1990 Buick Century 3.3 Won't Idle

[bell345]

The engine will not idle unless you disconnect the mass airflow sensor. Replaced sensor (MAS) and car does the same. No change. No error codes stored. With mass airflow sensor disconnected, the car starts up jerking from an idle and then is ok. The minute you connect the mass airflow sensor the engine dies. What else could it be? It does give an error code when the MAS is disconnected. Cannot find any vacuum leak. Anybody have this problem? Also it doesn't jerk from the idle when the car is cold. I did get the second MAS fron a junk yard. You can feel the engine idle "hunting" when driving down the road but it dosen;t stall with MAS disconnected.

[Brandon Riddle]

I've got a very similar problem with my 3.3 Century. I retreived a code 34 which is a MAP sensor. I called around a few parts stores and finally a Buick dealer. The dealer informed me that there is no MAP sensor on my car! Anyway I'm back to the drawing board to cure this problem. Any info you have would be much appreciated.

[xx69rynoxx]

On the throttle body right to the left of where the intake tube comes in is a black box with the plug into it. take that off and look at the back of it. it has 2 resistors on it which measure the air temperature and change the air/fuel ratio to comepensate for the air coming in. at hotter temperatures there is less resistance so the engine delivers less fuel. when the temp is lower the resistance is higher and the engine delivers more fuel as a result. check to make sure that these 2 resisters are intact and that the plug that plugs into the sensor is plugged in completely and directly.after doing this, it may be helpful to reset you ECU by disconnecting the battery for about 15 minutes then letting the car idle for about 10 to relearn your setup. check vaccum tubes as well.

[Brandon Riddle]

Originally Posted by Brandon Riddle

I've got a very similar problem with my 3.3 Century. I retreived a code 34 which is a MAP sensor. I called around a few parts stores and finally a Buick dealer. The dealer informed me that there is no MAP sensor on my car! Anyway I'm back to the drawing board to cure this problem. Any info you have would be much appreciated.

After going over every possibility I focused in on a problem with the fuel injectors. They had power and I checked the groud (located on the upper mounting bolts of the transaxle. Finally I picked up a set from U-pull it and slapped them on. Instant sucess! The car starts and runs perfect. No more surging and dieing out. I came across a technical service bulleitin which stated that the chemicals in fuel injector cleaners deteriorate the insulation inside the injector coils which in time creates a short. The TSB also stated that these injectors are designed to be "self-cleaning" and do not require fuel injector cleaner. So if youv'e got a no start or surging problem thats seems to be a mystery, check out the injectors. I was baffled because all 6 went out almost simultaneously, causing a no-start problem.

[xx69rynoxx]

so ya just got 6 new injectors? how much did that run ya? cuz im idling kinda rough and its a lil shaky around 75 mph for me im thinkin im havin incomplete combustion in a cylinder because of fuel drip...and have u looked at prices on new ones? please let me know...thanks

[Brandon Riddle]

The u-pull-it injectors were @ $70 for all six. I think that new ones will run about $50-60 a peice. I think I must have got really lucky with the set I picked up because it made a huge difference. Good luck!

[bell345]

I started this thread. The problem turned out to be a faulty fuel pump that was partially working, There was not enough pressure in the fuel system. The MAF was fine. Fuel rail pressure should be as high as 50 psi, mine was 12. Replaced fuel pump. Car runs great.

[michael wittig]

Originally Posted by Brandon Riddle

I've got a very similar problem with my 3.3 Century. I retreived a code 34 which is a MAP sensor. I called around a few parts stores and finally a Buick dealer. The dealer informed me that there is no MAP sensor on my car! Anyway I'm back to the drawing board to cure this problem. Any info you have would be much appreciated.

i have 90 century,got a code 34 also.
dealer said he had none in stock.
i go to another place and they give me one.
cant find out wfere to put it.

[jibbijib]

There is no map sensor on the 3.3 motor. I have a Haynes manual, and no where it states that there is a map sensor. Hope that helps. that other place ripped you off. check your o2 sensor. Could be that. Fuel pump maybe, vaccuum lines. all that fun stuff. make sure you got the right book, and right section for the code reader as well.