Ford 289 surges and coughs

[david martin]

Hi,

I have a boat with a 66 Ford 289 with EDIS ignition and port injection from a Ford 5.0 that I'm having trouble idling. It will start at 10% throttle position but surges, coughs and dies after a few seconds.

I read coughing is a symptom of a lean fuel mixture and have played around with the WUE values in the warmup wizard. I increased the WUE values for 80-130 degs 10% but saw no change so went back to default.

Attached is my tune if anyone wants to review it. Thanks for any help.

[Steven]

David,

You might need quite a bit more then 10% until your VE table is dialed in. Don't forget to adjust the after start enrichment too.

Steven

[david martin]

David,

You might need quite a bit more then 10% until your VE table is dialed in. Don't forget to adjust the after start enrichment too.

Steven

Steven,

Thank you for the fast feedback! I'm hesitant to adjust the WUE much more due to the mega manual suggesting no more than 15%. Since I saw no change at 10% I figured it was something else. I did however adjust the ASE cold and hot % values + and - 10% and unfortunately did not notice a noticeable change. Each new setting I tried twice.

[kjones6039]

I submit that a data log to go with that tune would be in order.........

Ken

[david martin]

It idles!

While searching "surge" I came across a post suggesting to increase the req_fuel setting. I previously had it set at 19.9 which was what the calculator recommended. I increased to 22 and noticed improvement, I ended up at 24 with a decent idle.

Ken - I attached my tune and data log at req_fuel of 24. If you or anyone else is willing to skim through and point out any concerns I would greatly appreciate it!

Thanks

[david martin]

Well... I got a little ahead of myself. At 10% throttle and 1200 rpm it idles smooth, but if I drop the idle below 1200 it surges between 600-1400. I increased the req_fuel all the way to 26 and saw no change.

[kjones6039]

Haven't had a chance to look at your logs yet, but something did jump out at me. I don't agree with jacking ReqFuel around in order to change fueling. That can/should be accomplished using the ve table and a number of other settings, such as WUE, ASE, etc. Bottom line...... Let MS calculate it and leave it alone!

I will look at your log this evening and see if we can identify any other issues.

BTW..... I see you have EGO disabled. Are you using a WB o2 sensor for tuning fuel?

Ken

[david martin]

BTW..... I see you have EGO disabled. Are you using a WB o2 sensor for tuning fuel?

Ken

I have a innovate LM-2 that I will use to monitor AFR. The LM-2 is a standalone AFR data logger, although I believe it use the standard LC-2 wideband controller that I could probably temporarily wire into the MS harness for easier tuning and data logging.

[kjones6039]

I could probably temporarily wire into the MS harness for easier tuning and data logging.

I have done exactly that with my own LM2 when I had a wideband failure...... You will certainly want to use a wideband to accomplish any meaningful tuning.

IMO of course.........

Ken

[david martin]

I could probably temporarily wire into the MS harness for easier tuning and data logging.

I have done exactly that with my own LM2 when I had a wideband failure...... You will certainly want to use a wideband to accomplish any meaningful tuning.

IMO of course.........

Ken

Ken,

Were you able to connect the wideband from the LM-2 and display the AFR in tunerstudio? Or did you view the AFR on the LM-2? After looking closer at my LM-2 it appears the controller is integrated into the LM-2 module.

[kjones6039]

Were you able to connect the wideband from the LM-2 and display the AFR in tunerstudio?

David,

The short answer to your question is........... Absolutely!
For all intents and purposes, it is the same as wiring up an LC1. You should have the cable (Innovate p/n 3811) in your LM2 kit. If not, they are available from Summit for $30.

Ken

[david martin]

If I return the req_fuel to the MS calc'd value what is the best way to control the surging?

Should I have IAC enabled? The MS manual recommends disabling the IAC until the motor is idling smooth.

If it matters, the IAC is a Ford 2 wire PWM.

[kjones6039]

If I return the req_fuel to the MS calc'd value what is the best way to control the surging?

