RPR Posted June 24, 2019 Share Posted June 24, 2019 Engine is a V8 3.5 block with a 3.9 top end and 14 CUX. Stepper motor has less than 350 miles on it. On start up, gets an immediate surge to @ 1500 rpm, then drops down in three "steps" to steady idle at 700 rpm. Takes a few seconds. Idles fine. When driving, it wants to stay in high revs as I downshift, such that after letting off throttle and rolling up to a traffic light, it will remain at 1500 - 1700 revs until braking starts to cause a stall, or after what seems an unduly long amount of time, it will drop to idle. Checked throttle cable and assembly - no sticking and drops cleanly to rest. So, thoughts? Vacuum leak? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted June 24, 2019 Share Posted June 24, 2019 Have you set base idle speed? Also, this can happen when MAF is unplugged/dead. Quote Link to comment Share on other sites More sharing options...
RPR Posted June 24, 2019 Author Share Posted June 24, 2019 Think a reset? Gunge on the MAF? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted June 24, 2019 Share Posted June 24, 2019 Ummm, and another thought, any vacuum leak can do it too, or badly connected breathers. Setting base idle: https://www.roverparts.com/TechTips/Base_idle_setting_procedure.cfm Quote Link to comment Share on other sites More sharing options...
RPR Posted June 24, 2019 Author Share Posted June 24, 2019 Will reset ce soir and report back. Quote Link to comment Share on other sites More sharing options...
RPR Posted June 25, 2019 Author Share Posted June 25, 2019 (edited) Seems better 😎 Thanks for the advice. Edited June 25, 2019 by RPR Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 25, 2019 Share Posted June 25, 2019 Isn't this (sometimes) something to do with the speedo signal to the ECU to stop it stalling as you roll up to the traffic lights? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted June 25, 2019 Share Posted June 25, 2019 Yes, can also be that! Quote Link to comment Share on other sites More sharing options...
RPR Posted June 25, 2019 Author Share Posted June 25, 2019 Doubtful. The speedo hasn't been connected to anything for at least 12 years... Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted June 26, 2019 Share Posted June 26, 2019 The ecu needs the signal to know when you are coming to a halt. Quote Link to comment Share on other sites More sharing options...
Carloz Posted June 27, 2019 Share Posted June 27, 2019 On 6/26/2019 at 6:58 AM, Bowie69 said: The ecu needs the signal to know when you are coming to a halt. Should it be connected? Never known a speedo signal is needed on the 14CUX? 🤔 Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted June 27, 2019 Share Posted June 27, 2019 Some get away without, others find a huge improvement, go figure. Quote Link to comment Share on other sites More sharing options...
RPR Posted July 30, 2019 Author Share Posted July 30, 2019 So, the reset wasn’t a long term solution. I replaced the stepper motor and gave the housing a good cleaning. After thrashing the carp out of it at the LR National Rally this weekend, it has settled down at 700 rpm. Getting up Imogene Pass to 13,000 feet was a thrash! The county had opened the Ouray side, plowing through some 10ft drifts earlier in the week. But the Telluride side wasn’t open because a 300 yard section just shy of the top was wiped out by avalanche! The first pics are of Ophir Pass, a mere 12,000 ft, the last one is Imogene at 13,000. 2 Quote Link to comment Share on other sites More sharing options...
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