Idle air control issue

Anything about Ford EEC tuning. TwEECer and Moates questions dominate, but there's some SCT and OBD-II knowledge too.

Moderators: cgrey8, EDS50, 2Shaker, Jon 94GT

Post Reply
PoweredByAFR185
Gear Head
Posts: 23
Joined: Mon Dec 20, 2010 6:34 pm
Location: Acworth, GA

Idle air control issue

Post by PoweredByAFR185 » Sun Oct 07, 2012 4:41 pm

IAC randomly is raising idle to 2k and holding it there. I run in open loop, never modified idle scalars or functions, and car has been running awesome for the last six months since I tuned it with quarterhorse/be. All of the sudden, last week, there is no telling when it will do it, usually when stopped at a light, all of the sudden the rpms raise up to 2k and never go down. Tried a few things:

1. swapped IAC motors with 2 new ones, all do the the same; no change
2. tapped on IAC while at high idle to see if they were stuck open; no change
3. unplug IAC while at high idle, and idle definitely drops to the point of engine stalling, immediately plug it back in before engine stalls and boom, back to 2k rpm..
4. turned off engine and restarted and everything is back to normal... until driven for a few minutes then idle goes up on its own again.

It's definitely something in the tune... unplugging IAC drops idle, turn off-turn onbrings it back to normal.

What do you guys think it is?
1988 Hatch

414w
AFR 225's
Reichard Racing Trick Flow TFS-R 351 air-gapped lower
Trick Flow TFS-R 90mm upper intake
Accufab 90mm tb
CompCams 236XFI hyd. roller cam
MSD 42lb Injectors
Aeromotive rails, A1000 pump, filters, regulator, sumped tank, 8an feed, 6an return
PMAS 95mm lightning MAF
Ford A9P EEC-IV, with Moates Quarterhorse 1.6, loaded with GUFB/A9L modified tune
Tremec 3550/TKO; Pro 5.0 shifter
Kooks 1-7/8'' longtubes
3'' H-pipe'd exhaust, Flowmaster Super 44's, dumped

decipha

Re: Idle air control issue

Post by decipha » Sun Oct 07, 2012 4:50 pm

probably an rpm adder screwed up

log dsdrpm and see whats up

read over idle air 101

PoweredByAFR185
Gear Head
Posts: 23
Joined: Mon Dec 20, 2010 6:34 pm
Location: Acworth, GA

Re: Idle air control issue

Post by PoweredByAFR185 » Sun Oct 07, 2012 7:38 pm

Thanks for the tip, decipha. Before I had time come back to the forums to read your response, I swapped out the A9L for a spare A9P. Plugged the moates into that, fired it up, has run flawlessly since. I guess the actuator on the board that controls the IAC was on its way out. And its all starting to make sense, because before this high idle issue arose, Ive noticed the last month or so, its been running a little different... not wanting to high idle as easy on cold startup, the dashpot coast down wasnt as good... but thanks for all the help.
1988 Hatch

414w
AFR 225's
Reichard Racing Trick Flow TFS-R 351 air-gapped lower
Trick Flow TFS-R 90mm upper intake
Accufab 90mm tb
CompCams 236XFI hyd. roller cam
MSD 42lb Injectors
Aeromotive rails, A1000 pump, filters, regulator, sumped tank, 8an feed, 6an return
PMAS 95mm lightning MAF
Ford A9P EEC-IV, with Moates Quarterhorse 1.6, loaded with GUFB/A9L modified tune
Tremec 3550/TKO; Pro 5.0 shifter
Kooks 1-7/8'' longtubes
3'' H-pipe'd exhaust, Flowmaster Super 44's, dumped

PoweredByAFR185
Gear Head
Posts: 23
Joined: Mon Dec 20, 2010 6:34 pm
Location: Acworth, GA

Re: Idle air control issue

Post by PoweredByAFR185 » Thu Oct 11, 2012 5:13 pm

Update: it wasnt the eec. Its still doing the same thing with the 2nd eec. I did some datalogging and saw something interesting. When the idle randomly shoots up, the dsdrpm stays constant at 864. The normail idle duty cycle is 49% at 864 rpm, when it shoots up to 2k, its at 100%. All of my fn875's are where they should be. I also cleared ram on the moates, reloaded tune, same issue. Im beginning to think this is a hardware or be issue. Any thoughts?
1988 Hatch

