?'s about a 1989 300E

1535 Views 5 Replies 2 Participants Last post by alpinee30, Apr 3, 2009

alpinee30

Discussion Starter · Mar 30, 2009

first I was wondering where the intake air temp sensor is, is it in the air flow meter, cause I didnt see anything else that resembles a temp sensor on the entire intake? this is a different sensor question Next question is I found a new temp sensor for the dme/ecu via the internet, the one in the head on this car has two poles the one on the internet is three poles any reason why? I wanna change this one cause its running really rich unless you have another suggestion what that might be running rich from? Next question is from a standstill, it backfires and hesitates for a sec then takes off any suggestion what that might be, I hope its not a intake valve leaking. I have tons of questions so bare with me. Cylinder head? This one mercedes guy says a 2.6L head on this 300E block will make it a screamer is this correct and if so what cylinder head is it a 260E or a 2.6L 300E head or are they the same or is this misinformation. Any help will be appreciated we are running this car in the enduro racing against v8's the 260E we ran last year lacked power and threw a rod so we are trying to set this one up so atleast runs good.

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augapfel

· #2 · Mar 30, 2009

First of all, the intake air temp sensor (IAT) fits into the flex duct between the air cleaner and the radiator support *if your car is equipped with one.* The 86-88 49 State cars don't seem to have one. CA, I can't say... 89 up, can't say...
There are several different coolant temp sensors for reasone that I don't fully understand. A lot of service literature shows 4-pole sensors but my 88s all have a 2-pole sensors. Apparently a good way to identify the sensor is by the color of the top plastic piece. Mine are all green top sensors. Don't measure resistanc ebetween poles. One pole is for the fuel injection ECU and the other is for the ignition system. Measuer between each pole and ground. Easy test -- resistance values should be about the same for each, say *approximately* 200 hot to 8000 cold IIRC.
The 2.6 head is definitely a differnt casting number than the 3.0L. Don't know why but i think the CR is the same for both engines so the screamer business sounds like
BS to me. The heads are clearly marked 3.0 and 2.6 if you pop the rocker cover.
The bottom end of the M103 is really stout so if you blew one up you must have been really abusing it :-(

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augapfel

· #4 · Mar 31, 2009

The "like a TPS" is a simpler Idle/WOT switch. At idle terminals 1&2 are shorted, at WOT terminals 2 and 3 are shorted. Any ther time the two pairs of terminals are open. Primitive? Yes.
The FPR vacuum line goes to the weird-shaped "hose" between the top of the air cleaner and the side of the rocker cover. No, not manifold vacuum...
As for the front vacuum switch on the head, the one you are asking about goes to a port on the throttle body. Upper one IIRC.
Idle speed is not adjustable. Something like 650 RPM in neutral or park IIRC.
There's no visible difference between the 260E and 300E under the hood. Vacuum, air intake, coolant hoses, all exactly the same...

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