KE-Jetronic (CIS-E) has a fuel pressure regulator with a compensation for intake manifold pressure. At cruising (vacuum = low pressure) the system pressure is lower and at full load the pressure is higher accordingly. This should work with boost also: the system pressure should add the boost pressure to the original spring controlled regulator pressure. The higher system pressure should give a higher flow to the injectors and a richer mixture. Has anybody experienced or measured this kind of a mixture richening effect on boosted KE-Jet systems?

tomant

The FPR was designed to work from a vacuum up to ambient air pressure. Asking it to work under boost is probably out of the design spec.

I supercharged a (non M-B) car I owned a while back and had to replace the FPR with an adjustable one that was designed to work under both vacuum and boost.

Just my $.02.

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles

Thanks, bobs. You are right that the FPR was designed to work from a vacuum to ambient pressure. I just wondered if it had any headroom to work with boost also. At cruise and light loads the EHA will correct the mixture so the FPR propably won't do much to the AFR anyway.

At full load (=boost) the EHA control shouldn't be on so there the FPR could help a little. Did it have any affect on the full load mixture or did the operating range end at ambient pressure? Was the FPR in your supercharged project of the same type as the Bosch KE-Jet's?

tomant

The CIS-E didn't like the boost pressure in the FPR and the mixture went even more lean. Maybe the higher fuel pressure acting on the upper chamber pressure leans the mixture out. Well, you don't know before you try it out.

tomant

I am swapping my 190E 2.0 engine to a european 1999 W202 C200 Kompressor engine (M111.944). It is very similar in performance to the C230 K and has many common parts with it. 1997 Mercedes-Benz C 200 Kompressor Estate S 202 car specs

Can anybody tell me how the stock fuel pressure regulator of a late 90's W202 230 K (and 200 K) works with higher boost than the stock 7 psi (0.5 bar), thanks?

tomant