Won't Idle

[mtbraun]

Well I finally got everything put back together from my winter project. I set FP at 43 (key on vac off) and gave it a whirl. Won't idle on its own. It will stay running if I tap the gas when it is ready to. O2 jumped around a bunch at first and then settled in at 50!

I've replaced all vacuum lines and don't think I have a leak there. New O2 sensor so I'm confident the reading was accurate. I am running just out of the down pipe as I'm waiting for my new exhaust to show up. I'm also still running the stock chip until my TT shows up.

Thoughts would be appreciated.

 

[mtbraun]

I unplugged the MAF and fired it up again. It runs much better, but still idles rough. It bounces between 800-1100 RPMs, pretty choppy idle. At least with the MAF unplugged it will run, whereas before it would die if I didn't punch the gas. Does this suggest the MAF sensor is bad? Would having the MAF unplugged cause the rough idle or is that likely due to something else? My O2s came up nicely also after unplugging the MAF.

 

[mtbraun]

scanmaster readings while idling:
AF-06
L8-43
Int-130
BL-105
TPS-.42
IAC-00
MAL-34(obvious wiht MAF unplugged)

 

[vkasm1]

Your iac counts are zero when they should be higher( around 25-45 i think) . What have you done to the car since last time that it was running right. Usually when I see IAC at zero with engine running means the computer is tryng to bring rpm down do to a vacume leak. I would get the right chip in to see if it clears up If it doesnt then I would start diagnosing it.

 

[mtbraun]

I've had a rough idle for some time and this winter dove into it and fixed/changed a lot of stuff while I had it apart. Valve springs, timing chain, vacuum lines, water pump, Adj FPR, walbro, hotwire kit, rewelded cracked headers, gaskets/seals all around, and new DP/exhaust coming yet. The only vacuum lines I didn't replace were the hard plastic ones going to the MAP sensor and the one to the vacuum ball off the tee. Even got rid of the old plastic block and went with aluminum. TT chip is in the mail this week so I might sit tight until that arrives.

 

[usetaboost]

hard to tell what is actually going on until your computer relearns. If it has, what's your 02 reading at idle and warm? It almost sounds like a bad maf issue. Need more info off your scanmaster. make sure you post what the coolant reading is also. Needs to be 160 or above for closed loop. Have you got any drive time since you hooked the battery up?

 

[WIKEDV6]

How long was the motor sitting? How old are the injectors? I assume they are stock according to what you said about running the stock chip. The number one problem I ran into time after time firing up a motor that sat for a while is clogged injectors. it fires up and dies out or you have to play with the throttle to keep it running. That can be a frustration experience. If the injectors are stock then they are 25 years old, it maybe time to move and a get good set of new injectors. If they are not stock, then there is your problem if you still have the stock chip with some bigger injectors.

Some more info on the combo would be nice to actually nail down the issue but I would try the TT chip first, that makes a whole world of difference .

HTH
Prasad

 

[Repairman69]

I'm having the same problem.car starts then runs for a minute or two then shuts off .if I turn idle screw up it stays running.i just got car know no history.any help would be great..first time with 3.8 turbo I'm a FORD TECH sorry ..

 

[THensley]

MT has not said if he uses the accelerator can you keep it running ? but being patient and waiting for TT chip is going to be your best bet.

I'm having the same problem.car starts then runs for a minute or two then shuts off .if I turn idle screw up it stays running.i just got car know no history.any help would be great..first time with 3.8 turbo I'm a FORD TECH sorry ..

turn idle adjuster up tell IAC read 25-40 I prefer 25 -30 Then readjust TPS to .42
It's ok to be a Ford TEC just apply what you know listen to what we say.

 

[Joe Rainville]

I was fighting a rough idle, and had to pull out an old school vacuum gauge to help diagnose the issue. I ended up having 5-7" of mercury at idle, when it should have been 20-25". Turns out I had a few vacuum leaks, but the big problem was that the previous owner installed a new timing chain and top gear, but didn't change the lower gear from factory. So, the chain stretched and timing jumped a tooth or tow. After finding the main bearings down to the copper, my very poorly rebuilt motor is now down to the bear block for a proper rebuild.

 

[pacecarta]

MT has not said if he uses the accelerator can you keep it running ? but being patient and waiting for TT chip is going to be your best bet.

turn idle adjuster up tell IAC read 25-40 I prefer 25 -30 Then readjust TPS to .42
It's ok to be a Ford TEC just apply what you know listen to what we say.

op MT posted this 12.5 yrs ago , if hes still waiting for tt chip he has the patience of a saint

 

[THensley]

op MT posted this 12.5 yrs ago , if hes still waiting for tt chip he has the patience of a saint

holly crap I usually look at the dates just a good reminder