Crusty Rusty Leaky Squeaky 67 Step

[mcbassin]

Very clean work on the bed access panel and fuel system! Bummer about the belt squeak, my buddy chased the exact problem on his 67 Camaro. I don't know what he ended up doing to fix it..
Very informative thread as always.

[Hart_Rod]

I have a question on your "dim" check engine light. Where does the signal for this come from? Are you tied into the original check engine light that came with the harness?

[Vic1947]

Originally Posted by Hart_Rod

I have a question on your "dim" check engine light. Where does the signal for this come from? Are you tied into the original check engine light that came with the harness?

Yes, the harness had a brown wire with a white stripe marked MIL. According to the instructions... "It is recommended that a MIL also be installed in a visible location in the passenger compartment. This circuit requires any 12V low current light and an ignition 12V power source. The ECM MIL output supplies the ground for the circuit."

The relay box has a separate LED MIL in it that seems to operate correctly and doesn't have the dim glow when the engine is running. Only the redundant light on the dash connected to ignition 12V and the MIL wire displays this behavior. If the circuit works by supplying either a ground or an open, there should be no dim glow. Light would be either on bright or off.

However, I ran across a post on one of the forums that said the ECM worked by supplying ground when a fault is detected or 12V when running and no fault present. If that were true, I could see how the light might have the dim glow since the charging system operates at 13.5V+ which would result in a net 1.5V+ difference across the redundant MIL. I don't recall where I saw that post, but offhand it doesn't sound correct. So I've just been ignoring the dim glow. I need to pull the console to fix the starter wire problem, so I may throw the meter on the MIL wire and see for myself what it's doing.

[Hart_Rod]

Originally Posted by Vic1947

Yes, the harness had a brown wire with a white stripe marked MIL. According to the instructions... "It is recommended that a MIL also be installed in a visible location in the passenger compartment. This circuit requires any 12V low current light and an ignition 12V power source. The ECM MIL output supplies the ground for the circuit."

The relay box has a separate LED MIL in it that seems to operate correctly and doesn't have the dim glow when the engine is running. Only the redundant light on the dash connected to ignition 12V and the MIL wire displays this behavior. If the circuit works by supplying either a ground or an open, there should be no dim glow. Light would be either on bright or off.

However, I ran across a post on one of the forums that said the ECM worked by supplying ground when a fault is detected or 12V when running and no fault present. If that were true, I could see how the light might have the dim glow since the charging system operates at 13.5V+ which would result in a net 1.5V+ difference across the redundant MIL. I don't recall where I saw that post, but offhand it doesn't sound correct. So I've just been ignoring the dim glow. I need to pull the console to fix the starter wire problem, so I may throw the meter on the MIL wire and see for myself what it's doing.

I had an issue with the CEL on my Dakota Digital gauges. The light wouldn't work correctly until I wired in an incandescent bulb parallel with that circuit.

[Vic1947]

Originally Posted by Jason7121

On my Ls swap I wired a check engine light and mounted it on gauge cluster bezel. Ecm provides ground when a fault is detected and other wire is 12v ignition feed. Hope that helps people that were curious.

Hey Jason, that certainly seems more logical than switching between ground and 12V. I ordered the CEL from your link. The description didn't say whether it was LED or incandescent, but if it worked for you it's worth a try.

Originally Posted by Hart_Rod

I had an issue with the CEL on my Dakota Digital gauges. The light wouldn't work correctly until I wired in an incandescent bulb parallel with that circuit.

Interesting tip, Rob. LED bulbs and SMD's don't always play nice with conventional components like turn signal flashers, so changing the load may be a solution. When I get the wiring and relay box exposed to fix the starter wire problem, I'll do a test to see if something like that makes a difference.

Got the Continental Elite/Gatorback serpentine belt installed today and it's quiet as a church mouse. Don't know how long it will stay that way, but it was great to hear nothing other than exhaust noise. Now I can remove the alternator and send it back to the manufacturer to have the regulator replaced and then dyno tested. Hope to find some time to get the bed back on this weekend. We finally had to put my dad in a skilled care facility. It's a hundred miles from here and we've been back and forth nearly every day getting him set up. The place is in his hometown, so he's been pretty upbeat since moving in. Truck stuff has had to take a backseat, though.

[Vic1947]

The bed is back on, although I'm still doing some adjustments. Found out that with the Accuair in the lowest position, the driveshaft just barely kisses the bottom of the air tank. So if you moved forward, it squealed a little bit. So I spaced the tank up .400" while the bed was off and now the top of the tank just barely touches the underside of the bed. To remedy the situation, I installed the 1/4" thick, square rubber insulators between the frame and the cross sills. I'm still figuring out how snug the fasteners need to be for it all to sit just right. Posted a photo below of the access panel in the bed. Should never have to pull the bed again for fuel tank maintenance.

To all who expressed their opinion that the carbon fiber side mirrors looked out of the place, I say thanks for being honest... and check out the replacements. These are '69 GTO/Chevelle mirrors. My second new car ever was a '69 GTO Judge and I always liked the profile of the side mirrors. The passenger side is at the limit, adjustment wise, but you have a clear view out of it. The driver side view is way better than the ones that were on there. I was able to position them to cover the existing holes, so I sealed them with a dab of silicone and it's good as new.

