My '87 240DL has started hesitating a lot in the last couple weeks and it had been suggested that it is my injectors. It runs pretty rough cold, but it goes away if I've been driving for awhile. Can anyone give me suggestions as to what could be the problem? I also had someone suggest putting in an additive called BG44K - will that actually help? I would appreciate any suggestions. Thank you.

the gasoline vapor will condense onto the inside of the cold metal intake manifold and the mixture that gets into the combustion chamber will be too lean to work right.

In the olden days, B4 the EPA/feds/CAFE demands, that problem was "fixed" by using a choke. The device closed off some or all of the air passage into the carbueretor. In the modern FI days, the problem has to be fixed some other way.

Cold start injector or valve just adds more vaporized gas into the manifold. The 1982 and older B21F engines may have this "fix". Newer ones, the B23F and B230F from 1983 on use a tweaking of the injector control by the ECU. It gets a signal from the engine ambient temp sensor to tell it to add gas.

That's the sender that you may need to check out. It is mounted in the block, on the LH side, and has two wires, one BN-SB (or SB) that's a ground and one BL that goes to the ECU. (SB is black in Swedish)

There are other sensors in the area, the knock sensor has one BN wire, and the coolant temp sender which has a single yellow wire. Don't get'em mixed up.

Good Luck,

Bob

:>)

Can you define running rough? Missfires, no power, surges, dies suddenly????

Start with ensuring that tune up type basic maintenance has been done. Plugs, points, wires, cap, rotor, clean throttle body, fuel filter, air filter in other words the things that can affect performance. It may be your injectors but there other more likely things. If BG44K is an injector cleaner no harm in trying it. I am always wary of suggestions from "someone" who say things without any diagnoses or knowledge of the problem.

The engine temp sensor (not the guage sender) should be checked. It can affect cold performance as it tells the ECU to enrich the mixture untill engines heat up.

Where's the temp sensor? Since the colder weather came my 82 DL has suddenly gone to very low idle when cold in the morning. Once it warms up, it's fine. Thanks

I have gone over the usual tune up kinds of things twice to see what the problem is -- nothing. I too am a bit skeptical about this BG44K stuff. But to answer your question, my car hesitates upon acceleration from a stop or at low RPMs. Once I am at highway speeds, the problem disappears until I either slow down or once the engine is sufficiently warm. I too thought about the some kind of temp sensor since it is clearly a temperature-related symptom. I have also read something about a cold start valve. I'm not enitrely certain how such a device works on my car, (BTW, I think my car has the 2.4L B21 or B24 engine - not certain exactly what the model number is), but it says this valve, if faulty, can cause poor cold performance. Is this the same as the temperature sensor you are talking about? Bottom line is whatever is wrong, it isn't sufficient to cause major problems, it's just annoying, and a bit unsafe since I don't know how to time pulling into traffic because I don't know how my car will respond. But I do appreciate your suggestions. Thank you.

As far as I know you would have the B230F engine, this will be indicated on a label under the hood. Don't think you have a cold start valve. I am surprised your car takes that long to warm up, by the time you get the highway, get on it accelerate cruise for a while and then have to slow down I should think you would be already fully warmed up. How long does it take for the temp guage to get to normal? You may have a thermostat issue as well. Temp sensor is under intake manifold about under # 3.