Author Topic: Poor running issue, please help. (Read 10021 times)

Jimmy Lewis · « **on:** May 02, 2008, 08:27:31 PM »

Hey guys, I'm in need of a little diagnosis. Well, this last week I slowly tore everything out for my clutch replacement, got that all wrapped up today and I must say it is a world of a difference, but....

Along with the clutch swap I decided to do the TB heater delete as well, deleting the snake of hoses as per tits1's thread regarding it. I'm sure I got all of the major things right, hose running from valve cover to throttle body, manifold to ICV to air boot, and I decided to run a hose running from the coolant junction to the port between cylinders 2 & 3. When I originally started the car to slip the clutch into the driveway where I did the clutch, the car ran like absolute crap, before anything was done to hoses. So, I think the problem already existed before the work was done...

For the last 6 months or so my mileage has been in the absolute pits, averaging 15mpg, sometimes as low as 12mpg, and sometimes up to 20mpg when I do nothing but get on and off the highway. I think my oxygen sensor is bad, as well as my plugs and plug wires. I bought plugs today and some techron to hopefully clean out the injectors from sitting for almost a month. Do you guys have any ideas? One more thing, there is a small diameter hose that comes off a small round thing at the end of the fuel rail that I never ended up anywhere, it looks very worn, any ideas of what it is? And now for the stupid question; there is an arrow on the ICV, should this arrow point towards the intake boot or towards the manifold, I'm sure I have it right, because the car idles better than it does the other way, but who knows. Thanks in advance.

Wise Old Dog · « **Reply #1 on:** May 02, 2008, 11:31:49 PM »

Sounds like you have a disconnected FPR vacuum hose. Running rich probably.

Jimmy Lewis · « **Reply #2 on:** May 02, 2008, 11:39:28 PM »

Is that what you think the hose is? Where should that hose coming off the fuel rail go to?

Wise Old Dog · « **Reply #3 on:** May 03, 2008, 07:14:46 AM »

http://www.realoem.com/bmw/showparts.do?model=AF93&mospid=47305&btnr=13_0308&hg=13&fg=15

Hose #11 ?

Jimmy Lewis · « **Reply #4 on:** May 03, 2008, 07:38:55 AM »

Yes sir. It is just laying there not attached to anything, I guess that could be an issue, haha.

Wise Old Dog · « **Reply #5 on:** May 03, 2008, 09:04:30 AM »

IIRC there is a small hose nipple on the throttle body that it connects to. A b#tch to get at.
This hose basically controls how much fuel pressure goes to the injectors. At full throttle the vacuum drops and allows the regulator to open up and increase the fuel pressure. With zero vacuum at the FPR, like you have, it is maxed out 100% of the time. Plus you have a vacuum leak at the throttle body nipple.
This would cause a rough idle and poor fuel economy.

Somebody correct me if I didn't get this right.

Jimmy Lewis · « **Reply #6 on:** May 03, 2008, 10:11:06 AM »

I will definitely pull the TB and find the nipple you are talking about, it seems that the hose has simply worn so much that it fell apart, that may explain why the fuel economy was so bad and when it finally decided to fall off, made the car run so bad. Thanks, I'll look into it, but any other opinions are welcome as well.

250k318is · « **Reply #7 on:** May 03, 2008, 12:07:54 PM »

not to but in but im having similar problems after removing the tb heater but my car just won idle if you give it some gas it runs but as soon as you let off it dies any clue of what may be happining

Wise Old Dog · « **Reply #8 on:** May 03, 2008, 01:09:16 PM »

The #1 reason these engines do not idle correctly is vacuum leaks. Everyone who owns these high mileage cars should inspect ALL vacuum hoses and the connections. In addition, the intake manifold gaskets leak as well, especially with age.
There is no way to visually inspect ALL of these areas and be 100% certain that they are leak free.
Therefore, as I have stated in several posts : Get a spray can of carb cleaner or similar. Make sure you have the little red nozzle extension attached. And with the engine running, spray a SMALL amount on each hose connection, and all intake gasket areas upper and lower. In addition, check the intake boot and associated connections. When you come across a leak, the engine will immediately increase idle speed and smooth out. It is so easy to do this. The intake manifold fasteners can be tightened a little more if you find leaks there.

