AdsoYo

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I just finished my 24x conversion and need some help. Vehicle info is in the sig. It fired right up when I started it, better than it ever did before. However now it sounds like it's missing (sounds like there's a giant hole in the exhaust) and the tachometer is motionless at 500 rpm while idling even though it sounds like it's at 800-900.

When I rev the engine, the tach moves fluidly like it should, although I'm sure it's reading low. The miss is still present at higher rpm's also. Harder to hear, but the car vibrates. I've got 3 trouble codes: P0463, P1336, and P1637.

I also can't shift into 2nd, 3rd, 4th, or 5th with the car on. Only 1st, 6th, and reverse. I haven't tried driving it on the street because of the miss, just idled and driven back and forth in the driveway.

One of the things I'm most concerned about are the timing gears. After I pulled the chain, I accidentally rotated the cam independent of the crank. I read on here that aligning the gears dot to dot is a fool proof way to ensure proper timing, so I went ahead and did that before putting the chain back on. Is this true and can I stop worrying about them being misaligned? Really don't want to take all that apart again.

I had PCMforless tune the PCM and BP automotive build the harness. Everything else came from EFI Connection. Any help is appreciated!

95TAVERT

I am far from a expert but I have went through a 24x conversion. There is a couple basic things you need to double check one is to make sure the firing order in the LS1 pcm is correct for the LT1. also make sure the injector order is correct, The LT1 is different than the LS1 also. You might also double check your Left bank and right bank O2 sensors, make sure they are not switched. Good luck

If you have HP tuner or some other tuning devise will tell you all this stuff, but its complicated also.

AdsoYo

iTrader: (1)

Yeah, I emailed EFI Connection and they said the tune is most likely the issue. Called BP and he said the same thing. Sent PCMforless an email but haven't heard back. I'm surprised it's a tuning issue. PCMforless said themselves, and I've read on here, that they have done plenty of 24x work. I could understand if it wasn't making the same power or something, but misfires? And 4 of my gears locked out?

Good news is EFI said my trouble codes don't relate to a poorly running engine. 0463 and 1637 should be programmed out and 1336 needs the crank learn procedure. They also said I installed the timing set correctly, whew!

AdsoYo

iTrader: (1)

I did some testing today using an Interceptor scan guage by Aeroforce. First thing I did was remove all spark plug wires and test their resistance. All of them were between 30-40 ohms. I reconnected them and jacked the car up. Sure enough, had the reverse lockout plugged into the skip shift. Started the car and it still sounded bad but at least now all my gears work!

I decided to drive it around the block. It was sluggish, it vibrated, it sounded bad, but it drove ok and never threatened to shut off. The tachometer always read half of what the actual rpm was. It reads 500 rpm when the Interceptor reads 1000 rpm, 1000rpm when the Interceptor reads 2000 rpm, 1500 rpm when the Interceptor reads 3000 rpm. By the way, there was never any backfiring or popping at any time during all this, just sluggishness and shaking. And the shaking/ vibration isn’t that bad.

I also noticed the bank 2 O2 sensor isn’t reading correctly. It wouldn’t move out from 445 - 450 mv range. Meanwhile the bank 1 O2 was bouncing from 003-999 like it should. Before 24x both O2 sensors worked perfectly.

If it would be helpful, I can record other readings such as MAF, MAP, BLM’s later.

93camaro_zzz

iTrader: (13)

Adsoyo, one thing I know is that if you leave an O2 sensor unplugged, it will read exactly how you are describing, 445-450mv. Don't ask me how I know. But anyways, maybe just make sure that it is plugged in and wired up properly and all of that jazz. Also, if you didn't know already, hptuners can do the crank relearn (called a case relearn) procedure. So if your tuner uses hptuners, he could try it out to see if that solves alot of your problems. I know if it were me, I would give it a try for sure. Good luck!

