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Great news on finding the culprit! Just checked out a smoke generator on eBay as I am sure I will be chasing similar issues when I get mine reassembled. Thanks for the tip.
Way to stay with it, and didn't think it was a compression problem as I was reading along tonight.
Now, it sounds like that engine runs as good as it looks.
Brian.
Thanks Brian, I just have my fingers and toes crossed that it stays this good and nothing else creeps up. I firmly believe that a dozen little problems all added up. Every step got better and if it wasn't for a slight odd exhaust note, I probably would have stopped hunting a while ago. I need to do some more detailing under the hood but I think I will take a break under the hood for a bit
Originally Posted by AirtekHVAC
Very good news guy! Glad she is running well.
Thanks Ron, its funny that it really ran so well with so many issues. Idle and exhaust sound was really the only clues that I picked up on. Now that its at its peak, I can really tell the difference. First off, the car is ridiculously quiet now and the power is much smoother throughout the rpm range.
Originally Posted by kiwiokie
Great news on finding the culprit! Just checked out a smoke generator on eBay as I am sure I will be chasing similar issues when I get mine reassembled. Thanks for the tip.
I ordered the one that is made from an ammo box. It was well made. They are apparently easy to make but for $60 including shipping, I decided to let someone else have the fun making it. I left the air cleaner in place and just sealed the intake ends. I used the small port on the front of the intake to introduce the smoke (the one that gets plugged on manual cars). I choose not use the booster so I could simultaneously test the HVAC, vacuum locks and cruise control.
Now.......will it last this good or am I just fooling myself. We shall see!!!
Interesting. I did not expect the way to test for leaks would be to fill the system with smoke. I assumed you would just run the engine and waft the smoke around the suspected leak sources and see if the smoke was drawn in.
Interesting. I did not expect the way to test for leaks would be to fill the system with smoke. I assumed you would just run the engine and waft the smoke around the suspected leak sources and see if the smoke was drawn in.
I imagine the fan and accessories would make that a little harder. The way I did it took less than a half a minute to expose the leak.
As is typical with this car.......today the misfire came back.
After 3 weeks and 100 blissful miles of perfect running, today it decided to be an a$$ again. Drove to work this morning fine. Parked 9 hrs, start up and started to misfire almost immediately. Got worse as the 13 mile drive home continued.
Gave it a quick smoke test when I got home and it's still tight. No leaks. Nothing appears to be amiss.
I must tell you, I am at a moment of weakness here and getting to the end of my patience.
Your previous misfire was over a certain low RPM range wasn't it? Your description suggested to me the new misfire is more continuous which made me think of something electrical.
Your previous misfire was over a certain low RPM range wasn't it? Your description suggested to me the new misfire is more continuous which made me think of something electrical.
GOOD point. Yes the previous issues with mis fire were very concentrated. In other words, 2200 rpm or so would really wake it up. This misfire is not quite as severe and also seems to linger a lot longer.
Had a little time today to work on the car. I strongly suspect that cylinder one is running lean.
After running the car for a short while, I turned it off and cracked the fitting at the injector for #1. A couple of drops comes out of the line but not much. This does not hold true for the other lines.
I pulled the hardline for #1 and forced welding wire thru it. No debris came out and I was able to get the wire through. . I reinstalled the line but no change.
I am suspecting that the FD has a partial blockage on #1. This may explain why the problem is somewhat intermittent. It may be a loose piece of debris. This lean condition would also help explain why the compression is down on this one cylinder.
I am going to pull the FD and see if I can flush it out.
Did a balance flow test today. This is lines only without the injectors.
Right back ---->front of engine Left bank <----- front of engine
#1 is clearly getting the least amount of fuel by far even before injectors come into play.
I considered that the injectors would likely cause some backpressure allowing a more been fuel distribution but there is no rhyme or reason to the flow pattern.
Ya know... Once you get the system apart and look at the pieces it's amazing that it works so well let alone at all.
The fuel distributor has the little diaphragms that meter flow based on a pressure bias that's modulated both by the WUR and by flow in the FD. It's a nightmare! I see how my car runs better and worse with different tanks of gas and realize that fuel viscosity plays a huge role in system operation.
