Cold Start Issue

[jazzyfunkykool]

I've had my Sniper now for 2.5 years, but have always had some "quirks" to how it drove. I've spent a lot of time on this forum understanding the system and tuning the system for better driveability.

I cannot seem to solve the cold start issue that I've been having. Car specs are:
1965 Mustang, Blueprint 302 long block, Summit dual-plane intake, Sniper EFI, Tri-Y headers, T5 transmission, hydraulic clutch.

Idle is at 800 and IAC is set to 2%-10% at hot (however, no matter what I do, sometimes it still get to 0% after being driven and it runs fine).

Currently, lows in Houston are in the 30°-40°s. The below test was with ambient temperature around 50°F:
1. Start car.
2. Car starts to ramp down idle progressively. (Sometimes it sounds like it's surging.)
3. Once the steep part of the idle Ramp Down has commenced, I put car in reverse and then 1st.
4. As I let clutch out and idle down the street, I come to a stop sign and depress clutch and apply manual brakes.
5. Idle drops and the car seems to shutdown, but then restart automatically. Sometimes it's very quick, other time it sputters, dies, and then restarts quickly. Usually I do not give it throttle because it catches itself.
6. Handheld restarts as well
7. Continue driving and now shift from 1st to 2nd, then depress clutch and apply brakes at stop sign.
8. Idle drops and car will do the same as # 5, but sometimes, fights before dying, catches itself, then restarts.

This continues to happen as I drive for the first 1-5 minutes. The idle is also very rough and choppy and there are a lot of vibrations in the car. It almost feels like it's misfiring.

AFR is between 12.5-14/15 during this time.

As the car warms up, the idle stalling stops and as it gets heat soaked, everything smooths out and no more stalling. The car drives beautifully.

I've tried to datalog this, but I don't know if it is datalogging properly because the handheld unit, and the fuel pump, reset whenever it stalls, but it automatically restarts. (I don't have to turn the key to turn the car over again.)

I've tried to upload datalogs that I attempted to do as well as my Global Config File, but the forum is saying I cannot upload .dlz files? EDIT: I have uploaded this now.

I'm not able to view the PC Tuning EFI software because I use Macs and do not have access to a PC right now. Thank you all in advance for your help.

[Danny Cabral]

Global Configuration Files (GCF) and Datalogs must be "zipped" (compressed zipped folder) in order to attach directly to a forum post ("Upload Attachments").

[jazzyfunkykool]

Thank you. That worked and I've uploaded the files. The 8.11.21 is the baseline tune that I believe I was operating from.

[GPatrick]

I'll have to look at the datalogs a little more, but initially you have a few potential problems. Closed Loop is disabled below 100°F, so when first driving you're only working from the Base Fuel Table. Second, CL Compensation has been restricted to 15% and at the end of datalog 1 when it finally goes into Closed Loop the Compensation is already at 12%. When troubleshooting a problem you should probably open up the Closed Loop to 50% so you can see in the datalogs what the system is having to do to reach targets. I would remove the temperature restriction. If it was disabled for some reason, that should be addressed rather than disabling a useful function.

Next, Acceleration Enrichment AE versus TPS RoC has been set to zero for a RoC of zero up to 13%. This will likely affect how the engine responds to light throttle input, likely more of an issue when cold.

You have a progressive throttle linkage. In some manifold configurations this can affect fuel distribution and the performance of timed advance. How is your vacuum advance connected (if used).

I don't see a full cold start, but many Holley supplied CTS sensors read incorrectly when cold. When the engine is fully cold from sitting overnight, turn on the ignition and before starting the car, navigate to the monitor display and compare the CTS & MAT values. The CTS & MAT should be within a few degrees. If the CTS is reading 10° or more higher than the MAT, it should be replaced. When the CTS reads high the temperature enrichment will be incorrect as the engine warms up.

If you're hesitant to make these changes, keep a copy of your current Config File. Make the suggested changes and then use Save As and use a new name to save the Config File. Load it up and see how it runs. If you don't like it, you can revert by simply loading your old Config File.

