I, my Friend's John, and Glenn are at a loss. We have tried everything we can think of to try and solve this problem to no avail.

I did the 24x conversion, initial startup went well. Car fired up on ls1 tune. We looked at each other and was like yes it runs. Ok, well we contacted Ben (t/a Kid) I believe to help us with a base tune. (he has went well beyond anything we could have asked for, and spent a lot of time helping us). Im so thankful Ben.

Ok, well the car starts fine, drives great around town at partial throttle. and some aggressive throttle.Normal driving conditions the car is spot on. Will rev to redline smooth as silk. Go WOT, from low end rpms climbs fantastic. get around 5-5.5k rpm's and above then car starts to stumble. Every time it usually right around those rpm's. Sometimes might go a little higher. Have had very very few occasions where it would go to red line flawlessly. That usually happens when it has first been fired up and make a wot pass within a few minutes of running. Car seems to get worse as it gets to operating temp. When under heavy load it seems worse. Like on expressway in 5th or 6th and the car starts stumbling almost immediately.

Here is everything we have tried

Another set of coils - No Change

a new crank sensor - No Change

3 sets of plugs - gapped 35, 2nd set 50, 3rd 45 - No Change

A new set of plug Wires - No change

Changed location of ground for coils - No change

Changed and measured feed to coils - No change

Checked wiring going to crank sensor - checked good

Tried a different PCM - not a 411 like my original one was - No change

Tried a flash of different OIS on LS1 PCM and at the same rpms this one will just shut off completely. again drive around normal, will take aggressive acceleration, start great. under wot shut down @ 5-5.5k rpms. same spot the other ois stumbles.

oh yea logs show nothing, no knock at all. cam counts from what I know look fine, only thing u see in the logs are some dips in the rpms under wot. You can feel it much more than it shows on the logs. There are other things I am sure we have done, but just off top of my head this is what I remember. Glenn and John have helped so much, one (Glenn) gets like 3 hours of sleep a night between helping and going to work. The other (John) has spent his 3 weeks of vacation helping me on the car. for at least a week and a half spent trying to diagnose this problem. First part of the week was installing rebuilt tranny, 9 inch and various other things. I do not even get the code that shows I need crank learn. I am at a loss. Please someone help! I am open to try anything at this point. Please while my friends still consider me a friend.

P.S. This is no reflection on eficonnection. The parts they sent are of very nice quality. I am not bashing by any means just looking for some advice to solve this problem. We have ordered a single roller timing chain to see if crank walk is too extensive and maybe under hard acceleration is pushing the reluctor out of range of the crank sensor. Even though I am confused as to why this only happens after it get's warm. We are just out of options. I am running a cloyes double roller. If I remember right with the double they are at 1.017 and we was 1.019. close but just maybe not close enough. We have shaved the timing cover as well to move the sensor closer to no avail, nor any change at all.

parts used for 24x:
96/97 timing cover clearance for double roller
DIY wiring harness - Parts to complete the harness - BPautomotive
ls1 coils, and truck coils - Both sets tried

 

Silly idea, but try cleaning the MAF. Also, double check your grounds.

 

Actually, Not silly at all. But I knew there was more. We cleaned the maf as well as tried 2 other as Ben said the air looked turbulent while trying to help us get a tune. So now we have the stock one on cleaned with a screen.

We are going to go over all the pcm grounds again. Good call as that was on our list.

Thanks

 

Have you thought about trying the tune in SD?

Mine is a 24x conversion as well, and I am having tuning issues as well right now. I was seeing some stumble randomly, but mine was under partial and moderate load, not WOT. We did an SD tune in it and it fixed the stumble (but I am still tracing down a random injector pulse I am hoping a new PCM will fix).

 

Going to try the Single roller timing chain this week. We will see if this will take care of my problem. If not will try an sd tune. I am unsure at this point if it is anything to do with the tune. Or lets just say we have seen fuel trims from rich to lean no change and trims near perfect. problem still there. timing tables played with advanced and retarded and no difference. But it is not something I have completely ruled out. Going to try the chain and go from there.

Seems others are as stumped as I am? Not much advice being given. After grounds checks again, chain, and trying sd tune my only other option is going back to opti which is my last resort. But I am running out of options. It is painful to even think about that at the moment but again I am running out of options.

Call911 I do appreciate you taking time to respond as well as your advice..Thanks

 

It does seem complicated, and perhaps there's just not many people looking at this thread with experience enough to respond?

