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

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Odrapnew
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Neutral rev - RPM overshoot - surge - die

Post by Odrapnew » Thu Jun 30, 2022 8:30 am

Well, I had this all written up and must have forgotten to submit, so here goes again.

I've been tweaking my idle settings and getting close to reliable return to idle (or at least not stalling).
One thing I'm dealing with is if I rev the engine in neutral (or with clutch in) and let off, the RPM will drop quick, overshoot, surge and sometimes die.

I can get it to die almost every time if I turn the steering wheel (power steering load) when rpm are dropping. Really annoying during parking lot maneuvering.

This also happens if I'm at stop sign/light and creeping up waiting my turn to go. Add a little throttle and engage clutch to creep forward, declutch and close throttle, it'll surge and sometimes die.

I can get it to settle if I give it a tiny bit of throttle.

I did some logging and noticed that when I blip and close the throttle, the ISC status will go to preposition for a split second and then immediately go into dashpot/decay. The RPM's haven't dropped enough to hit the preposition, so it's decaying almost as soon as the throttle body is closed and RPM's drop.

When cruising down the road, it'll go into preposition because my speed is above the dashpot MPH (set at 10). If I continue to slow down below 10mph, dashpot will decay and idle will settle nicely.

I remember stock programming would allow the engine to rev, settle at about 1100-1200 rpm, and then decay to idle.

Should the ISC status sit at preposition for a few seconds before decaying when doing neutral/stopped (almost stopped) revs?
If so, what setting(s) should I adjust?
'89 Notch, 304(5.0), Novi2K@13psi (currently not installed) TFS heads, TFS Stage 1 cam, Cobra intake, 60lb'ers and Pro-M 80mm, longtubes_x-pipe_flowmasters and more crap that doesnt increase power. 437rwhp@5500(and still climbing)/438rwtq@~4000rpm Tweecer R/T w_BE and EA

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cgrey8
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Re: Neutral rev - RPM overshoot - surge - die

Post by cgrey8 » Thu Jun 30, 2022 11:50 am

Just a guess, but you may try increasing your PREPOSITION value for idle when at Part Throttle. This will give you a little more distance to decay from when you go Closed Throttle. The other option is to reduce the decay rate during idle DASPOT decay from PREPOSITION.

In GUFx strats, there's also the DNPPM and NDPPM which are the Drive-to-Neutral ISC Air Adder and Neutral-to-Drive ISC Air Adder respectively. These add air to the ISC on neutral/drive transitions as described. The Neutral-to-Drive Adder is often needed to prevent Automatics from stalling when putting it into drive. The amount of air added compensates for the increase in engine load due to the transmission drag of being in drive or reverse. The lack of any contribution on stock tunes intended for manual transmissions when applied to an automatic vehicle is why they often conk-out when being put into gear.

And if you are only trying to protect from a declutch condition, then DASMIN can help here. I believe what this does is define a minimum flow for the ISC while in drive to ensure a sudden declutch where PREPOSITION has already decayed as happens when you are closed throttle, rolling to a stop while in gear and push the clutch in right as the vehicle speed starts to bog the engine. This setting can help with parking lot issues too.
...Always Somethin'

89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', GUFB, Moates QuarterHorse tuned using BE&EA

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Odrapnew
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Re: Neutral rev - RPM overshoot - surge - die

Post by Odrapnew » Thu Jun 30, 2022 12:54 pm

Thanks for the input.

To clarify my original post, when I stated the line below, what I meant is that my DASMIN seems to be OK.
When I declutch at anything above 10mph, it goes to my DASMIN setting, rpm hang there until I get below 10mph and rpm drop nicely to idle speed.
When cruising down the road, it'll go into preposition because my speed is above the dashpot MPH (set at 10). If I continue to slow down below 10mph, dashpot will decay and idle will settle nicely.
Unfortunately that's not active when creeping (under 10mph), so the dashpot value starts higher and drops quickly past the DASMIN value along with RPM. By the time dashpot decay slows down, it's already too late and RPM dip.

