AdsoYo

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. 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. Any help is appreciated!

timnfxr

As for the miss and vibration, it is probably caused by the timing gear dot misalignment. It will affect the cylinder/valve/ignition timing drastically. That should be corrected first. Then you can address the shifting issues.

AdsoYo

I actually did have them lined up dot to dot when I put the chain back on.

ACE1252

Was the 24x conversion done by itself or were there other upgrades at the same time? If other upgrades or changes were done, what were they?

After putting the chain/cam gear on, did you rotate the crank two revolutions to see if they lined back up dot to dot?

97WS6SCharged

P0463 is because the computer is expecting a different resistance from the fuel level sender. You will need to have a segment swap done on that portion of the tune to get it to work correctly. Do a google search for 411 pcm fuel level segment swap and you should find out how to do it.

P1336 is a problem with the crankshaft position sensor. The misfires you're describing are causing it to go whacky because the crankshaft is accelerating and decelerating at a rate that it cannot predict.

P1637 is a problem with the alternator circuit. The PCM is looking for a certain voltage and it's not getting it. Have the alternator inspected and check the wiring for shorts.

As long as the gears were lined up dot to dot you should be fine. Are you still using a single row timing set? There have been issues with double rollers not showing the proper signal for the 411 pcm.

PCM4Less and BP knew this was a Gen 2 motor and not an LSx motor, right? If the harness is constructed for an LS1 then 4 of the cylinders would be firing in the wrong order which would cause many of the symptoms you're describing.

LT1 18436572
LS1 18726543

AdsoYo

Along with 24x, I replaced the fuel pressure regulator, deleted EGR and installed block-off plates, and put a breather on the EVAP line. I did not rotate the crank after putting the chain back on. Is there a situation where they wouldn't line back up?

I read that the 0463 and 1637 codes can just be programmed out since they don't apply? The alternator worked fine before the swap. Still using a single row timing set.

Once I get the car road worthy I'll take it to the dealership and have them do the relearn procedure for the P1336.

PCMforless and BP did know it was a Gen 2 LT1. PCMforless double checked the tune file and confirmed it was programmed correctly for a LT1. BP is guaranteeing me he built it correctly. He also said my transmission issue is from plugging the reverse lockout into the skip shift solenoid. I'll check that one tomorrow but I'm pretty sure he's right.

Would the misfire cause the tach to be pegged at 500 rpm? Is that typical misfire behavior? Or is something else going on? I'm planning on getting test lights for the spark plugs/coils, injectors and testing all those components soon.

Injuneer

Could you explain in more detail what you did? By "breather" do you mean a small pleated paper filter? If so, exactly where in the EVAP system did you put it - at the canister or at the engine? Do you still have an EVAP solenoid blocking the line? Is the EVAP purge functional, or has it been deleted?

The code indicates that the PCM has not "learned" the normal crankshaft variations that result from the healthy firing of the cylinders. Have you even had this procedure done at all? The PCM has to be commanded by a scan tool to perform the "learning". The learn procedure cannot be accomplished if the ratio of the cam position pulses to the crank position pulses does not match what the PCM expects. Does the 24X system offer more than one option on the sensor pulses? Is it possible there is a cam position sensor reluctor mismatch?

I wouldn't see this fact it hasn't "learned" as contributing to the misfire, just preventing the PCM from detecting which cylinders are misfiring, which hinders your diagnosis. But a mismatch on the cam or crank pulse count ratio would probably screw things up pretty badly.

AdsoYo

This is what I did. Everything else has been removed and vacuum caps placed on the intake. The EVAP system can't work with the LS1 PCM.



I haven't had it done because I haven't driven it due to the misfire. Like you said, it doesn't affect engine operation, it's just for diagnostics. As soon as I can drive it to the dealership, I'll have them perform the learn procedure.

I don't think it's possible. The 24x system offers one crank reluctor with 24 teeth, and one cam reluctor with a half-moon shape. Those components come directly from EFI Connection and they both can only install one way.

Injuneer

I honestly don't know the details of the 24X system. I'm just trying to work logically through the info you provided. For example I have no idea if the cam position disc can be loose, but I'll ask you if its a possibiliy.

With regard to the filter on the EVAP purge line, you are now possibly venting your fuel tank vapor into the engine compartment. Why not unhook the tank vent line from the canister and put the filter on the end of that line, leaving the fuel vapor at the rear of the car?

AdsoYo

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.

AdsoYo

A loose cam reluctor is possible, but I put red loctite on the screws so I don't think that's very likely.

Good idea about the EVAP line, but from what I've read, leaving the line hooked to the canister continues to remove gas odor. Otherwise even with the vent in the rear of the car, the cabin could still smell of gasoline.

97WS6SCharged

You can tune out any code you want but I would venture to guess that your fuel level gauge will not function correctly if you just remove the code. Same for the alternator code, the battery may not be getting the correct voltage which can cause issues with over or under charging.

The tach is reading low because the tach output in the PCM is likely still set for a default LS1 reading which outputs a signal to drive a 4 cylinder tach. Don't ask why it just does. I believe the high/low resolution numbers need to be 3/3 instead of 6/6 in the PCM but I don't recall for sure (I may have it backwards).

You can check the O2 sensors easily enough by swapping them from side to side and see if the the problem follows the sensor. You could check the bank to bank table of the PCM to see which sensor is assigned to which cylinders.

I don't believe the misfires are a programming error since you cannot change the actual firing order in the PCM, you have to do it by rewiring the harness. You could disconnect the battery and pull the red and blue PCM plugs and check the leads with a multimeter.

Front of the engine
1 ... 2
3 ... 4
5 ... 6
7 ... 8


Blue 3 should run to injector 2 on the LT1
blue 4 - inj 3
blue 43 - inj 4
blue 44 - inj 7

Red 27 - coil 4
red 29 - coil 7
red 67 - coil 3
red 69 - coil 2

AdsoYo

I've been emailing EFI, BP, and PCM4less during all this and got some replies. EFI said 0436 and 1637 are irrelevant to my car and to disable them. They also said the timing set is installed correctly and the codes are not indicators of the trouble I'm having (that includes 1336). They suspect a tuning issue and recommend using a wideband (which I don't have access to).

BP said he "hard swapped" the firing order in the harness. So it is wired like an LT1 would be.

PCMforless said if the harness was wired with the LT1 firing order in it, then he programmed it incorrectly and I'll have to send it back so he can program the LS1 firing order back in.

Both PCMforless and BP were under the impression that it was their responsibility to change the firing order. So there you have it. I've been missing on 2,3,4, and 7.

I'm going to send the PCM back to have it reprogrammed and will post results after I get it running again. I'll have him delete the 2 irrelevant codes and correct the tachometer. Hopefully that leaves the O2 sensor issue and nothing else.

AdsoYo

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.

Does anyone have any experience with running a mail order tune after 24x?

Injuneer

~450mV could also mean the sensor or harness wire is broken. The PCM is reading it's own bias voltage, with no voltage adjustment by the sensor.