[alpinee30]

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.

 

[augapfel]

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 :-(

 

[alpinee30]

Alright so I was right kinda, theres a dummy plug that I thought was for the intake air temp sensor, right where you where talking about. But there might be a sensor still there, since we are using a the old 260E air box and this 300E is a 89. So there could be two wires laying somewhere in the engine bay but I didnt really find any. Oh and about those sensors on the head so these cars have one pole going places instead of a +/- i am use to my 86-87 bmws but its all still bosch just alot of differences. Alright well I will see if this car still has a iat sensor wire laying around. Anyone have a pic of the engine bay of a 300E since I am a little confused as for the vacumm lines, the 260E is the same but it seems different or this 300 has been tampered with a little. FPR line I need to see where that line goes and the front sensor on the head has two vacumm lines and I know one goes to the wheel well and the other I have no clue but then again this could be cause we are using the 260E intake air box. Also no advice on the backfire/hesitation from standstill. Also anyone know what the idle is suppose to be set at on the 300E. Also there is a switch on the throttle not tps is like a micro switch is that switch suppose to be pressed in at idle? oh thanks augapfel for the info so far, hey I am from pa also LOL.

 

[augapfel]

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...

 

[alpinee30]

Yeah that switch, I was just wondering if it was suppose to be pressed in at idle since stuff was messed with before we got the car. Oh I guess I had the fpr hooked up at the wrong spot LOL. Yeah the throttle body has a little hose on it bypass to the lower one so I guess the one goes to the front sensor do you know where the lower vacumm line goes not sure if it was blocked off on the 260E or not? I had stuff written down on a paper plate LOL but who knows where that went. I knew stuff didnt look right from day one. thanks again it will sqaure away some of the headaches I have been having since I pulled the whole wire harnesses from the back of the car to the dash I only left the fuel pump, fuel level sender, o2sensor wires intact. YOu think since I had the fpr hooked up at the wrong spot can cause any problems prolly not but I would thought I would ask.

 

[alpinee30]

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 :-(

Alright not sure but the 2pole green sensor, I checked the resistance and it was showing weird numbers .2 when hot and 3.00 when cold both poles came up the same then I tried an analog one when it was cold and it said 5 1/4 I think I am going to test again. I dont think I did it wrong, but it was showing figures I never seen before. I tested many things before but these figures dont seem right and I am confused LOL I wrote the numbers down but I forgot the notes but I can remember those around the numbers it was reading. OH and I did test it red on one pole and the negative on the aluminum intake manifold. But both poles where the same readings.