I need help from the experts. My 328 has been running rich, so I decided its time to adjust the fuel mixture baseline. I do not own an EGA, so I tried using an analog dwell meter. I connected the dwell meter by back probing the frequency valve, but the reading is steady at 60% no fluctuations of the needle at all. I did disconnect the O2 sensor before measuring the duty cycle. I have spent several hours researching the old threads, here and at the other site, but have not found an anwser, as to why I am not seeing the needle fluctuation as expected. The car starts without any issues, runs goods, except when at high altitudes (above 9000 feet) when it drops idle rpms to about 700, and it is a little hard to start the car. The only problem I have noticed was the fact that it was running rich. I concluded that by the amount of carbon build-up on the plugs, and at the exhaust tips. Also, I just replaced the O2 sensor, and the old one was covered with carbon. Concluding.....I am lost. Why the dwell meter needle is not fluctuating like expected. I tried very small adjustments to the 3mm allen screw at the fuel distributor, but did not cause any change to the dweel meter behavior. Any advice will be greatly appreciated. Thanks. Milton
If you unplug the O2 sensor, I believe it's correct for the FV duty cycle to go to some fixed default value. Without an EGA I think you could try two things at warm idle: 1. With the O2 sensor unplugged (and the FV duty cycle at the fixed default), adjust the mixture screw until the voltage output of the O2 sensor is 0.5~0.8 V (even though the O2 sensor is unpluuged you can still measure its output with a voltmeter). 2. Then when you plug the O2 sensor in (and the system tries to hold an average value of 0.5V coming from the O2 sensor), the average duty cycle should be about the same as the default (i.e., when the O2 sensor is plugged in and you tweak the mixture screw, the average FV duty cycle should change).
Can't help with the O2 sensor Vvalue (I use a good infrared bench CO machine), but make certain to adjust from lean to rich on the 3mm grub screw and remember, the adjustment is the reverse of the the intuitive (lean to rich is CW, looking down from the top on K-Jet cars). I say that because on the carb mixture adjustment, from rich to lean is CW. -Peter
Milton -- I forgot to ask if you've actually verified that you are running closed-loop at warm idle (i.e., does the O2 sensor output, when plugged in, swing slowly between 0V and 1V)?
Have you checked the warm up regulator? There is an ohms-reading test for this part. The warm up regulator is actually a fuel pressure regulator and, consequently, this obviously affects mixture on CIS equipped cars. The WUR will affect mixture based upon three variables: a) the temp of the WUR itself as it heats off the engine block temp (this affects motion and position of the internal bimetalic arm), b) the level of internal vacuum/low pressure as controlled by the input pipe from the throttle body, and finally, c) the electric input directed by the ECU reading off the thermo time switch. If you think the WUR may be affecting things here then let me know as I have a brand new one available - [email protected]. Good luck!
Thanks you all for the suggestions. Steve, as you suggested, I set the O2 voltage output at approximately 0.70v, using the mixture adjustment screw at the FD. After re-connecting the O2 sensor, the dwell meter still remains steady, without any fluctuations. Just took her out for a ride, and she is running great. Starts easy while hot. I am going to let her cool down now, and tonight after work, I will try to start while cold to see if there is any trouble there. I will keep you posted. Once again, Thanks. Milton
Glad to hear you're making progress, but are you also not seeing variation in the O2 sensor voltage output when you're not seeing variation in the FV duty cycle? I.e., no variation in the O2 sensor voltage output would indicate only open-loop operation (like a dumb K-Jet) and not closed-loop operation (like a K-Jet with Lambda). I'm not as familiar with the 328 system to know if warm idle operation is supposed to be closed-loop for sure (but I would have guessed that it was -- along with part-throttle cruise). IIRC, other 328 Owners have mentioned an intelligent connection between the thermocouple ECU (pin 4) and the injection ECU (pin 6) that prevents closed-loop operation until the thermocouple ECU reports a temperature of 300? deg C. The 328 schematic shows such connection, but it doesn't explain what's going on inside the ECUs. Those thermocouple ECUs are notorious for going wacky with regard to their "slow down" light function so your "special" one with the extra function won't be any better IMO. Wouldn't be the end of the world to always run your system as a dumb K-Jet, but it's not the greatest IMO. Anyway, just wanted to suggest that you do somehow eventually verify it does correctly run closed-loop when it should be in that mode. If the cold-running now has trouble, you'd have to suspect/check the WUR output pressure as Cliff suggested (and possibly un-tweak what you just tweaked ).