I don't know how the single chain would change anything, but then again, I'm not sure how doing an SD tune on mine fixed the same problem you are having, but it did. I am suspecting that in my case, its possible I have a bad MAF as I never changed of before just going SD.

At any rate, I wish you luck, and sorry I am the only one offering ideas. I would hate for you to go through all this and have to back to the options also. Its gotta be something. Just need to figure out what.

Have you checked the O2 sensors? If something is not sensing correctly it can throw off your ability to tune.

 

Before pulling the front of the engine apart to change the timing set, I would watch the crank sensor signal with an oscilloscope to verify the crank signal looks good at all RPMs.



EFI Connection's 24x system does two things:
1. Provide a 24x LS crankshaft signal.
2. Provide a 1x LS camshaft signal.

If those two signals are working as they should, then the rest is basically tuning (assuming all other sensors, harness, etc are good).

 

Yes both have been replaced with new o2's. And we are thinking possibility of single chain because of reluctor to block face on mine measured .002 more than efi connections standard for good on a double roller. We are thinking maybe a possibility of with maybe some crank walk at wot might be pushing it further. We will check end play once it's apart again this time. Some things we did not think about checking while assembling last time. I have tried 3 maf as well to no avail. Have tried unplugging maf as I assume that would put in sd but if so no difference. It's such a shame I ifni can not figure this out as the car is so responsive to throttle and smooth. Again appreciate your ideas and throw anything you got out there I'm game to try anything at this point. I'm sure there is something we are missing just not sure what it is yet. I will keep this updated as to what the single chain does once finished.

 

Thanks s10wildside got a guy local that said will check It for 70 dollars. Is it something that can be checked while driving as idle and revving to red line there is no stumbling. It is very smooth?

 

Is this 24x system made for the double roller? there has been many issues with people trying to keep a double roller as it moves the reluctor ring slighlty foward causing a bad reading I just stuck with a good single roller and never had a problem since.

 

They have a kit that works with a cloyes double roller, That is the kit I bought. it requires you to clearance your 96-97 timing cover or the purchase a billet one from eficonnection. It has been proven to work with the tolerances they have on there instructions, but I am .002 over. So thinking maybe with crank walk at wot it is pushing me just outside. will find out soon.

 

We have a 24x LT1 kit that works well with most double row timing sets. However, because issues sometimes arise when the aftermarket timing set geometry is other than stock, we designed a new 24x conversion that eliminates the double row timing set concerns (because it includes a new double row timing set with cam signal milled into the face of the cam sprocket). The first prototype is illustrated below. There have been very minor changes since this design. Estimated availability is fall 2013. Most parts are ready to go now.

Click on the image for a 3D PDF of this assembly.

 

FWIW, I am running a double roller (LT4 heavy duty). Mine was measured spot on and checked out perfect with the oscilloscope. My issue with he stumble didn't go away until I did a SD tune (there is more to the SD tune than just unplugging the MAF).

I am still fighting a random injector pulse. The tech from 24x had no ideas past what I had already tried.

 

will have to look into the sd tune more as it looks. Could you elaborate on what would cause the stumble using a maf? Is there something on the scans themselves that should reveal the problem to us? Everything seems to look normal to us, and nothing the tuner himself mentioned looked out of the ordinary.

Was thinking this was going to fix my problem. It will be installed tomorrow. Now I am starting to think maybe not. But anyways will rule out another possibility. Also will take it to get an oscilloscope ran on it to just be sure.

 

Well, like you I had a tuner do the tuning. Even he is not sure why the SD tune fixed it, but it did.

 

All the sweat and tears has payed off. I am one satisfied 24x customer. The car is silky smooth. Pull up top aboslutely np now. We switched to the single roller and measured all clearances again with this single roller was 1.007.

Call911, once again I appreciate you taking the time to help me try and resolve this problem. It really is appreciated.

I appreciate others advice on trying to resolve this as well. My intent was not only to look for help in resolving this but was also a point of reference for anyone else having the same issues. I know how frustrating it is when your hunting and looking for someone else having the same problems and when a solution is posted there is hope and a great possibility it will resolve your problem as well. Please always reply when the problem is fixed it helps other readers. I hate nothing more than finding someone with the same problem after advice is given then there is nothing from the op stating if fixed or not.

Thanks again a very happy 24x customer,
Mike

P.s. Might I add I a have the best friends in the world. thats right be jealous. lol they had it tore down for me last night. both at seperate times yesterday took time out of there day and went to the garage and tore everything off if I had gaskets I would not doubt they would have had it back together. That is just one of many many many things they do for me.