97lt1camaro

iTrader: (3)

The tach reading half of normal is in the tune. I think it's called tach resolution or something. Mine did the same thing when I did my 24x swap. I'll check
My tune tonight and report back

AdsoYo

iTrader: (1)

Thanks guys. I was able to spend some more time in the garage. PCMforless got my reprogramed PCM back to me and it made a noticeable improvement. It still didn’t run well so I decided to investigate the exhaust leak noise. Turned out my #8 spark plug was loose. I removed it at one point to inspect it and didn’t tighten it past finger tight so I took it out, cleaned it and installed it correctly. Again it made a noticeable improvement but still it runs rough.

I looked at the passenger side O2 sensor since it’s still reading 450mv +/- 5. Sensor was plugged in and screwed in tight. I’ll try swapping sides tomorrow but it worked just fine before 24x. The BLM’s were completely split as far as they would go.

I know of one guy locally who has hptuners so I'll be giving him a call. I heard the case relearn was only useful for misfire detection and didn't affect engine operation?

97lt1camaro: did you run a mail order tune after 24x? Any driveability issues? I want to know if a rough running car in this situation is par for the course or if it should actually be running smoothly. Thanks.

AdsoYo

iTrader: (1)

Checked resistance on spark plug wires. All 8 are ~30 ohms. Checked passenger side coils, all 4 are firing. Drove around the block with both O2 sensors unplugged and got no difference. Swapped sides and the passenger side is still stuck at ~450mV. Any ideas on that one?

Car starts right up every time. Feels shaky and sounds like there’s a tick in rhythm with the rpm at idle. Sounds louder underneath the car and on passenger side. Engine revs in neutral no problem, shakiness goes away and it sounds great. While driving around the block it feels like it has turbo lag. Super boggy until 2000 rpm or so and shakiness is worse the more throttle I give it. Still have to nail down the patterns on all the driving symptoms though.

AdsoYo

iTrader: (1)

I went back into the settings for my scanner with the intent to enable banks 3 and 4 to see if maybe they were reading something. The scanner only showed banks 1, 2, and 3 so enabled bank 3. Started the car and saw bank 1 still acting normally from 003-999, bank 2 still stuck at ~450, and bank three acting normally from 003-999. Does this mean BP pinned the harness incorrectly? Did he accidentally connect them to 28 and 68 instead of 26 and 66? I've sent emails to Aeroforce and BP and haven't heard from either yet.

Drove it a little more today. Driver's side is leaned out as far as it will go, passenger side is as rich as it will go. It was shaky and has no power. The more gas I give the more it shakes. I'd like to check the pin outs for the coils and injectors also. Does anyone have a link or can you post them?

GMRACER13

iTrader: (1)

Have you double checked that the injectors are assigned to the correct banks (e.g. O2's) in the PCM? The LS1 engine has a different firing order than the early small-block Chevy and LT1 engines. Specifically, cylinders 2&3 and 7&4 have been swapped. Because of this the wiring for the injectors and coils to those cylinders have also been swapped as part of the conversion (typically at the pins on the PCM). You need to change the injector bank assignment in the tune for the O2's to function/read correctly. Typically, cylinders 1, 3, 5 & 7 are "Bank 1" (driver's side) and cylinders 2, 4, 6, & 8 are "Bank 2" (passenger's side) . You need to change it so that cylinders 1, 2, 4 & 5 are on Bank 1 and cylinders 3, 6, 7 and 8 are on Bank 2.

Cylinder—Bank
1—0
8—1
7—1
2—0
6—1
5—0
4—0
3—1

I think in EFI Live Bank 1 is represented by "0" and Bank 2 is represented by "1".

I hope that makes sense.

camar0corey

iTrader: (22)

I doubt this is your problem, but at the time I did my 24x setup my fuel pressure regulator had started to leak. Tuner kept pulling fuel from the driver side because the o2 readings kept reading rich, but it never leaned out. Well because it was getting fuel from somewhere beside the injectors. Oops!

Which PCM did you use? 411?

