Why does my car ping going up hill then if I step on the gas getting the rpms up it quits?

Question

I have a 1995 Grand Jeep Cherokee

Answer 1

Usually this means cheap gas or the wrong octane level gas recommended for your vehicle. Look in your manual; are you supossed to use mid-grade fuel, maybe premium. Most newer vehicles suggest or require at least mid-grade, sports cars require premium fuel and premium oils, otherwise you can void your warranty. I'm sure that you're vehicle isn't covored under the warranty still, but just a head's up to other readers. Try going to a different gas statio than usual, or switch to a higher grade of fuel. When's the last time you checked your oil? When's the last time you had your oil changed? When's the last time you had a fuel system cleaning? If you have a Jiffy Lube near by, the price for a Fuel Injection Cleaning is $69.99, but they let the customer sweet talk them into a better deal. When's the last time you had a tune-up, i.e. new spark plugs, spark plug wires, and cap & rotor? Are you losing power going up-hill? By the way, even though premium fuel is more expensive at the pump, in the end it usually ends up saving you money, because your vehicle burns it slower, therefor you go through it slower and have to fill up less often. Also, if you switch from cheap fuels and oils to premium fuels and oils, you'll feel the difference when you drive the vehicle. Chances are it'll run smoother than ever. Next time you get an oil change, ask about an oil system cleaning service, this removes excess sludge that has built up in the engine over the last 11 years.

Answer 2

When you go up a hill, the engine is running slow but pulling hard. The tendency under this condition is for the engine mechanicals to run slightly behind the ignition system. As a result, your ignition timing is ahead - the spark plugs are lighting the fuel slightly before they should, and this is what is making that pinging sound. On a 95 Grand Cherokee, this is likely due to wear and tear. It isn't good for the engine, but it may be one of those things you have to live with. Alternatively, you could try higher octane gas (more expensive though) or take it to a shop to have it looked at. Depending on which engine you have, the timing may be adjustable.

Answer 3

Usually, at light throttle settings, the timing advances as much as possible to give you maximum gas mileage. Unfortunately, sometimes this results in a little pinging or spark plug knock. If you press further on the gas, that will cause the timing to retard a little for more power at the given RPM, and that will cause the spark knock to go away.

Try running fuel with a higher octane rating that what you usually put in the tank. If the spark knock is minor, I wouldn't worry too much about it. If it's persistant and heavy, engine damage could eventually result. Check your spark plugs as well. If it's really bothersome, take it to a shop you trust and have them check it out and adjust the timing. In older vehicles, the buildup of carbon on the top of the pistons and combustion chamber will make the problem worse. I ended up retarding the timing on my 1989 GMC for the same reason; it's run fine ever since.

Answer 4

The Pinging is called Detonation. A higher Octane fuel could help prevent this. Either that or shift to a lower gear to raise the RPM's. Do not allow the vehicle to be detonating for a long time. If your timing is adjustable, it could use adjustment.

Answer 5

Sounds like pre-ignition/"spark knock".

It likely is lugging and struggling in a high gear at low rpm (prime condition for this to occur) and then downshifts to a lower gear (assuming auto trans) where it's not lugging anymore.

I had a 2.8L/auto S10 Blazer that used to do that.....trans always upshifted on hills when it shouldn't have.

Answer 6

try using a higher octane fuel and the next time you put gas in add some fuel injector cleaner if it persists have your timing checked

Answer 7

Not hi enough octane fuel, air cleaner clogged, timing too far advanced, needs tune up?

Answer 8

Timing is bad or you may be using the wrong fuel.

Answer 9

Fuel injectors are clogged.

Answer 10

sounds like the timing is way off