RPM's spiking
 

I recently bought a 2000 Durango. It has the 4.7 engine with 104,000 miles. I have had 2 problems occured in the last 2 weeks. First the trans felt like it was starting out in third gear. Would drop into first if I pulled it down into first manually and then shifted it into drive. After shutting it off and starting it later, it works fine. Took it in and they couldn't find any codes with the scanner and the trans shifts fine.
Then this weekend the RPM's started spiking when idling occasionally, between 500-700 rpm, and when on the highway I could see them spiking between 100-300 with the cruise on. Any ideas? Thanks in advance.

Jack

is the a/c and defrosters both turned off?? the a/c compressor (which runs with the defrosters) would cause that kind of spike at idle, of course that would but up for a while then down and you should be able to hear it cycling with the spikes (unless you need a recharge than it would be constantly trying to engage the compressor)

Erratic idle is a TPS and it might be your trans issue as well. Replace the TPS and tune it in. Tuning it give max performance but not needed.


Throttle Body

Cleaning your Throttle Body on a 5.9L and 5.2L and IAC sensor
https://dodgeforum.com/forum/1st-gen-...ttle-body.html

4.7L Throttle Body cleaning and IAC:
http://www.craigcentral.com/durango/tb.pdf

TPS (Throttle Position Sensor) Replacement for RPM surging and/or engine idle issues.
https://dodgeforum.com/m_53303/tm.htm
https://dodgeforum.com/m_1059612/...tm.htm#1059612

Throttle Position Sensor Modification for increased Performance. Scroll to TPS Modification:
http://bionicdodge.com/Download/Spee...d%20Tricks.pdf

I have never had avehicle spike that high for the AC at idle. I did shut the defrosters off when I noticed the spiking start while I had the cruise on though.

Jack

Thanks. I just got some info from a Dodge mechanic and he said the same thing. Change the TPS. Said it could have caused the trans issue and it won't throw a code either. Looks like I may be spending some time here looking for info on the Durango.

Jack

i have never noticed the spike at cruise, but at idle it is not uncommon to spike as high as 700 rpm (not that its easy to notice that kind of jump very precisly since the tach is only marked in 500 rpm increments, mine can hit the 1/2 way point btwn 500 and 1k w/ the a/c on at idle)

the tps is a very likely culprit (i forgot about it, my bad) but my idea is still cheaper to check the stupid stuff off first

The erratic idle with a TPS usually runs in the 300 RPM surging range as the torque management is engaged and disengaged (lock up and unlock of the torque converter). This is REALLY noticable during cruise control enabled.

Also while your at it, clean Throttle Body clean inculding IAC. This is why I included all the links to do it.

I had the exact the same thing with my 2000 4.7 durango. change your tps. If it gets bad enough it will actually stop the tranny from shifting out of first gear. That's what happened to me. Thought my tranny was shot. Nope, it was the tps. now all is good with it. Hope this helps.

I changed the TPS and the Durango is running great. I will clean the throttle body and IAC sensor when time permits. Had it out Sunday for about a 250 mile run and she ran great and got close to 18 MPG. Thanks to everyone for the help. The trans has not acted up since the first time so I am hoping that was due to the TPS also.

Jack

Remember to reset your PCM anytime you replace any sensors or after messing with intake or even spark plugs you should do a reset: Engine Code Index (Check Engine Light?) Look in here at the top of the first post.

We're Dodge mechanics as well......LOL