Hi,

First post. Currently a 1999 Trooper owner-original owner. Owned a 1996 Rodeo and a 1993 Trooper before this one.

Automatic 4WD, 3.5L 6 Cylinder

My question: I''ve had a loud banging/thumping noise for the better part of 2 months intermittently coming from (what seems like) my undercarriage whenever I accelerate. It''s a loud, noticeable (both audibly and physically feeling the bang in your seat/legs) noise that everyone in the car hears/feels.

It occurs as the engine is shifting from one gear to the next and the
RPM''s are moving upwards (i.e. the 10-20MPH acceleration, then 25-40
MPH, etc...). On the deceleration, it occurs when the MPH gets down to around 5-10 MPH and the engine is downshifting (i.e. approaching a stop sign/red light).

When it happens, it may be there at 2pm, I shut the car off when I make a quick (5-10 minute) stop at the store, restart it and the bang/thump is gone. Or, it will be there at 6am when I leave for work and then again at 6pm as I leave work.

Is this a Tranny problem? Rear end? Engine mount? As I said it''s intermittent. I get no warning lights on the dash whenever this occurs.

I brought it to a mechanic, but of course they said that it wasn''t doing it when I brought it inand it wasn''t. They told me to bring it back when it happens againbut I haven''t done that only because it seems to happen in the AM when I''m leaving for workand I don''t have the time to stop...or at night when I''m on the way homeand
they aren''t open then.

Any info would be appreciated

Thanks!

check your exhaust hangers.bad or broken hangerswill cause the pipes to"bang" againstframe parts underacceleration.





Christian-

Thanks for the response. In the last few weeks the problem has come and go...but now i notice a "chirp" from the tires when I hear/feel the bang as I''m accelerating...so I''m thinking it''s not the exhaust. It''s got to be something to do with the drivetrain/tranny. I brought it back in to the shop I go to and the mechanic says unless he hears/feels it and since there are NO codes that come up when he hooks it up to the computer, there''s nothing he can do except to start replacing things he thinks it could be. There''s no Isuzu dealership within about a 50 mile radius of my home/work so it''ll be a chore to get it to an Isuzu dealer and have them look into it.

I was thinking of bringing it to a Aamco/Gibraltar tranny shop to see if they can check the tranny but haven''t gotten to that point yet.

well I would still look at the exauhst for the banging, but I do not know much about the isuzu automatic transmision.I can tell you that if the tires "chirp" when it is shifting gearsit will be the trany. the trouble is going to be finding out what is causing it to do that. in the old days of non electronic auto trany''s it would be the modulator, or a shift valve. but now with all the censors and electronics it could be any number of things.





Christian-