I recently purchased an 87 2.5 automatic. It has been sitting for a bit over one year with a full tank of gas. I have noticed that on inclines or hills, what sounds like valve lash or pinging starts. its definately upper end, not rod knock.
i usually attribute this to either bad gas, or bad timing. since setting the timing is not possible on a 4cyl DIS motor, is it possible that bad gas could be causing this?
Other than a high idle for 2 minutes on a cold start-up, it has no other symptoms that i notice.
could this be related to the high idle at cold start-up thing?
thanks
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06:02 PM
PFF
System Bot
Ken_86gt Member
Posts: 574 From: WILLIAMSBURG Registered: Jan 2004
I don't know how long the gas takes to go bad, a year might be pushing it. You probably should eliminate that potential problem before you get to far into trouble shooting the problem. Run it down or take some of it out, spread the gas into other cars a little at a time. Put some good fuel system cleaner in and a new tank of gas and see how she runs then.
I know this won't help you out, but just an FYI......I have had the pleasure of owning and helping to sell many low mileage (re: brand new) Fieros over the past several years. These are cars that had 100-200 miles on them when they were parked in 1988. The fuel pumps were trashed and I replaced them all, but believe it or not, the 15+ year old gas in the tank still burned when I fired them up.
I think you shouldn't have any problems with year old gas, but who knows?
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08:49 PM
Francis T Member
Posts: 6620 From: spotsylvania va. usa Registered: Oct 2003
Gass does go bad, but I wouldn't expect to to in a year. Why don't you just dump a bottle of 104+ octain booster in the tank. That should take care of the knock if it a bad gass issue. If you decide to dump the gass, just remove the fuel line from the rail, put a hose on it, and let pump drain the tank. Oh one more thing, if it is bad gas, don't get on you, it will likely stink like all hell and may even make you want barf up lunch. Been there done that, unfortunately with an MR2 that had been sitting for a maybe four years.
This came up at one of my sports car club meetings. One member is retired from Exxon Oil. Gas years ago lasted quite a while. Due to new formulas and additives, he said it starts breaking down in a matter of months. He has quite a few collector cars and he wont keep over a few gallons in each so he can drive it out every so often and put a few back in. Sta Bil will help.
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01:13 PM
Fastback 86 Member
Posts: 7849 From: Los Angeles, CA Registered: Sep 2003
If your Fiero has been sitting for a long period and the tank was not full, condensastion will form inside the tank. the less gas, the more condensation. Over the winter months this could build up enough to cause problems on a car that hasn't run in a while. Might want to change the spark plugs too. Ed
Don't add anything... run the tank down low and fill it with fresh gas. Fuels have a number of things that change with age. Adding octane booster or anything else is a waste of time and money. A tank or two of premium gas might be a good idea. Chevron or Texaco if you can get it. If you can't get those buy a bottle of Techron at any parts store and follow the directions on it. The Techron is to help clean out the engine, not raise octane. Unles the engine is really bad off that stuff should help.
The engine will likely still knock after that no matter what gas you use. You may also find that the knock is a function of what time of year it is... Mine does it when the area changes from summer to winter blend each spring and fall.
There is a known issue with 87 and some later DIS L4 that causes it. Assuming there are no other fuel system or mechanical problems... There is a PROM update for the ECM that is supposed to prevent it. The PROM numbers are in my cave in one of the L4 articles. (The DIS ignition one) There is also a GM TSB on it.
I have not tried the updated PROM in my car yet. If you change the PROM be careful or you can damage the ECM.
You may also need a sensor or two. I would replace the MAT sensor on any 87+UP DIS 2.5l. Replacing the O2 sensor is a good idea on any used car.
------------------ The only thing George Orwell got wrong was the year...
Well, iI ran what was left out of the tank to almost fumes. i then put in a full tank of premium and added a bottle of fuel system cleaner.
I'll be damed if the knocking did not stop almost imediately!
On a side note; wow! 3 months?!? and it starts to go bad? i can only imagine that in California, where i live, that it is 3 months or less since they put in more junk in the gas here than in other states, amazing.
I am going to have to pay more attention to the gas in the cars i have sitting around in the future.
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08:17 PM
Fastback 86 Member
Posts: 7849 From: Los Angeles, CA Registered: Sep 2003
Well, iI ran what was left out of the tank to almost fumes. i then put in a full tank of premium and added a bottle of fuel system cleaner.
I'll be damed if the knocking did not stop almost imediately!
On a side note; wow! 3 months?!? and it starts to go bad? i can only imagine that in California, where i live, that it is 3 months or less since they put in more junk in the gas here than in other states, amazing.
I am going to have to pay more attention to the gas in the cars i have sitting around in the future.
You're out here in the crazy state too? Very cool, what part? Think you can make it to the Rally Through the Valley April 22 in San Juan Bautista?
I bought an 88 ElDorado that a tree fell on and was left sitting for several years. When I put a hot battery in it, beat on the starter a few times and finally got it to turn over, it fired right up. So I took off in it and it seemed to run pretty good (other than the rotten tires, no windows and no brakes!)
im southern CA, seems like everything Fiero oriented is mid ca or northern, southern ca is dead for Fiero stuff
What about West Coast Fiero over in Marina Del Rey? We don't have any shops like that up here. Theres a club in that area by the same name, as well as Fieros of San Diego and Fieros of Santa Barbara. They just had the Desert Run out to Palm Springs last month.
