C4 noob Q&A.

[Firevette]

Just some of the things I've seen posted over the years. I still have a ton of stuff to add. Just dont have time right now, i'll add more later...feel free to add your own.... this might turn into a good sticky, im sure we will get some tech noobs around here before long! Some LTX related stuff would be good too.

Q. How do I fix XXXXX on my C4???

A. Buy a factory service manual (FSM). Its the best tool you can buy for your C4. It's best to consult your FSM before doing anything on your car that you are unfamiliar with.



Q. My L98 C4 won't burn the tires. I thought Corvettes were fast, whats wrong with my car?

A. You need to be sure all aspects of your car are where they should be. Check all normal tune up parts and replace as needed. Check all filters, including the fuel filter. Check timing. Most L98's like a bit more base timing. See how it runs from 6-10* btdc. Most stock L98's should have enough go to turn the tires over from a stop.



Q. The airbag light on my 1990 is always on, what gives?

A. The 1990 had a problem with corrosion between the airbag sensor and the frame. The sensor needs to be removed and mounting surfaces need to be cleaned, then replaced using dielectric grease. Consult FSM.



Q.What kind of rear differential is in my C4?

A. All 84's had a Dana 36. All 85-96 C4's with a standard transmission have a Dana 44. (including ZR1) All 85-96 C4's with an automatic transmission have a Dana 36. Gear ratios varied by year/option/transmission choice.



Q.Can I remove the catylitic coverters and/or AIR pump from my L98 without setting off the service engine soon light?

A. Yes



Q. Can I remove the EGR from my L98 without a service engine soon light?

A. No. EGR will need to be taken out of the tune.



Q. Will C5 wheels fit my C4?

A. Yes. They are bolt on for 88-96, 84-87 will require spacers.



Q. Will a Holley Stealth Ram intake fit under my hood?

A. No. Not in out of the box form.



Q. There is coolant on my passenger floorboard and/or steam coming from my defroster vents. Where is it coming from?

A. Your heater core probably just gave out and will need to be replaced. Good luck!



Q. My headlights dont always flip up/down or get stuck sometimes, whats wrong?

A. The headlight motors use nylon/plasic gears and bushings to drive the headlght assembly. These parts crack and wear out. This is normally the problem. You can buy the gears and bushings for a minimal cost and rebuild the motors yourself, or buy new/rebuilt motors at a much higher price.



Q. Where is the battery on my C4?

A. It is behind the driver side fender panel. This panel must be removed to R&R the battery.

[85corvettekws]

Some more info on the C5 wheels fitting the C4, I have a 1/4" spacer in the front and 1.75" adapters in the rear. It's important to run adapters and not spacers in the rear. There isn't enough thread to grab if you try to use just a spacer.

[zz4vetteguy]

Originally Posted by Firevette

Q. My L98 C4 won't burn the tires. I thought Corvettes were fast, whats wrong with my car?

A. You need to be sure all aspects of your car are where they should be. Check all normal tune up parts and replace as needed. Check all filters, including the fuel filter. Check timing. Most L98's like a bit more base timing. See how it runs from 6-10* btdc. Most stock L98's should have enough go to turn the tires over from a stop.

Originally Posted by Firevette

Q.Can I remove the catylitic coverters and/or AIR pump from my L98 without setting off the service engine soon light?

A. Yes

or if you know what you are doing, or know someone who does, they can bore it out so it looks like it is still there.

Originally Posted by Firevette

Q. There is coolant on my passenger floorboard and/or steam coming from my defroster vents. Where is it coming from?

A. Your heater core probably just gave out and will need to be replaced. Good luck!

Yup, good luck with that one...ask me how I know.

Originally Posted by Firevette

Q. My headlights dont always flip up/down or get stuck sometimes, whats wrong?

A. The headlight motors use nylon/plasic gears and bushings to drive the headlght assembly. These parts crack and wear out. This is normally the problem. You can buy the gears and bushings for a minimal cost and rebuild the motors yourself, or buy new/rebuilt motors at a much higher price.

If you go with the motors though, make sure it is turning the right way...ever see a headlight go the wrong way?

Originally Posted by Firevette

Q. Where is the battery on my C4?

A. It is behind the driver side fender panel. This panel must be removed to R&R the battery.

Not hard to get to, but a PITA

[85corvettekws]

There is an alternate method of removing the battery. You can unbolt the Cruise Control, then loosen the support bar that crosses over top of the battery and fandango the battery out. This way you don't mess up the body lines of the car by removing that panel and replacing it.

[YorkL8apex]

Well it time for me to replace mine but will probably just pull the side panel off to do it.

Welcome to the Barn!

[leec4ce]

Originally Posted by YorkL8apex

Well it time for me to replace mine but will probably just pull the side panel off to do it.

Welcome to the Barn!

But always nice to have a backup plan

[zz4vetteguy]

Originally Posted by leec4ce

But always nice to have a backup plan

When I had my C4, I always had to have a backup plan...never sure what was going to happen when I turned the key in her later years.

[dclafleur]

I know on my '85 there is a different gear in the headlights that does not have the delrin bushings. I had to replace the whole gear set when it went out.

[SQUIRMIN VERMIN 84]

Originally Posted by 85corvettekws

There is an alternate method of removing the battery. You can unbolt the Cruise Control, then loosen the support bar that crosses over top of the battery and fandango the battery out. This way you don't mess up the body lines of the car by removing that panel and replacing it.

P.O. had removed cruise from my car so it was a no-brainer to "fandango" the battery out thru the top and under the diagonal body brace without loosening the brace(yes, it can be done with the proper cuss words and the sacrifice of the use of a finger or two), but still preferable(to me at least), to popping off the quarter panel.