Yes if its over 100 that's what it means, its trying to allow more air in. My bet is that his counts are all over right now, but not an indicator of a problem if the TPS voltage is wack. I'd make sure any vac leak is fixed and the TPS is set properly before I adjust the IAC or remove/clean it.

 

Good point. Don't introduce more variables.

 

Great thank you. I will check it as soon as I can. I’m very new to working on cars so I’m sure it will take me quite a while

 

Welcome Aidan652!

One more thing to add to your list would be to verify that your CTS has not failed. The CTS is a Coolant Temperature Sensor and it is quite important to the Engine Computer Module.

The CTS affects the fuel ratios that your car is getting. If the CTS "thinks" that your Corvette Engine is 350* (F) the car will assume that you don't need additional fuel. If the CTS fails the other way it would make the computer "think" it is 20* (F) which would then make the system enrich-en the fuel mixture to compensate for the cooler weather. It would be like driving a car with its "Choke" on all the time.

It is critical to have an "actual" Engine Temperature being sent to the ECM so the car runs the most efficiently.
The CTS is located at the front of the intake system with a three pin connector on my 1988 C4. The resistance values read at the CTS are then crossed with a chart in the manual that has the temperatures and their resistance values.

Take some time and measure the battery voltage at the battery, Red wire to 12+ and the Black lead to the Battery Ground (0). Record that number. Now with the Red wire on the battery and the black wire on the engine block for a ground, what is that Voltage number? Compare to the first number and they should be the same. Now measure the voltage at the fuse panel, that number should be the same or very, very close to the full battery voltage. If not you have some electrical connections that need some attention.

A Battery is critical to the your Corvette so make sure it has clean connections and watch the water level if it is the old fashioned Flooded Lead Acid Battery. Corvettes also have several chassis ground wires under the Corvette. I had one hanging loose and after fixing it my antenna worked again.

Important tools:
Factory Shop Manual for your year Corvette
Fuel Pressure Gauge Set
Volt Ohm Meter
NOID light set

Good Luck with your Corvette. With all the help you are getting here somebody has to hit it!

Best regards,
Chris

 

87 C4’s have a cold start injector so maybe thwt is an issue killing the start time? If OP has Multecs, might be a good time to send the CSI to FIC for cleaning and changing injectors and regulator at the same time?

 

It can, this is why I suggested he check FP with the car running and note how it drops off once the engine is shut down. If the pressure drops like a rock then you have an indicator of an issue there.

 

I'm not sure about the thermo switch used to control the CSI. Can you elaborate? Is it computer controlled? Could that also cause a problem? If so, how do you diagnose?

 

I don't recall any way from memory to diagnose the CSI directly but its the same as the other injectors. Its unlikely only one has failed. Multiple will have gone by this time. Watching the pressure will give an indicator if theres a possible problem to check later.

ECM does not control the CSI, it doesn't know when you've deleted this injector. I believe it is fused off a 3A fuse labeled CRANK, so you can try removing that fuse and it should disable it entirely to see if it cranks better, but that won't cause a TPS Code 22 and is on down the list of things for him to check directly.

 

Great. Thanks for the help guys. I just ordered a Fuel Pressure tester just because it was cheap. Will attempt that once it gets delivered. Sounds like there are a lot of things I can try out. I will make a list and run down from easiest to hardest until I figure it out. Thanks again. You guys are really a big help. I will keep you all posted

 

Get a scanner. It will help

 

Since the injectors fire as one, any failed injector would affect the ramp-up on the scope. If you haven't, watch the video I linked to, he explains it far better than I can. The only reason I suggested that is b/c the OP stated he was considering getting a scope to test the system. I partially agree with what you say re: the regulator, but that wouldn't allow fuel to dump into a cylinder(s) causing the hard start/smoke.

 

You don't think that I'd the regulator fails and pushed fuel into the manifold it could do that?

 

This is clearly a "cold start" issue on this Corvette.

The Cold Start Injector's Thermo-Switch is "fairly" easy to check as it is located on the front of the engine. The CSI could be Injecting additional fuel if the Thermo-switch closes and there is power to the fuel injector. I do remember that when my CSI was operating the Idle RPM was raised a good deal to like 1200 rpm for a short time and went down as the engine warmed up.

IF the engines's Coolant Temperature Sensor sent incorrect readings indicating that the engine is very cold, then the ECM will activate the equivalent of a "Choke Effect" and enriches the fuel mixture accordingly. The CTS can make the fuel mixture rich enough to make Black smoke while idling or running when it thinks it is very cold when in fact it is 80* degrees. Sometimes the CTS can be made to be more accurate if the connectors were cleaned occasionally but most of the time it is easier to replace it. It would be very helpful to have a scanner to allow you to monitor what the engine is "Seeing" in real life.

If the CTS had failed thinking it was very hot (300*) instead of the correct temperature the engine would be hard to start. Very difficult in cooler weather.

 

So good news and bad news. Good news is that we know that we have a air leak. I hooked up the fuel pressure gauge and the car with the ignition on gives off 40psi and then dropped to 0 within a minute. Very fast. Car started and isles and revs at 40psi but once it’s turned off it drops to 0 within a minute again. Bad news is I don’t know what to do now. Maybe check a bunch of lines? Maybe the fuel pressure regulator?

 

FPR seems like its fine if youre holding 40psi normally. You can attempt crimping the return line at the tank at shutdown and seeing what happens. The fuel pressure should hold after shutdown, so the fuel is probably being dumped into the engine by a bad injector(s) stuck open, which then simulates a flooded engine when you restart it.

This still would not cause a Code 22. Spray soapy water on every vac line you see.

 

ok thanks. Will try that. The code 22 doesn’t come on anymore so I don’t think that’s a problem.

 

Looks like a good time to get a set of injectors for your Corvette. It "could be" the CSI dumping fuel but frequently is the injectors themselves as they wear out. I had a the same problem one day and when I pulled the injectors out I found the leaky one really quickly. You could see the evidence of the gas leaking from it.

Check the injector wires to be sure that they are NOT without insulation. The computer sends a ground signal to inject, if you have a open ground making contact with the block that could also make an injector squirt fuel. The car sends 12 volts to one side of the injector whenever the car is "on" so a shorted to ground wire could. I have seen the brittle insulation come off several wires on these engines so watch for that.

99% likelihood that it is a bad injector. For about $170 you can get a set of eight injectors for your Corvette. A lot of people use FIC but I have used South Bay Injectors for years with great success. Good Luck!!

I would still check the CTS on your car to be sure it is accurate.

Best regards,
Chris

 

How do you know you have an air leak?

Crimp off return and turn the key to run but DON'T CRANK. If it gets to pressure and holds, you have a regulator problem. If it doesn't, turn the key to run and don't crank, and a second as your assistant does it, crimp off the return line.

If the regulator is bad, see if you have Multec fuel injectors. Change them if you do while you are there.

 

OK. Sorry it has taken me so long to get back to this forum. I have been busy with school. I did what you asked and when I crimp the return line and turn to run, the pressure drops just like usual. But when I had an assistant crimp it off right after i turned it to run, the pressure stopped where it was (10). What do you think I should do now? Thanks

 

So you crimped off the return line and turned the key to run and it didn't hold? Kinda sounds like something before the regulator then. I mistyped. You should do the assistant test with the FEED line. So turn the key and watch the pressure go up and soon as he hears you turned the key, crimp off the FEED line. See if it holds. If it does, I would suspect the pulsator in the tank.