Mechanics

WHY IS MY UTE SHUDDERING WHEN I SLOW DOWN.

2001 Holden Rodeo • 320,000 miles

(i brought this recently so have no previous records of service).

I have a 2wd holden rodeo ute which shudders and shakes when coming to a stop, misses when accelerating on highway and revs out to 3000rpm before changing from first to second gear. It is a auto 4 speed 3.2l v6.
when idling in gear I can hear the revs slow right down and what could be described as a timed droning noise (knock), almost like a piston ring as catching.
Its that bad I put in in nuetral just so I dont have to listen to it. (Its my only transport so I pray it doesnt catch on fire of anything lol) when cold it I dont let it warm right up the transmision makes a PING metal niose as I put it in reverse. I am only getting about 5km/litre but thst might be normal. I havent had it running great to do a comparison.

Now for the kicker. If I put it in overdrive NONE of these syptoms exist it drives absolutely PERFECT!

I have changed the oil, air and fuel filter. Changed plugs and engine oil and the trans fluid was mint with it oozing out the level plug and being bright red.

so. What it it? Transmission, diff, pitston rings or a sensor, switch?

I have had the transmission dash light come up twice on long drives, however it removes itself the next time I start the car.

i look forward to you response.
Avatar
RATTA
June 19, 2012.



Just thought id elaborate on the miss, either short shifts and under low idle struggles along or it rockets ahead ringing out at nearly 4000rpm, and when I say ringing I mean it, its like only half the engine is working. Other thing I forgot to mention is that the LHS sparl plug closest to the firewall had oil on the tip and thread. This is in addition to the knock/droning sound, shaking at low speed (usually coming to a stop) and auto trans makig metalnclunki when engaging gear (usually reverse).

Tiny
RATTA
Jun 19, 2012.
It sounds like you have a few issues.
The shuddering is either grooved brake rotors or loose axles or possibly even misfiring of the engine. To an extent. Less likely but possible is that the wheel bearing is bad.
The fact that overdirve makes everyting better makes me think you have a bad computer and that it needs replacement. It sounds like you have some other engine and transmission problems that are mechanically related as well.

The computer might/mightve been the cuase. I disconnected the battery for 10 mins and took it for a 40min drive across town without any of the major issues returning.

Even the shuddering disappeared, so its definately not the rotors.

The only thing thats not right is the idle, the revs bounce between 500 - 1500rpm when engaged in gear with the brake aplied and when in park. However in nuetral it returns steady idle around the 900 mark. What could this be?

Tiny
RATTA
Jun 25, 2012.
It is most likely the Idle Air Control Valve, IACV. It is located on the intake manifold near the throttle body. It is a solenoid that changes ports to keep idle steady with changes in temp and engine load and to keep it at its set idle which is usually around 800 RPM. Sometimes the ports can get clogged and need to be cleaned, but that usually causes stalling, so you need to replace the IACV.

Cool il replace the IACV next pay. In the meantime the computer has picked up its old habits, with touchy acceleration on highways and it randomly revs out on not all cylinders. Im gonna clean the plugs this time then reset it and see how long that lasts. Would you recommend just ditching the old computer all together and buying a new one or could it still be something else instructing it to perform like this.

Tiny
RATTA
Jun 27, 2012.
As far as the computer goes you can find places that remanufacture or repair them. If you use the search engine on this site it will give you some ads on the page that will have ECU rebuilders near you and they will be reputable.