I've spent some time trying to balance a FD and injectors. It's time consuming, at the least. A few ideas for you:
Flow without injectors should give some idea of the overall balance. There's wide disparities in the jars so something isn't right. When was the last time you ran fuel system cleaner through it? I like Seafoam and Techron. Maybe do a half-tank of each. Far easier than taking things apart and not getting them back right. (Trust me.)
Try measuring the injectors. This'll require moving them one-at-a-time to the same tube. Maybe some of those are off as well. Crossing strong injectors to weak tubes, and vice-versa, may give some better flow results overall.
You can clean the injectors by soakng them in fuel injector cleaner or the solvent of your choice and blowing them out with compressed air. I've woken up some this way. Makes a difference.
Is that flow at idle or full? Check the dribble at idle and just off-idle. Check at full, too. You'll at least know what conditions aren't working. I think you'd expect bad flow at low rates and decent evenness at higher rates from what you've described.
From memory your FD was rebuilt. I think there is a factory set adjustment screw for each port. Do you know if they had a test rig to adjust the balance at each port for even flow? Glad to see someone else found a way to repurpose all those Gerber jars!
Ya know... Once you get the system apart and look at the pieces it's amazing that it works so well let alone at all.
The fuel distributor has the little diaphragms that meter flow based on a pressure bias that's modulated both by the WUR and by flow in the FD. It's a nightmare! I see how my car runs better and worse with different tanks of gas and realize that fuel viscosity plays a huge role in system operation.
I've spent some time trying to balance a FD and injectors. It's time consuming, at the least. A few ideas for you:
Flow without injectors should give some idea of the overall balance. There's wide disparities in the jars so something isn't right. When was the last time you ran fuel system cleaner through it? I like Seafoam and Techron. Maybe do a half-tank of each. Far easier than taking things apart and not getting them back right. (Trust me.)
Try measuring the injectors. This'll require moving them one-at-a-time to the same tube. Maybe some of those are off as well. Crossing strong injectors to weak tubes, and vice-versa, may give some better flow results overall.
You can clean the injectors by soakng them in fuel injector cleaner or the solvent of your choice and blowing them out with compressed air. I've woken up some this way. Makes a difference.
Is that flow at idle or full? Check the dribble at idle and just off-idle. Check at full, too. You'll at least know what conditions aren't working. I think you'd expect bad flow at low rates and decent evenness at higher rates from what you've described.
Best of luck
Thanks Glen. Before I read your reply, I did the same test with injectors are got nearly identical results. I pulled the FD and inspected it without disassembly. Clean as a whistle and plunger is nice and smooth. I blew some shop air thru it and got good flow of air thru all the ports. I know that doesn't really mean much. Reinstalled everything and drove the car again. Behaves the exact same way. Misfire at lower rpm.
I have some original injectors and tested them as well with similar results.
Injectors are new, the FD was rebuilt back in 2013 but the car hadn't gotten a lot of miles due to the first engine. I would estimate 1200 miles on the injectors, accumulator, fuel pumps and FD and about 1000 of that is on the new engine.
I use techron every other tank but everything is clean clean clean as I have been inspecting it.
Originally Posted by kiwiokie
From memory your FD was rebuilt. I think there is a factory set adjustment screw for each port. Do you know if they had a test rig to adjust the balance at each port for even flow? Glad to see someone else found a way to repurpose all those Gerber jars!
I know some FD have an adjustment on the top for each port. Not sure if the cast iron ones have that but that would be very helpful. I would love to know what mechanism causes internal balance on this.
This was rebuilt by a guy in NC. Unsure what testing was done
I may move onto a flow test on the fuel pumps. Wonder if a low volume would cause the uneven distribution. The only wrinkle is that the car doesn't seem to get fuel starved at all. Runs like a raped ape to 5k
I must admit. I felt bad wasting the baby food until I smelled it. Yuck!!!
I had a very similar issue after rebuilding my '79. I had literally replaced every CIS component from the tank to the injectors. Car suffered from a misfire at idle (especially when hot). Through process of elimination I decided to swap my "new" rebuilt fuel distributor with another rebuilt fuel distributor. Problem solved and the OB has been running like a scalded dog for the last 12 years.
07-23-2017, 09:33 AM
