buick misfiring problem

[agairob]

This has been ongoing problem for over 1 year now. I have a Buick century ’98 the engine rattles at idle while at gear, especially when brake is realized and car starts to inch forward with no gas applied. Sometimes it gets so bad that it only fires on 5 cylinders, but it is not consistent. I had someone replaced 5-th and 6-th injector and still the problem exists. It is driving me nuts! Avery time I take it to the shop they keep on telling me that it is a injector problem. Because that problem has been not solved for such a long time, I have noticed lately that it does gets worst in summer time and than almost disappear in winter when air temperature is low. I wonder now if that mite be pointing towards different problem than injectors. I also have replaced fuel pressure valve, just for the hack of it. Please halp!!!

[The Real Bingo]

Well when you mention how it differs in temperature change it makes me think its some kind of air/fuel mixture problem. The computer may be messed up and have it running too rich, so in the summer, when the air isnt as dense, there is too much fuel and not enough air to get the most effecient combustion. When the weather is cool and the air is dense, the richness evens out, since the more air the engine takes in, the more gas it needs. Probably a computer problem, if thats what in fact is wrong.

[Bovon]

It can also be burned valves, bad timing chain/belt, fuel injector pump...even cracked heads.

About 8 to 10 ounces of automatic transmission fluid in the gas tank every fill up for a few hundred miles will clean and keep clean the injectors.

Originally posted by Bovon
About 8 to 10 ounces of automatic transmission fluid in the gas tank every fill up for a few hundred miles will clean and keep clean the injectors.

That's a new one!

[Gomer]

give these forums a shot maybe as well
http://forum.doityourself.com/forumd...p?s=&forumid=2

welcome to Techimo BTW =)

[pickel]

An intermittent crank sensor could be the culprit. My friend had an Oldsmoblie with the same symthomns. Have you checked the ignition timing ???? Might be a little to far advanced. Check ALL your connections and vacumn hoses.

[truckpuller]

Heres just a few more things to check if it seems to be temp sensetive possiblity of coolant tempature sensor oxygen sensor or possibly spark plug wires also maybe coil pack since there is no distribuator . Also how many miles on vehicle . Have you changed fuel filter? May need to take vehicle to a repair shop that has a scanner and scan the computer for proper data of outputs and inputs of sensors and or controling devices .
Hope that this may help you

[Bovon]

Originally posted by Whir



That's a new one!

I bought a new Toyota diesel pickup in 1981.

I would get about 28 to 30 MPG from new..I thought that was a bit low mileage according to others I knew that had small diesel cars/trucks...I had it back in the Toyota place several times.. they assured me that was good mileage for that truck/engine

In 1983 and 130?? K miles later, the mileage had dropped off to about 25 MPG 'on the highway'.. Took it in to a Toyota dealership in Miami, and the word was.. I needed all new fuel injectors... at something like $50 each?..I can't remember the price..maybe that was installed...anyway, I didn't have the cash for that much, and it was running ok..so, I left.

Later that week, I was in the RR diesel shops in Hialeah Fla. (a suburb of Miami). During some chit-chat with the master mechanic, I mentioned what was going on with my PU, and the deal about needing new injectors. The mechanic told me to put about 1 "coke" bottle of automatic transmission fluid in the fuel for each fill up for about 1000 to 1500 miles, then put a bottle full in there about every third fill up.

In less than a month, the fuel mileage had increased to between 40 and 45 miles per gallon.

Those same fuel injectors were still in the engine when I sold it in `88..still getting 40 MPG.

Seems that the automatic transmission fluid is a very high detergent lubricant that doesn't burn that much, but cleans the injectors, valve stems, and other parts of the combustion area of the engine.

Wow. I'd be sort of afraid to try that in a gasoline engine though...

[Bovon]

Originally posted by Whir
Wow. I'd be sort of afraid to try that in a gasoline engine though...

Why?... I have used the fluid in gasoline engines since then...there is little difference in the design and construction of a diesel engine and a gas burner...just some compression ratio and timing is the basic difference. Back when gasoline shot up so high in the 70s, people flocked to diesel engines in autos... GM (for one) converted thousands of gasoline type engines to use diesel fuel. They didn't perform that well..but satisfied the customers demand for fast deployment of diesel autos in the US. (Diesel fuel was about 50 cents per gallon, and gasoline shot up to around $180/$200 per gallon)...when you could find some...before the oil cartel cut us almost off of ANY oil...gasoline was around 60 to 75 cents per gallon.

BTW...there is a lesson here for those of you born in or after the 70s, and harp on the US warring with the oil cartel countries..calling it a war for oil. I know for sure..from past experience..the countries that supply us with oil can shut us down...over night. This is one of the reasons we (1) do not go after our own oil reserves and (2) why we are buying a surplus of oil to store in underground salt caverns.

True diesel engine design is much heaver duty than its gasoline counterpart. I had this demonstrated to me by a mechanic in a shop once, when he asked me to pick up two crankshafts nearby..one was for a diesel and the other was for a gasoline engine..both engines were compatible in size and power duty levels (i.e., 8 cyl, V-8 GM engines). The crank from the diesel was probably 1/3rd again as heavy as the gasoline engine crank.