E21 Hard Starting

Received: 3/17/97 21:23 From: EC Gaitley, ecgaitley@CCGATE.HAC.COM

I think whoever discovers the elusive cure for the hard starting, poor running, surging, etc problems many of us are experiencing should get a prize. My '82 320is has many of these same problems and I've been living with it for over 3 years. It seems that a week doesn't go by when I don't read of another E21 owner with a similar problem looking for help on this and the other digest. So far my mechanic has been unable to diagnose the problem. He's adjusted the aux air valve, mixture, etc. to no avail. I tried disconnecting the Lambda sensor, no change here either. My only recourse has been to start methodically replacing the fuel injection components one by one, starting with the cheapest. So far I have replaced the cold start injector, warm-up regulator, aux air valve, and all 4 injectors. My next plan is to replace both fuel pumps and the fuel pressure accumulator. If this doesn't fix it, my last resort is the actual fuel distributor ($400 or so).

This was/is a good plan, Ed.

As with any hard to diagnose problem, start replacing the least expensive parts and work up to the more expensive parts. Most E21's, given their age, could use new parts anyway, and it's very inexpensive to do it yourself. Don't assume anything. For starting/running problems the least expensive parts are usually the basics, like plugs, rotor, cap, vacuum lines, etc., and should be the first parts checked/changed, along with checking and cleaning wire harness connectors. Sometimes, while you are replacing parts you stumble upon the real problem.

My experience with my 83 320i was due to a very unstable idle during warm-up, especially on cold days, and a lack of power even when warm. After a couple of months of tinkering I happened to bump the fuse box and SHAZAM, just like that, the problem was gone! Days later it returned. Playing with the fuse box led me to the wire harnesses that plug into connectors on the box. The harness on the passenger side closest to the front needed the contacts in the connectors cleaned and re-sprung for better contact. Haven't had a problem since. While it was running poorly, I had visions of a new fuel injection system. Good luck! -Art

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Received: 3/19/97 06:11 From: Walter G. Bariel, barie@diamond.nb.net To: E12Digest, E21Autos@ix.netcom.com

As an owner of 2 present and 1 retired K-jet FI car in the past 10 years. I have spent a lot of time dealing with these problems. I will say that ,in my opinion, the number 1 (numero uno, without a doubt, no question about it ...) problem is vacuum leaks. It only takes a very small leak to cause hard cold and warm starting. I can not stress enough that you really have to look carefully for the vacuum leaks. This includes: - the PCV hose(s) (must not have cracks and must fit tight on both ends, usually they soak up oil and balloon where they connect to the valve cover) Most people just assume that they are tight enough...not true. Replacement of the this hose pretty much corrected a hot start problem on my '79 320i. - the hoses to and from the aux air (slide) valve. These hoses harden up and although they look ok they will no longer seal well (made worse in really cold weather where the metal nipples contract and the hose is hard as a brick and therefore starts leaking since it can't contract enough to hold on to the nipple).

- For '79 and earlier 320i's the hose from the EGR valve to the bottom of the intake manifold. Although it is some different type of rubber I've had one crack. - Intake hose (i.e. the hose from the air flow meter to throttle body). Again these crack and the cracks are not obvious. (problem I had on my L-jet 528i) - Other vacuum lines (including the ones to the charcoal canister) - The injector o-ring seals (This one is a real killer since the leak is on the engine side of the throttle where there is a lot of vacuum to suck air in). This problem killed my Volvo for a few weeks this winter until I figured out what was wrong. The o-rings looked great but the starting problem when away completely when I replaced them.

One thing I've found is that if you do fix some vacuum leaks then you maybe able to lean out the idle mixture and the car will usually run better overall in terms of midrange torque, emissions, and gas mileage. The other common problems are incorrect mixture adjustment, cold-start injector dead or not working, dying main fuel pump or dead in-tank pump(low pressure), bad control pressure regulator (usually stuck in the warm, high pressure/lean condition) and bad ignition system condition (i.e. the car is in need of a tune up).

There are other cases such as bad injectors (Try some Techron if you think this is your problem) and bad fuel distributors (usually caused by water in the fuel) however I've seen a K-jet car run decent with injectors that had poor spray patterns and opened at the wrong pressures (i.e my Volvo with 160K miles). My Volvo also suffered from so much crap (blow by etc) on the air flow flap and linkage that it would stick once in a while. A can of gumout loosened up everything nicely.

Regarding ignition, if the car idles too fast when warm but the ign timing and fuel mixture adj is correct and you need to crank open the idle screw to keep the car running when cold check that the vacuum retard system is working correctly (i.e connected). It seems that on cars as old as ours that people just yank out stuff assuming that it is useless emissions stuff when it really does have a purpose other than emissions and it helps the car run better. *************************************************************************** ** Walt Barie (barie@nb.net, http://www.nb.net/~barie) '82 320i '79 320i (retired) '80 528i '80 Volvo DL (with K-jet also) ***************************************************************************

Received: 3/17/96 8:25 PM From: Chris P , chrisp@doe.carleton.ca From: chrisp@doe.carleton.ca (Chris Pawlowicz) To: Tazz@aol.com

You said you replaced the cold start valve right? With a new working properly adjusted one? I am speaking of the 'extra air slider valve', not the extra fuel injector thingy. When cold the air slider should be wide open, letting in extra air, raising the idle speed. There is a bimetallic strip heated when the engine is running to close the valve as the engine warms up. On my '81 320i the valve was sticky, and was not adjusted right. After lubricating (?) lots of WD-40.. I threw it in the freezer to make sure it worked. When cold it should be wide open. Mine was barely open. The screw/bolt arrangement adjusts the spring holding the valve open and I had to hold the valve open and tighten the screw at that position. Have you checked all this stuff ?

chris pawlowicz '89 325i '81 320i ex

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