Idle Problems - LT1 w/New 24X system

[tes96ta]

I recently upgraded to the 24X LS1 Ignition system due to an Opti issue. I will say that my engine idled like a champ on the stock opti setup but at high rpm the opti just came apart internally. Anyway I have a fresh built 383 LT1 engine. Fairly aggressive cam, CNC ported factory heads intake so and so forth. Anyway Like I said the engine idled awsome with the opti but since I've upgraded to the 24X system I'm having all kinds of idle issues to make it simple here is a list:



Terrible cold idle won't run unless I keep foot on the throttle

Very erratic idle once warmed up. Seems to idle fine one minute than it keep wanting to cut out the next minute.

As time goes on the idle seems to be getting progressively worse.

When warm the idle some time won't hold and I keep my foot on the throttle and then all of a sudden the RPMs just shoot up for some unknown reason.



I just got an HP Tuners Suite and been trying to see if I can locate a problem. I'm not super versed in tuning but I know some basics functions.



From what I can see Bank 1 LTFT are pegged out. I'm not sure if its rich or lean new to HP Tuners Dash Board but the meter read full to the top and indicates 25.0. Bank 2 LTFT seem to be right in the middle.



Anyway I'm not sure if I have a mechanical issue (nothing mechanical has been changed) or if I have a tuning issue???



Any help??

[flame]

Do you have the fuel injector bank table correct for the LT1 firing order?

[tes96ta]

I had the base tune completed by PCMforLess.com. I assume they did it correct. Though I will say I've been reaching out to them for help and I haven't gotten much of any.

[tes96ta]

This idle issue is driving me nuts. Today while trying again to get it to idle (with negative results) I noticed something odd. When I had the engine off and the ignition on I was looking at the HP Tuners Dash board and Chart. With the engine off and ignition on I noticed that the Bank 1 LTFT was pegged out to 25%. When I touched the throttle just enough to open the blade to 2% the LTFT reading went right to 0. Then when I let off the throttle and it went back to 0% the LTFT jumped back up to 25%. Is this normal???

[540gts]

Did you get it straightened out? Sounds like I have about the same set up and I would be glad to share my tune with you, it idles great. I am out of town till next week, but I could post it then? It's a 383 forged 11.4 compression, 195 AFR heads, 58 mm T body, 238/246 605/618 110LSA custom comp cam

Also I was having some issues like this when I started a thread a couple weeks ago, you might search under my threads,

[tes96ta]

I'm still having the problem.

Here are my Specs:

Cam Specs: Intake / Exhaust
Valve Lift .604 / .577
Duration @ .050" 238.1 / 242.9
Adv. Duration 271.7 / 274.2
Lobe Separation 108.0*

Vacuum @ idle approx. 850 rpm 8"-10"

CNC Ported Stock Heads and Intake
12.4:1 Compression
58mm TB
Kook Headers

[540gts]

OK That's what mine was doing and I had the Left bank and right bank O2 sensor wires switched. I will post tune when I get home, wont be until Tuesday or Wednesday. our spec are not to far off, of coarse you will want to save your tune and then save mine separate. I am having shift issues with my 4L60E, have you had any trouble with yours?

[tes96ta]

Its funny you mention that cause I noticed recently that my trans has been shifting odd lately

[540gts]

Mine has been a nightmare, tuning the trans sounds so easy, but there are some tricks to it, just got mine straightened out today, When you rev that fast and make that much power there is more to it than shift points. my stall is 3500-3700 Double D, what is yours?

[tes96ta]

3800 vigilante

[jason k]

Post your tune and a log of it running and trying to idle And did u do anything to the trans for the conversion??? U will need to swap valve bodies, Efi connection recommends a 97 and up transmission, the 3-2 shift solenoid and valve line up are different among other things. Been fighting with mine for awhile Finally got it straightened out Hopefully....

[540gts]

Post your tune and a log of it running and trying to idle And did u do anything to the trans for the conversion??? U will need to swap valve bodies, Efi connection recommends a 97 and up transmission, the 3-2 shift solenoid and valve line up are different among other things. Been fighting with mine for awhile Finally got it straightened out Hopefully....

I am the same way, been fighting with mine, I haven't changed the valve body and I am using a 1 PC trans, which is 95 or 96. I think I finally got it but won't know for a few (out of town)days, the tune was very difficult to figure out, especially WOT, much more than just MPH and RPM. Especially on high HP, high torque, high stall, but shifting good now, going to the track next Thursday, hope it holds.