250k318is · « **Reply #9 on:** May 03, 2008, 01:14:58 PM »

every things tight as for leaks the car wont stay running to check without someone givin it some cas could i have something wrong with my idle control valve im searching into how to cle and inspect this befor i go and buy a new one

Jimmy Lewis · « **Reply #10 on:** May 03, 2008, 03:37:02 PM »

Thanks man, I've done the carb cleaner deal in the past with the cracked mess under the intake, and it works well. The intake boot has worn quite a bit, I'm going to have a new one on the way. Regarding leaks, my only leak is that small hose, the others have very tight connections with hose clamps and I trust that they are sealed. I used new gaskets for the manifolds so I assume that they are sealed well. I'll get it fixed man, thanks for the help.

Jimmy Lewis · « **Reply #11 on:** May 03, 2008, 06:32:40 PM »

Oh the beauty of new spark plugs. My plug on cylinder 3 was badly fouled, probably from the richness of the mixture. Installed new plugs and added some techron injector cleaner and now it purrs like a kitten. Off idle power is better than ever, it pulls smoothly without any sort of hesitation. I never got into it because I'm going to take it easy on the new clutch for a couple days, but from what I see the problem is solved. Thanks Dave for all the help, I'm lucky to have you an Eric in my backyard man, you guys know your stuff.

Jimmy Lewis · « **Reply #12 on:** May 04, 2008, 01:31:27 PM »

Scratch that idea, the new plugs fouled in a matter of driving the car for maybe 20 minutes and now it is running even worse. There are no vacuum leaks and no exhaust leaks, so the only left now is that the oxygen sensor is bad, but would a bad o2 sensor cause the plugs to foul so quickly? What other reasons can you guys give to such a rich fuel mixture? According to the Bentley for the M20 cars, the o2 being faulty shows the exact symptoms I have, poor mileage, poor off idle power, etc. It seems that the car runs relatively ok from around 2000 - 4000 rpm, anything lower or higher, power is nil with chugging. I really need to get my car back on the road, thanks guys.

Wise Old Dog · « **Reply #13 on:** May 04, 2008, 02:25:16 PM »

O2 sensors are not designed for the life of the car. There is a mileage interval that they are supposed to be changed at. Even if your O2 is not bad, it is probably way past due if it is OEM. $30 gets you a universal Bosch sensor that you splice into your OEM plug. This would eliminate the O2 as a cause for your problem.

Has the car ever run correctly?
There are other problems that could cause this. Have you checked to see if the ECU has thrown any codes?
Your valve timing could be off due to a stretched chain. Even an old chain can be re-timed to get it back to specs. You could have a faulty FPR, I don't know how to check it, I just replace it, $60
Could be your ECU, I have one you can swap to check if yours is bad.
Isn't troubleshooting fun?

Jimmy Lewis · « **Reply #14 on:** May 04, 2008, 08:24:01 PM »

Well man, I'm banking on the FPR as the issue. I've never checked the CEL codes in the car, but the way it is running, it seems to me to be a fueling issue. After driving it some today, it runs very inconsistent and comes in and out of chugging, as if it is getting the proper amount of fuel then is either choked or is getting an excessive amount. The condition of the vacuum hose makes me think maybe having no vacuum to the FPR may have caused it to fail somehow. My question is, wouldn't an issue like bad plug wires or a bad o2 sensor cause the engine to just consistently run bad? The o2 is probably either bad or on its way out but I have read where guys run without one and the car just runs rich rather than the way mine does. With the above said, do you agree the FPR is the most probably cause of the issue?