EFI Idle issues

[EmptyGarage]

I've read the threads that discuss idle issues but they are all centered aroud CIS systems. My engine has been converted to EFI and I need to track down the cause of stalling at idle.

The car idled fine for my first year of ownership but after winter storage I’ve had a issues this summer with stalling at idle. Initially car idled at about 900 rpm’s

Chronologically things progressed as

At first of summer the car started fine and would idle fine so long as accelerator peddle was not touched (knowticed idle speed had dropped to 750 rpm’s) Reving car even a little would cause car to stall once it was allowed to idle on it's own. Moving car out of garage to driveway was enough to cause the car to stall when allowing to idle on it own. Re-start the car and it would idle on its own until warm and then it would be fine. If anytime before car was warn you revved engine...car would stall if left to idle on its own but on re-start would idle fine.

Move forward a few drives. Car takes longer to warm and when driven at night with low ambient temperature car never seemed to idle without stalling. I could still start and car would idle so long as I did not touch accelerator.

last drive. Took on highway drive and car worked fine on highway. Car would not idle reliably even after a long highway run and full operating temperature ( 1/3 mark on temperature gauge). I say reliably because I stopped in a parking lot to let wife out and while there, and after some peddle work, the idle did settle at 750 rpm’s and worked fine (10 min) . At that point I put headlights on and that started “idle hunting” where rev bounced from 250 to 1500 rpm’s until it stalled. Car would stall at stops before pulling into parking lot and rest of drive home. I could keep car running by heel-toe accelerator.

One last observation. The exhaust used to pop significantly at decel but that seems to have stopped as of my last drive.

No engine or other work done to car over winter. Because car idled fine last year I’m thinking a vacuum line is where the problem might be. I’ve seen vacuum diagrams from CIS cars and I’m wondering if what vacuum lines would still be used on a EFI engine and if WUR would still be part of the system.

[sjf911]

What is the setup of your EFI for idle control? Closed loop, open loop, 3-wire frequency valve, 4-wire stepper, etc.? Are you seeing swings in AFR at idle and what is your idle advance set to?

[drmatera]

^ ditto sounds like the idle control valve is going-going-gone

[s5uewf]

what type of EFI are you using?

Sort of sounds like the mixture is off at idle and also since it is idling so low the alternator is kicking in to charge up the battery and that is making things worse when the light are on.

If you go to the Electromotive site and download their free TECgt install guide there is an entire section on setting idle. You may be able to use their tips to tune your idle up.

Do you have enough air getting in at idle? I only ask because I am wondering if you had more air entering at idle would you get more RPM's at idle? Assuming your mixture is not rich as it is and vacuum is not leaking - adding air should increase your idle - and you may then have to adjust mixture again.

You should have a cold idle and warm idle mapping ... if so, you may need to adjust both as it sounds like you have issues when cold and when warm.

[TurboKraft]

More details would help diagnosis: EFI type, manifold & t-body type, etc. Pictures, too.

[EmptyGarage]

I've been surprised by an obligation to make a business trip starting this weekend and not returning until weeks end. I've been busy preparing, so accept my appolagies for posting and then being absent.

I'm looking for photos of engine. I have some of the engine removed from the car that shows the EFI modifications and thought they would be of most help. They are from the engine builder.

My wrenching experience with EFI is ..non existent.. so it's taking me a while to get the answer for some of the technical questions that some have posted. I'm working on them and will post when I return next week...

Car is not equipped with a wideband sensor so no AFR's . I looked at WUR and all the sensors have been unplugged ..so I answered my own question..The WUR is not part of the idle control system.

[EmptyGarage]

I found the picture so I had to get them on. The Car is run with a DTA pro Engine Management System

Can someone help by identifying this part?

[EmptyGarage]

I dug up some of the EMS specifications, the idle Control Functions first:

DTA
Idle Control Functions

Open or closed loop idle speed control via PWM valve.
Closed loop idle target speed temperature dependant.
Active base PWM map for easy calibration.
Fuel enrichment table calibrated versus PWM percentage.



Diagnostics and Test Features.

Full sensor diagnostics and fault recording.
Extensive engine run time recording at different load and speed conditions.
Ability to exercise injectors and coils without engine running for fault finding.
Back to top




S80 PRO

The S80 and S100 ECUs represent the top of the range, differing only in the number of individual coils and sequential injectors they can handle.

Comprehensive input and output features are provided allowing sophisticated 6, 8 , 10 and 12 cylinder engines to be controlled easily and successfully.

