SL/R129: 1991 SL500 R129 Low Rough Idle and Dies on Acceleration
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1991 SL500
1991 SL500 R129 Low Rough Idle and Dies on Acceleration
Just picked up this California clean car that doesn't roll. It starts with super low idle. If I try to step on gas peddle it dies. If I manually press down on air flow meter it idles fine. If I manually throttle and press down on air flow meter it revs fine. When cold I need to initially give it a lil bit starting fluid. If keep spraying it idles higher. I don't know if it's electrical
I checked following:
I checked following:
- checked fuel presser at prime and run at fuel distributor.
- vacuum leaks
- cam sensor
- cleaned and checked OVP valve.
- OVP relay fuse
- all other fuses
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From: SF Bay Area, CA
190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
Assuming this is the old KE-Jetronic fuel system have you checked the duty cycle at idle and at 2500 rpm.
Does it stall both when engine is cold and hot?
Does it stall both when engine is cold and hot?
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G550
Attached is a copy of a troubleshooting table from "Bosch Fuel Injection & Engine Management" (c. 1989) for Bosch K-series fuel systems. Maybe something useful there. The book is still in print -- you should be able to find a used copy for ~$20 online.
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From: SF Bay Area, CA
190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
(1) What will you swapping out? The fuel filter?
(2) Can you restate below. I am not following:
I checked following:
I would like to go thru 1-3 questions first but you need to do the following before anything else:
(a) check system and lower chamber fuel pressure (both at idle and 2500 rpm)
(b) check the duty cycle at idle and at 2500 rpm
I would not do anything until you go thru a and b.
To answer your question: No this can not be something electrical. There is almost nothing electrical about your stalling (the way it is stalling)
You seem to be not getting enough fuel to the injectors during acceleration from your description. That is only controlled by the FD.
I can suggest some test but let us know the answers to questions 1-3 and results of (a) and (b).
(2) Can you restate below. I am not following:
I checked following:
- checked fuel presser at prime and run at fuel distributor.
I would like to go thru 1-3 questions first but you need to do the following before anything else:
(a) check system and lower chamber fuel pressure (both at idle and 2500 rpm)
(b) check the duty cycle at idle and at 2500 rpm
I would not do anything until you go thru a and b.
To answer your question: No this can not be something electrical. There is almost nothing electrical about your stalling (the way it is stalling)
You seem to be not getting enough fuel to the injectors during acceleration from your description. That is only controlled by the FD.
I can suggest some test but let us know the answers to questions 1-3 and results of (a) and (b).
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1991 SL500
(1) What will you swapping out? The fuel filter? Yes
(2) Can you restate below. I am not following:
I checked following:
(3) Has this car sat for extended time (like years).?
I think so. It's a California car I was given from original owner. He lived in Florida and was in his daughters garage in California. So yes probably sat for years.
(2) Can you restate below. I am not following:
I checked following:
- checked fuel presser at prime and run at fuel distributor.
(3) Has this car sat for extended time (like years).?
I think so. It's a California car I was given from original owner. He lived in Florida and was in his daughters garage in California. So yes probably sat for years.
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MBWorld Fanatic!
Joined: Mar 2016
Posts: 1,369
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From: SF Bay Area, CA
190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
If it sat for years, that is trouble with the fuel system. Generally needs a flush before starting the car after sitting. Even for just one year.
So you only checked the system or lower chamber pressure but not the differential pressure between the two? You need to do that and verify that the pressure difference is in the range of 0.4 Bar.
And the finer tuning is done with the Duty Cycle measurements at idle and 2500rpm. The duty cycle is a critical measurement alongside with differential fuel pressure measurements. Next is to see if there are ECU emissions codes that you can read out from the diagnostic port, your model has a code reader built in.
After these are done and check out, the diagnostics begin.
(1) Is there a Check Engine Light on?
(2) How many miles on the car (Assuming the Odometer still works). This is critical in ruling out or suspecting certain component failures as they have a certain expected life.
So you only checked the system or lower chamber pressure but not the differential pressure between the two? You need to do that and verify that the pressure difference is in the range of 0.4 Bar.
And the finer tuning is done with the Duty Cycle measurements at idle and 2500rpm. The duty cycle is a critical measurement alongside with differential fuel pressure measurements. Next is to see if there are ECU emissions codes that you can read out from the diagnostic port, your model has a code reader built in.
After these are done and check out, the diagnostics begin.
(1) Is there a Check Engine Light on?
(2) How many miles on the car (Assuming the Odometer still works). This is critical in ruling out or suspecting certain component failures as they have a certain expected life.