414w
AFR 225's
Reichard Racing Trick Flow TFS-R 351 air-gapped lower
Trick Flow TFS-R 90mm upper intake
Accufab 90mm tb
CompCams 236XFI hyd. roller cam
MSD 42lb Injectors
Aeromotive rails, A1000 pump, filters, regulator, sumped tank, 8an feed, 6an return
PMAS 95mm lightning MAF
Ford A9P EEC-IV, with Moates Quarterhorse 1.6, loaded with GUFB/A9L modified tune
Tremec 3550/TKO; Pro 5.0 shifter
Kooks 1-7/8'' longtubes
3'' H-pipe'd exhaust, Flowmaster Super 44's, dumped

fidstang
Regular
Posts: 234
Joined: Sun Jul 16, 2006 8:15 pm
Location: Mid-Michigan

Re: Idle air control issue

Post by fidstang » Fri Oct 12, 2012 1:17 am

PoweredByAFR185 wrote:Update: it wasnt the eec. Its still doing the same thing with the 2nd eec. I did some datalogging and saw something interesting. When the idle randomly shoots up, the dsdrpm stays constant at 864. The normail idle duty cycle is 49% at 864 rpm, when it shoots up to 2k, its at 100%. All of my fn875's are where they should be. I also cleared ram on the moates, reloaded tune, same issue. Im beginning to think this is a hardware or be issue. Any thoughts?

Kind of sounds like a corrupt strategy file. Happens to my CBAZA a lot more often than it should. Only difference is mine will all of a sudden stall, when looking at the logs I see weird things like pw maxed, maf voltage good but showing a high flow of air, ISC maxed and trims go max rich too. I always open up a different strategy and then the correct one right after and it all disappears. Could be the calibration file is corrupt to. Try a fresh upload from the eec to start a new calibration, but after you reload the strategy. Then compare the old calibration with the compare function and make the same changes to the new one that you have in the old one. See if that helps.
94 Cobra:
10.27:1 327sbf, Edelbrock Vic. Jr heads, Victor 5.0 EFI, XE276HR w/1.6RR, 80lb/hr Siemens injectors, HPX slot MAF, 65mm fox body TB conversion, 1 and 5/8" BBK shorty headers, Xpipe with stock mufflers, T5 trans, aluminum drive shaft, 3.73 gear, and no smog, AC or EGR.

Running a Vortech V1 SQ-trim head unit with a 2.95" pulley, but without a belt while I tune for N/A.

CBAZA- J4J1

91LX Hatch: Build put on hold until I finish school.

PoweredByAFR185
Gear Head
Posts: 23
Joined: Mon Dec 20, 2010 6:34 pm
Location: Acworth, GA

Re: Idle air control issue

Post by PoweredByAFR185 » Fri Oct 12, 2012 2:42 am

Fid, I'll try that next. What makes these files go corrupt?
1988 Hatch

414w
AFR 225's
Reichard Racing Trick Flow TFS-R 351 air-gapped lower
Trick Flow TFS-R 90mm upper intake
Accufab 90mm tb
CompCams 236XFI hyd. roller cam
MSD 42lb Injectors
Aeromotive rails, A1000 pump, filters, regulator, sumped tank, 8an feed, 6an return
PMAS 95mm lightning MAF
Ford A9P EEC-IV, with Moates Quarterhorse 1.6, loaded with GUFB/A9L modified tune
Tremec 3550/TKO; Pro 5.0 shifter
Kooks 1-7/8'' longtubes
3'' H-pipe'd exhaust, Flowmaster Super 44's, dumped

PoweredByAFR185
Gear Head
Posts: 23
Joined: Mon Dec 20, 2010 6:34 pm
Location: Acworth, GA

Re: Idle air control issue

Post by PoweredByAFR185 » Fri Oct 12, 2012 9:33 pm

Another update: I downloaded another strategy file... the A3M1, and I tuned it to suit. Exact same tune changes as the previous A9L. Same issue. I called Moates and decribed the problem in detail and he said this would be the first problem like this he has encountered. He said when they fail, they fail altogether; they stop data logging, wont hold tunes, etc. Just my luck. I'll send the chip back to Moates and see what they say.
1988 Hatch

