Can't get my car to idle!

[RedDragon93]

I've been battling this thing for a few months. Not sure if anyone can get me any insight? Car runs like a scalded dog but it will not idle to save my life.

[Six_Shooter]

What is the engine and components you are using exactly?

What have you tried?

[RedDragon93]

5.0 SBF Stock Bottom End
Trickflow 11r 190cc heads
Trickflow Stage 2 Cam
Trickflow Track Heat Intake
39/lb Cobra Injectors

I don't know what to try honestly. I've smoke tested the intake for vacuum leaks and found nothing.

[Six_Shooter]

Stock TFI?

As many details as possible to help us help you...

[RedDragon93]

Yes I have the stock TFI. I am using a Blaster coil and MSD plug and play dizzy.

[Six_Shooter]

So by "can't get it to idle", you actually mean that it doesn't have a stable idle?

I see the RPM vary quite a bit on your MSL.

Usually this is a VE table and/or spark issue from my experience. Your VE table is rather odd, with a peak kinda in the middle of it. You might want to fond a VE table for a similar application, or maybe try out the VE generator in TS (If you have a registered copy).

Your MAP and PW follow each other. Looking at where the VE and spark tables are following, there is quite the difference in VE there.

What I do when trying to get a stable idle on a fresh tune is to set all of the cells in the area where the engine wants to idle to the same vale, this way the PW will stay quite stable and should reduce any surging. Once you get the surging to stop you can then get the engine to idle lower through VE, SA and IAC/throttle angle adjustments. I sometimes also set all of the cells in an idle area of the SA table the same as well, especially if the engine does flatten out enough for my liking with just VE adjustments.

[RedDragon93]

The VE and Spark tables are from a base map provided by DIY Autotune. I'm using a MSPNP2 for a foxbody. I started tuning the car a few days ago and quit to try and figure out the idle issue, which is why that peak is there.

I'll try to set spark and fuel tables to the same values in the cells where it should idle and see what happens.

[Six_Shooter]

That's a really odd VE table for any application. It's something I wouldn't even attempt to use personally.

However, don't just change the VE table where it should idle at this point, change where it is idling. Meaning change the cells around where it should be idling and even beyond that to get the idle stable, then you can start getting the cells outside of where it actually idles to where they need to be. It's a back and forth game, and a lot of trial and error sometimes.

I have also found that retarding timing can smooth out a misbehaving idle to get initial tuning done, then add more timing back in once you get the VE close. After adding timing back in you might find that the AFRs go a bit lean that will cause a need to readjust the VE table slightly.

Don't shoot for a 14.7:1 (Gasoline) AFR ratio right away, shoot for low 14s to high 13s to get a stable idle and then you can lean it out after you get it stable, again adding timing might be all that is needed to leaning out the engine to get where you want it.

You might also be shooting for too low of an idle depending on your cam. Some engine just will not idle like a stock engine at 650 RPM, some need 700, 800, 1000 RPM idle depending on how radical the cam is.

A stable sufficiently lean idle is generally one of the most difficult things to achieve when it comes to tuning EFI. You're trying to get the engine to produce just enough power to keep it from just stalling essentially without running too rich and be able to return to that same stable idle after the engine has seen at load at higher RPMs. This is why I recommend what I do to novices, go higher on idle RPM to start with, go slightly richer than you want in the end, get it stable first, then lean it out and reduce idle speed.

[RedDragon93]

I'll give all of this a shot! I hope I can get it worked out!

[RedDragon93]

It's idling a ton better, but now it's just high. I have the fuel dialed in around 14.0 at idle but it's around 1000 rpma. Ideally I'd like it to idle around 800. Also, on a cold start if I back the idle screw out it will not stay running unless I'm on the gas. Any ideas? I just assumed once fuel and idle rpm were set the warmup enrichment would take care of the rest?

[slow_hemi6]

Very similar duration cam to mine. I can idle 800 in gear ok but that means I have an out of gear idle of 1000rpm. So for a manual car 800 would be my normal idle with my 226/230@0.050 duration. I don't think you are using idle advance correctly. At the moment you are set for 1000 and that is where you are actually idling. No headroom there. You should have your RPM below figure more like 1200 because it is your TPS below that should be your primary threshold. When ever you want to accelerate you push the pedal which throws the idle advance out and you go back to spark table. Set like this I run 17 degrees of idle advance which helps a lot.

[RedDragon93]

Which idle advance mode should I use??

[slow_hemi6]

I use load but rpm should work as well. All of the threshold are used for the operation of either of those modes. It does not go into idle advance till all thresholds are met. if one threshold goes outside its set parameter then idle advance drops out.
If your rpm threshold is equal to your idle then it can flip flop in and out of idle advance even if the other thresholds are being met.
You need some hysteresis on the thresholds that vary a bit like rpm does. If you could get your idle to 800 rpm then 1000 rpm would be a pretty good threshold giving 200 rpm hysteresis but until/if you get to that idle rpm you would need more like 1200 rpm. (200 above current idle).
The fastest reacting thresholds are probably TPS, MAP then RPM. I like to set tps as the tightest threshold as it is fairly stable and fast reacting. This is how I like it set as I drop a couple of degrees when coming out of idle advance and into spark timing map control. ie when I put some load on the engine to pull away.
I have a milder and lower compression engine that I have at 20 degrees idle advance. The one I have at 17 is set there because it makes a lot of heat above 17 with 11:1 comp.

[RedDragon93]

Update for you all. Car has been sitting for most of the time in between my last post and now. I can't seem to wrap my head around this idle issue, but I don't want to keep trying to tune if something is out of whack. I had a friend come by and play with a few of my settings in TS and we found that when we backed off the timing in the IGN table it had a dramatic affect on idle stability, however we had to lower the IGN timing in the IGN table to 5 degrees to get a fairly stable idle at around 800-900 RPM. This seems way off base to me. I will load current tune and data log for viewing. Any help is appreciated.

[whittlebeast]

Flatten the VE all around where the motor idles and verify if you set the timing to fixed timing at some degree that you have a known good timing mark and verify the timing comes up correct at the crank.

Andy

[RedDragon93]

I'm starting to wonder if my timing is not set right. But when I set the MS up to run 12 degrees fixed, and I crank the dizzy to match, the idle was way off since MS was commanding 12 and the motor liked my setting of 5 if that makes sense?

[slow_hemi6]

I have never seen a TFI with a 0 degree trigger angle in the Trigger Options. Normally around 10.