An extremely high level of environmental protection has been implemented in its design allowing safe use in extreme conditions such as grass track, off road, marine and motorcycles.
s80_ecu
ECU Functions


Engine Configuration

20,000 rpm capability
Flexible and easily adapted to different OEM, crank, cam sensor arrangements.
Genuine four and two stroke support.
Twin spark engines.
Twin injector engines.
Sequential or grouped injection.
Individual coils, wasted spark or distributor.
Unequal coil firing capability.
Unequal injection angle capability.
Delayed sequential injection.
User controlled fan activation.
Sensors can be calibrated individually with a lot of preset options supplied.
Flexible Tacho Output
soft and hard rev limits

Main Fuel and Ignition Functions

Two main fuel, spark and turbo maps selected by a dashboard switch.
Comprehensive start up fuelling options both time and temperature dependant.
Air, coolant and manifold pressure compensation maps.
Throttle transient increase compensation.
Throttle transient reduction compensation.
RPM and load breakpoints can be calibrated by the user.
Throttle or MAP as load.
All maps with one or two dimensional with interpolation as required.

Lambda control functions

Extensive lambda parameters table to ensure stable closed loop operation and emissions requirements can be met where needed.
Full three dimensional lambda target map.
Auto-tuning function.

Turbo Control Functions

Open or closed loop turbo pressure control via PWM valve.
Modify target turbo pressure by gear selected.
Modify target turbo pressure by vehicle speed.
Two control maps selected by switch on dashboard.
Active base PWM map for easy calibration.

Idle Control Functions

Open or closed loop idle speed control via PWM valve.
Closed loop idle target speed temperature dependant.
Active base PWM map for easy calibration.
Fuel enrichment table calibrated versus PWM percentage.

ALS Control Functions

Full ALS ignition and fuel maps.
ALS valve control together with map switching controlled
by dash board switch.

Cam Control Functions

Open or closed loop cam advance control via PWM valve.
Static offset table to zero out electrical movement effects.
Active Cam Target Advance map, load and speed dependant.
Active base PWM map for easy calibration.
VTEC Control

Water Injection

When not being used to control the camshaft, cam base PWM map can be used instead for water injection, giving complete load and speed dependence.

Flexible Input/Output

Three uncommitted input tables which use 0 5 volt inputs or any input the S60 knows already, linked to fuel and advance modifiers and a PWM output.

Launch Control

Fully flexible first gear launch capability.
Extensively tunable to individual vehicles.

Traction Control

Fully adjustable from the dashboard.
Measured from all 4 wheels

Full Throttle Gear Shift Cut

Shift cut capability with 1ms resolution, variable for each gear with
full switch de-bounce capability.

Voltage Compensation Tables

User configurable voltage compensation tables for injector dead time
and coil on time (dwell time).

Firmware

The ECU firmware is flash upgradeable via the serial port with a special cable and software. Current firmware and software published on www.dtafast.co.uk.

CAN PC Communications.

The ECU can communicate with the PC via our
USB -> CAN converter. This solves the problem
of unreliable USB -> RS232 converters.

Data Logging

Up to thirty six separate items can be logged.
Three user selectable logging frequencies.
Up to 16 hours logging capability.
Graphing can be done on-line to the ECU.

Diagnostics and Test Features.

Full sensor diagnostics and fault recording.
Extensive engine run time recording at different load and speed conditions.
Ability to exercise injectors and coils without engine running for fault finding.

Other Features

Waterproof Enclosure
Sealed Latching Connectors
Size 134 x 240 x 46 mm
Weight 1130 gm


All outputs protected against over temperature and over current
Inputs protected against severe wiring mistakes and accidents
Reverse battery protection
Alternator load dump protection

Input and Output Features

Inputs

Crank Shaft (Magnetic and Hall Effect)
2 x Cam Shaft (Magnetic and Hall Effect)
Throttle Position
Coolant Temperature
Air Temperature
Manifold / Barometric Pressure
2 x Lambda
Oil Pressure
Fuel Pressur
Oil Temperature
Battery Volts
3 x User Defined Analogue (Shared Use), 1 x User Defined Switch
Launch Switch, 2 x Traction Control Switches
Shift Cut
4 x Wheel Speed
ALS / Second Map Switch



Outputs

8 x Coil Drivers
8 x Injector Drivers
Tacho
Fuel Pump Relay
Fan
Turbo Pressure Valve
Turbo ALS Valve
Cam Control Valve
VTEC Valve
Idle Valve
Shift Light
5 x User Programmable Aux (Shared Use)

[race911turbo]

Bad MAP sensor........turn on laptop, start S-80 software, start your engine, click on display and test function, > real time info,> check your MAP sensor reading. reading should be around 50.......

[race911turbo]

Originally Posted by EmptyGarage

I found the picture so I had to get them on. The Car is run with a DTA pro Engine Management System

Can someone help by identifying this part?

That is Bosch idle control valve.