414w
AFR 225's
Reichard Racing Trick Flow TFS-R 351 air-gapped lower
Trick Flow TFS-R 90mm upper intake
Accufab 90mm tb
CompCams 236XFI hyd. roller cam
MSD 42lb Injectors
Aeromotive rails, A1000 pump, filters, regulator, sumped tank, 8an feed, 6an return
PMAS 95mm lightning MAF
Ford A9P EEC-IV, with Moates Quarterhorse 1.6, loaded with GUFB/A9L modified tune
Tremec 3550/TKO; Pro 5.0 shifter
Kooks 1-7/8'' longtubes
3'' H-pipe'd exhaust, Flowmaster Super 44's, dumped

User avatar
Paulie
Tuning Addict
Posts: 501
Joined: Thu Oct 23, 2008 9:05 pm
Location: Chicagoland

Re: Idle air control issue

Post by Paulie » Sat Oct 13, 2012 12:35 pm

Is your throttle status indicating closed throttle when this is happening? Can you post a datalog?
1990 Mustang 5.0, HCI, Vortech S-trim, FRPP 42# inj., PMAS MH95, A9L, Moates Quarterhorse, BE/EA, Innovate LC-1.

PoweredByAFR185
Gear Head
Posts: 23
Joined: Mon Dec 20, 2010 6:34 pm
Location: Acworth, GA

Re: Idle air control issue

Post by PoweredByAFR185 » Sun Oct 14, 2012 11:59 am

The iscflg is at 1 when this is happening. I assume this is closed throttle status? Also, the throttle position voltage is at .85
1988 Hatch

414w
AFR 225's
Reichard Racing Trick Flow TFS-R 351 air-gapped lower
Trick Flow TFS-R 90mm upper intake
Accufab 90mm tb
CompCams 236XFI hyd. roller cam
MSD 42lb Injectors
Aeromotive rails, A1000 pump, filters, regulator, sumped tank, 8an feed, 6an return
PMAS 95mm lightning MAF
Ford A9P EEC-IV, with Moates Quarterhorse 1.6, loaded with GUFB/A9L modified tune
Tremec 3550/TKO; Pro 5.0 shifter
Kooks 1-7/8'' longtubes
3'' H-pipe'd exhaust, Flowmaster Super 44's, dumped

PoweredByAFR185
Gear Head
Posts: 23
Joined: Mon Dec 20, 2010 6:34 pm
Location: Acworth, GA

Re: Idle air control issue

Post by PoweredByAFR185 » Tue Oct 16, 2012 1:52 pm

Update: Clint notified me that in the early harnesses that there was a diode just before the iac connector. Sure enough there was a diode in mine, and upon more research, people have had these diodes go bad and it messes with the iac. I went ahead and removed the diode per instructions. Turned the engine on and it idled like a champ. For about 15 min. Then all of a sudden it shot up to 2k rpm again, just as before, and instead of commanding 35% duty cycle like the previous 15 min of idling, it was now commanding 78% duty cycle. So problem still exists. Im at a real loss. This tune was perfect for 7 months and now it has a bug of wanting to command such a high duty cycle. For now i just turned the iac off in the tune. But i want it back right. Any other thoughts are welcome. Thanks
1988 Hatch

414w
AFR 225's
Reichard Racing Trick Flow TFS-R 351 air-gapped lower
Trick Flow TFS-R 90mm upper intake
Accufab 90mm tb
CompCams 236XFI hyd. roller cam
MSD 42lb Injectors
Aeromotive rails, A1000 pump, filters, regulator, sumped tank, 8an feed, 6an return
PMAS 95mm lightning MAF
Ford A9P EEC-IV, with Moates Quarterhorse 1.6, loaded with GUFB/A9L modified tune
Tremec 3550/TKO; Pro 5.0 shifter
Kooks 1-7/8'' longtubes
3'' H-pipe'd exhaust, Flowmaster Super 44's, dumped

User avatar
Paulie
Tuning Addict
Posts: 501
Joined: Thu Oct 23, 2008 9:05 pm
Location: Chicagoland

Re: Idle air control issue

Post by Paulie » Tue Oct 16, 2012 4:12 pm

I have seen the two 10 pin connectors on the back of the intake manifold cause issues like this. Are the jumper harnesses installed on yours? Have you cleaned those connectors?
1990 Mustang 5.0, HCI, Vortech S-trim, FRPP 42# inj., PMAS MH95, A9L, Moates Quarterhorse, BE/EA, Innovate LC-1.

