engine idles great cold but poorly when warm question

[maca]

Hey guys
I have a 360 Magnum engine that is supercharged with a vortech supercharger. It is running a solid roller cam. I set the valve lash when the engine was hot to the cam specs. I then measured it when it was cold and copy that across the engine.
When I first start the engine when it's cold it sit's there and cams over very evenly and very smoothly. Once the engine reaches running temperature the idle changes to a very rough shaky uneven idle. The only thing I can think of is the valve lash that may cause it but I have checked that. I am running a fitech throttle body EFI System which controls afrs.
Any ideas on how to get a better warm idle.

[PackardV8]

JMHO, but unlikely the valve lash is causing the rough idle.

Yes, " I am running a fitech throttle body EFI System which controls afrs"

Even so, you really, really a digital readout from your O2 sensor. I'd been fiddling carbs and EFI for fifty years and didn't know how much I didn't know and/or was taking for granted until I got that readout. Until you can follow in real time, you are just assuming the FI Tech system is doing what they said it would. There can be vacuum leaks, sensor, IAC or wiring problems that confuse the simple brain box and might be causing your idle fluctuation.

[user-23911]

Did you sort out that long list of other problems?

[MadBill]

I'd say there's zero chance that the wider hot lash is hurting the idle; the opposite is more probable. Running a carb with no choke, an engine that cold starts and runs well immediately is too rich. Check over your cold start spark, fuel and RPM tables and compare with the warmed-up values, looking for any big changes at the temperature where the idle falls apart.

[racear2865]

Have you run a copy off of DATA LOGGING. You can see what is happening at idle. Also which cam setting did you select 1 or 2 or 3 or 4. At idle, you are not totally on AFR. send me a copy of data log at idle and I will try to help. You have a few idle adjustments that will help. this what the file will look like oops just found will not allow me to upload .csv file

reed

[Amilcar]

It has a display to show parameters on a running engine doesn`t it? MAP/AFrs/RPMs/Air temp/water temp
You`ll see right there , what`s going off when it gets hotter.
A simple minor leak on exhaust and the lambda sensor has no clue what`s going on.
Superchargers blow air crazy hot too, the box may be pullling off timing advance/fuel if not properly tuned.

[CharlieB53]

The first thing that comes to mind is temp sensor inaccurate. The O2 sensor should show the difference as the engine warms. But if the temp sensor isn't correctlly telling the ECU the motor is warmed it may be staying way too rich and misfiring.

[My427stang]

What is the IAC motor showing for a value when running, both hot and cold?

Lot's of FITech users fight with static throttle plate setting at initial setup. Some have too much IAC compensate for tight plates, some have not enough. Seen it reported both ways.

When you look at that, look at all the log values, seen reports of MSD feeds doing funky things to RPM values in the FITech software too. All easily fixed, but the logs are your friends

[Paul Rig]

why are people using wideband's at idle anyway?
Your better off dropping fuel till it stalls. Then start adding it back till it starts and idles properly while at operating temp. then you can start working on your cold/start map.

[RednGold86Z]

What is your Idle Target RPM? Huge cams may need over 1200+, while a stock ish cam can handle 650. Adjust (open = counter clockwise) the throttle screw to get the warm IAC steps to basically 0 (more open screw results in lower IAC steps). With automatics, I often cheat, and when in park i have it at 0 and have a slightly higher than target idle speed.

What is your IDLE Target AFR? (big cams need 14.3+, medium cams 13.5 - depends on the engine, some like lower).

What is your idle spark advance? (bigger cams need 20+).

What is your idle MAP when running? A big cam is 80+ kPa, and needs a high idle target, high advance, and leaner target usually. A medium cam is less than 60. Stock is low 30's.

[user-23911]

That's what a vacuum gauge is for.

Use it to get best vacuum at idle while adjusting AFR and timing.

Nothing else required.

[RednGold86Z]

That's what a vacuum gauge is for.

Use it to get best vacuum at idle while adjusting AFR and timing.

Nothing else required.

If you did that, you'd end up typically too rich and "too much" timing. With a properly set up EFI with wideband AFR control, with timing control and idle control, you can usually get pretty close to ideal without the guesswork, and you can find the right combination on the fly from button clicks. It has a vacuum gauge built in with the MAP sensor.

For idle spark advance, with the FiTech system (except the versions that don't have timing control), there is a stability control built in that automatically advances when the RPMs drop, and retards when too high. If the base idle advance is set too high, the advancing when RPMs drop will have little effect, and things can get unstable.

If the AFR target is set too lean at idle, the engine efficiency changes from using all of the air to using all of the fuel. The fuel is being varied a bit to get the target AFR, and things can be a little unstable if it's targeting mid 14's, if timing control isn't used.

Other things that can possibly be happening are EMI related, causing errant signals on the RPM input (TACH) - watch the dashboard in the handheld to see that the RPM signal is not showing anything unreal. Make sure no wires are touching or very near the plug wires and CDI wires if you have it.

[maca]

Hey guys thanks for all the responses.
I will be working on the car again this weekend so what check all the suggestions out.
One very frustrating problem I have is with the fitech is since I bought it new from fitech 10 months ago the data loging option is not working. I have been arguing with them all this time to try and get it fixed. But they just keep giving me excuses so I can't data log. This is been going on for 10 months.
I checked the AFr etc at idle and they are very similar to the once when hot. But I will take note of what they are and post them here

[GT350_R]

Hey guys thanks for all the responses.
I will be working on the car again this weekend so what check all the suggestions out.
One very frustrating problem I have is with the fitech is since I bought it new from fitech 10 months ago the data loging option is not working. I have been arguing with them all this time to try and get it fixed. But they just keep giving me excuses so I can't data log. This is been going on for 10 months.
I checked the AFr etc at idle and they are very similar to the once when hot. But I will take note of what they are and post them here

When cold the EFI system is not going to reference the 02 sensor, then as temps come up then the computer will look at the oxygen sensor. I'd hazard to guess that since it runs ok on the hard coded cold start program and runs badly when temps start to come up, and it would be looking at the 02 and fuel maps, then likely the map needs reworking. This assumes no air leaks anywhere close to the 02, including the header gaskets or header/collector gaskets.

If the FiTech allows for modifying the map, you really need to get the data logging working and then get someone to look at what it shows. But,first be sure the O2 is good, no codes, and be really sure there are no air leaks which could be confusing the O2.

Another thing to consider, If data logging is not working, maybe there are other, bigger problems, like a bad ECU.

I tried to get an MSD and a FAST EZ systems to work on my motor before I gave up and moved to the FAST Sportsman with programmable fuel maps and solved all my problems. Good luck.