Vehicle was in an accident. I dont know how it ran before.
We did repairs and on start up the idle pegged at 4k.
Cleared the KAM and cleaned the TB.
The idle now pegs once on cold start and settles down to around 900 rpms. After driving for about 10 minuets the idle will begin to creep up to around t … at a stop or at idle. Smoked the intake for leaks and none found, fuel trim also indicates there are no vac leaks. During the erratic idle, scan data indicates that the desired throttle and actual throttle positions match. The idle learn PID will switch beteen LEARNED,NOT LEARNED and DASHPOT depending on the idle speed.
Replaced the TB with a Ford TB. Same thing. Reluctantly replaced the PCM with a Ford New PCM. Same issue.
The transmission is slipping/shuddering. Can bad clutches affect the idle on this vehicle?
Does scan data showed desired RPM? What about desired and actual throttle position? Alan
Yes. The desired RPM does not match the actual at idle. All of the the APP and TP PIDS match. (Honestly I would expect a code on a vehicle of this age, if any one the redundant throttling PIDS didn't match)
Can you post scan data? Be sure the load PIDs are there and intake pressure if available. VSS too.
Randy- Screenshots? Its Autel, never loaded this type of data before. Im using Autel because it has more PIDs than Snappy.
When you say that the intake was smoke tested for leaks. Did the gauge show no leaks as well as no smoke coming out, or did you just not see any leaks? Do you have excess crankcase vacuum? Was the vehicle hit in the front?
No smoke,no gauge indication. Whats excessive for this engine? Yes hit in the front.
I use a bosch smoke machine that has the .040 and .020 evap leak indicators. Normally as long as I see it below .040" leak I call it good. I suppose you could also block your smoke machine hose and see what dead head pressure is, that should be close when testing for intake leaks if the engine matches dead head pressure. I don't remember these cars real well, but is there an adaptation process…
maybe some pinched wires around impact area? what about desired idle rpm vs actual? Throttle opening percentage? is throttle open enough for RPM to actually go that high with no load? once idle goes down is throttle closed completely or very close? seems like an input problem. can't see something like APP causing an issue like this without setting an APP Code. i wouldn't think trans problems…
Have you tried disconnecting the evap purge flow solenoid? Have seen these cause high idle concerns.
I had same year focus here yesterday with the shudder youre asking about. It had a perfect idle. Just a bad purge solenoid that intermittently leaked(with a p0456). But trims would go out and idle would more become rough and not HIGH.VERY easy to plug it off if you suspect that… I would say to try and do a battery reset to confirm kam reset but you replaced the pcm so that shouldnt…
It smells like burning clutch while idling and the Clutch Slippage PIDS match my RPMs. If that matters. To clarify the idle doesnt stay at 2k. Itll creep that high then sorta fluctuate down. Unstable idle I guess is a better descriptor.
Was this washed under hood after body work was completed? Chased some bizarre readings due to moisture in a connector or two. Possibly coolant from the accident in a connector?
Is idle issue only in gear? You mention you smell clutch material, so I'm thinking is it possible the PCM anticipates a certain load on engine with trans in gear, yet clutches are slipping not providing the load it anticipates in gear, thus the issue? Just a thought.
While sitting in the car pouring over the scan data, the clutch smell seemed to get stronger. I decided to back it out of the bay and park it for now. Thats when I discovered I no longer have reverse. Broke the news to the service writer who is going to inform the customer….Not sure where we go from here.
You may look. There was a quiet by back program on those generation DSG transmissions. We had a customer get one paid for last year.
Good point forgot about that …..DPS6- 7 years or 100k which ever comes 1st last I heard . Gobs of TSB's
Rudy When it has it's idle issue, does fuel trim indicate lean? Just thinking an air leak that comes and goes for what ever reason. This is for Randy, the Autel maxi sys had it's graph issues, they have made it much better in the Ultra. You can now merge 4 pids on the same graph, and the lock up issue, when graphing multiple pids has been rectified. Still is not to snappys level, but getting…
Randy, Shoot me an email. When I have some extra time I will learn how to transfer/post an Autel review(pid log) file. The first one is always a pain to figure out a way. I would like it to be more than just a picture. If I don't find a way, then several pictures will have to do. … Mike
Well folks, customer picked up the vehicle. Sorry, no resolution. Appreciate the input.
Maybe the load % PID would have showed why the PCM wanted a higher idle. Before I dust off the smoke machine, I check fuel trims at a idle.
I did check the fuel trim, did you read what I initially wrote? The load PID was never greater than 25%, even when the idle went higher. In my experience 20%-30% is fairly standard for a 4 cyl at idle.
I don't normally pay much attention to the load PID so I can never remember from manufacturer to manufacturer how it's calculated but I don't believe you can make a blanket statement that 20-30% at idle is normal for a 4 cyl. As I remember having it explained some manufacturers use idle as the base reference point when calculating load so at hot idle you'll be close to 0%. But then what about…
My "blanket statement" was prefaced by "in my experience" I know there are many variables and I welcome corrections to my experience. I dont know if 25% is normal either, since the car is gone there isn't much more I can do. Too bad. I hate open ended issues.
Alan, Thats old school pre-CAN. Calculated and absolute load are standardized now. With modern vehicles, you need to add Pratio to understand what is going on and that is because they manipulate throttle plates and vvt which adds another layer to what the generic term “load” really means to us.