PoweredByAFR185
Gear Head
Posts: 23
Joined: Mon Dec 20, 2010 6:34 pm
Location: Acworth, GA

Re: Idle air control issue

Post by PoweredByAFR185 » Tue Oct 16, 2012 4:33 pm

Paulie, no i havent tried cleaning the connectors. No 10 pin jumpers. Ill try that tonight. Do i clean all the grease off of the pins? If so, should i apply new dielectric grease?
1988 Hatch

414w
AFR 225's
Reichard Racing Trick Flow TFS-R 351 air-gapped lower
Trick Flow TFS-R 90mm upper intake
Accufab 90mm tb
CompCams 236XFI hyd. roller cam
MSD 42lb Injectors
Aeromotive rails, A1000 pump, filters, regulator, sumped tank, 8an feed, 6an return
PMAS 95mm lightning MAF
Ford A9P EEC-IV, with Moates Quarterhorse 1.6, loaded with GUFB/A9L modified tune
Tremec 3550/TKO; Pro 5.0 shifter
Kooks 1-7/8'' longtubes
3'' H-pipe'd exhaust, Flowmaster Super 44's, dumped

cougarnut281
Tuning Addict
Posts: 1075
Joined: Sat Apr 21, 2007 3:36 pm
Location: Kentucky

Re: Idle air control issue

Post by cougarnut281 » Tue Oct 16, 2012 8:14 pm

throttle status of 1 is dashpot mode. -1 is idle. Which would make sense since in dashpot mode it will kick open the iac.

Sounds like the TPS is doing something funny and kicking the eec out of idle mode. Watch the tps voltage and see what it does.

User avatar
Paulie
Tuning Addict
Posts: 501
Joined: Thu Oct 23, 2008 9:05 pm
Location: Chicagoland

Re: Idle air control issue

Post by Paulie » Tue Oct 16, 2012 9:31 pm

PoweredByAFR185 wrote:Paulie, no i havent tried cleaning the connectors. No 10 pin jumpers. Ill try that tonight. Do i clean all the grease off of the pins? If so, should i apply new dielectric grease?
I usually spray some contact cleaner in both connectors.
1990 Mustang 5.0, HCI, Vortech S-trim, FRPP 42# inj., PMAS MH95, A9L, Moates Quarterhorse, BE/EA, Innovate LC-1.

User avatar
Paulie
Tuning Addict
Posts: 501
Joined: Thu Oct 23, 2008 9:05 pm
Location: Chicagoland

Re: Idle air control issue

Post by Paulie » Tue Oct 16, 2012 9:37 pm

cougarnut281 wrote:throttle status of 1 is dashpot mode. -1 is idle. Which would make sense since in dashpot mode it will kick open the iac.

Sounds like the TPS is doing something funny and kicking the eec out of idle mode. Watch the tps voltage and see what it does.
For the ISCFLG, dashpot is -1, preposition is 0, RPM control is 1 and RPM lockout is 2.
I do agree though, TPS could be doing something strange. I would still start by cleaning the two 10 pin connectors.
Also there is a pid for throttle status, should be "TS", and should be -1 at closed throttle.
1990 Mustang 5.0, HCI, Vortech S-trim, FRPP 42# inj., PMAS MH95, A9L, Moates Quarterhorse, BE/EA, Innovate LC-1.

cougarnut281
Tuning Addict
Posts: 1075
Joined: Sat Apr 21, 2007 3:36 pm
Location: Kentucky

Re: Idle air control issue

Post by cougarnut281 » Tue Oct 16, 2012 9:45 pm

My bad. I was thinking of the ts flag.

decipha

Re: Idle air control issue

Post by decipha » Tue Oct 16, 2012 11:05 pm

decipha wrote:probably an rpm adder screwed up

log dsdrpm and see whats up

read over idle air 101

PoweredByAFR185
Gear Head
Posts: 23
Joined: Mon Dec 20, 2010 6:34 pm
Location: Acworth, GA

