No, we tested the by pass valve when the issue was minor. Even with the valve open, the engine was able to rev up to 5500 / 6000 rpm. Now it's not anymore possible.Is it possible that yours has now stuck open = no boost? .
This is part of the programmed tests.Do you have a fuel mixture (fuel/air ratio ) meter on the car or any way of checking the mixture (emissions equipment at a garage?) .
The second pump, under the hood.Which fuel pump did you replace? .
How did you adjust this on the "regelventil" (petrol pressure regulator)?I checked my system and control pressure and adjusted the control pressure on the regelventil. With a fuel/air ratio meter on mine, I found that my mixture was leaning out under part throttle/moderate load (high vacuum) conditions. Under full load mixture was fine. I sometimes get that full load pop/cutoff, but still believe that is wastegate/bypassventil related. .
According to my mechanician, it's indeed either the enrichement on the DL unit, either the regelventil. Do you confirm that Alpina in Buchloe is able to fix these problems ? Do they replace the parts or repair them? Is it possible to have an idea of their prices?My problems, I determined, were likely centered around the vacuum enrichment mechanism on the main Pierburg DL unit. The vacuum unit itself may be the culprit (not holding vacuum), and also the cam that this vacuum unit follows (raumprofil) was very worn in areas (shape worn off). I was going to machine a new raumprofil, but decided to send the unit off to Alpina for complete rebuild. The price really isn't bad, considering what a stock Bosch fuel distributor for an BMW of this vintage costs these days. Plus, with the unit completely renewed, I can take it out of the equation when troubleshooting/tuning.
Exactly my symptoms.... How is it possible that the engine stumbles as of 3000 rpm with the valve open? Anyway, this will be checked tomorrow. :lightbulb:Two years ago, mine was stuck open, and my car exhibited similar symptoms - no boost pressure was being made, it ran somewhat acceptable up to about 3000 RPM, and then burned very rich and stumbled a lot after 3000. We removed the gate to check the diaphragm action and found the valve stuck. Applying air pressure to the top of the diaphragm caused it to release. I lubricated the valve shaft with graphite powder and have not had any problems with it since then. Best of luck, and please post your findings...
Unsure. Mine is the Motronic version, so there are certainly differences. It's possible that with my Motronic version, fuel mapping may have caused it to run extremely rich (it was blowing black smoke out the back). I'm not certain if the Motronic was sophisticated enough to do anything more than associate RPM to a certain amount of injector duration. I do not think it has any (electronic signal) input for boost pressure. I am just unsure if and how it may relate to your Pierburg controlled engine. It's worth a look, though. Again, knowing your fuel/air ratio (too lean or too rich) at the RPM it's failing at should help you diagnose.Exactly my symptoms.... How is it possible that the engine stumbles as of 3000 rpm with the valve open? Anyway, this will be checked tomorrow. :lightbulb:
Even in the garage. The engine works more on less fine at idle, climbs up hardly to 3000 rpm, then the rpm falls suddenly down until its turns off completely.but this stumbling above 2500-3000rpm, is it only when you are trying to accelerate hard, or does it not want to run above 3000 even sitting in the garage?