[sjf911]

That is a very nice setup, Looks a lot like one of Chris's at TurboKraft. That is your idle control valve (ICV).
I would suspect your ICV or the programming for it is misbehaving. You need to be able to look at what the ECU is doing when the car stalls (is it even entering closed-loop control?) and document what the specifics are of your idle control algorithm (idle advance, ICV frequency, PID values, entry criteria, etc.). It sort of looks like a 2-wire ICV which I know others on the MS forums have had issue with in a PWM mode. The stock Carrera is a Bosch 3-wire which I have used without issue in this mode.
Do you have any way of logging your ECU data or interfacing with it using a laptop? If not, you could remove the ICV and thoroughly clean it or empirically replace it and if that doesn't fix it then you will need to find someone who can work with your specific ECU to diagnose the issue.

[race911turbo]

Check your MAP sensor reading with laptop first, for DTA system you need to have Win XP.
Do you have Dyno box? it is a control box for ECU link to laptop...

[xbmwguy]

wow nice looking set up but a half bay???

[Ken911]

he still has AC.

[EmptyGarage]

I've connected the ECU with my laptop and made two videos; 1) shows the general engine settings and things like the idle control setup 2) is real time readings while car idles and then is given some throttle.

The car worked fine before so I'd like to approach this issue assuming that the tuning is correct and that some sensor or other component has failed.

This is first attempt at recording computer screen with camera and posting to you tube. the videos are best watched at full screen. If they are not clear enough let me know and I'll repeat in the next few days.

Video 1 Movie 0001 - YouTube

This is a bit long but I was trying to give time to read information on each page displayed..

Video 2 realtime data - YouTube

This is a start-up after 2 weeks of not starting. the idle seems to be searching for correct RPM more on second start then first. Although DTA screen short only shows small rise in RPM when I give the throttle a push the in car tach registered a 5ooo rpm peak when pressing throttle.

[race911turbo]

Okay, you got DTA P-8 pro. For your idle parameter > MAX duty cycle > I would reduce it to about 50%.
DTA P-8 pro idle function does not work well for me, my idle control valve was 3.2 Carrra 3 pin idle control valve. Now I ran my DTA P-8 pro without idle control valve.
You got early 964 2 pin idle control valve, there is a screw on the idle control valve body, you can adjust you idle speed higher. BUT..........it is easier to disconnect your idle control valve to locate your problem. Use 2 plugs to block idle control valve inlet and out let first.
Have you check your spark plugs, coil pack, spark plug wires? MAP sensor looks fine but set your General Engine seting >pressure ,KPA to 80 ( just incase MAP sensor fail you can be able to drive home.)

[EmptyGarage]

I'll start by removing the ICV to clean and check its operation. When I have it removed I'll plug the inlet & outlet and try starting to see if issue persists.

Running car without ICV should tell me if the ICV is regulating the idle or not. Once the ICV ihas been confirmed as operational and cleaned I'll install and running again to see if issue persists.

[Have you checked your spark plugs, coil pack, spark plug wires? MAP sensor looks fine but set your General Engine setting >pressure ,KPA to 80 ( just incase MAP sensor fail you can be able to drive home.)

I have not checked spark plugs, coil pack, spark plug wires ...The car starts fine and runs fine under power so I believe that I'm getting good spark. After ICV is eliminated as a problem I can move on to other possibilities.

I found this procedure for checking ICV:

To check the idle air control motor remove the unit, with the wires connected turn the key to the "on" position without starting the engine, the idle air control should move in or out. If the idle air control motor does nothing it has probably failed, replace it with a new unit and recheck system. Note: while the idle air control motor is removed clean (use aerosol carburetor cleaner) the passages the idle air control uses to control idle air speed, also inspect the idle air control for a build-up on the seating (pointed) end and clean as necessary.

[sjf911]

That looks like the description for checking a 4-wire stepper ICV like the GM.

[EmptyGarage]

With just a two wire can I just give the thing 12 volt or 9 volt from 9 volt battery and see if it is working.

Put 9 volts to the ICV and it snaps into action so with only 2 wires there is not much more I can check on this. the inside of the connecting hoses and ICV itself are clean of particles with only a small amount of oil when wiped.

I removed Intercooler to get to the ICV and I'm wondering if I can start engine with intercooler removed ?

Also if the car is started without intercooler would I expect it to perform differently at idle then with intercooler connected?

I want to start car without the ICV connected and with the two air hoses plugged.

RACE911TURBO stated "it is easier to disconnect your idle control valve to locate your problem." I can watch the realtime data from the ECU but what will I be looking for to locate the problem?

[sjf911]

The only 2-wire valves I have seen were open/close where voltage applied would open the valve and then they would close with spring action. Should be able to test it with 12V. Try blowing through it without voltage and then with voltage.