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Cold Start Idle Issues...

848 views 11 replies 3 participants last post by  MarkassBauer 
#1 ·
Ok so, when first start of the day, starts fine starts to idle down a little while warming up, closer to 1,000 RPMs then it just revs up on its own to 2,000 real quick like I tapped the gas, then calms back down but will keep doing this on its own... if I shut it off and restart it will usually not do it any more... but that's not always the case... any ideas? I replaced TPS with factory Mopar/Holley NOS with no avail. No CEL either...
 
#3 ·
Is this a 2.2L Intercooled 16 valve DOHC T-3 or a Non-Intercooled 2.5L T-1?
(8th digit of the VIN is the engine code)

Check for any stored fault codes, not all codes will illuminate the CEL.
If no codes physically examine all vacuum lines looking for cracked, soft, collapsed lines.
Pay close attention to the PCV lines.
 
#4 ·
This is a 2.2 non-turbo SOHC converted to MPFI, so 4 injectors and turbo intake manifold, but no turbo. No fault codes flash when I check. No PCV hoses or any other vacuum lines leaking. Forgot to mention this stops happening once in gear. And once I drive a little ways even just a few blocks and put it back into park it won't do it again, until next morning...
 
#5 ·
We need to narrow things down.
1)Does the throttle body and/or AIS pintle have carbon deposits?
2)What is actual TPS voltage when the problem is occurring?
3)What is engine vacuum doing when the problem is occurring?
 
#7 ·
Question 2 - Actual TPS Voltage
Backprobe the Signal (OR/DB WIRE) and Signal Return (BK/LB WIRE) Lines with your DVOM at the TPS connector and read closed throttle voltage when the problem is occurring.
TPS voltage should be below 1.00 volts @ closed throttle and not move.

Question 3 - Engine Vacuum
You can tell me what engine vacuum is reading by reading Map Sensor Voltage.
What is Map Voltage at idle before the problem occurs and while the problem is occurring?

MAP VOLTAGE
http://www.turbododge.com/forums/f4/f14/344296-code-13-diagnostics.html
 
#10 ·
Still working on it, but I will update with fix. My old ladies FFV Spirit has a weird idle issue right now as well. Hers idles just fine until warmed up, then will bog down every few seconds, and typically only in park or neutral but will do it in gear if stopped long enough and warmed up. Car will NOT do it when cold. Both still completely drivable and I'm working from home now so rush is not there lol :/
But will report with any for sure findings ASAP.
 
#11 ·
The only thing that is different between cold running and warmed up is when warm the vehicle will be in closed loop operation so check for fault codes and take a look at O2 voltage to see if you are rich or lean which may give you an indication of whats going on.
 
#12 ·
Ok gentlemen, both cars are FIXED. I HATE throwing the parts dart, but as a true TD'er I tend to hoard Mopar TD parts, so doing so doesn't cost me any new monies. So, wether this makes ANY sense or not, what absolutely tried and true fixed my issue was a new IAC motor or idle air control valve, had 2 NOS Mopar ones so I figured why not try. It's been 5 days now and not a weird icold idle sense! Now the last time my IAC went out, it was my factory Mopar one and the car would idle way high on its own, all the time got or cold, car would cruise up to 55 mph on its own and hangout there until I hit brake. My buddy I was with had a newish BWD or Borg Warner brand one on a parts car, so I swapped mine out with that one about a year ago, just stating so we understand that failing IAC's may show different symptoms.

Ok Cats car, we changed the cap, plugs, rotor, wires as well as a NOS Mopar HEP(again I had 4 of these, 3 now), her car is FIXED. Being that it wasn't necessarily misfiring, couldn't get wires to arch, and all 4 plugs looked perfect, I'm assuming it was really her HEP. Anyway hope this helps you guys! And thank you for the support!!!
 
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