Deputy_Dangle

Hi guys,

I tuned my car myself last summer and for the first car I've ever tuned it has been running really well for the past year. Last week I installed an ATI 25% under drive balancer and now the engine refuses to idle.

I've tried everything I know to fix the idle but have had no luck. I"ve adjusted the idle airflow table, VE table, idle spark advance table, I tried pulling timing out of the high octane table, adjusted the target idle speed, and im sure I've tryed several other things I can't recall.

On the tune that was in the car prior to the pulley install, the engine will start and hold a fairly stable idle for 15-30 seconds and the die. If I up the Idle airflow table up a little it will hold and idle but it overshoots the idle as the revs fall and dies.

setup includes:
Built 347
Dart pro1 heads
Cam 232\234 .598 112lsa
Fast 78
Ford green top 42lb injectors
TSP LT's
Vararam
Innovate MTX wideband (not ran into HPtuners)

I couldn't figure out how to attach scan\tune files to this post but I can email them if anyone would like to look at them. Any and all help/suggestions will be appreciated.

Thanks in advance
Clay

Deputy_Dangle

This is the tune from before I installed the balancer

directnosfogger

set you first column in the spark column to like 34 degrees or somethin much higher than you would normally run. it should help offset your underspark table and help to keep it running at least until you can dial it in.

Deputy_Dangle

I tried setting the idle up a little higher, around 32* without much luck. Last week retuned the VE, Maf, and RAF. The idle is much smoother but it still will randomly die on decel sometimes, other times it will softly land at 950 and idle like a champ. It seems worse with the a/c on but does still die sometimes with the a/c off. If anyone can help me get this figured out I will paypal you some beer monies.

I still cant get scan files to attach but I can email them if anyone would like to look at them. This is the current tune.

tblu92

To correct engine dying or stalling after lifting OFF the throttle requires an adjustment to the "Throttle Follower" table---There are 2 one for in gear and one for P/N if an automatic
To correct dying surging stalling you subtract a % to the entire table Start with -10%
If you go to far you will get the opposite affect idle hanging--then simply back off some
When dead cold or 1st started warm the engine is in "open loop" mode after that it swithhes to "closed loop" sounds like it runs fine in OL but as soon as it changes to CL it starts acting weird--Looking at your mods it's most likely because of your LT's
Try setting the 02 switching points lower--( side affect of LT's is erroneous 02 readings)
remove about 100 points to the entire table That should help the CL operation
ALSO check your LTFT's and make sure they are all slightly negative or ideally 0 My guess they are way positive

Deputy_Dangle

Sorry, I forgot to mention the car runs in OL full time and was tuned using a Innovate MTX-L WB now logged through the egr.

When I retuned the VE all trims were +\-5%. But I had to scale the VE back at idle a fairly good bit because the idle is more steady when lean, I feel this may be because the WB is not very accurate at idle.

I haven't tried adjusting the throttle follower because I was under the assumption that it and the throttle cracker both decayed to zero when the clutch is pressed, I may be wrong though so I will defiantly give it a try. I have adjusted the throttle cracker a little but it didn't seem to do anything.

Again, thanks for the help

tblu92

I don't think you are getting fuel trim corrections when running in open loop-Even if your data logger shows you are--In true OL mode the fueling is set entirely with the Open Loop Normal table---This is the drawback of an OL tune---But in some applications you have no choice-----In your case----I see NO reason or advantage for not running the STOCK MAF closed loop tune---Your cam is easily tunable as are your LT's and your large injectors ( Ford 42 LB redtops are an overkill for your application) remember Ford injectors are rated at 3 BAR so on a 4 BAR LS engine they are more like 47 lb.
My old car with 475 crank and 390 RWHP I ran the stock 28 lb injectors with absolutely no issues---Larger injectors than needed don't make more HP and are a bitch to tune for driveability--seems like exactly where you are !!! make sure you have scaled your IFR table correctly---put the MAF back on!!!!

Deputy_Dangle

I agree that this is a very tunable set up. I still run the MAF, I am just in OL, I'm not running SD. I scaled the IFR table with one of the calculators found on HPTuners forum which shows the green tops to be about a #52 injector at 58psi.

The VE and MAF are tuned via AFR error histrograms that log my wideband and are for the most part =\- 5% for VE and +\- 2% for the MAF. But i have scaled the idle areas of both VE and MAF back about 15% because the car seems to idle much more steady at a AFR reading in the high 15's to low 16's. But I believe the AFR reading is off at idle due to the cam overlap and LTs.