AdsoYo

iTrader: (1)

Thanks for the info on the injectors. I haven't checked because I don't have any programs to check it with but I found a guy in town with HPtuners and he agreed to look. I had PCMforless email me my tune file so I have it in hpt format and Tunercat format. Anybody else want to take a look? And yes it's a 411 PCM.

AdsoYo

iTrader: (1)

I checked for continuity of all coils and injectors at the PCM. They are all plugged into the correct spots. I didn't check for O2 sensor continuity but I did check the pinouts and the spots where rear O2's would be, are empty.

I'm totally lost.

I emailed my tune to a local shop that has HPtuners. He said his experience is with Fords but took a quick look to ensure the firing order was correct and said the LS1 firing order was programmed in.

Shownomercy

iTrader: (1)

IDK how you have your coil packs located but I had my coil pack wired correctly but the order of coils was off. So #7 coil was getting say #5 signal. Made for some horrid back fire and weird 02 readings.

GMRACER13

iTrader: (1)

I'm not talking about the firing order. I'm talking about which bank each injector is assigned to for proper O2 reading/correction. Typically all the injectors on the driver's side are bank 1 and all the injectors on the passenger side are bank 2. With the LS1 PCM conversion two of the injectors on the driver's side (bank 1) need to be assigned to bank 2 and two from the passenger side (bank 2) need to be assigned to bank 1.

S10Wildside

You cannot change the engine firing order in the PCM calibration.

HP Tuners has an engine firing order table in the diagnostics section of their software, but that is not going to change the engine firing order.

AdsoYo

iTrader: (1)

sorry guys, should have clarified injector firing order. And GMRACER, yes I knew what you meant. The local guy I emailed my tune to didn't mention the bank assignments in his reply but I asked him to double check. Now that it's Monday, I can call him and find out for sure.

As for the coil packs, I'm using the bracket that EFI sells. No chance of crossed spark plug wires and I checked for continuity at each coil, not the engine harness pigtail. And the O2 readings seem normal, it's just that my Interceptor gauge shows bank 1 and 3 while bank 2 is stuck at ~450.

AdsoYo

iTrader: (1)

So the guy swapped banks on 2/3 and 4/7. Said he was able to drive it around the block. He recommended changing spark plugs because half of them were fouled. I said go ahead, here's the old ones:



It doesn't start very well, sometimes it cranks and cranks and then just stops. Otherwise it starts but it makes that clicky/ grindey noise. I was able to drive it home but it's obvious 1 or 2 cylinders still aren't quite right. Idle is way off. It drove well enough for the few miles home and I'm sure it just needs some fine tuning. Fuel trims while cruising are within 18% of each other. Idle is a different story.

AdsoYo

iTrader: (1)

I went scouring the internet for someone to help with the tune. Managed to find someone on hptuners forums who's programmed a few 24x LT1's. He took a look at my tune and said it was really rough. He said it had the stock LS1 fueling and spark tables. This is more than a little infuriating since I paid pcmforless $250 for it. He reprogrammed it for an LT1 and my car runs SO MUCH BETTER. Acceleration is especially smooth, idle and part throttle cruise is still a little rough.

This brings me to a new question: The car idles quite high, like 1700-1800 rpm. If the car sits long enough, the idle will eventually come down to about 850 and when it does, it's quick. It's not a gradual reduction of idle, it's 1800 then snaps down to 850. Also when it's idling at 850, it sounds like it's almost dying. Like it's having a lot of trouble maintaining 850. Also if I blip the throttle, like give it a quick press, the rpm will stay up at 1800 for a while again then quickly drop to 850 like before.

I don't think it's a vacuum leak because the idle eventually drops to where it should be. I don't think the throttle is sticking either. I'm going to drive it today and keep an eye on TPS/IAC, although it worked fine before 24x.

T/A KID

iTrader: (12)

Hey I'm glad the tune works better (this is Ben Charles on hp tuners) there could be some underlying issues (vac leak, exhaust leak, tb issues, etc) if u like I can send you my idle config n that way I can see exactly what it's doing.

You have my email, just hit me up