Just bought my first ever corvette -- a 1991 C4.

I have never dabbled in cars and only know extremely basic things such as changing a tire, changing the oil, checking oil, etc. I am trying to learn from the very basics and work my way up to doing my own repairs, but I would like some advice. The car has issues I want to tackle but without knowledge or lifts, it's hard for me to even be able to visually learn and identify problems.

Some issues I can smell and feel when driving:

Gas pedal vibrates; car sputtering when hard accelerating from a stop
Gas pedal vibrates; car sputtering when normal/hard accelerating while driving ~40 mph (if I let off the gas while going 40mph and try to accelerate, sputtering occurs)
Odd metallic (unsure? doesn't smell like fuel) smell occurs when driving for more than 10 minutes
Car heats to 210-220 when idling -- fan will kick on and cool

So my question is what are some fairly simple/important items that I can begin to look at and check without lifting the vehicle? Any and all advice is appreciated as I don't know much. Please feel free to provide more than just easy suggestions as I can use those to learn more.

Thanks

Edit: Also to throw in there -- I can't seem to access the OBD1 port. I have read it is supposed to be under the right knee but I see nothing. Could it be behind the panel under the steering wheel where the knees are?

 

Welcome to the wonderful world to C4 corvettes and welcome to the forum! Lots of knowledgeable people here.

Couple of very basic suggestions:
1) Did the car come with an owners manual? If so read it from cover to cover as lots of useful information. If you don't have one get one.

2) Get yourself a copy of the 2-volume Factory Service Manual specific to 1991. They are specific by individual year and will help you to do things on your own. One really good thing about them is that they have these diagnostic flow charts to assist you in getting to the root cause of a problem.

3) The engine is controlled by a computer but the computer decides what to tell the engine based on ..... the information that the computer receives from about 10 different sensors. As the sensors age they may send bad information to the computer that causes the engine not to perform as expected. Here's a link to some general info: https://www.corvette-web-central.com...etteStart.html

4) The C4 is not a car that you want to "throw parts at" hoping to see if "that solves the problem". This can get expensive quickly so you want to learn how to diagnose issues to determine the part that needs to be replaced. The FSM noted above helps you to do this.

You don't need a lift but a good floor jack and 4 heavy duty jack stands will come in handy. You can also build yourself some wooden ramps to drive the car up on.

 

"Car heats to 210-220 when idling -- fan will kick on and cool"

Don't worry, that is a normal reading in traffic. If the fan comes on all is good.

 

The ALDL / DLC / ODBI port should be on the right side of the driver's side (about opposite where you'd expect to find an ODBII port). It could be tucked up behind the knee panel there. Mine was. Be aware that the ODBI on these cars is fickle. I tried an ODBI reader and it just wouldn't talk to the car. Wound up with a MT-3100 and that's been useful.

Second the FSM suggestion: it's well worth the time and money to invest. The trouble-shooting charts are really useful. I have a PDF based one and the hard copies and I've found that I prefer the hard copy when I'm out with the car.

Does your car have and LT1 motor? Are there two fans? If that's the case, it may be that the primary isn't cutting on. I just dealt with this. The secondary cuts in when the temperature gets high or when the A/C is on and will cool the vehicle until you're stuck in traffic on a hot day. You might see if it heats up at idle.

Best,
Jerry

 

Oh: odd metallic smell... Is there something loose under the hood resting on the exhaust or block?

J

 

Is the ASR light coming on when this happens? (Corollary: does the ASR light work?) Is the SES light on? (Likewise... Dies it work?)

 

The only thing that will cost you more money to maintain than a Corvette is a boat!

 

Yep, I got both of them and they can really empty the wallet for sure!

 

No ASR in 91. Started in 92.

 

91 is L98. There are two fans as that started in 90. And if everything is operating correctly, the car will cool itself even when stuck in traffic.

 

a wooden boat and a house in the country...

 

My advice is first get yourself the Factory Helm Inc service manual for your year. Can try ebay, can still order them from Helm new, just get one. The Haynes or Chilton manual you might get at Autozone is woeful in comparison, but it may have a picture that the Helm does not, so I do have them too.

Always budget for some repairs, don't go spending money on modifications. Its an old car, it'll need things. A scanner such as an Actron that can read OBD-1, or a laptop + ALDL cable + Tunerpro software will be a necessity at some point, even if its not for this particular problem. Your ALDL port is on the driver's side, just above your right knee. Follow the carpet from the kick panel to the gas pedal and you should see it. A piece of carpeting could hide it. Its trapezoidal.

Sputtering - likely needs a tune up, first I'd inspect for burned wires on the exhaust manifolds. I'm assuming no SES light is set, in which case you need to pull that code first. You can use the paper clip trick, search the archives, if you don't have a scanner yet.

New plugs, wires, cap & rotor, fuel filter. You don't need to splurge on high-end parts for any of it, its all relatively cheap. Delco Rapidfires, Delco cap/coil/rotor. I splurge on MSD 8.5mm wires but thats just me, even my modded motor has a stock HEI cap and fairly cheap Autolite plugs. The manual does have tests to go through for the coil to determine if it needs replacement. You'll need a digital volt meter.

Check FP at the fuel rail with a gauge to check possible fueling issues there. Hook it up, fire the engine, it should hold about 40-45psi. Give it a little throttle and see if it holds roughly, then shut it off and watch the pressure reading. It should hold, if it plummets its possible the injectors are leaking/stuck open.

Your operating temperatures are normal. Only get concerned when coolant temps get to the 240F range. You have AL heads, so if it gets to 250-260F, pull off and let it cool down.

 

Welcome to the World of Corvette Ownership !!!

I couldn't agree more with the posts saying to get a factory service manual !!!

IMHO - the next thing t do is to change all the fluids. Engine Oil (& Filter), Coolant, Trans lube, rear diff lube, even power steering fluid and a brake fluid flush. Next thing I would do is what Vader86 discussed - a basic Ignition tube up - plugs, wires, cap & rotor. You have no idea how old the gas in the car is - so run the tank out, and fill it up with nice fresh premium fuel, and then throw a new fuel filter in for good measure. If the rad hoses are soft, or look old - you might want to change them when you do the coolant change.

The fluid service should cost you about $150 - $200 in parts, and the Ignition tune up around another $100 in parts (depending on how much you spend on plug wires).

Check for fluid leaks when you're under the car. Many times it's something simple that causes the leaks (e.g. a loose bolt).

As for the smell - it could be a leaking fluid, it could be a partially clogged cat - it could be a lot of things - only good way to tell is to eliminate things once by one.

 

Ummmm ... Not even close. You've never priced parts for Porches or Italian Cars have you ??? Let me introduce you to Iron brake rotors that can cost $2K each - or Carbon Rotors that cost $10K a pair. Wanna pay $150 for an oil filter for a Lambo ???

 

Before getting under the car you need to do a search on how to jack up / lift a C4 Corvette because if done in the wrong place you could damage the car. Not saying you don't know how to jack up / lift a car but corvettes have certain locations and spots for jacking / lifting. This is a simple step that is often over looked.

 

Gee, I thought I was on the Corvette Forum, my mistake!

 

I apologize for getting back to this forum so late.. been taking care of a few things.

A HUGE thank you to everyone who replied. I will look into everything commented and see where it takes me. Looks like I have quite a journey ahead, but it's something I planned to do over the next couple of years.

I appreciate even the smallest bits of advice. THANK YOU.