Hey all, A friend just bought an '83 400i and took delivery of it on Friday. The car is in excellent shape cosmetically but has not seen much road use in recent years, and thus is in need of a major tune up. We've ordered the necessary ignition parts (cap, rotor, wire sets and plugs) but in the meantime have a couple of issues at hand: 1. The car idles rather rough (mixture is set VERY rich, as evidenced by black, sooty plugs). Idle drops very low when the car is put in gear, almost to the point of stalling out. 2. It also smokes like a locomotive. Definitely black, but why someone would have the mixtures set so rich is beyond me. I have the 400i shop manual but can anyone shed some light on what might be going on here (if anything abnormal). I just can't imagine why someone would have this car running so poorly (unless they were an amateur mechanic and really screwed things up). Any particulars on the 400i that we might look for before and/or after the tune up? Do the MSD boxes fail? Cheers, Aaron '82 GTSi
Not sure if the 400i had O2 sensors, but most other Jetronic cars of the era did. Check them and the connections. (I'll probably be corrected quickly by the more informed members here..)
I gather that your friend did not test drive this car or have a PPI done. Tell him welcome to 400i ownership and get him to sign up on FChat! I don't think that it will be too complicated to sort out. The Bosch K-Jetronic fuel injection systems are generally reliable and fairly easy to tune. They were also used on many Mercedes and BMWs of the early 80's (not to mention your GTSi right?) and so many mechanics are familiar with setting them up. Could another possibility be cold start valve might be sticking, keeping the mixture rich? This would be something to check if only one side of the engine is running rich, since there are two separate systems and it would be unlikely that both sides would fail at once. Can't comment on the MSD, other than to say that they are a common replacement for the stock ignition box that costs three times as much. I've never heard of any big problem with either the stock (other than that they are sensitive to being jumpstarted) or the MSD. A proper mixture setting and a new set of NGK BP6ES plugs (or similar heat range) may do wonders. Or it may not! But start with the easy stuff first! ;-) John
Hello I encounter this situation : The car starts perfectly when cold. First attempt, it works. When the engine is hot, it is quite impossible to restart, have to wait until the engine gets cooler. According to what said John, can be sticking cold start valve, keeping the mixture rich. My contribution to Aaron pb would be : -my car's ignition probably needs tuning, as your friend's car, -it might be because of a sticky cold start valve - but in my case, smoke does not look especially black, it looks normal. I hope it helps your search for a diagnosis. By the way, John, would you have any idea to fix the start valve ? I add something : this injection system also fits Porsche 928 I think. Olivier
The injection system is the same as most of the high end 6 Cylinder cars from BMW at that time (633,635,733,735 etc) standard Bosch (no 02 sensor), if it's belching out black smoke there is a strong chance the Valve guides are worn, Before jumping off the deep end, complete the service you've obviously got planned, and whilst you've got your head in the engine bay perform compression and leak down tests wich will give you an indication of where to start.......or if something major is wrong when to stop
I have no idea where these valve guides are but according to what said John: So a question would be : is there black smoke on both sides ? Olivier
Olivier The valve guides I was refering to where the ones in the Cylinder heard that guide the inlet and exhaust valves, they wear allowing oil to get into the combustion chamber (or burn off ontop of the exhaust valve) if you look at Al's 400 daily driver thread you'll see what I mean My point was, that before jumping into the fuel injection system it would be prudent to first ascertain the overall condition of the engine.
I don't know how to test the cold start valves, but they do seem to be fairly accessible. You can find a diagram of all of the fuel injection system parts for the 400i on the Ferrari UK website, using their "isoview diagram" feature. Also check to make sure that the air filters aren't so dirty as to be clogged up. A really heavily clogged air filter could reduce the amount of air getting into the engine and thus result in a rich mixture. To confirm if the black smoke is caused by a too rich fuel mixture, pull some of the spark plugs (some from each bank of the engine since there are two separate FI systems) and check their condition. A very black but dry, powdery coating on the electrodes is a sign of a too rich mixture. A very black but wet and oily coating on the electrode is a sign of burning oil. The ideal color is a medium to light brown. Usually the black smoke itself is confirmation of a rich mixture, since heavy oil burning would create a bluish white smoke. If the blue-white smoke is heaviest on acceleration, the problem is likely to be bad rings. If the smoke is heaviest on letting off the gas and during deceleration, the oil burning is likely to be from bad valves and/or valve guides Adjusting the mixture is a fairly easy job, one that many competent garage mechanics can do. As I said, the Bosch K-Jetronic FI was a fairly common system during the 80's and adjusting with a screwdriver and a meter to measure exhaust gases is fairly straightforward. Make sure that the mixture isn't set too lean however, as that could cause some very major problems such as burned or broken pistons. I wouldn't rely too heavily on my advice, since I am by no means a trained mechanic and who knows how wrong I can be when I get into this stuff. You might try posting this in the tech section as well. John
Sounds like the hot start relay is bad. If it isn't working the car will be a real ***** to start when hot. Pull the relay board and see if you can hear it click as you start the car hot. The hot start relay sits all the way on the right and is the largest relay on the board.
Use a 3mm t-handle allen wrench to adjust the mixture. The adjustment is in between the black "rubber" boot and the fuel distributor. Look for a silver tube, drop the allen wrench in... and walla!
Andrew, Ok, I got your point now. I apologize, I did not get it at first reading and what I said about the sides was no relevant. Again I apologize. Your approach is right. Fine tuning won't bring much in case the cylinder head is faulty. Olivier
The problem can be related to the changes made to the K-Jettronic to make it EPA legal and the state of that stuff (the closed loop O2 system including sensors, frequency valves, etc.) Ferrari published a separate manual for the 400i injection system (400i: Injection repair manual # 178/79). I found one on eBay. You're friend may want to look around and see if he can find one. Of course it doesn't cover the stuff added to make it US legal. I do know 400i will run really great when they are configured as it left the factory!
This could be a really easy fix. I had a jag xjs v12 with the same exact problem. The problem with mine was a hose connection came off the ECU and caused the car to go to full rich. Don't drive the car until you get this fixed, you'll just clog up your catalytic converters and foul the plugs out and the car won't run. Just check all the connections to the ECU and make sure nothing is disconnected.
The 400i uses mechanical injectors. It has been my experience that these injectors clog and/or leak causing black smoke and poor idling. Bosch sells a tester/cleaner device or an injector shop can check them for you. I just did this to a Boxer and bought the HC levels from 530ppm to 14! The car idles beautifully and passed the Mass. emission test with flying colors. The car had five bad injectors. Cost new is about $40 each from Worldpac. Ciao, David
David, Do you have any specifics on the injectors like product number or what other cars they are used in? Thanks, Al
When you pull the injectors out you will find a Bosch part number engraved on the part. That number will not be the same as a Ferrari part number, Get yourself a new set of O rings also. I am not sure what the number would be for a 400i. More than likely the Bosch part number has been superseded. Sometimes the injectors clean up nicely when you run some ordinary cleaning solvent through them. I use Zep 143 and my Bosch tester. Ciao, David
Check all your basics first before swaping any parts. Cam timing, ignition timing, FUEL PRESSURE, condition of plugs and associated components (wires, extenders, etc). Check for moisture around electrical connections, check for vacuum leaks around the fuel head, check to be sure there are no cracks or openings in the airflow snorkels to the throttlebodies, check the fuse panel for poor connections, check for poor grounds. All of these simple things will cause any number of issues. You must have a strong foundation before any real trouble shooting can begin.