[Jason7121]

On my Ls swap I wired a check engine light and mounted it on gauge cluster bezel. Ecm provides ground when a fault is detected and other wire is 12v ignition feed. Hope that helps people that were curious.

[Jason7121]

https://rover.ebay.com/rover/0/0/0?m...2F141185251951
This is what I used

[Low Elco]

Glad to see you're gettin' 'er back together! Hope your Dad is happy in his new place.

[rkn463]

I just got caught up on this, wow it looks great! I like the new mirrors, good call on that. All of the electronic problems you ran in to are disappointing, I expected better out of GM.

Kudos for hanging with it.

-Richard

[Vic1947]

Originally Posted by Low Elco

Glad to see you're gettin' 'er back together! Hope your Dad is happy in his new place.

Thanks, Chip. Vern told me you've been under the weather a bit. Hope you're headed back to 100%. I think Dad is adjusting pretty well. He seems to enjoy renewing old acquaintances... although at his age, there aren't as many as there used to be.

Originally Posted by rkn463

I just got caught up on this, wow it looks great! I like the new mirrors, good call on that. All of the electronic problems you ran in to are disappointing, I expected better out of GM.

Kudos for hanging with it.

-Richard

Thanks, Richard. I think what got me the most was when we were broke down in Nacogdoches and the GM dealer refused to even check the codes with a Tech2. When I told them that GMPP had assured me any dealer could work on the C&C LS engines, they said, "Not us."

I've been working on the universal bed mat cutting out all the various openings. They're made out of some tough material. Finally figured out a combination of a jig saw, various hole saws and a coarse drum sander works the best. It would have been nice to find one that fits out of the box, but this will have to do.

[Vic1947]

Well, a lot of water under the bridge since I last wrote. I finished up the bed mat and got everything back in place. Looks a lot nicer than seeing the butt ugly access panel. Plus it's much more anti-skid than the spray in liner.

I also repaired the starter circuit wiring and ran a dummy wire for use with an ECU controlled fan relay in the event the PWM fan controller takes a dump. Having the wire there will probably mean I'll never need it, but just in case. I wired a new MIL in parallel with the one in the dash and it didn't work initially. Finally figured out I'd piggybacked it onto the wrong wire where it came out of the loom. When I test fired the engine, it went out completely as did the MIL on the dash. I tried several configurations, but the dash MIL looks to be working correctly now. Not sure what happened, but I left the new MIL wired in parallel with the old anyway.

Pulled some much needed maintenance (oil change, fluid checks, etc.) Also removed all the plugs to have a look. They looked pretty crappy, but I figure they're like that due to all the past fuel issues. They should clean up after some highway miles. While all this was going on, I removed the ignition switch and put the fuses back in the Advanced Keys pushbutton start only to find the truck would crank but not start. I put the stock ignition switch back in and it started just fine. Put the fuses to the AKPBS back in and it started with no problems. So I just left the stock switch plugged in and cable tied it up under the dash for the time being.

It was finally time for a test drive. Ryan and Rachel (twins from Houston) are visiting, so Ryan and I hit the road. Drove less than a block before deciding something wasn't right. Popping and banging like it did the time I had a vacuum leak. Pulled over and checked but that wasn't the problem so we limped back home.

When I originally installed the vacuum referenced regulator, it was set at 60psi out of the box. But when you attach the vacuum hose, it pulls about 5 or 6psi off at idle. According to the documentation that came with the LS3, it needs a vacuum referenced regulator set at 60 psi. So I adjusted the pressure up to that amount at idle and it seems to be running better although not 100%. It still has an intermittent low speed surge and is harder to start than it should be. It will start on the first try as long as you don't even rest your foot on the accelerator pedal. I have a bad habit of driving with two feet and if I come up to a stoplight with my left foot on the brake and the right still resting on the gas pedal, it will want to stall out. So I'm going to have to retrain myself to either use my right foot for everything or move it well away from the gas if I need to stop.

I've read that poor idle quality, hard starting, stumbling and etc. are fixable via the tune. However, I'm reluctant to take it back to the guy that did the work on it back before we went on our trip. His communication skills left a lot to be desired. I don't know whether I could take the truck in to my local Chevy dealer who sells the GMPP crate engines and have them return it to the original tune to see if that improves it or not. It's drive-able but it doesn't instill confidence when it displays these little quirks.

I have an Innova 3160g code reader / scan tool due to arrive tomorrow. Jason7121 recommended that I connect a scanner and drive around to capture some live data. It should also allow me to see if the ECU toggles between open and closed loop like it's supposed to. I don't know if the permanent emission codes that were set are interfering with the operation or not. Will post more when I know more.

[Hart_Rod]

Vic - vacuumed referenced regulators should be set with the vacuum line off. Also, within the tune, the fuel pressure should be set the same all the way across instead of a sloped line. Fix theses 2 things and install a new set of plugs and I think you will be pleasantly surprised at how different it runs.