[tes96ta]

I never knew anything about converting the trans over to an LS1 version when doing the 24X. I currently have a 1994 fully built trans in the car. I have noticed that since the conversion the transmission has been acting different. Before the conversion it shift perfect. Now it shifts though the gears quick and TCC Locks-up as soon as it hits 3rd gear no matter the speed. It never used to do that. And yesterday after driving it I noticed trans fluid on the floor. No leaks anywhere then I discovered that the fluid was coming from the vent on top the trans. It's never done that. So do I need to get a completely new LS1 version trans??? Can I install a LS1 style trans valve body into my 1994 4L60E?? THis is all new to me but the thing with the trans is completely new information.

As far as the idle goes it still will not idle when cold. But once it gets to 170* it idles perfect! Cold Idle is just a beast!! I just don't understand why it idled perfect hot or cold with the old Opti but now that I've converted to LS1 PCM and coils now the idle is a mess. I just cant figure it out. Anyway I could post the tune and a log of it idling I just need someone to explain to me how to do it.

If someone could answer these questions at least the trans question for me ASAP. I planning on taking the car on a trip this thurday and I need to know what to do before then. THanks everyone for you help and keep the suggenstions coming.

[540gts]

I am far from expert, but I am learning. The problem is not the conversion, or the PCM it's the tune or the information in the PCM that has changed and now needs to be corrected. As far as the trans goes, some people get by without changing anything and others have to change things, if I remember correctly it's the 3-2 downshift solenoid and I think one other thing, will check for you Tuesday. Was the converter installed prior to the conversion? With mine it took some time getting it to lock and shift correctly as well as the WOT and non WOT shift points. Not sure why the mail order tunes have trouble with this conversion but they do. I started with a PCM for less tune, motor was fine trans was terrible, then a Schwankee engine tune, once again motor was fine but trans was terrible, after a lot of research and help from a local friend I am getting it dialed in.

[540gts]

As far as posting tune and log I will try, hope I don't leave any steps out.

1 you hit reply 2 then hit go advanced 3 then scroll down and you will see "manage attachments" click on it, 4 then top right hand corner you will see"add files" 5 this will open up your HP files, double click on the files you want and they will load in the top box. 6 then drag files from the top box to the lower box and click done.
I am on my IPad so I can't be sure I didn't miss any steps, but I don't think I did.
Hope this helps

[tes96ta]

Yea I had PCMforless do my original tune with the stock ignition and pcm and it was right on the money. So when I decided to do the 24X I was told they could do that to. So I had them do it and it's been problematic ever since. And now that I'm having issues their customer service is not what I was expecting at all. All Bryan keeps telling me to do is "open the Throttle blades it's not the tune" I did that and it doesn't help at all. I'm not even going to attempt to try to get there help with the transmission. So I'm done with them. They can clearly do a factory tune but out side of that I don't think they know what they are doing. The converter in the car is the same one that has been in there for a while now. I will try to get everything posted later. Got Mother's Day stuff going on today.

[tes96ta]

As far as posting tune and log I will try, hope I don't leave any steps out.

1 you hit reply 2 then hit go advanced 3 then scroll down and you will see "manage attachments" click on it, 4 then top right hand corner you will see"add files" 5 this will open up your HP files, double click on the files you want and they will load in the top box. 6 then drag files from the top box to the lower box and click done.
I am on my IPad so I can't be sure I didn't miss any steps, but I don't think I did.
Hope this helps

I hope this worked. Anyone feel free to look at the tune and share your opinions. I'm still working on trying to figure out how to data log and save.

Base PCMforLess 383 Street Tune.hpt

[540gts]

I hope this worked. Anyone feel free to look at the tune and share your opinions. I'm still working on trying to figure out how to data log and save.

Base PCMforLess 383 Street Tune.hpt

To log, 1 hook up HP tuner and open 2 start car 3 click on start log in the upper middle of screen, open , it will take 5 seconds or so, when finished click on stop log, then click on play back this also takes a few seconds, if it's something worth saving? Save as. You can choose the display you like either gauges or graph, graph you can pause it and move your mouse back and forth to check any given moment in the log. Also not that in log play back at top of page you can adjust the speed 1 through 10.

I presume you know this but, in the gen 3 section there is a transmission threads that deal with transmission alone.

[tes96ta]

I presume you know this but, in the gen 3 section there is a transmission threads that deal with transmission alone.

Yep just started a thread over there.

[tes96ta]

Poor Idle Log.hpl


Heres Alog for my idle. Can anyone tell what is wrong?