Hello guys;

I'm sending out a call for help. I've just finished up some work on the engine, and now she's got a few problems.

First, the work recently done: intake manifold, throttle body and egr valve removed, cleaned, new gaskets all around. New knock sensors installed. New part-load breather tube installed. Fuel injectors ultrasonically cleaned and flow-tested (I'll do a post on this later), then reinstalled. New thermostat installed. Proper torques all around for re-installation.

I did note that I would likely have a vacuum leak where the brake booster vacuum line connects to the induction elbow. This connection was a bit difficult to remove, and then for re-install it feels much too loose. So there's that.

Here are the problems as I see them now.

1. Car starts, but with difficulty.

2. Quite a rough idle.

3. There is a mix of gas and condensation dripping at the slip-joint where the left-hand catalytic converter meets the exhaust. Not pure gas, but the sniff test says there's some gas in it.

4, Fuel trims indicate a problem. Here's what Torque is giving me-

Fuel trim
1x1: -3.1 %
1x2: 1.6 %
2x1: 19.5 %
2x2: 1.6 %

Long-term Fuel Trim 1: -15.6 %
Long-term Fuel Trim 2: 14.8 %
Short-term Fuel Trim 1: -4.7 %
Short-term Fuel Trim 2: 19.5 %

Anything under 10% is considered "normal," and before this work all fuel trims were under 10%.

5. Significant and increasing amounts of white exhaust coming from the left-hand pipe and smelling a bit of gas. Also small amounts of smoke / exhaust coming up from behind the engine.

OK, so I have at least one vacuum leak. Given the work that's listed above, and these fuel trims, does anyone have any ideas on where I should start looking? Would a loose brake booster line vacuum connection be enough to bring such havoc to my engine and fuel trims? Or do these fuel trims point to something else?

Random notes: There are no rich or lean codes being generated, at least not yet.

I did a fuel pressure test per JTIS before the work above was done, and it checked out perfectly.

I also went over everything thoroughly, and did not see any missed vacuum line connections. Looks like everything is connected. But there IS that iffy brake booster line connection, but wouldn't that affect fuel trims evenly in both banks?

Please give me your thoughts. I was really hoping to go for a drive on this beautiful day.

 

Part of the throttle body removal procedure is to disconnect the battery before removal and to reconnect after TB refitting. As a result, the engine starts with default mappings and learns the TB, gradually adapting to it. You're not going to get the "normal" fuel trim readings on initial start up that you had prior to the work. This is going to take some running time.

Difficult start and rough idle has to be more than this. It could be the vacuum leak pulling in air and sending the fuel/air crazy and/or harness plug connections to the TB loose or damaged.

Unburned gas anywhere near the cats is not what you want.

Graham

 

Graham-

Thanks for the response. Battery was disconnected for all the work, and I did a hard reset before attempting the first start.

It's interesting (and concerning, and discouraging, and...)- the left bank cat is the one dripping the gas/condensation mix), and the left pipe is putting out more and more white smoke. I can see no reason for a head gasket failure now and the exhaust smells more gassy than sweet.

I did a quick "incense" test around certain vacuum lines and the intake ports...lit the wife's incense and held it close to check the smoke for movement...didn't come up with anything obvious.

Strange there are no lean or rich codes...yet. Seems like I read somewhere though that the ECM watches the trims and if they're too high for some period of time, then the codes come...don't know if that's true or how long the engine must run to throw a lean or rich code. I haven't had it running more than 4 - 5 minutes at a time.

Hmmmm.....

 

All the right precautions with the battery disconnect so you'd expect no more than initial uneven running as the trims settle down. New gasket on the TB? No wires accidentally displaced from HO2S sensors?

Left bank head gasket failure does seem an enormous coincidence but I'd be tempted to run a compression test to rule it out.

4 - 5 mins running should be more than enough to get up to normal temperature and go into closed loop. It isn't necessarily sufficient to throw codes which variously require one or two 'trips' to register.

A 'trip' is an ignition cycle (ignition key OFF: wait 30 seconds: ignition key ON) plus a minimum coolant temp increase of 40 deg F after which the coolant temp has to reach a minimum of 160 deg F.

Running like that, it has to be setting codes.

Graham

 

Bump, please!

 

SOLVED THE PROBLEM. My fuel injectors were not seated correctly.

When installed the injectors after having them cleaned and flow-testd, (it was my first time doing so...always a rookie), I tried pushing them all the way down into their chambers, but they resisted...so I relied on the small metal clamps and bolts to push them down into proper position.

That was a mistake.

I removed all 8 injectors again, inspected the new o-rings (they were fine), cleaned out the injector chambers, and lubricated the o-rings with motor oil this time (used petroleum jelly the first time). Then on re-install, I pushed them down hard until I could feel a little "pop" as they moved into the proper position.

Buttoned her up, did another hard reset of the ecm, and voila...a clean start with a good idle and * no smoke * from the tailpipes. A spirited drive and I am a happy man.

So here's one learning point: it's said that excessive white smoke from the tailpipe means a blown head gasket, and that is often true. It's also said that overly-rich combustion brings dark or black smoke, and that is also often true. BUT - and I read this on another forum yesterday, confirmed in my garage last night- if you have a severely leaking fuel injector, with way too much gas pouring into one or more cylinders, you will get...lots of WHITE smoke created by the unburnt gasoline. I was afraid I had blown a head gasket, but alas, the only problem was my ham-fisted rookie installation of the fuel injectors the first time around.

 

A tip of the cap for finding and fixing your problem. Always a relief when it turns out that the mistake you made during the re-assembly process did not damage anything. So now it's time to crank 'er up and enjoy the car....