I like what kathy said about intake gasket

 

^ she's right, but mine's already new, changed when I did my HG.

 

It sounds like the problem is overfuelling...it happens in a hot motor when the system either undersenses the temp (temp sensor and/or connections) or the system that reduces the fuel delivery (a black relay usually on the left in the engine compartment as you face the engine) is faulty and allows the system to overfuel. In all your work you may have disturbed some wiring. I would look at these problems....In carbed engines, hot starting is very simple, but in injected engines, it is much more tricky as I found out with my old 760. PS...a noisy fuel pump..depends on the mileage. I had had a BOsch one last 190K. They get noisy around the 150K plus point, but any pressure related probs and it would not start from cold, so it is prob OK for now. If it is more than 160K on it, I would consider replacing it. Mike

 

I have pretty much gone through this car every which way I can think of, trying to pull trouble codes and checking different sensors. I tested the engine temp sensor through the pins in the ECU, tested the resistance of the O2 sensor, checked the fuel flow through both pumps, replaced vacuum hoses, spark plugs...NOTHING seemed to work...until....

I took a look at how the throttle cables were adjusted. Since my car is the 2.4 Jetronic system, the idle is set at the ECU and from what I understand, is not really adjustable. Well, my throttle cable was so slack, it was drooping, and I remember I had messed with the when I pulled the intake manifold off so the cable wouldn't kink. I had never turned the cable back the way it was before so I did one full turn on the upper throttle cable and the problem is magically solved. I don't know if I'm just masking the problem, but the car runs great and as far as I can tell, no sensors are out. I've checked so many things at this point that I'm just going to run the car as is knowing that there is nothing catasrophic occuring (like gas in the oil or something crazy like that).

As has been pointed out many times in this forum, when you do some work, go back over and over it because that is most likely that source of the problem. I'm pretty sure that my issue was self-induced. Just glad I've sorted it out.

 

Very hard to say without testing but SEVERAL things can cause a poor idle. You bought this car with a blown head gasket correct? They overheated it to the point where the headgasket blew correct? Now, did you use the same head that was on the car when it overheated? If so did you have it machined by a reputable machine shop and have it pressure tested and shaved etc? Did the check all the valves make sure they were all good? Did you replace any of the valve seals etc? Or did you just use a used head from a wrecking yard etc.? Did you give a compression check after you finished the job and made sure you torqued all head bolts to proper spec? Set timing with a timing light and set idle to proper spec? Now in this case there are so many variables that it would be hard to trace down problem unless we have ALL the facts. Did you reuse the computer temp sensor or use a new one? Start by doing a complete inspection and re-tighten on all bolts and check all connections that may affect idle. Check the intake manifold bolts and make sure no leaks from gasket. Here's the thing you don't know if the car ever idled good because you bought it damaged. So you have to check and test EVERYTHING and go down the list one by one. I would start by pulling all plugs and performing a compression check on all cylinders and checking my timing marks with a timing light and making sure everything is tight. This way you can check the condition of the plugs too and see if they are burning evenly. Then do a fuel pressure test while car is cold and warm. If all checks out you may have a sticky valve or need a valve adjustment, or bad injectors, bad computer temp sensor, dirty throttle body, bad MAF, O2 sensor,vacuum leaks somewhere, bad ECU or just a worn out motor...rough idle can be a nightmare tracing down and even worse on a car where it has been overheated and a turbo on top of that because they get way hotter then a non turbo and motors can be ruined easily when overheated enough. Anyway, start with tracing back to the parts you took off and the new parts you used and check your work...then begin to test, test, test. Be patient because it may take a long time to figure it out...if you ever do. Also, ask the seller if you can if the car idled rough before it overheated or if it always ran and idled perfect. Maybe it's had this problem all along? Good luck!

 

[QUOTE=pierce;271186]if the crank sensor was failing, the car would not run at all. NOT TRUE. NOT TRUE AT ALL!

 

Ha LOL I probabl should have read your last post before I posted but yes typically if the car was fine before we messed with it, always back track what ya messed with and make sure it's correct. Bought a car about a year ago a 92 245 that a guy had replaced his intake manifold gasket and after that would not start. He threw every part under the sun at this car and finally got fed up. Sold it to me for $100. The main ground was loose...tightened it up and the car fired up instantly....

 

if the ECU and ignition computer don't get pulses from the crank sensor, they don't know the engine is turning and don't fire the spark or the fuel, qed it doesn't run.

 

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Are you a mechanic with experience or are you just spewing out things you might have read somewhere? A crank angle sensor can be going bad.and cause all types of weird symptoms. Usually you will get a code but often not cauae car only gets a code when it will not start. I have replaced MANY crank angle sensors where the car would run and then die under load or just start and die etc. or start and run and.srive.just fine dor a while and then die. So please do not read something somewhere and think everything is so black and white or cut and dry cause it's not...Not trying to be rude just don't want people looking for answers to get the wrong information. The crank angle sensor could be weak but still sending pulses enough to start a car but the magnetic field is.not strong enough to keep it running or running under load. Trust me on this one, you might run into this problem one day and thank me for it...cost big $$ to diagnose this problem if your mechanic thinks the way you do...

 

my personal experience with crank sensors is on another Bosch equipped engines, where they tend to fail abruptly and cause a complete non-run situation which may come and go with temperature, or just fail and stay failed.

 

Not saying this is not true but trust me in A LOT of cases it can just be a weak crank angle sensor. So yes a crank angle sensor can just go bad and stay bad or it can go bad slowly and cause symptoms that will drive you nuts if you think "well it can't be the crank angle sensor because my car is starting and if it were bad my car wouldn't start..." This type of thinking will have you throwing every part under the sun at your car and then finally junking it or selling it unless someone with experience and intelligence says hey it may be the crank angle sensor try that....trust me I have seen it more than a few times especially on the 240's...also seen something as simple as worn wiring because the sensor plug is supposed to be clipped onto the firewall but a lot of times it falls and the heat melts the protective coating and exposes wire therefore causing it to ground out....in this case too the car may start, then not start or start then die...hope this info helps you out or someone else out one day...

 

the engine I mentioned above that I've experienced crank sensor failures on uses a hall effect sensor that reads notches on the crank pulley that drives the alternator belt. More than half the time, the failing is wiring related, in fact last time, rather than replace it with the expensive OEM part, I followed some internet advice, and took the generic bosch hall effect sensor which is identical except for the harness and connector, and made my own harness on it using high temperature thermocouple wiring.

but, yeah, this isn't a Volvo brick (its the BMW R259 'oilhead' engine, an 1100-1150cc opposed twin used on the R1100xx series of motorcycles, with MA2.2 or MA2.4 Motronic EFI), and the failure modes aren't necessarily related, however similar they may seem.

 

Just an update....I've been driving this car like I stole it all week and it's pretty hot and nasty this time of year in west Texas. Car is doing great, no hot start issues. So I really think it was just an improperly adjusted throttle cable. Really though, I'm not a pro, and my diagnostic skills are pretty crude. So hopefully I'm not masking some problem that I missed. But without engine codes, I'm at a loss as to what to start replacing because the engine runs great.

I'll just leave it alone, hell, it was only 500 bucks.