lately I start the car it shuts down
2nd start is OK if I let it run a bit then no stall and idles fine
I wonder if bad gas or something needs to be cleaned CRC throttle body cleaner
are gas treatments worth it?

 

How old is the gas?

You know that all gasoline has detergent in it already, right?

 

LOL it's a Corvette that gas can't be more than 3 weeks old
I drive the car

 

How long has it been doing this symptom? Longer than the current tank of gas?

 

Got gas on Oct 23 tanks was half full so gas mixed I usually go to wawa and get high octane
just started doing this 2 days ago

 

If you are going to do something, clean the TB. Find the easiest way you can see and forget about it. Take the TB off. This is a good time to do the coolant bypass mod. Take the top plate off. Take the IAC off. Take the IAC housing off. Mod it if you want to make it smaller or not. Clean the passages with brake cleaner. Spray the IAC pintle with a mist of brake cleaner and wipe it clean GENTLY. NO PUSHING. Reassemble with fresh gaskets. The CRC spray only cleans the butterflies and makes you feel warm and fuzzy with a shiny TB. It will take a lot to get into the passages.

If you really think the gas is bad, suck it all out and put in something new.

 

Probably not the gas then.

 

This is a good place to start.

 

Before taking TB off check it for carbon build up. If throttle body is "coked up" clean carbon with throttle body cleaner. If you decide to take it off and apart; you will new to check min air and TPS adjustments. What is the outside temperature? Codes. Coolant level? 89 L98 only requires regular. Premium can cause cold start troubles on engines where It's not required.

 

I got 93 octane at Wawa two weeks ago. It was the only time my '90 ran like crap. And the only time I've ever put gas in it from Wawa.

So, I dumped a can of Cataclean in the tank when it got down to a few gallons and ran it out and refilled with BP Ultimate (99 to 100) and it's running perfectly. Likely didn't even need to dump the Cataclean in the tank, but whatever. I already had it, so.

I won't refuel at Wawa again.

 

Care to elaborate on this? No real difference between the 88 L98 and 89 L98, and it states "Premium Recommended" inside of my fuel fill hatch.

Jared

 

It's all possible. I got gas at a major chain for eons. No issues. One day, it was bad. Hard to say why. It was a busy station at an intersection so it would have been tankered frequently. Before and after, I had no issues. My guess is maybe they were switching from summer to winter blend and added a bit too much additives or too little or might have gotten water or whatever.

 

L98 has 9.5 to 1 compression which is low enough for regular. Back in the 80s fuel quality sucked. There were alot of fuel injector failures related to the poor quality and lack of detergents in gasoline. It was to the point only Mobil high test was recommended because it had highest detergent content. Later as fuel quality improved snd now with Top Tier, premium is only recommended for high compression engines. The higher the octane the harder fuel to ignite. Cold engines need fuel that is easy to ignite. Between 50*-60* fuel related troubles show up more often, temperature is not cold enough for choke cycle so mixture canbe on the lean side. There are alot things that can cause cold start stalling.

 

So the fact that the freshly rebuilt and well maintained L98 in my 88 Vert rattles like a maraca when it is filled with 87 octane Shell gas, and the fact that it doesn't rattle at all when filled with 91 octane Shell gas has absolutely nothing to do with the fact that it says "Premium Recommended"?

I don't buy that crap at all. It's not all about what your compression ratio is. GM recommends you run premium fuel in your L98 Corvette because it has a preprogrammed timing curve, which is more aggressive than a typical 350 powered passenger car, which helps gives your Vette more power provided you run the fuel that is recommended. Higher Octane fuel is harder to ignite, therefore you are helping to combat detonation by running a higher octane. Even though our cars are old, they still have electronic ignition with 45,000 volt coils. Nobody is running points in their C4. One other I thing I do know about the gas they were selling in 1988.... far fewer stations were selling ethanol blended fuel. IMO, the gas you could buy in the 80's is far better than the watered down trash they sell today. Ethanol only has like 65% of the energy of gasoline when it burns.

I would lean more to it being other things causing cold start stalling..... not the octane of the fuel you are running. Which BTW to the OP, if you are running Premium, then you are running exactly what the manufacturer recommends you run.

I run premium, my car runs great and I've never had an issue starting it at any temperature. If the forecast calls for sun.... my Vette gets driven regardless of the temperature.

Good luck to the OP, you should pick up a FSM for your car, they have great troubleshooting sections.

Jared

 

One thing that concerns me is the reference to a freshly rebuilt engine rattling on 87 octane fuel. When it was rebuilt was the original pistons and heads used? It doesn't take much during a rebuild to up the CR on the engine from what I know and have read. Changing anything that affects the CR, fuel delivery or timing can affect how an engine runs on a particular grade of fuel, same with the ECM code if that was changed. Another thing is the knock sensors, whether they are good and hooked up or not.
Personally my 86 runs fine on 87 octane fuel and as far as I can tell it's not been opened up before I bought it and I know it hasn't since I've owned it and it has 95K miles on it. The only time I put higher octane fuel in it is when I'm getting it ready for winter storage, the non-oxygenated fuel I can get is either 89 or 91 octane but I prefer that for winter fuel other than alcohol mix.

 

I heard that too but now I am curious. I accept that high octane fuel is more knock resistant. Is there any scientific paper that says it is also harder to ignite?

 

The difference between your 86 L98 and my 88 L98 is the fact that I have aluminum heads. When GM installed the aluminum heads they didn't just do it to save weight. Having an aluminum head allows you to run more advanced timing because the combustion chamber stays cooler than it's iron counterpart.

Your 86 probably does run just fine on 87 octane, it is an iron head engine and does not share the same timing curve that my 88, or the OP's 89 have.

I of course was over exaggerating when I made the maraca reference. There is a noticeable difference in the amount of detonation when comparing 87 to 91 though. I made the mistake of putting 87 in my car and would only do it again in case of emergency.

The question about should we run premium fuel in our C4's has already been asked and answered...… https://www.corvetteforum.com/forums...mium-fuel.html

Jared

 

Just shopping for things in general, even groceries, I've kind of concluded that the quality of products and processes involved with ensuring their quality is dependent upon demographics. That's a much deeper discussion, though. Starting with the target demographic on the demand side all the the way down to the inner give a damn of the produce manager, or, in this case, the driver mixing the detergent.

For instance, if one types 'best local gas' into Google, almost all, if not all results, come back telling one who has the cheapest gas. Quality of fuel isn't ever returned in the results. People generally equate 'good' with 'cheap' rather than equating 'good' to 'quality.' And so they get what they get.

Me personally, I'd rather continue paying the $3.19 a gallon for the BP Ultimate. It seems to keep things observably clean. And even though my '90 is nothing to write home about in comparison with modern engines, it roars like a lion rolling down the road for what it is. Beats paying the Corvette tax on maintenace and unnecessary parts and repairs. I can't really do much under the hood myself these days, I'm recovering from a couple of heart attacks this year and several extended stays in the hospital. So I try to be as passively preventative as I possibly can. Same with all of the other fluids and lubricants.

Something I learned from my doctors is that basically every preventable disease and clog and bit of foreign debris buildup in the human body which causes its function to decline starts with what gets put into the gut for fuel. It's a good comparison. To me, anyway.

 

So does my Gorocery store gasoline. Why? B/c ALL gasoline sold for road use has detergent in it. How much? More than enough. Click HERE to see the pics of my spotless, ~150k engine.....

 

https://www.cars.com/articles/got-ba...1420683208297/