Hey guys,

I have been a frequent lurker at the site, but I believe this is my first post. Wish it was under better circumstance, but hopefully you guys will be able to point me in the right direction.

I own a 2003 Rango 4.7 with 175K miles and daily driver. Lately, I have noticed a slight hesitation/vibration in the front end. Feels like a little bit of shuttering and loss of power at the time. This occurs when braking to a stop, and accelerating from a stop. It is also more noticeable when I am turning the steering wheel, such as accelerating and making a turn from a stop sign. Generally, anything over 10 MPH, I don't feel anything wrong. Also can feel the low idle a little in park and reverse. I initially thought it was an air intake or vacuum line issue, but I'm not sure if I have tunnel vision. Might be another system such as fuel filter/pump or something else.

There are no check engine lights on. I have occasionally had the slight EVAP leak code from time to time. Also, the tach doesn't register any fluctuation in the RMPs...even when I feel like the idle is low. It doesn't really dip below around 600 RPM.

What I have done so far:
-Started simple with replacing the air filter. The old one was still fine, but figured why not.
-Removed and cleaned the throttle body valve. It was fine but again, I figured what could it hurt.
-While I had the throttle body off, I replaced the throttle position sensor and thoroughly cleaned the idle air control valve and surrounding area. I thought for sure that cleaning the IAC was going to do the trick, because that sob was disgusting.
-I have checked some of the accessible vacuum lines visually and with the carb cleaner to no avail. Didn't want to go crazy chasing a phantom vacuum leak unless I had a better idea that it was one.

Performing the above seemed to help a little bit, but the issue remains. The PCM has been reset obviously after the above changes and I haven't driven much since, so it's likely the computer is relearning everything. Perhaps after a few days of driving, the computer will adjust itself and the idle will settle down.

If not, here are the next steps I am considering, probably in the order of least to most expensive:
-Crankshaft position sensor
-Camshaft position sensor
-MAP sensor
-Power steering pressure switch

Other possibilities I have considered are the fuel filter/pump - which I would rather not do because I would have to drop the tank. Maybe dirty fuel injectors? Would a fuel cleaner additive help? Could it be an issue with the transmission/torque converter? Transmission fluid looked clear and was full.

On a side note, I changed the brake pads all around and shocks in the front. My thinking was that since it was happening when braking, that maybe the pads were worn and rubbing metal to metal. Pads indeed were in bad shape, but new pads did not help the vibration. They needed to be done anyway, so it was time well spent. But really was, and still am, looking for the solution for the problem.

Any suggestions would be helpful.

Thanks,
Rob

 

500-600 is normal idle for the 4.7, and generally very smooth, if the vibration is only when moving then that points you towards parts that are moving only when the car is in motion (IMO). does the shuttering/vibration persist through 2nd gear? does it stop when the car shifts? is the trans fluid actually clear? it should be a pinkish/red color the wrong fluid causes all sorts of issues.

 

It's rather hard to explain I suppose. I understand that the truck is at normal RPMs when this occurs. I guess the vibration that is occurring is similar to the feeling of a low idle/hesitation. It is occurring as I reach a full stop and as I start from a full stop. I thought it could also be the brakes, so I replaced the pads (no difference). It's not happening when the truck is going say 10 MPH or higher. It's only within a couple MPH of a dead stop.

As far as the trans fluid, I didn't mean clear as in color. I meant clear as in free of debris. The fluid is pinkish red.

Thanks for the reply.

 

Thanks for the help guys. The truck seems to be running a little better after giving the PCM a little time to re-adjust. I'm gonna put more injector cleaner in there - maybe seafoam it - and see how that works out for me.

 

Did you ever confirm what caused this specific problem, it sounds exactly like the problem I have with '03, 4.7l dakota. Many of the sensors are new, purge pump, brake booster valve, have been changed in last few months - I've cleared the PCM, after having a remaining P0441 issue - my thoughts are a very slight vacuum leak that corrects itself after fuel/evap/carb system happens in the first two minutes, or so. Thanks for any direction.

 

Still looking for the cause unfortunately. I have cleaned the Throttle Body, replaced the TPS, replaced the IAC, replaced the air filter, replaced the spark plugs.

Next steps are MAF and looking for vacuum leaks.

No improvement so far.

 

good direction, I will do the same. Also will take another look at my TPS - its new, not doesn't guarantee it was not faulty. A quick google search wtih these same syptoms, and the direction I have gotten from forum members seem to have those three as teh likely culprits -- TPS, MAF, Vacuum leak.. Will address this weekend. Thanks.

 

Good luck. If you get it figured out, let me know.

 

I didn't pursue any of my three directions, and after 2 months it had gotten worse -- to the point of stalling. Went to our trusty mechanics, and they smoked it -- Faulty Leak Detection pump, and a minor hose leak near the purge valve. the problem has gone away, the codes are gone, (so far)-- its a little rough, but I am hopeful its just the PCM re-learning how to tune the mixtures, etc --it cost me $500 I was hoping to avoid, and figure out myself,but overall I am glad its fixed.