distributor isnt happy and the ecu cannot tell when to fire the injector, since tbi is using the distributor to send cam position this is how the injector know when to fire. One other thing, if you have a loose injector plug it will run good sometimes and bad sometimes almost like it happens for no reason.. check those plugs. I chased that one for along time.

 

[colbystephens]

What's the spout plug?

I don't know much about gas engines... cut my teeth to a 6.2L, so this is all pretty new to me.

The distributor is kind of rusty. But I didn't have these issues with the 206,000 mile engine that was in it. So I'm not convinced it's directly contributing to this particular problem.

 

[sreidmx]

The spout plug is under the big black cover on the firewall, it's a brown single wire with a weather pack seal, it's the set the timing plug and disables the ecu timing control so you can set the initial timing which for your engine is 0 degrees btdc. The ecu will add the rest of the advance for you. So when you check it normally the ecu is always adjusting it which is why it's bouncing around. Idle should be somewhere 16-20 degrees when warm.
The distributor might not be it but 206 is a ton of miles and the bushings do wear out, new distributors from Autozone are 120$ and are actually better quality than anything I got from napa surprising to me..

 

[colbystephens]

Awesome! Thanks for the info. Maybe, wishfully, correctly seeing the timing will cure my problems.

 

[sreidmx]

Yea no prob, I have Intimate dealings with tbi.. We don't get along when she doesn't work,

 

[colbystephens]

I know the feeling... ;-)

 

[black dawg]

The timing connector he is talking about will be below the brake booster on your body style truck. Does the engine run fine while it is smoking?

 

[black dawg]

On the knock sensor, pretty common problem with replaced engines if there is paint in the threads in the block for the knock sensor.

 

[colbystephens]

The timing connector he is talking about will be below the brake booster on your body style truck. Does the engine run fine while it is smoking?

Thanks, and yes, it runs great. However, leading up to a particularly smoky blow out it will have a SLIGHTLY rough idle. That's before smoke appears. But once on the throttle, you'd never know they're was an issue.

On the knock sensor, pretty common problem with replaced engines if there is paint in the threads in the block for the knock sensor.

Good tip. Draining the coolant and running a trap through there may be in my future.

 

[dremu]

Good tip. Draining the coolant and running a trap through there may be in my future.

Somebody correct me if I'm wrong, but I don't think the hole goes all the way into the coolant jacket, thought it was just a blind hole into the block. Point being you may not have to drain the block.

-- A

 

[sreidmx]

Mine is blind no coolant.

 

[prolinews]

My 88 k5 did the same thing for years the 1st crank up of the day. By pure happenstance I fixed it. I checked my spray pattern on the injectors after a rich code popped up. It looked a little drippy under the light but not bad. I had a spare tbi with Chinese injectors laying around so I swapped out the injectors. To my great surprise it ran about the same but quit smoking out the neighborhood when I crank it up. I always assumed that the smoke was purely a result of worn valve guides pooling oil on the pistons after it was parked.