[Vic1947]

Originally Posted by Hart_Rod

Vic - vacuumed referenced regulators should be set with the vacuum line off. Also, within the tune, the fuel pressure should be set the same all the way across instead of a sloped line. Fix theses 2 things and install a new set of plugs and I think you will be pleasantly surprised at how different it runs.

Thanks, Rob. When I first installed the regulator, I wired the pump direct to 12V and checked the pressure. With the vacuum port open, it registered 60psi, so I figured I was good to go. It started and seemed to idle okay. However, the test drive performance was pretty bad. So that's when I adjusted the pressure up to 60 psi at idle with the vacuum line attached. It did run better, but I definitely need to reassess the situation. I don't have a Diablo or HP Tuner to make adjustments, which is probably just as well. I'm waiting to hear from Chip (Low Elco) who's having his GMC DD tuned tomorrow. If all goes well, I may give the shop he's using a try and will mention what you said about the fuel pressure curve. Thanks for the suggestions!

[Xeen]

I think you should take it back to the guy who tuned it and tell him you want him to reset it back to stock configuration and see how it runs at that point, without a baseline it makes it tough to diagnose potential problems.

[Jason7121]

If it has a mass air flow sensor make sure arrow on sensor points toward the throttle body I have seen this on backwards several times.

[Vic1947]

Originally Posted by KY_GMC

Hello Vic,

Here is a link to a solution to the same symptoms that you are having: https://ls1tech.com/forums/general-m...0151-only.html

Wow, that really sounds like what I'm seeing. I also ran across a post stating AC Delco made "weak" and "strong" MAF's, so I pulled mine and it's the "strong" one. So if the MAF is the culprit, it's not because it's the less desirable version. Would just flat out have to be defective... which is certainly possible. All the local auto parts have aftermarket MAF's in stock but not the GM / AC Delco. I've got a couple of weeks, so I can order one thru my local parts house. Meanwhile, I'll swap the O2 sensors and record some live data to see if anything else pops out at me. Thanks for the tip!!

Originally Posted by Xeen

I think you should take it back to the guy who tuned it and tell him you want him to reset it back to stock configuration and see how it runs at that point, without a baseline it makes it tough to diagnose potential problems.

That could be true, Brian. Only problem is... the guy who did the original tune is a Grade A jerk. I'm not going to waste any more time or money on him.

Originally Posted by Jason7121

If it has a mass air flow sensor make sure arrow on sensor points toward the throttle body I have seen this on backwards several times.

Thanks, Jason. Checked it when I pulled the MAF and it seems to be mounted the right way.

Will run some more diagnostics tomorrow and report back in.

[knomadd]

Hey Vic, Sorry to see you're still having problems with the LS. I did a quick search on Rock Auto to see if your MAF sensor was available through them. They have the GM part for $50.89, and an AC Delco version for $48.79. There are cheaper alternatives, but if you're looking for true GM, these are available, and they have cheap and fast shipping too.

[Vic1947]

Originally Posted by knomadd

Hey Vic, Sorry to see you're still having problems with the LS. I did a quick search on Rock Auto to see if your MAF sensor was available through them. They have the GM part for $50.89, and an AC Delco version for $48.79. There are cheaper alternatives, but if you're looking for true GM, these are available, and they have cheap and fast shipping too.

Thanks, Duane. I've used Rock Auto on a number of occasions and like their service and selection. Going to make a test run today and record some live data so I can replay it and look for anomalies. This is a new world for me and now that I have something to use for diagnostics, I want to tinker with it a bit before I buy any new parts. It's hard to ignore the symptoms pointing to a MAF that isn't operating quite right, though. Hopefully some of the data may confirm it.

[Jason7121]

Try unplugging the mass airflow sensor and take it for a drive see if it makes a change

[Jason7121]

If your filter is a type that requires oil sometimes that oil will get on the mass airflow sensor and skew the reading you can also try cleaning the mass airflow sensor with brake cleaner and Shop air

[Vic1947]

Originally Posted by Jason7121

Try unplugging the mass airflow sensor and take it for a drive see if it makes a change

Originally Posted by Jason7121

If your filter is a type that requires oil sometimes that oil will get on the mass airflow sensor and skew the reading you can also try cleaning the mass airflow sensor with brake cleaner and Shop air

The MAF looks like it did the day I installed it, clean as a whistle. However, unplugging it made a huge difference. It smoothed out at idle immediately and I was able to drive the short distance back home with no popping and banging. Do you believe this is due to a bad sensor or could it still be something in the tune?

I'm going to make another run and record data with the MAF unplugged. With it plugged in, STFT's were 25% on B1 and 28.1% on B2. Timing looked stupid too.

[Ol Blue K20]

I sure hope it's something simple.....all this computer stuff is beyond me.

[Jason7121]

I think the majority of your issue is with the tuning. I would still clean the mass airflow sensor and blow it out there I don't think you have a bad sensor

[duke_lbz]

what size is the intake tube? The tune needs to be modified if it is larger than stock size.