I'll see about upping max preposition and/or reduce decay rate.
I think reducing decay rate might be the ticket as it seems to be dropping very quickly from the preposition value. I've already cut those values down a TON from stock tune, but I'll keep going. It's definitely better than it used to be, but I think I just need to keep reducing the decay rate.
'89 Notch, 304(5.0), Novi2K@13psi (currently not installed) TFS heads, TFS Stage 1 cam, Cobra intake, 60lb'ers and Pro-M 80mm, longtubes_x-pipe_flowmasters and more crap that doesnt increase power. 437rwhp@5500(and still climbing)/438rwtq@~4000rpm Tweecer R/T w_BE and EA

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Re: Neutral rev - RPM overshoot - surge - die

Post by cgrey8 » Thu Jun 30, 2022 4:18 pm

Set DASMPH to something like 1MPH.
...Always Somethin'

89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', GUFB, Moates QuarterHorse tuned using BE&EA

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89fastback
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Re: Neutral rev - RPM overshoot - surge - die

Post by 89fastback » Thu Jun 30, 2022 4:59 pm

I was having that same problem running the tfs stage one cam for a long time. reducing decay rate in trouble areas along with adjusting injector timing to get my fuel dialed in at idle has made a huge difference for me I can now rev at idle without stalling or almost stalling. Also reduce the wet spots in my driveway from un burnt fuel coming out the exhaust
1989 mustang lx
Stock 302 bottom end trick flow stage one cam trick flow 170cc heads stock 93 cobra intake 24lb bosch injectors 75mm pro-m maf with screen stock air box and plumbing quarter horse with binary editor :twisted:

Odrapnew
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Re: Neutral rev - RPM overshoot - surge - die

Post by Odrapnew » Thu Jun 30, 2022 7:18 pm

89fastback wrote: Thu Jun 30, 2022 4:59 pm I was having that same problem running the tfs stage one cam for a long time. reducing decay rate in trouble areas along with adjusting injector timing to get my fuel dialed in at idle has made a huge difference for me I can now rev at idle without stalling or almost stalling. Also reduce the wet spots in my driveway from un burnt fuel coming out the exhaust
Just curious, what did you set injector timing at for idle?
I haven't looked at it recently, but I know my table is set at 500 across the board (carryover from last year).

Regarding my issue, I've pretty much solved it.
Need to tweak it a bit, but at least it doesn't die while sitting in traffic.

I increased preposition a little bit at 1800rpm and also reduced decay by a bunch (~50%).

It hangs a bit, but doesn't die or surge.....well, it'll surge just a tiny bit if I decel in gear until dashpot hits DASMIN and then declutch, but it doesn't die.
'89 Notch, 304(5.0), Novi2K@13psi (currently not installed) TFS heads, TFS Stage 1 cam, Cobra intake, 60lb'ers and Pro-M 80mm, longtubes_x-pipe_flowmasters and more crap that doesnt increase power. 437rwhp@5500(and still climbing)/438rwtq@~4000rpm Tweecer R/T w_BE and EA

89fastback
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Re: Neutral rev - RPM overshoot - surge - die

Post by 89fastback » Thu Jun 30, 2022 10:43 pm

that seems a little excessive for your decay rate. besides injector timing and decay rate I also work on dialing in Idle - ISC Drive Idle Air and Idle - ISC Neutral Idle Air. I made both of these the same because I have stick shift car. You can look at Idle - ISC Maximum Drive RPM and add the amount over stock idle 672
My idle is set to 768 (768-672)=96 Idle - Throttle Body Air Flow is important because it is used to help calculate air flow at idle.
The idle air write up would be a good read to help get everything dialed in properly http://efidynotuning.com/ hope this helps you.
I would like to take a look at your tune
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1989 mustang lx
Stock 302 bottom end trick flow stage one cam trick flow 170cc heads stock 93 cobra intake 24lb bosch injectors 75mm pro-m maf with screen stock air box and plumbing quarter horse with binary editor :twisted:

Odrapnew
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Re: Neutral rev - RPM overshoot - surge - die

Post by Odrapnew » Fri Jul 01, 2022 9:27 am

I did set the throttle body flow with IAC disconnected and timing locked, but I'm going to check it again.
I think I did that before I found a small piece of silicon or something that was wedging the IAC partly open after some driving.
Reference this thread: viewtopic.php?f=2&t=23372

I'd be happy to send my tune, but it's on my old (old) laptop.

I'll also have to double check the ISC neutral/drive idle air flow curves.

