A Fabricobbler's Guide to the Turbo Buick Galaxy- Cutlass Rehash
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Car is running, currently fighting a dead miss on 1 & 5. Have spark and checked injector pulse with a noid light. I swapped injectors and still dead on 1 & 5 but I could have tossed in 2 bad injectors from my hoard of like 18 GTP 37lbers.
I have good 60lbers to put in but I don't have a 60lb chip and haven't got my tunable ecm done yet so not much of a way to run the car with them.
I have good 60lbers to put in but I don't have a 60lb chip and haven't got my tunable ecm done yet so not much of a way to run the car with them.
Typical turbo Buick stuff.
Dead miss on 1 & 5. Header primaries on both are cold.
The narrow band o2 shows 350-450mv but my wideband shows dead lean, off the scale.
The plugs look pretty black & sooty that came out of 1&5. No significant raw fuel or oil on the plug
Checked spark and it's good. I can unplug 1 and 5 coils and no difference to the idle. Unplug any other and it pops bangs and wants to die. I swapped plugs and tried a different coil and no change.
Swapped injectors like I said and no change. Noid light tested the circuit and it's commanding the injectors as it should. Pulled the rail out of the intake and tapped 12v to the injectors and the pattern looks normal.
Fuel pressure is good.
Reset cam sensor position and it didn't change and not a problem. Aparently the cam sensor sets injector pulse start point and it should idle with the sensor unplugged but the engine dies immediately for me. That's the only hint of any problem.
Swapped ignition modules with no change.
Messed with fuel leaks for the morning. Bought the racetronix regulator 90° fitting but design error, there's no seal on the thread so the fuel just leaks past the theads. I jammed an injector o-ring between the fitting and the regulator internally and it fixed the issue but I'm not a huge fan so I might revisit it.
But it ran enough to back it out and wash the dust off.
So close to being able to drive it. Just need to determine what the issue is. I think it's injection or spark timing related, probably fuel. If It was spark I should have raw fuel smell and not be dead lean on the wideband. I think the engine clearly has the ability to spark and fuel, it's just not doing it at the right time.
Seal the jam nut to the body, don't seal the thread to the nut. Maybe I'm missing something?
Dead miss on 1 & 5. Header primaries on both are cold.
The narrow band o2 shows 350-450mv but my wideband shows dead lean, off the scale.
The plugs look pretty black & sooty that came out of 1&5. No significant raw fuel or oil on the plug
Checked spark and it's good. I can unplug 1 and 5 coils and no difference to the idle. Unplug any other and it pops bangs and wants to die. I swapped plugs and tried a different coil and no change.
Swapped injectors like I said and no change. Noid light tested the circuit and it's commanding the injectors as it should. Pulled the rail out of the intake and tapped 12v to the injectors and the pattern looks normal.
Fuel pressure is good.
Reset cam sensor position and it didn't change and not a problem. Aparently the cam sensor sets injector pulse start point and it should idle with the sensor unplugged but the engine dies immediately for me. That's the only hint of any problem.
Swapped ignition modules with no change.
Messed with fuel leaks for the morning. Bought the racetronix regulator 90° fitting but design error, there's no seal on the thread so the fuel just leaks past the theads. I jammed an injector o-ring between the fitting and the regulator internally and it fixed the issue but I'm not a huge fan so I might revisit it.
But it ran enough to back it out and wash the dust off.
So close to being able to drive it. Just need to determine what the issue is. I think it's injection or spark timing related, probably fuel. If It was spark I should have raw fuel smell and not be dead lean on the wideband. I think the engine clearly has the ability to spark and fuel, it's just not doing it at the right time.
Seal the jam nut to the body, don't seal the thread to the nut. Maybe I'm missing something?
And that is why I have a MSD distributor and a Holley TBI on mine. Good luck with the Buick voodoo.
I've seen this behavior before.
In that case one of the valves was burned bad enough it had trouble holding compression ONLY under combustion, but otherwise was OK. Had a valve job, problem went away.
Now I'm not saying you necessarily have burnt valves, but, wonder if something is off in the valvetrain that is having the same result.
You know, I've seen a turbo buick engine that compression tested 125-135 all 6 cylinders, but, the exhaust valves were varying degrees of burnt. Symptoms was it had one cylinder behaving exactly as you describe your #1 and #5.
In that case one of the valves was burned bad enough it had trouble holding compression ONLY under combustion, but otherwise was OK. Had a valve job, problem went away.
Now I'm not saying you necessarily have burnt valves, but, wonder if something is off in the valvetrain that is having the same result.
I did a compression check on the engine before I pulled it out of the wagon and they all checked 125-135. Granted it's been 18 months since sitting under my workbench but? I need to pull the drivers valve cover and see if if the pushrods are turning and ensure the valves are opening.
I agree, it should fire with spark and fuel.
I THINK it's fuel timing related, but I'm not sure. Hard to check with ancient EFI. Either that or somehow the timing chain jumped a tooth but I doubt it. It came out running fine so?
Interesting. I did check the heads over when I re-ringed the motor in 2017 and have maybe 5000 miles on it, they looked good at the time but I'm not sold nothin arose in the past few years I for sure need to check the mechanical side of things.
In other progress I am working through one of the old GM provided 'no start tree' and the ignition module is checking out as OK, but all the ones I have are 35 years old and a new one is $150 which is money decently spent towards diagnostics so I have one on order.
The motor in question that acted the same, coils packs were swapped and tested multiple ways. Injectors checked. Fuel rail checked, reg checked, harness checked. All came OK. May OK including trying ones off other running driving cars, same with coilpack, not just trying out the 1 of the 3 coils for the impacted cylinder. Crank/cam sensors were OK. Even tested to observe spark with tubes and what not, plugs out of engine, all seemed acceptable except a slightly weaker spark intensity on one, but, it wasn't even the hole not firing in car.
Ultimately owner pulled motor out of frustration, tore down, that's when valves noticed and had heads done. But, as I said, all 6 exhaust valves showed some burning but only one cylinder misbehaved.
It was reassembled freshened up with new gaskets, bearings, and valve job, the valve job being the only mechanical repair... sure added chip, different injectors, turbo, etc since money was being sacrificed to the turbo gods, but, none of those were befective coming off the old motor based on testing and swap out trials. Just the old valves.
So, thought it was an eerie parallel to what you describe.
But I also thought I remembered you converted your MAF, and, more on point, did a cam swap. Wasn't sure if, IF it was the valvetrain that made the issue on that other motor, well, maybe something in your valve train either separate from or related to the cam change (which I could be misremembering, maybe you didn't do one) could be a culprit. But if a valve isn't operating properly under running conditions that could impact compression and a/f at time of spark under running and impact ignition right? Again. Theory.
But it's best any retroactive explanation could come up with on that other motor that ran fine post reassembly. Just something to contemplate if nothing else will check out.
I'd leak down those two cylinders. You could have a couple of valves with a little crud on them keeping them from sealing.
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