Some of your symptoms sound like EMI/RFI induced resets. These can be seen in datalogs as negative time values in the datalogs.

Also check your ignition switch wiring to ensure that the Sniper isn't shutting of randomly. If you are using the ignition switch to directly trigger the Sniper you may want to consider a relay. Your voltage signal does look pretty clean so you may have done this already.

[jazzyfunkykool]

You have a progressive throttle linkage. In some manifold configurations this can affect fuel distribution and the performance of timed advance. How is your vacuum advance connected (if used).

My vacuum advance is connected directly to the back of the Sniper. That would be ported vacuum, correct?

Thank you. I forgot to mention that I do have the progressive linkage. The tune that I was using, was setup before I had installed the progressive linkage. Can I do any of these changes inside of the handheld?

[GPatrick]

The ported vacuum does not work with a progressive link since there's no flow in the rear barrels until the rear blades open up at 51% in your case. Some use the full vacuum port and enjoy some additional timing at idle. There's no solution for the ported vacuum other than going back to a 1:1 link. The Config File I looked at had the progressive link selected.

I'm not sure which of the settings can be changed in the handheld, but they may be in the advanced tuning. It's easy to do in the EFI software, but it looks like your system is at least one version behind so you'd probably have to update Sniper if you don't have the EFI software loaded yet on the computer. There would be no running advantage with the new version, but the tune changes need to be tested one way or another.

[jazzyfunkykool]

Thank you GPatrick. I don't have a PC to get the EFI software, so I'll have to see what I can find with the handheld. In order of my plan of attack:
1) Check for EMI/RFI via the EFISystemPro.com process.
2) Check CTS and MAT temperature when cold and replace CTS if spread is more than a few degrees.
3) Move vacuum advance to manifold advance.
4) Check Ignition switch wiring. I'm not really sure what I need to be looking for here. I'll take a picture of it going into the harness, as well as how the Sniper is wired under the hood.
5) Go back to my tuner to see if we can play with the Closed Loop and enrichment settings.
Is this good?

[GPatrick]

Sounds like a good plan.

[jazzyfunkykool]

OK, so checked the CTS and it's way off. Ordered this part to replace it with: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1. I'll post back when it arrives.

[GPatrick]

That should do it.

[jazzyfunkykool]

OK, got the new CTS sensor in and WOW. The car is so much better on startup and driving. There's still some issues with the cold start fuel as it's still a bit choppy, but infinitely better than where it was. I'm assuming the rest will have to be adjusted via the EFI software per your earlier recommendations of AE and Closed Loop Parameters.

The stalling issue is still happening when cold though, but because everything else is so much better, it's not as noticeable. I haven't had a change to start the car when it's dark to test the EMI/RFI, but I plan on doing so. I'm wondering if it will be better to upgrade the alternator to a new 1-wire or Ford 3G unit since the stalling seems to be RPM related?

I'm attaching some pictures I took of the current wiring of the Sniper. I have no idea what this means, but if there are more pics that you would need to see to make sure the Sniper is wired correctly, please let me know.

[GPatrick]

Your next priority should be the Closed Loop and Acceleration Enrichment setup as the values there are not conducive to good performance hot or cold. The Ford 3G alternator works quite well and is intended for use in EFI equipped cars. One-wire alternators seem to be hit or miss, they deliver a lot of amps, but not always a clean signal. I swapped to a Ford 3G on both of my old Fords and they provide consistent clean voltage down to idle.

[jazzyfunkykool]

Am I able to change this setup via the handheld, and if so, what specifically do you recommend I change it to?

I was able to change the temperature setting in the handheld for Closed Loop. I changed it to 0°F. It allows me to go to -40°F, but I felt 0°F would be good enough. Yes?

[Danny Cabral]

See post # 2: https://forums.holley.com/showthread...ot-temperature (Related Forum Thread)

[jazzyfunkykool]

OK, so I needed to disable the Minimum CTS temperature. Is this correct (pic attached)?