Since we have similar setups, mainly the intake, cam, heads, just curious what your ISC idle air flow functions looks like.
Might be an ah-ha moment seeing settings from a similar setup.

Unfortunately I won't be able to dink around with this until next week (out of town).
'89 Notch, 304(5.0), Novi2K@13psi (currently not installed) TFS heads, TFS Stage 1 cam, Cobra intake, 60lb'ers and Pro-M 80mm, longtubes_x-pipe_flowmasters and more crap that doesnt increase power. 437rwhp@5500(and still climbing)/438rwtq@~4000rpm Tweecer R/T w_BE and EA

89fastback
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Re: Neutral rev - RPM overshoot - surge - die

Post by 89fastback » Wed Jul 20, 2022 11:40 pm

Well my ISC idle air flow function is not really much different from stock.
435.4420 1.7010
20.4117 1.7010
17.6874 1.2226
12.2457 0.1528
9.5281 0.0332
1.6877 0.0797
0.0000 0.0930
Getting my fueling close as possible was the only thing that helped. Before that i was having no luck with decay rate at all no matter what I change it did nothing for neutral rev. Make sure your maf transfer is consistent from cell to cell and you don't want any of them lean rich then lean again or rich lean rich. I went threw all the cells from .5 - 1.2 volts all are about 2% lean. Along with that messing with injector timing made. Have you changed your Idle - ISC Gain Multiplier vs RPM to match your target idle.
1989 mustang lx
Stock 302 bottom end trick flow stage one cam trick flow 170cc heads stock 93 cobra intake 24lb bosch injectors 75mm pro-m maf with screen stock air box and plumbing quarter horse with binary editor :twisted:

Odrapnew
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Re: Neutral rev - RPM overshoot - surge - die

Post by Odrapnew » Thu Jul 21, 2022 2:44 pm

My decay rates are much lower than that.

I observed my low decay rates are now causing another issue. The decay is so slow, it's staying in dashpot mode for too long.
What's happening is that rpm's drop below target rpm, but since it's in dashpot, timing is not used to compensate so it starts surging. If I'm lucky, it'll finally drop out of dashpot and go into idle control and timing bounces around until it settles down.

Most of the time it starts surging and if I don't give it some throttle, it'll stall. Well, giving a bit of throttle resets dashpot and the loop starts all over.

The above may be caused by fueling being off. I haven't been able to tell if the engine likes leaner or richer idle.

When you say 'rich, lean, rich' in the MAF curve, are you referring to the flow rate not following the voltage?
Trying to think how to explain.
These are just random numbers discussion.

Example of good.
1V = 50kg/hr
1.1V = 60kg/hr
1.2V = 70kg/hr

Example of bad.
1V = 50kg/hr
1.1V = 80kg/hr
1.2V = 70kg/hr

If that's the case, I'm fairly certain in my MAF curve, lower voltage = lower flow, but will confirm.

For the Idle - ISC Gain Multiplier vs RPM function, yes, I adjusted that to align with my set target idle speed.


I'm tempted to start fresh based off the factory tune and make only necessary adjustments.
I have a feeling the changes in the tune are starting to get way off and I just need to reset and start fresh.
'89 Notch, 304(5.0), Novi2K@13psi (currently not installed) TFS heads, TFS Stage 1 cam, Cobra intake, 60lb'ers and Pro-M 80mm, longtubes_x-pipe_flowmasters and more crap that doesnt increase power. 437rwhp@5500(and still climbing)/438rwtq@~4000rpm Tweecer R/T w_BE and EA

Odrapnew
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Re: Neutral rev - RPM overshoot - surge - die

Post by Odrapnew » Sun Jul 24, 2022 8:24 am

I pulled the upper intake off again to check lower intake bolts because I was getting an intake whistle and I noticed the IAC duty cycle was higher than before (from 35% up to 45% at same idle). That's usually a sign of vacuum leak.

Most of the lower intake bolts took an 1/8 of a turn to hit torque. Went through the pattern a few times until they stopped.

While I had the upper off again, I was looking it over for any obvious issues and looked at the throttle body thinking there doesn't appear to be a gasket between TB and intake. This is a cobra intake, so no separate EGR spacer.

