[Krista]

jolts when coming to a stop

i have a 1999 ford taurus, and ever since i bought it, it would jolt when i would slow down and come to a stop. my boyfriends instructor told him it was the mass air flow sensor, so thats what were thinking it is.. soo im trying to find if anyone has had that problem. and we have changed the iac but it didnt fix the problem..soo please help me..

 

[01SE]

I don't see anything wrong with high idle on a cold engine, as Vulcan in my '01 Bull does the same. Regarding jolting, I'm not so sure.

 

[901-Memphis]

The IAC is usually the culprit, but the next place to start could be cleaning the MAF with MAF cleaner. Pretty easy to do just take airbox open and spray the MAF a little. Only use Mass Air Flow quick dry cleaner as anything else could leave a residue and cause the same issue.

Also is all the other maintenance up to date?

Air Filter, Fuel Filter, Plugs/Wires?

I had a problem with my engine dying until i finally cleaned the IAC and put new plugs and wires on it. A really dirty air filter could cause these problems.

The jolting is the issue i imagine can you describe it a bit better? Its not unusual for the engine to start at around 2000 RPM and slowly work its way down to around 1k or lower within 60 seconds or so.... normal starting for my engine all its life.

 

[Krista]

thing that have been done

cleaned mass air flow with proper cleaner
new plugs
new plug wires
new IAC
almost new air cleaner

the jolting has been happeneing since i started driving the car about a year ago. its not a violent jolt it just acts as the IAC is malfunctioning, it jolts about 3 times then stops. we changed the IAC and it didnt help the situation at all. then about 2 months ago it started getting a rough idle when started, the rough idle lasts for about 30 seconds so we are going to change the fuel filter since we dont know when it was last changed. the jolting feels like its kicking in and out of gear when you are comming to a stop, like i said we changed the IAC and it did the same. can a bad mass air flow sensor do this? I know the mass air flow sensor meters the incomming air, so my theory is the mass air flow is telling the ecu it has alot of air comming into the engine so its telling the injectors to give it more fuel causing the jolt. if that makes sence to you guys.

 

[Krista]

SOoo....Any thoughts?!?!

 

[BigPip]

I would search for a possible vacuum leak. Easy to do with a can of Carb Cleaner. start spraying all the vacuum hoses and don't forget to go around the brake booster.

 

[jw89sho]

Fixed a car with high idle and jolting downshifts just today... I found a vacuum leak from a hose that was laying against a pulley, and a fitting on the air hose disconnected, apparently from an air filter change with poor workmanship. Fixed those issues and both problems were resolved.

 

[Krista]

okay thanks! i will have my boyfriend look for a vacuum leak this weekend!

 

[Krista]

well we checked everywhere for a vacuum leak and could not find anything...does anyone else have any thoughts of what it could be..