The surging can be corrected by proper tuning of VE and Timing tables (among others). There is considerable information regarding idle tuning available in the Tuning portions of the Manual and this forum. You would be well served by searching for posts concerning surge issues. I can not over emphasize NOT using ReqFuel for this purpose. Hopefully, the guys with the big brains will chime in here and confirm what I have said!

Should I have IAC enabled? The MS manual recommends disabling the IAC until the motor is idling smooth.

My preference would be, to leave IAC disabled until you get the surging issue resolved and establish a stable idle. Just my way of doing things though.

IMO, you really need to get that wideband hooked up and going! For all the reasons I pointed out above.

Ken

[DonTZ125]

I'm not a Big Brain (tm), but everything I've read about tuning is in line with Kevin's comments - the ReqFuel term is a configuration value, NOT a tuning variable. Set it, forget it, then dial in your VE map using your WBO2 sensor.

[kjones6039]

OK, I give up! Who is this guy, Kevin???

Ken

[DonTZ125]

Like I said, not a Big Brain, and I need to occasionally pitch out cluttery things like unused 'v' and 'i' letters taking up badly needed room ...

[david martin]

Timing is something I haven't tried adjusting. I'll keep reading and maybe give it a try this weekend.

Should I be adjusting the VE table to control idle. The manual recommended a steady idle before VE tuning.

[kjones6039]

Should I be adjusting the VE table to control idle.

Certainly! You can adjust the cells in the idle area, of the ve table, in order to obtain the correct idle mixture.

Once again, this points out the need for a functioning wide band sensor!

Ken

[Steven]

David,

I respectfully disagree with Ken about wide band sensors (he is right about everything else, though).

You don't need a wide band sensor to tune idle VEs. As it says in the manual, you should tune the idle for minimum MAP (i.e. maximum vacuum) if your vehicle is not 'emissions-controlled'. Megasquirt isn't intended for emissions controlled vehicles. Try to lower the MAP kPa as much as you can by adjusting the active area of the VE table when fully warmed up and idling, keep the VE numbers relatively 'flat' around the idle speed and MAP, and you'll get the best idle mixture for your car.

In the case of emissions controlled vehicles, the catalytic converter needs a stoichiometric mixture, and a narrow band sensor is fine for this (especially at idle and under closed loop control conditions).

A wide-band sensor is mostly useful for tuning high load and high speed areas of the VE table. It can offer reassurance to those just getting started in tuning. But remember that racers of all sorts tuned very high output engines for many, many years before wide band sensors came out, and some of those engines ran pretty damned good!

Steven

[kjones6039]

David,

I respectfully disagree with Ken about wide band sensors (he is right about everything else, though).

You don't need a wide band sensor to tune idle VEs. As it says in the manual, you should tune the idle for minimum MAP (i.e. maximum vacuum) if your vehicle is not 'emissions-controlled'. Megasquirt isn't intended for emissions controlled vehicles. Try to lower the MAP kPa as much as you can by adjusting the active area of the VE table when fully warmed up and idling, keep the VE numbers relatively 'flat' around the idle speed and MAP, and you'll get the best idle mixture for your car.

In the case of emissions controlled vehicles, the catalytic converter needs a stoichiometric mixture, and a narrow band sensor is fine for this (especially at idle and under closed loop control conditions).

A wide-band sensor is mostly useful for tuning high load and high speed areas of the VE table. It can offer reassurance to those just getting started in tuning. But remember that racers of all sorts tuned very high output engines for many, many years before wide band sensors came out, and some of those engines ran pretty damned good!

Steven

Please allow me to clarify! My advice was based on my understanding that the OP already has an LM2 wideband.

Evidenced by this post:

I have a innovate LM-2 that I will use to monitor AFR. The LM-2 is a standalone AFR data logger, although I believe it use the standard LC-2 wideband controller that I could probably temporarily wire into the MS harness for easier tuning and data logging.

I have looked for and failed to find, in the foregoing discussion, anywhere that i may have told him that he could not tune idle without a wideband. I merely attempted to encourage him to install the one he already has! I would certainly never discourage any new user from using one for tuning all fuel related related functions, if he has access to one.

One last word and I will shut up and go back to my corner!

It can offer reassurance to those just getting started in tuning.

Does our OP not meet that criteria?

Ken