Pulled TB off and this is what I found. Pretty sure thats been like that since I bought the intake 20+ years ago. I don't remember ever pulling the TB off.

Any chance this may be causing my tuning issues? (Idle surge and the odd leaning out issue in my other thread)
20220724_070226.jpg
20220724_070226.jpg (140.81 KiB) Viewed 305 times
'89 Notch, 304(5.0), Novi2K@13psi (currently not installed) TFS heads, TFS Stage 1 cam, Cobra intake, 60lb'ers and Pro-M 80mm, longtubes_x-pipe_flowmasters and more crap that doesnt increase power. 437rwhp@5500(and still climbing)/438rwtq@~4000rpm Tweecer R/T w_BE and EA

acgarib
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Re: Neutral rev - RPM overshoot - surge - die

Post by acgarib » Sun Jul 24, 2022 9:11 am

As long as the sealant provided an air-tight seal then it should have been fine. With the throttle body off the intake I would use that as an opportunity to use an actual gasket.

I was having a similar issue with stalling after revving in neutral. I have an auto so I don't have to worry about coasting to stop signs, but what fixed the issue for me was:

FN882 - Dashpot Airmass Max Clip. Adjust for better dashpot control to prevent stalling or cruise-control when revving. Raised values at low RPMS in particular.
5 16384 2.000
4 5000 2.000
3 3500 1.000
2 1100 0.700
1 0 0.800

FN879 - Dashpot Decay. Adjust for better dashpot control to prevent stalling. The last little bit of dashpot really takes forever to decay, but it solved my stalling issue.
7 2.500 0.0100
6 2.000 0.0500
5 1.250 0.0149
4 0.750 0.0100
3 0.500 0.0039
2 0.250 0.0007
1 0.000 0.0007


Can you tune up FN111 to have more timing at slightly lower RPMS than idle so you can have at least a rudimentary spark control during dashpot mode? I'm not sure if FN111 works during dashpot mode.
1991 Mustang, AOD transmission, stock small block,Twisted Wedge heads, Track Heat intake, XE270HR-12 cam, Vortech SI at 11 psi with power pipe, 255 lph fuel pump, 80lb injectors, draw-through 90mm LMAF, A9P EEC-IV with Quarterhorse

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Paulie
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Re: Neutral rev - RPM overshoot - surge - die

Post by Paulie » Mon Jul 25, 2022 11:34 am

acgarib wrote: Sun Jul 24, 2022 9:11 am
Can you tune up FN111 to have more timing at slightly lower RPMS than idle so you can have at least a rudimentary spark control during dashpot mode? I'm not sure if FN111 works during dashpot mode.
FN111 is active when the throttle is closed, which includes dashpot mode. FN839 is a multiplier of FN111 when in dashpot mode.
1990 Mustang 5.0, HCI, Vortech S-trim, FRPP 42# inj., PMAS MH95, A9L, Moates Quarterhorse, BE/EA, Innovate LC-1.

Odrapnew
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Re: Neutral rev - RPM overshoot - surge - die

Post by Odrapnew » Mon Jul 25, 2022 12:13 pm

I added a gasket to the throttle body and also replaced the IAC gasket since I had it apart.
No real change to how the car runs, but makes me feel better that I have a couple good gaskets in there.

My neutral rev overshoot seems to be gone with significant reduction in decay rate.
I still get the overshoot if I coast down in gear and then press the clutch in, but it seems to catch itself.

My latest issue is surging that sometimes starts as it settles down into idle.
Once dashpot is decayed and it goes into idle control, it sometimes catches itself, others it'll surge more until it shuts off.
It's really bad when I'm trying to pull into my garage because I have to do a 3 point turn so I'm on/off the throttle, which makes surging worse.

Fairly certain it's fuel related because the IAC/dashpot/timing don't jump around as it starts surging because it usually starts during dashpot decay.

I really need to bring my laptop to work even when I don't drive the car so I can look at the tune.
'89 Notch, 304(5.0), Novi2K@13psi (currently not installed) TFS heads, TFS Stage 1 cam, Cobra intake, 60lb'ers and Pro-M 80mm, longtubes_x-pipe_flowmasters and more crap that doesnt increase power. 437rwhp@5500(and still climbing)/438rwtq@~4000rpm Tweecer R/T w_BE and EA

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