Thanks in advance. My son and I just got back from an epic 1800 mile road trip in my ‘89 roadster. The car is low miles and all original. The car performed flawlessly and all my gauge readings were normal throughout the trip. The only performance issue that has recurred in my 3+ years of ownership has been a consistent “hard starting” issue when cold. The car kind of grumbles to life, picking up cylinders along the way for about 5-6 seconds before it reaches a steady idle. I’ve recently replaced the cap, rotor, plugs and wires thinking that may have been an issue (needed to be done either way), but that didn’t really change anything. Once started and warm the first time on any given day, it fires off immediately when restarting. I’m pretty convinced it’s a fuel or sensor issue at this point. The injectors have been replaced by a PO so I’m not sure what brand or size they are. I’m going to pull codes later today but am wondering if these symptoms are indicative of anything anyone else may have run into. I only run the highest octane I can find, all filters and fluids are new/up to date. When starting cold, I always let the pump prime before firing.

 

One overlooked maintenance that may help is cleaning the throttle plates, dirty plates can make your base idle bit lower than the setting and make the IAC make up the difference taking a few seconds.

. Cleaning plates is easy with car off remove the air tube turn the throttle linkage to open the plates and with a clean rag wipe the bores and plates you'll be surprised how much sticky goo you will wipe out. Give it a try see if it makes a difference.

 

89 does not have the cold start injector correct? So what helps it fire off cold, anyone?

 

The ECM gives it a starting boost, depending on the temperature, using the 8 injectors.

 

Great advice, thanks. I’m going to do that tomorrow.

 

Indeed, '88 was the last year of that damn "9th injector"...

What is your fuel pressure at startup and after warm? Do you smell fuel at the regulator hose?

You might check the resistance readings at the engine coolant temp sensor to see if it changes smoothly while warming up.

 

Nope, no 9th injector. The ECM adds an extension to the pulse width for cranking based off the CTS.

I second making sure the throttle plates are clean, and the IAC housing is clean. Something free to do to eliminate a few issues before you start buying parts is to to a min idle set. Make sure base timing is at 6*, make sure the IAC is clean and doing it's thing, and that the throttle is opened enough to all the ECM to have control. I also second checking your fuel pressure to make sure you are seeing around 43PSI vac line off and fuel is not getting sucked into the manifold, and then verify the CTS is sending proper temp readings to the ECM.

 

Have you verified that you Coolant Temperature Sensor is giving "accurate" readings? Your situation sounds like a bad CTS reporting that the engine is warmer than it really is to the ECM. If reading warmer than reality then it would start easily when warm but be a bear when cold. There is a chart in the FSM where you can compare the resistance value to a temperature reading.

If the CTS is bad that would be a simple fix. It is clearly the first place I would start looking.

Leaking injectors would make the Hot starts more difficult with the excess of fuel. If they were replaced 3 years ago they should be fine.

Since you are in Ijamsville MD you are not far from Tony's Corvette Shop down in the Gaithersburg Air Park. They are a TOP Corvette shop and will help any Corvette owner have a better experience. Great people and unbelievable amount of knowledge inside those walls at Tony's Corvettes.

 

Had that hard start problem but replaced fuel pump, started right up with no problems yet.

 

Cars of this vintage have had bad injectors that cause all kinds of starting and run problems. Installing a new set of injectors fixes all kinds of problems and from what I have been told it runs like a new engine.
The research is out there on the Forum and more.