I have a 1997 E320 it cranks and runs for 20 seconds the most then dies,usually it's more like 2 seconds running,i changed out the cps and it started and ran for almost a minute then just died again,i have fuel pressure and no codes,weird thing is if i step on the gas it instantly dies also i took off the MAF and it looks clean,left the MAF off and started the engine while blocking the intake hose and it ran for as long as i blocked the intake hose,anyone have any ideas?

 

Your symptoms appear to point to the MAF since disconnection enables the engine to continue running.
The MAF sets base line fuelling and then updates this every fraction of the second whilst the engine is running.
The MAF sensor gets dirty/ages and this impacts the base line setting usually causing the engine to run weak.
You cannot see the active part of the MAF when you remove it from its housing.
Have you tried cleaning it. 50% success rate.
If cleaning doesn't work then get a genuine MB/Bosch MAF sensor ensuring you get the correct one.
Ohlord posts state where these can be got from other than MB.

HOWEVER MAF problems usually set codes P0170 / 3

A further thought is whether the controlled 5v power supply to the MAF is correct. If this voltage is incorrect it impacts the output of the MAF whilst the MAF is fully functional. Unfortunately I can't remember the pin out connections in my head but there aren't too many combinations to wade through.

Good luck.

Stuart

 

Thanks snancekibut it doesn't really run without the maf installed,with the maf installed it only runs if i block the intake hose and even then it is very very low rpm's and as soon as i unblock it it dies out,do you still think that it still points to the MAF? thanks again

 

I'm confused as to when and under what condition it runs.

I thought, maybe incorrectly, that it runs with the MAF disconnected but not when it is connected.
By disconnected I mean, with the sensor removed but the hole plugged.

Looks as though I have misunderstood.

Looks as though you mean with some other hole closed off.

Clarify and I will have another go.

Sure all the vacuum hoses are connected and in good shape.

Stuart

 

Thanks for the reply Stuart,there is no change whether the MAF is connected or disconnected,i did have it runnning when i thought there might be a leak in the intake hose so removed the section of pipe which contains the MAF and i blocked the remaining intake hose leading back to the engine, there was minimal air getting into the throttle body butthe engineran for as long as i was blocking the opening,A symptom which i have noticed which i'm unsureif it's normal on this engine is thatwhen the ignition key is to the run position. There is an electrical motorrunning sound coming from throttle body butterfly valve,is this normal? Also when i step on the gas the throttle body butterfly valve doesn't open more than 3 degrees,is this my problem or is it normal operation for the throttle body? To me my symptoms of engine starting and then dying sounds like fuel or air starvation and if the motor in the throttle body which operates the butterfly valve has died this would cause my problem.... is this a possibility,Can it be tested?Can the butterfly valve be manually opened?
Thanks in advance.
Nelson