Hi, I'm looking for some help diagnosing my Dodge Dakota, when the weather is warm >28C the car starts revving and is very unstable for the first 8-10km dropping to 500rpm revving to2500 rpm, engine temperature indicator is normal, anyone any ideas?

 

Welcome to the forum.

Do you have any codes?

I'll move this to the 3rd gen forum.

 

First suspects that come to mind would be MAP and IAC sensors.
Are there any fault codes? Is this a first start up thing for the day, meaning once it does it the first 8-10km is that it for the day, or does it continue throughout the day?
A good Throttle Body cleaning could be in order.

 

I'm not 100% certain, but I believe in a previous thread describing similar symptoms, the problem turned out to be a faulty Throttle Position Sensor.

If you replace any sensors, make sure to use only OEM...The engines in these trucks don't seem to like aftermarket ones.

**Edit: Another thread from yesterday here with similar surging symptoms (and shifting issues also as the problem got worse) seems to point to your solution being a replacement *OEM* Throttle Position Sensor.

 

Hi, Thanks for the quick reply's

I wasn't sure about third or second generation, I know there are more recent models than mine so guessed second. Thanks for the correction.

There have been no error codes until today.

I have changed the Throttle Position Sensor and the neighburing air temperature sensor
and the Idle air control valve before without result.

Today I unmounted the airbox in front of the throttle body and tried to clean the throttle body a bit, the throttle valve was quite clean to start with but the back of the throttle body is not,
I don't stock the liquid to do that properly so used some dry cloth,

I noticed I also could replace my air filter, it is not very dirty but gave it a vacuum for the time being.

Then I took it for a test drive and there is a small difference but the problem is not fixed yet, I must add it is 8C less hot than when I posted my previous post and that does seem to make a difference.

Today it did pop-up error code P0507 twice but this only indicates the RPM is to High in Idle
weird because it has been higher previously and did not generate any error codes.

my next step would be to order some throttle body cleaner and a new air filter, any advice on those? or maybe other things to try?

Many thanks!
Best regards
Kris

 

I should also add, today during the test drive the revving als went away after more or less 10km, it does not come back when the car stops for a short time but it would after a few hours

 

P0507-IDLE SPEED PERFORMANCE HIGHER THAN EXCEPTED

Theory of Operation
The objective of the Idle “Speed Rationality is to monitor the ability to achieve and maintain a steady idle condition.
The monitor will judge the functionality of the idle speed control system by monitoring RPM during idle. If RPM does not come within a calibrated deadband of target idle speed, a timer is started. If the timer reaches its maximum threshold without any sign of the RPM trending towards control, a soft failure is generated.

² When Monitored:
With the engine running at idle, MAF <250 mg/tdc, air temp >-17.8°C (0°F) and <-7°C (19.4°F) enable after coolant temp >70°C (158°F) or air temp >-7°C (19.4°F), coolant temp >-7°C (19.4°F) <130°C (266°F), canister purge <100% duty cycle, and no VSS, MAF/MAP, ECT, TPS, ETC, CRK Sensor DTCs nor any fuel system or injector DTCs.

² Set Condition:
Engine speed is 200 RPM or more above idle speed for 7 seconds. Two Trip Fault. Three good trips to turn off the MIL.

Possible Causes

• AIR INDUCTION SYSTEM
• VACUUM LEAKS
• THROTTLE BODY
• PCM

 

Anyone any experience with this package?
Would this be any good?

http://www.3m.com/3M/en_US/company-u...1501528&rt=rud

 

Hi
I finally got my new cooling system water temperature sensor and installed it today
What a difference I think this fixed it

Many thanks to you all for the advice

 

Hi Folks, turns out I made an improvement on the issue but did not solve it, does anyone know the life time expectancy of parts like the water cooling pump and radiator? could it be that my engine is overheating? (12 years, 85.000miles) many thanks