Cold start and warm up really high idle with mptune - Turbo Dodge Forums : Turbo Dodge Forum for Turbo Mopars, Shelbys, Dodge Daytona, Dodge SRT-4, Chrysler PT Cruiser, Omni and more!
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post #1 of 5 Old 08-22-2019, 08:25 AM Thread Starter
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Cold start and warm up really high idle with mptune

Ok looking for some help, The issues are. Cold starts (overnight or setting 8 hours at work) hit the key wait for fuel pump to prime. Then cranks and cranks then after about 4-5 seconds of cranking it starts to pop and cough to life then all is fine. Its starts just fine hot even setting for a few hours. No problems there. Has new accufab adjustable FPR and new areomotive stealth 340 pump. Also using E85. Once started it runs pretty good everywhere else. The 2nd problem is after I do some calibration changes (86 GLHS STG2 and the base cal with a 3 bar 1000cc injectors) the next morning it'll have the same cold start long cranking then starts. After about 30 seconds of running normal 1200 rpm itll jump to like 1800-2000 & stay there for a good 5-8 minutes then bounce down to normal idle 950 ish. Then go back to 1500-1600. And this morning it wouldn't come back down to idle till I shut the dam car off. Then restarted it. Then was normal. What the heck is going on? Some cals I've had jump up (cold) for a minute or so then drop down and be normal for then on. Thease last few have been ANNOYING longer high idle during warmup. Any help would be GREATLY appreciated! About ready to go MS system on this thing.
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post #2 of 5 Old 08-22-2019, 10:55 AM
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Re: Cold start and warm up really high idle with mptune

I know nothing about MP Tune, however, basics are basics.

Your long crank in the morning sounds like it may be a basic fuel pressure issue, rule out basics as being the problem before moving on to your tune.
Connect a fuel pressure gauge in the morning, turn the key on, does fuel pressure rise to specs and is it at specs cranking before the car starts?

As far as the idle, what is the controller seeing when the car is cold as far as Coolant Temp, Map, Throttle Position and how many AIS steps is it asking for?
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post #3 of 5 Old 08-22-2019, 11:29 AM Thread Starter
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Re: Cold start and warm up really high idle with mptune

I have base fuel psi set to 48 psi. I can cycle the key 3 times (really priming the system) no real difference. It will cycle the pump and bump it to where I have it set. I should go back a lil bit. It was just fine when on gasoline (pump 91 & h20/meth injection. This reared its head when going to E85. I scaled my 96lb injectors for 65lb injectors. It was pretty close requiring minimal changes to get it to run good when warm. Coolant temp is rite on par. Closed tps voltage is 1.07v idk about aic counts. Thing is it (once it starts) goes into a normal 1200 ish rpm fast idle. With afr's showing 14.6-15.1 then the idle will jump to like 1800 or so and just hang there for about 5-8 minutes.
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post #4 of 5 Old 08-23-2019, 08:28 AM
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Re: Cold start and warm up really high idle with mptune

As I already stated I know nothing about "Tunes", I can only help you with checking basics.
On a stock vehicle TPS closed throttle voltage needs to be below 1.00 volts, the closed throttle voltage is usually in the .50 - .70 range.
Above 1.00 volt the controller see's an open throttle and increases AIS counts/sets for decel assuming you will come off the throttle at some point, same as it does when you are cruising at 50 mph.

On a stock vehicle at closed throttle AIS counts will be in the 20 - 25 range with TPS voltage below 1.00 volts.

What is base idle set to?

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post #5 of 5 Old 08-23-2019, 11:08 AM Thread Starter
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Re: Cold start and warm up really high idle with mptune

Base idle rpm in mptune is set for 930 idle. And for the most part its rite on when idling normally. I did discover yesterday. My NEW accufab fuel psi regulator bleeds off fuel psi within a few minutes setting. I'm know that ain't helping the cold starts at all! Found the ball seat inside of it. It's not seating fully around it at all! I lapped it in to the ball. That helped but still drops slowly down. My stock style regulator slowly drops vaccum (when hooked up to a vac pump) is the reason I swapped on a new regulator to begin with. I'll adjust the tps down just below a volt and see I it helps. It did it this morning again. But not neer as long (high idle wise)
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