Hello Corvette people

My car seems to be smoking out the tailpipes.
I noticed it a little bit earlier this year but it's more obvious now that I have hollowed out my cat and added a new borla cat back.

I tried the search but didn't have any luck. I remember reading White smoke is water, Blue smoke is oil and Black smoke is fuel.
Is this accurate and how concerned should I be?
I don't need to pass any emisions tests but I just don't like the look of the black smoke puffing out of the exhaust on start-up.
I know it does it when I start the car, not sure about when I'm driving.
Thanks in advance for any help.

 

I think the 87s had the 9th cold start injector, it is more than likey running a bit fat in the morning.

Have you had someone start it and you watch it? Can you confirm it's gas? Have someone start it, cup your hand over the tail pipe and smell the gunk coming out.

Valve seals are a common problem on L98s... a little bit of fat, a little bit of oil... see?

 

first guess rich 2nd ??? tomorrow

 

Thanks,
I just started it up again, revved it a bit and shut it off.
I could smell gas in the exhaust without bending down.
A friend was standing behind the car saying the smoke looked a bit blue.
Little bit of fat, little bit of oil sounds right.
As far as running rich goes, what are my options to correct it.
I have an adjustable fuel pressure regulator that I have not installed on the car yet. Will this help? I'm sure the fuel injectors are the original ones as well.
What is the story on the 9th injector?
Thanks

 

"As far as running rich goes, what are my options to correct it."

Find to cause of it running rich, and fix it. The 9th injector is for fuel enrichment for cold starts. If there is something wrong with tahe system, it could be the cause, among many others.

RACE ON!!!

 

Thanks CFI-EFI nice to hear from you again.
Where should I look to find the cause of running rich?
What are the most common things that I should look at first?
thanks

 

There are many, many, possible causes. Without following the trouble shooting charts in your Helms, you are shooting in the dark. The book approaches it systematically, in order of likelihood.

RACE ON!!!

 

Okay, that is what I will do.
I have the Haynes book, do you reccommend getting the Helms or will the Haynes walk me through the same stuff?
Thanks again

 

Occasionally I find the Haynes is easier to use since it has an index but the Helms is the bible for R&R.

Use the ECM's field test mode (described on my site) to see if it goes into closed loop and stays there when you raise the idle. If so your O2 sensor & coolant temp sensor are ok. If the coolant temp sensor is defective the ECM might enrichen the mixture too much before it goes into closed loop mode.

Put a gauge onto the Schraeder, prime the fuel rail and monitor how fast pressure bleeds off. Also check static resistance of the injectors when warm; they all should read around 16Ohms.

You can monitor power to the cold start injector with a DMM to see if the circuit is working properly.

If you are using a little oil and getting some blue smoke on start up, replace the valve seals and use new keepers. This job is a little tedious but not realy difficult. My local Chevy dealer had a complete set of upper & lower seals for int & exhaust for around $50 US.

If you install the AFPR be sure to first measure stock fuel pressure at idle with the vacuum hose disconnected. Then you have a starting point with the AFPR. An AFPR won't cure a rich condition; it's purpose it to add fuel at WOT. The ECM uses feedback from the O2 sensor to set A/F at idle and part throttle.

 

lot's of good info thank you.
The valve seals job sounds a little over my head.
Most likely because I don't even know where they are on the motor.

I have a fuel pressure guage so that I can handle.
The o2 sensor is new so it shouldn't be the problem.

I plan on keeping the car for a while so it sounds like the Helms would be a good investment.

I want to see what happens when the car is started once warm.
This should also give me some indication as to weather the cold start is working, wouldn't it?

Whatever I do it's a winter project.

 

The 9th is located between the dri side plemun tubes,... down low. (Follow the pipe off the back of the dri side fuel rail.) Unplug it, (2 wires, 1 conn), and see if it will start cold. It may stumble a bit, depending on the temp. What color is the smoke?

 

The Haynes is OK for how to remove and replace parts, but I don't think there is any substitute for the Helms, for explaining HOW systems operate and for providing trouble shooting charts. If you do ALL the tests for a given problem, AND test the components, called out in the Helms, you can save a lot of money by NOT replacing GOOD parts. You can order a Helms, here. By the way, Helms prints the Factory Service Manual, for Chevrolet. THAT is what they are selling on that site.

RACE ON!!!

 

the Haynes is OK, but there's no substitute for the Helms flow charts for trouble shooting-that's something you don't find in a Haynes.

 

I went to the Helms site and saw that the book is $75.00.
Was I looking at the right book?
This seems a little pricey to me, I might ask for it for Christmas.

 

The needless replacement of ONE unnecessary part, or a trip to the repair shop for a problem YOU couldn't track can EASILY exceed the cost of the book. A Helms, a DVOM, and a little patience can save you a small fortune.

RACE ON!!!

 

You can on occasion find a used Helms here or on Ebay but yeah, they aren't cheap. I also got the second smaller electical diag. book at the same time. That one has saved some time more than once to diagnose circuits.