Problem with static ignition timing, please help

OK, details first: This is a '97 Chevy 2500 with a Vortec 350 and an 0411 PCM. PCM has been in the truck for ~30k miles and has been fine until recently. This all started about a month and a half ago when we had a week straight of torrential rains and the distributor took a dump. Replaced it, and she ran again, but then noticed my scan tool was saying 'open loop fault', turns out one of my O2's was just flat - dead. Replaced both front O2's, now goes into closed loop no problem. Now she runs better, no vacuum leaks, I've checked a half dozen times and verified distributor timing is spot on, but I have 2 problems and I'm not sure if they're related.


1: Start the truck, put it in gear (any gear) and it stalls. Give it a little throttle as soon as it drops in gear and it'll chug a bit then be fine. Once it's warmed up it rarely does this, mostly just cold start.

2. Ignition timing. it's as if it's in some kind of 'limp mode'. Doesn't matter if I'm driving down the road part-throttle cruise, taking off from a light, flooring it, etc - it NEVER deviates from between 15* and 16* of ignition advance.


What gives? What would make the PCM do that with the timing? This seems to be the hardest question to answer, and all the tuners I've asked have no idea. So, here I am. Hopefully somebody here understands the 0411's ignition strategy and can point me in the direction of what could be causing this. Thanks for looking.

Attachment 55490


Log file attached. Most things look normal. I saw 5* of knock retard at one point, but ignition timing still never changed?

post tune

OP Is this a 24x conversion??? I see your using the 411pcm

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Originally Posted by 32433s10

OP Is this a 24x conversion??? I see your using the 411pcm

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It is not a 24x conversion. I'm wanting to do one at some point (and have the kit) but it's just an 0411 on my otherwise stock L31 currently.

I'm a noob here. But how are you using that pcm with the old 5.7 vortec engine harness?

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Originally Posted by 32433s10

I'm a noob here. But how are you using that pcm with the old 5.7 vortec engine harness?

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Re-pinned the harness for the Red/Blue plugs, added wires for the PRNDL and 1 to the EGR. The PCM is running an OS from a 2002 Express Van, the last year they used the L31 motor. The late Express van with an L31 had an 0411 from the factory, The truck has had the 0411 for 3+ years now, I don't have the pinouts and what was changed handy, but ti's been done many, many times now.

Oh ok now I understand.

Food for thought - I played with the distributor some more, and got it off a tooth, then put it back. CEL is on, for case learn. Went to do a case learn with my HPTuners, and it won't do it. I've followed the instructions 15 times, and the button remains greyed out the entire time. Thoughts?

CASE learn does not work with HPT. I have never successfully made it work, but have used tech 2 immediately after trying hpt without issue.

You absolutely sure your distributor is timed right? Not sure on the proper way to go about timing it, but it sets a "camshaft/crankshaft correlation" code on startup if distributor is turned wrong. The way I set it is to just turn the distributor slightly and reset the code, and repeat until you no longer get the code.

The part that caught my eye was your timing being "stuck" on a certain degree. One time I was able to get the code to stay cleared with the distributor off one tooth. (obviously I thought I had it right then) That made it act exactly like you are saying. Finally figured it out when I noticed that turning the distributor one way made it stick with a higher degree and turning it the other way made it go lower. Kept on turning it the way that made it go higher and figured out it was a tooth off. It acted normal then when I finally got it in the correct position.

If your distributor is at the proper place then maybe it could be a problem with the camshaft sensor? (which is in the distributor)

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Originally Posted by 98vortecSilverado

You absolutely sure your distributor is timed right? Not sure on the proper way to go about timing it, but it sets a "camshaft/crankshaft correlation" code on startup if distributor is turned wrong. The way I set it is to just turn the distributor slightly and reset the code, and repeat until you no longer get the code.

The part that caught my eye was your timing being "stuck" on a certain degree. One time I was able to get the code to stay cleared with the distributor off one tooth. (obviously I thought I had it right then) That made it act exactly like you are saying. Finally figured it out when I noticed that turning the distributor one way made it stick with a higher degree and turning it the other way made it go lower. Kept on turning it the way that made it go higher and figured out it was a tooth off. It acted normal then when I finally got it in the correct position.

If your distributor is at the proper place then maybe it could be a problem with the camshaft sensor? (which is in the distributor)

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This is excellent info, thanks. FWIW - the distributor in the truck is one of the billet ebay units. Lots of success stories online. I had one that lasted about 2 years, and they replaced it under warranty recently. These ebay distributors - they can't be turned, the hold down sits on flats on the distributor body. I think they're designed to make install easy so you can't turn it and screw it up. As soon as I get time I'll play with the distributor more I guess and see what I can find out. This is very quickly making me want to say screw all of this and pull the motor and convert it to COP and sequential injection. This whole distributor nonsense on a vehicle built in 1997 is ridiculous anyhow.

I'm with you on calling out the distributor as nonsense. Problem is I had went and bought a billet accel unit before I figured that out. :( I can hardly justify the cost of converting it tho, when I remember the cheapy rebuilder pistons I'm running with 10psi of non intercooled boost. I actually figured it would have melted down by now and I could go with an ls swap.....

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Originally Posted by 98vortecSilverado

I'm with you on calling out the distributor as nonsense. Problem is I had went and bought a billet accel unit before I figured that out. :( I can hardly justify the cost of converting it tho, when I remember the cheapy rebuilder pistons I'm running with 10psi of non intercooled boost. I actually figured it would have melted down by now and I could go with an ls swap.....

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It's really NOT that bad. I made this thread just over 2 years ago....I've been collecting parts ever since. The ONLY reason I'm not just converting it in the truck is because when I did intake gaskets, there was an inch of sludge in the lifter valley. That, and it pours oil from every office on the damn thing. My rationale: the minute I go to put some go-fast parts on it, it'll dislodge some sludge, plug the oil pump pickup - and ruin everything I just bought. So, I'm just going to wait until I finally assemble most of the parts and have the cash, and going too pull it, tear it down and send the block off to be hot tanked, and reassemble.

http://www.fullsizechevy.com/forum/g...onversion.html


Basically:

My stock Vortec bottom end (have it)
TBI Swirlport heads
TPI intake (purchased)
Stock LS truck coils (purchased)
Marine cam (purchased)
1.6 rockers (purchased)
Whatever injectors I need
re-tune my 0411 that I already have
EFIConnections 24x crank trigger kit (purchased)

Only thing I'm not sure about is accessory mounting with the TPI throttle body, but I'll cross that bridge when I get there. I've had my eyes peeled for a good deal on 810 swirlports (supposedly the 810's have a bigger valve stem and hardened seats, were used in HD trucks with the TBI engine). Hoping my business takes off and I'll finally have the money to finish at least 1 of the 3 project

Why not install at top dead center