Good Evening MCF,
So, I'm driving down the road, I take my foot off the gas, RPMs drop to about 1100, I hit a small bumper, RPMs jump to about 1600 and I feel the car serge forward. Then the RPMs drift back down to 1100 unless I hit another bump. This is a totally new Mystery! I'm thinking it is either a Vacuum leak from a hose that bounces with the car, or a connector that is loose and bouncing with the bump. Either way, although it's not a terminal disjunction, it is a Pain in the Lower Extremities! So what do you guys think? Electrical or Vacuum?
I'm going to be doing a good deal of work on her this w/e. So if I can be pointed in a direction it would Really help. Thanks guys!

 

Sadly, at this hour, I'm not sure...

 

I'm gonna say, that your issue is going to be beyond the help of on line. It's probably going to be one of those issues that'll take you A LOT of hair pulling troubleshooting....or A LOT of descriptive posts to narrow it down.

 

JC:

Heres a guess,
I'm thinking possibly a bad wire at the TPS (Throttle Position Sensor) Or possibly a issue with the TPS itself? That is a strange thing to have happen.... Maybe.... The throttle cable is sticking, frayed, or throttle plate is loose on the throttle rod. (Its what the plate is screwed to)... Maybe... you have a stretched out/broken return spring on the throttle body? How long has this been happening...Or is this something new/recent?

Anyway its somethings to consider...
Hope this helps!

 

Thanks guys. This problem just started last Thursday. I've got at least 1code. My bud from work is going to bring in his Mac scanner tomorrow so I can see what the PCM has to say. In the mean time I am going to do the Wiggle Test and theStarter fluid test. I'm not feeling to confident on this one. I know sometimes the great minds of MCF have to be Stumped, just wish it wasn't Me doing the stumping.
! Will Keep you informed of what I find!

 

Yah, a scan tool is "almost" always a time saver as far as narrowing down the issue...especially if your friend's MAC tool is a 2-way (he can command sensors on/off)...keep that friend around..lol.

 

So I think the Wiggle Test worked. I ran the car at lunch. Let it idle down, then grabbed the main harness and shook it. Sure enough, the idle kicked you. Sincerest thing I worked on was the TPS wiring that was the first place I looked. The connector wasnt seated right. So I unplugged and plugged it back and took her for a quick drive on a bumpy road. It seems like the problem is fixed. But I gotta see what she does on the 22 mile ride home?

 

JC:
Pls besure to let us know... If in fact it was the connector on the TPS..(Partially unplugged) Incase... someone else runs into the same issue!
Thanks for the Heads up!

 

I'm in the car now getting ready to go home. She is idling a lot smoother But I will post my findings!

 

Well it's running better But I think I mat have to swap out the TPS. Maybe the IAC too! We will see. Going out to make a run for a friend now.