getting idle to settle down after blip

[PAracer]

Just got my project car started for the first time an hour ago. I'm looking for advice on my TwEECer pertaining to idle operation.

I have my idle speed set to 1000 rpm using otherwise stock D4U1 parameters. I noticed that when I blip the throttle, rpms don't want to return to idle. They like to sit right around 2k. I'm sure there is some way to get more predictable operation. Any opinions, suggestions, or advice.

Part of this email is intended to get my problem solved, the other side is that it seems to be typical (at least for me) enough an issue to have a solution in a searchable database.

Thanks guys!

 

[nkb93]

Mine behaves similarly, it stays up at ~2k for a sec, then comes down really slowly. Usually I can get it to come back down to idle more quickly by giving it another small blip.

I'd be interested in a solution to this as well.

 

[NotSoSlowSHO]

Typically this is caused by a sticky IAB valve, failing TPS, or dirty MAF.

Basically anything that has anything to do with air entering the motor. Metering, or measuring.

 

[SHOZ123]

Probably your dashpot settings. They are off because of the higher idle speed setting.

Be sure the TP is adjusted properly, clear the memory then adjust the dashpot settings down and let the car relearn idle.

 

[Off Road SHO]

What Paul and Kenny said....But first, check to make sure that the throttle body plate is closing all the way. If it is, then go through all that stuff the smart guys mentioned.

Tom

 

[SHOZ123]

What I found when closing the TB 100% on my Gen 3 was an occasional stall at idle. This may have been due to the IAC don't know.

What fixed it though was to put .05" gap at the throttle stop and them turn it in a 1/2 turn. Disconnect the battery and let the PCM relearn idle.

The IAC duty cycle for idle is a learned feature in the PCM.

 

[PAracer]

Was that due, perhaps, to a dead spot in the iac solenoid? Adding a small gap in the throttle body would have the IAC function in a different range of motion.

What I am dealing with is not only while idling , I have the same situation while driving. RPMs hardly drop at all unless I force them down by braking in gear.

I would love to hear what the following functions mean in the TwEECer. Dashpot decay rate, ISC airflow in drive vs. RPM, and ISC airflow in neutral vs. rpm. I have learned from searching the internet that these will be the functions to cghange to set idle characteristics.

Also, I am interested in knowing which EGR type specifies not having EGR function. Since my car is now coverted to mtx, I have no EGR equipment.

 

[SHOZ123]

I have different software and am OBDII. But from what I read from SCT and Ford the TP should not close completely. If so it may bind.

There are settings for IAC decay rate and the actual IAC. sounds like these need tweaking.

 

[PAracer]

What issues may I be facing since this car was a victim of a mtx/atx swap?

I have cleaned the iac and found no change (the same iac was fine with the atx)
swapping mafs did nothing. I tried the Pro-M 75mm that was on my father's car.
TPS was fine on the previous setup.

This is really confusing. When I look at the values for the D4U1 vs what is posted for mustangs, the numbers are so different that I refuse to touch the factory settings.

 

[rktmn]

I am not very knowledgeable when dealing with electronics, but I installed an Optimizer to my MAF, and I can control my idle and my AFR with a screwdriver.

So far, it has worked for me. I am sure that I must be doing something wrong, but it solves the problem.

I also have one on my 5.0 Bronco II. I am using a 77 Pro m MAF calibrated for 30 LB injectors, (I have the stock 19 LB injectors on the engine now), and I have ben able to adjust the idle with the A/C on or off, and the truck runs great. It is very responsive, and at no time does it hunt for the idle or stall. It was doing that before.

I had replaced the Throttle Possition Sensor, coil, sparkplugs, Throttle Air Bypass Valve, fuel pump, MAF, and TFI Ignition, with no possitive results. When I finally installed the Pro M 77 with the Optimizer, I was able to tune it in a couple of days while driving around town.

I did the same with my SHO.

I suggest to take a look at the OPTIMIZER. You can always resell it on ebay.

Jose

 

[SHOZ123]

I saw some turbo neons using this at my last dyno session.

 

[PAracer]

I think I have it figured it out now. A little fiddling with my dashpot function, and ISC drive and neutral functions have got the car idling nicely. I did check each of the components that have been mentioned to verify that my equipment was working.

Now that this is taken care of for now, I would love to find someone within a reasonable distance from Philly who knows the ins and outs of the TwEECer. There are several of us here with serious mods and little to no tuning knowledge. We would love to have a dyno tune sessin, and having a hired assassin would make efficient use of our time.

Thanks guys!

 

[Axianator]

I would love to hear what the following functions mean in the TwEECer. Dashpot decay rate, ISC airflow in drive vs. RPM, and ISC airflow in neutral vs. rpm. I have learned from searching the internet that these will be the functions to cghange to set idle characteristics.

If you can stay tuned for the long-overdue TwEECer FAQ and EEC Tuning manuals, then all of your Q's will be answered.

In the meantime, you can find some incredibly long (and potentially boring) dribble about the functions themselves sttraight from the factory engineers if you search through either of these factory strategy documents:

http://autos.groups.yahoo.com/group/tweecer/files/Documentation/GUFB.zip
http://autos.groups.yahoo.com/group/tweecer/files/Documentation/LHBL1.zip

Also, I am interested in knowing which EGR type specifies not having EGR function. Since my car is now coverted to mtx, I have no EGR equipment.

Passing a value of 2 to the "EGR System Type" scalar will prevent both V6 computers from searching for a functional EGR system.

 

[PAracer]

Passing a value of 2 to the "EGR System Type" scalar will prevent both V6 computers from searching for a functional EGR system.

Thant fixed my cel.

Once I get my intake hose (hopefully it shows up today), I can start all over with my 80mm MAF.

 

[operdot]

My car has also suffered from an atx - mtx conversion where i kept the atx ecu and removed the egr. Somehow my car does not light up the cel or the egr light which is good, but i do have the idling up issue when i press the clutch in.

I'm just wondering is changing the ISC Dashpot Decay Rate via Tweecer the only way to fix this?

 

[Axianator]

I'm just wondering is changing the ISC Dashpot Decay Rate via Tweecer the only way to fix this?

Without some creative thinking, the only way to alleviate this now-known idle problem is to reprogram the computer via the ISC airflow functions that have been mentioned. The good news is that these parameters can also be modified via an LPM or aftermarket chip with the proper programming software. For truly accurate and predictable results, though, you will need a datalogging-capable TwEECer RT (or similar means of logging data from your PCM) to affect the necessary changes and "cure" your idle problem.