Gang,
More stuff with my car.
I had alot of work done on straightening out the car last year. Now it is a real dream to drive. Only issue now is the stumbling, starting about 1500 rpm. Much of the time the motor stumbles to 3000 or 3500, sometimes it stumbles to 2000 or 2500 rpm and rarely, it runs like a r.... ape from 1500 to 7000.
It sounds like a fuel cross over problem with the upper fuel rack not quite delivering sufficient fuel. All of the electrical bits have been changed.
Could it be a distributor problem as the car has the original distributor. Don't know if it has an advance or not.
Ideas?
dom
MFI Stumbling
Moderators: hot66, impmad2000, Barry, Viv_Surby, Derek, Mike Usiskin
MFI Stumbling
domtoni
1969 911E
ER Polybronze bushings, turbo tie rod ends, and 21/26mm torsion bars
1969 911E
ER Polybronze bushings, turbo tie rod ends, and 21/26mm torsion bars
Dom,
It sounds to me like the main rack is probably ok but it is too weak on the lower (idle) rack setting - try setting the idle mixture 3 or 4 clicks richer (clockwise) and road test again. If the pickup improves it was too weak at idle, if not and you now have a big flat spot then it was too rich and is perhaps best taken care of by weakening the main rack (clockwise) by a few clicks....adjustment of the main rack will also have effect on the idle and transition mixtures.
Remember that all adjustments MUST be made with the engine turned off!
Chris
It sounds to me like the main rack is probably ok but it is too weak on the lower (idle) rack setting - try setting the idle mixture 3 or 4 clicks richer (clockwise) and road test again. If the pickup improves it was too weak at idle, if not and you now have a big flat spot then it was too rich and is perhaps best taken care of by weakening the main rack (clockwise) by a few clicks....adjustment of the main rack will also have effect on the idle and transition mixtures.
Remember that all adjustments MUST be made with the engine turned off!
Chris
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Mick Cliff
- I need to get out more!
- Posts: 3277
- Joined: Mon Apr 26, 2004 7:51 am
- Location: Selby
pmjt's 66 S on MFI?? I don't think so?
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MFI - check - measure - adjust. Search this forum or Pelican for fuller information. Actual adjustment of the mixture is, I think, the last thing you should do. Several other steps first...
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MFI - check - measure - adjust. Search this forum or Pelican for fuller information. Actual adjustment of the mixture is, I think, the last thing you should do. Several other steps first...
Merc B Class diesel
Porsche-less
Porsche-less
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Mick Cliff
- I need to get out more!
- Posts: 3277
- Joined: Mon Apr 26, 2004 7:51 am
- Location: Selby
Thanks guys for the kind comments.
Here is what happened:
- The car was set to the correct mixture last autumn. I drove few miles last year.
- This year I have knocked off 650 miles. The mixture was analyzed on friday and found to be very rich. At revs, it was at 9.8, the Bosch meter goes up to 10, and much higher than the factory recommended, and much higher than it was set last year.
- After the mixture was adjusted, the car bucked alot on a 100 mile drive.
- Yesterday, with less than 1/4 tank, a bottle of Forte fuel line cleaner was added, and I drove the car at revs for something like 10 miles before adding 49 liters of fuel.
- After filling with Shell Optimax, and with a few more miles, the car started to pull like a train from 2000 rpm. After a further 20 miles, the bucking came back but just noticable. None of the violence in the bucking was shown as on friday afternoon.
When the car pulled, no hesitation was shown, and it went like stink.
- When the car came from the states in 1999, the guy who got it running said something was broken in the distributor, and he fixed it. The dizzy was never recalibrated. Paul is in Spain until tomorrow, so I should find out what he did upon his return. I think a spring was replaced, so the advance could be a problem.
I plan to have the dizzy checked and probably a Pertronix ignition installed.
After the events of the past few days, I think:
- the car still has some gum deposits in the tank and the fuel lines. It makes sense to run more fuel line cleaner through it, while measuring the mixture for it to remain stable. If the mixture continues to strengthen, then that indicates that the lines are still being cleaned.
- once the dizzy is done, and calibrated, then I think I am in pretty good shape.
- my gut feeling is the issues should be solved.
Does anyone have any experience with dirty fuel tank and lines and if so, what did you do to clean them?
Thanks for the kind comments.
Best
Dom
Here is what happened:
- The car was set to the correct mixture last autumn. I drove few miles last year.
- This year I have knocked off 650 miles. The mixture was analyzed on friday and found to be very rich. At revs, it was at 9.8, the Bosch meter goes up to 10, and much higher than the factory recommended, and much higher than it was set last year.
- After the mixture was adjusted, the car bucked alot on a 100 mile drive.
- Yesterday, with less than 1/4 tank, a bottle of Forte fuel line cleaner was added, and I drove the car at revs for something like 10 miles before adding 49 liters of fuel.
- After filling with Shell Optimax, and with a few more miles, the car started to pull like a train from 2000 rpm. After a further 20 miles, the bucking came back but just noticable. None of the violence in the bucking was shown as on friday afternoon.
When the car pulled, no hesitation was shown, and it went like stink.
- When the car came from the states in 1999, the guy who got it running said something was broken in the distributor, and he fixed it. The dizzy was never recalibrated. Paul is in Spain until tomorrow, so I should find out what he did upon his return. I think a spring was replaced, so the advance could be a problem.
I plan to have the dizzy checked and probably a Pertronix ignition installed.
After the events of the past few days, I think:
- the car still has some gum deposits in the tank and the fuel lines. It makes sense to run more fuel line cleaner through it, while measuring the mixture for it to remain stable. If the mixture continues to strengthen, then that indicates that the lines are still being cleaned.
- once the dizzy is done, and calibrated, then I think I am in pretty good shape.
- my gut feeling is the issues should be solved.
Does anyone have any experience with dirty fuel tank and lines and if so, what did you do to clean them?
Thanks for the kind comments.
Best
Dom
domtoni
1969 911E
ER Polybronze bushings, turbo tie rod ends, and 21/26mm torsion bars
1969 911E
ER Polybronze bushings, turbo tie rod ends, and 21/26mm torsion bars
Latest update.
Viva Forte fuel line treatment.
After one week sitting in the garage, the car is 95% better than the last post.
After a 30 mile drive yesterday, the following happened:
- exhaust emissions were from 3.5 to 7.5%
- the car pulled from under 2000 rpm up to 7000
- a point of hesitation and some insignificant bucking happened between 3100 and 3500 rpm
The problem seems to be pretty much solved.
Points learned:
- make sure the fuel system is clean
- make sure the carbon is burned out of the engine
- make sure both of the above points are followed before undertaking anything major
Best
Dom
Viva Forte fuel line treatment.
After one week sitting in the garage, the car is 95% better than the last post.
After a 30 mile drive yesterday, the following happened:
- exhaust emissions were from 3.5 to 7.5%
- the car pulled from under 2000 rpm up to 7000
- a point of hesitation and some insignificant bucking happened between 3100 and 3500 rpm
The problem seems to be pretty much solved.
Points learned:
- make sure the fuel system is clean
- make sure the carbon is burned out of the engine
- make sure both of the above points are followed before undertaking anything major
Best
Dom
domtoni
1969 911E
ER Polybronze bushings, turbo tie rod ends, and 21/26mm torsion bars
1969 911E
ER Polybronze bushings, turbo tie rod ends, and 21/26mm torsion bars