2004 Buick LeSabre Drivability Issues

christmasbabe

After inheriting the 2004 Buick LeSabre (99,730 miles). I noticed a bit of sluggishness, low gas mileage (15 mpg city) and a bit of a rough idle. So I decided to get a tune up. The mechanic changed plugs and wires and done an oil change. (New AC Delco plugs and wires). The next day I noticed a huge change in the cars function, BUT NOT FOR THE BETTER! I drove my daughter to school. Upon my drive home I felt a lag. Next I felt the car begin to stutter, shimmy then surge. This happened approx 4-5 times as I tried to drive home. I prayed I'd make it home! The car never stalled out and no check engine light shown. Next I decided to look for anything loose, worn out or odd under the hood.. Nothing looked odd, but I did locate a couple loose connections. I then secured them. Next day I took the car for a 5 mile drive. The car ran fine. The next day I drove approx 2 miles. I thought I felt what seemed like a delay in the transmission shifting. I stopped at the store for a couple things. Upon my trip home (approx 1/4 mile after leaving store) the car began to stutter, shimmy and then surge (engine temp was still warm). This behavior continued on and off all the way home. *Car never stalled out and no check engine light ever appeared at this point. Next day I decided to let the car idle to see if I could recreate the issue. Once the engine was fully warmed the car once again started to shimmy, stutter and then surge. The car then returned to normal (well the normal slightly rough idle). After approx 5 minutes the car again began to shimmy, stutter and then surge, but this time it stalled out. I decided at this point to leave well enough alone. *No check engine light has come on yet! I took it back to the mechanic.. The mechanic has supposedly checked the spark plugs and wires. They showed no issues. He also supposedly cleaned the MAF. He thinks it could be the MAF or Ignition control module.However, he is totally unsure due no check engine light. He is telling me it's fine to drive (The surging SCARES ME!) The mechanic is hoping I continue to drive the car in hopes the check engine light will come on. As I mentioned I feel it's too unsafe! I am confused why all of this started after a tune. I am also confused as to why the car only carries on when fully warmed. PLEASE point me in the correct direction as to what could be wrong with this car!?!? * Car normal idle is at 1000 rpm. During surge jumps to 1500. After surge with no stall idle dropped to approx 750. Thank you!

imidazol97

Check the rubber hoses on the engine that have vacuum. Take off the plastic gray cover on top. On the back of the engine there may be a 1/4 inch rubber tube coming out of the vacuum source on the intake manifold next to the large rubber tube that goes to the brake booster. Check both for hardness and cracking.

But the higher suspect is on the front of the engine. At the right side is a block that has two small vacuum tubes coming off. Part of this may be hard nylon which connects into rubber. One tube goes along the front of the intake to the passenger side and does a "U" and comes back to a purge valve. Check for cracks or rotted areas that are letting in air.

Your idle is high. I believe my 2003 idled at 750. I suspect a device that connects to the diagnostic port under the dash that shows the correction applied for mixture will be away from zero because it's compensating for extra air coming in. Then when engine is warm, it's not able to adjust enough for the air.

If you don't find any vacuum leaks in hoses, try spraying carburetor cleaner around the edge of the manifold and the rubber hoses and connections with the engine idling. A few folks had intake manifolds that warped and loosened on one side when warm vs cold allowing extra air in. I the engine sucks in the carburetor spray which is flammable it will change idle sound/speed due to the disruption in the air mixture balance.

Another worse case to think about is the metal lower intake gaskets where it meets the heads seeping. Does the car lose any coolant. You need to fill to a set mark with engine dead cold. Then drive and watch over weeks and see if it loses coolant by checking the level with engine morning cold sitting in same level spot. The gaskets deteriorate and need tto be replaced. Coolant in the oil can be detected with an oil analysis of the used oil. In higher amounts, the coolant might show as milk shake appearance to the oil on the dipstick after running the engine. The coolant could be affecting the mixture in the cylinder. When engine is hot, the coolant is under pressure pushing some through the gasket seal. When engine is cold, no pressure. You could try warming up engine with cap loosened to first click so any pressure building is vented into the reservoir tank. If it runs well with no pressure, that narrows your checking.

The double vacuum lines coming out are below the #2 and slightly left. One goes to the fuel pressure control and the other goes to a purge valve that turns on to pull air through the charcoal canister to recover the gas fumes it caught.

The leaking, if any, of coolant past the lower intake gaskets wouldn't have started JUST the day the plugs and wires were replaced. So that points more to either an improperly gapped plug, a damaged spark plug wire, the end of the wire on the plug not completely snapped on leaving a gap for the spark to jump, a bad ignition coil, or something on the engine like the rubber hoses disturbed working around them and they started leaking air where they were rotted or hardened and cracked now.

Another possibility is the wrong spark plug was put in. These engines are very susceptible to wrong plugs. They don't like off brands often used to save money. And they should have AC Delco Iridium plugs. AC Delco makes cheaper plugs such as platinum that used to be used in 3800s in the 90s and cheaper still. ACDELCO 41101 is the plug that came in the car. Check your receipt for the actual plug put in.

Check at rockauto.com and drill down through the menus to "ignition" where you'll find many various plugs but the Iridium plug is listed along with its 0.060 inch gap required. This is what came from the factory IIRC.

http://www.greatautohelp.com/sensor-location/3800.html

See items listed on webpage matching numbers.

TurboJeffy86

Awesome web reference! I'm a do it yourself fixer to go a amateur degree. My buick LeSabre is 20 years old but only 81K miles, minor issues are appearing regularly. Coolant replacement, purge solenoid. Front end wheel vibration when turning. So I'm always seeking better help than just limited YouTube cheesy videos.