The car idles very well with no surging or dips if it catches it self, but about 1 out of every 4-5 times I clutch in and roll to a stop the car will die. Other than that the tune seems to work very well.

jarnold

Could be as simple as a dirty EGR Valve. That will make it idle badly. Leans it our getting to much Air if it stuck open at idle. As old as your car is this could be the problem.

Deputy_Dangle

I wish it was that simple but the car doesn't have egr.

tblu92

So if you are running your MAF and trying to tune simply with the VE table you are NOT using the MAF table to correct fuel trims you will find that it takes hours and ours for the VE table adjustments to take affect ----- MAF changes happen immediately
I think oyu are wasting your time to correct the LTFT's using the ve table
Remember the VE table is only used during rapid changes in airflow below 4000RPM'a
So you are better off to make LTfT changes with the MAF table--The throttle followwr is used all the time to correct dying and surging-- regaurdless of a CL tune oe an OL mfless tune--- If I were tuning your car with your cars intended use I wouls absolutely tune using the MAF which wi;; make drivability and HP a the best numbers

Deputy_Dangle

I appreciated your help but I don't think we are are on the same page about what I have done. I reread this thread and it may be my fault because I haven't given out very much information on what I have done. So let me try to explain better.

Last Summer a friend and I tune my car after I installed a new engine. My friend has tuned many cars for local guys and I had faith in his abilities to do a good job. After the tune the car always ran well although somewhat rich at idle. A few months ago I bought an ATI UD balancer for the car and after the install the car refused to idle at all.

I had HPtuners so I began looking at the tune an noticed it seemed pretty far off from what it should have been. The injector data was incorrect and the VE tables had been scaled back to compensate for the bad data as well as the MAF table not being tuned. I erased this tune completely and started over with the stock tune.

I made idle adjustments to the stock tune so the car would idle in garage and I could get started tuning.

First I failed the MAF, set the tune to speed density and tuned the VE tables so that fuel trims where +\- 5% using AFR Error% histograms that loged my wideband, I didn't use LTFT's. Once all the fuel trims where in order, I set the tune back to MAF OL and failed the VE table and tuned the MAF Table to +\- 2% using a AFR Error% histogram also using my wideband and not LTFT's.

Once the MAF table was in order, I set the tune back to OL using both the tuned MAF table and VE table and I revisited the Idle to attempt to nail it down. I got the idle very steady while at 0 mph but sometimes he car would die when rolling to a stop in neutral. This was somewhat a random event as I couldn't seem to pin down a certain scenario that caused the engine to die other than it usually only happened at lower speeds. I thought the throttle cracker may be off at lower speeds but any changes I made didn't seem to help the situation.

The car is still in OL with all fuel trims disabled as it has always been. But it is a using MAF and VE, it just isn't using the narrow band O2 sensor's for fuel adjustments.

Last night I added 60% air to the throttle cracker in 400-1000rpms columns and smoothed to the rest of the table. I drove it this way for about an hour, and while it never died it did dip down to around 650rpm each time I came to a stop. I added about 3* timing to the idle area of the HO timing table and smoothed to the surrounding cells and this seems to have helped alot. It now idles around 28*. The Rpm's now will dip to about 850 rpm and surge back up to around 1200rpm where they stay until I reach 0 mph where they fall to the commanded 950rpm. I think I may have added to much air to the throttle cracker which may be causing the surge but I may not really sure.

Again, thanks for your help Tblue92.

tblu92

Well from what I learned at EFILIVE the only time you need to tweak the cracker is if you install a larger T-Body--- Your symptoms sound exactly like a follower issue
Remember that the only time the VE table is used is during a "rapid change in airflow below 4000 RPM's" and then only as a reference to create an average--So my opinion still stands that all your tweaking of the VE table to correct idle and dying problems is useless---subtract 10% to your follower to eliminate idle hunting --rinse and repeat

Deputy_Dangle

I also thought adjusting the cracker was more of a bandaid than actually solving whatever problem I am having, but it worked so I went with it. I will try adjusting the follower with the stock cracker table and see what happens. But do I need to reduce the Follower airflow table or the follower decay?

tblu92

Decay rate "in gear" or in "P/N" wherever the problem is --NOT the delay rate----