My 2.8 was taking it's time firing when the engine was warm. It started quickly when cold.

The Distributor was re-built, the engine was re-timed to 12 degrees, and I have an MSD ignition, but still, it started hard when warm.

But, holy octane Batman!

I put 94 Octane in it and the hard starting disappeared like it was never there.

While I am thankful I found the cure, does anybody know why the phenomenon?

I'm not sure why 94 octane would cure that. The higher octane rating just prevents the fuel/air mixture to prematurely combust in high compression engines.

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1986 Fiero SE

Octane creep from carboned up cylinder(s) effectively raising comp ratio, maybe?
Or hot carbon in head giving a "pre-knock" situation?

You might have a bad injector spray pattern and the fuel is not burning completely, making a carbon buildup or a bad valve guide/seal letting oil into cylinder. Giving a buildup.

TG

Thanks TennT.

You may be on to something.

I suspect it got lots of bad gas before I bought it.

I think I'll put some cleaner thru it.

Thanks for the thought.

We used to run some Ford trucks fairly hard and they seem more prone to this than others we have used. They were also carb engines that pulled a lot of weight. We noticed that over the years we had to go from 87 to 89 to 92 octane to stop the ping.
To clean em out, we used to slowly pour about 10-12 oz. of water through the carb while it was running. It'd help, but I don't know about trying this on a Fiero, or any cat equipped car anymore. It could ruin an O2 sensor, I just don't know.

I have done it to a Chevy PU and the cat will get VERY HOT!
Carpet melting hot!! But it did help.
Think you could beg or borrow someones water injection kit and run it for a while to see if it helps? I'm curious now, but that may be more trouble than it's worth.
Maybe a few cans of injector cleaner might work, but make sure your injectors are compatible with the cleaner. I've heard that some can damage the insulation in windings in the injectors. Someone here will know.

Let us know what you find out,
TG

yeah try some injector cleaner, i dont think that you have to worry about the windings being messed up by the cleaner since we put 1 bottle in my dads car every week almost and thats been for over 6 years and he hasnt had to replace his 2 injectors (crossfire Injection - Rare thing only made 1 or 2 years)

Arns, I have the same problem, fires up instantly when it's cold but, takes a crank or two to get it running when its warm. I use 94 Octane religiously and it obviously doesn't make a difference for me. Someone told me it has something to do with the cold fire injectors working on the first start up and not on a warm start. I don't know that much about engines (yet) but it sounded good to me.

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I found a kinda neat thing earlyer that alot of older people will know about.. If you get Sea Foam, and run it through the vacuum booster line, while the engine is running, it will clean things that you never new was dirty, and will get rid of missfires due to dirty linings and guides. And if you run a can of it through with your new high octane gas, youll quell KR and fix alot of false missfires... you could try it and see if it works, its worked on a lot of differnt things that I've worked on... And its easyer than replaceing injector that dirty up after a few thousand miles again.

Oh, and BTW it'll make your car smoke for a second or two, but it wont hurt anything.

[This message has been edited by StansGT (edited 09-29-2003).]

Arn, I always used the expensive gas when I owned the car. Obviously I had the same problem too. The problem started right after I got the MSD installed.

I hope that helps.

DJG