Re: Idle air control issue

Post by PoweredByAFR185 » Tue Oct 16, 2012 11:18 pm

Thanks for all the suggestions everyone. The tps voltage does in fact vary a little bit during idle. It ranges from .85 to .71. This might be another indicator of the 10 pin connectors needing some tlc. Will update everyone when i perform the next steps.
1988 Hatch

414w
AFR 225's
Reichard Racing Trick Flow TFS-R 351 air-gapped lower
Trick Flow TFS-R 90mm upper intake
Accufab 90mm tb
CompCams 236XFI hyd. roller cam
MSD 42lb Injectors
Aeromotive rails, A1000 pump, filters, regulator, sumped tank, 8an feed, 6an return
PMAS 95mm lightning MAF
Ford A9P EEC-IV, with Moates Quarterhorse 1.6, loaded with GUFB/A9L modified tune
Tremec 3550/TKO; Pro 5.0 shifter
Kooks 1-7/8'' longtubes
3'' H-pipe'd exhaust, Flowmaster Super 44's, dumped

fidstang
Regular
Posts: 234
Joined: Sun Jul 16, 2006 8:15 pm
Location: Mid-Michigan

Re: Idle air control issue

Post by fidstang » Thu Oct 18, 2012 11:18 am

PoweredByAFR185 wrote:Thanks for all the suggestions everyone. The tps voltage does in fact vary a little bit during idle. It ranges from .85 to .71. This might be another indicator of the 10 pin connectors needing some tlc. Will update everyone when i perform the next steps.
I would suggest performing a idle/TPS reset after you clean those connectors and check the throttle cable for correct function with no binding. Also check to make sure your throttle body blade is not sticking, make sure you check it without the cable hooked up, also while doing this with the KOEO measure the voltage of the TPS slowly throughout the blade sweep range and watch for sudden dips in the output.

Then if all is well mechanically, follow Decipha's suggestion in his post.
94 Cobra:
10.27:1 327sbf, Edelbrock Vic. Jr heads, Victor 5.0 EFI, XE276HR w/1.6RR, 80lb/hr Siemens injectors, HPX slot MAF, 65mm fox body TB conversion, 1 and 5/8" BBK shorty headers, Xpipe with stock mufflers, T5 trans, aluminum drive shaft, 3.73 gear, and no smog, AC or EGR.

Running a Vortech V1 SQ-trim head unit with a 2.95" pulley, but without a belt while I tune for N/A.

CBAZA- J4J1

91LX Hatch: Build put on hold until I finish school.

PoweredByAFR185
Gear Head
Posts: 23
Joined: Mon Dec 20, 2010 6:34 pm
Location: Acworth, GA

Re: Idle air control issue

Post by PoweredByAFR185 » Sat Oct 20, 2012 2:50 am

Update: Seems as if issues are gone! It was a bad TPS sensor.

I started by cleaning the 10-pin connectors, and pinched the females a little bit so the bullets on the male ends would have a tighter fit. After about 10 or 15 minutes of idling, it started again. So looking at the datalogs, I noticed the TPS had dropped its initial voltage from cold start to warm idle around 1/10th of a volt - from .91v to .80v. Thats pretty significant. So I went and bought BWD TPS sensor and logged the voltage fluctuations. Upon returning to idle, the voltage was dead on, consistent, every single time.

I heard from somewhere, can't recall at this time, that if there is a fluctuation of more than .04v from initial TPS voltage at start up, it can cause some issues. Maybe there's some truth to this?

Thanks to everyone on here for the help. I'm so thankful for this forum.
1988 Hatch

414w
AFR 225's
Reichard Racing Trick Flow TFS-R 351 air-gapped lower
Trick Flow TFS-R 90mm upper intake
Accufab 90mm tb
CompCams 236XFI hyd. roller cam
MSD 42lb Injectors
Aeromotive rails, A1000 pump, filters, regulator, sumped tank, 8an feed, 6an return
PMAS 95mm lightning MAF
Ford A9P EEC-IV, with Moates Quarterhorse 1.6, loaded with GUFB/A9L modified tune
Tremec 3550/TKO; Pro 5.0 shifter
Kooks 1-7/8'' longtubes
3'' H-pipe'd exhaust, Flowmaster Super 44's, dumped

Post Reply

Who is online

Users browsing this forum: No registered users and 12 guests