Well, here is the update. After letting the engine cool down overnight, she started without any issues in the morning. Answering your question 91tr, she does goes into closed loop. Although, I was never able to see any oscillation on the dwell meter, I did observe the O2 voltage variation. Last Sunday I took her out for a 400 mile round trip, and she ran perfect. Once again, thank you all for your support and help. Milton.
I had a similar problem with my 308 QV late last season. Car seemed to be running rich, was kind of doggy off the line, but ran ok otherwise. Idle was a little irregular and didn't sound quite right. Checking the duty cycle at the Frequency Valve, there was no change when messing with the fuel mixture adjustment. I don't remember exactly what it was, but it did not change. Several things to check ... I'm pretty sure that the 328 is pretty much the same as the late (84 & 85) Qv's in this respect. 1) there is an oil temp. switch that signals the ECU to go into closed loop. I don't recall whether it is open or closed when cold, but it is easy enough to test with an ohmeter both when hot and cold. It is accessed from under the car, and is more or less above the shift linkage. You'll see some oil lines and/or pipes there, there is a union that has the switch in it. In my case I found this switch disconnected, but that was not the whole problem. 2) Check the throttle switch for proper operation. There should be continuity between 2 terminals when the throttle is closed, and continuity between one of the same terminals and the other at WOT. Check by disconnecting the switch and probing the terminals. In my case, a big part of the problem was due to a dead throttle switch. If you do need a switch, go to a local import parts store and order it by the Bosch #, it was also used on several BMW's, and a few other cars of which the makes escpape me at the moment, but you will pay less than half of what you would from any of the F car parts suppliers this way. 3) There is a thermo switch in the bottom of the coolant reserve tank. Again, easy to check ... as I recall should be closed when cold, and open when hot. This mostly effects cold starts and idle speed during the warm up cycle. 4) There are two large electrical connectors on the drivers side of the engine compartment, down near the oil cooler. There could be some corrosion in these connectors, clean them. This too made some other problems go away. 5) Warm up regulators have been known to fail slowly over time, although I've been told that they do not fail as often on F cars as they used to on other CIS cars (VW, Audi, MB, etc). Might be worthwhile to check the pressures in the system to be sure. This could also cause the mixture to be off, although would not cause what you are experiencing (fixed duty cyle). 6) Remove the panel in the trunk that the FI ECU and relays are mounted to and again, clean and treat all the electrical connections there as well. I spent a lot of time troubleshooting this, and during the process had all kinds of weird problems. Cleaning all the connections mentioned above, reconnecting the oil temp sensor, and replacing the throttle switch seemed to fix it. There are also several relays that are controlled by the throttle switch. Make sure that they all click when moving the throttle. Do not try to figure out the logic of the wiring, it makes no sense whatsoever and many hours spent stairing at the wiring diagrams did nothing but give me several bad headaches. You can check these and many other things easily by disconnecting the safety switch (blue connector) on top of the FD and turning the key on. Be careful though as this will energize the fuel pump as well (unless you pull the fuse) so if you diddle the air flap you will be dumping fuel into the engine. Lastly, everything I've read says to set the duty cycle at about 55% for proper fuel mixture in the abscence of a CO meter. My car doesn't run right until about 65% or so. You also mentioned that you are using an analog dwell meter to set the duty cycle. There is a formula you need to use to convert the dwell readings to duty cycle, but I assume that you knew that and am only mentioning for the beneit if others who may read this. Of course, I forget what this conversion is as I have not had to use it in many years as I have a DMM that allows duty cycle to be read directly. Hope this helps, LMK if you have any further questions. Jeff
I am hoping someone can help me too. I have an 85 308 and every time I start the car in the garage, the exhaust is enough to make your eyes water. This is leading me to believe that the fuel mixture is too high. It also seems to hesitate when starting from a stop. If you think that the fuel mixture is the problem, is there AN EASY way to make an adjustment? The above (EGA, dwell meters, duty cycle) are all Greek to me. Maybe a picture of what tool(s) and what of what to adjust? Otherwise, I am probably going to have to bring it into Ferrari of Orange County. Thank you!
If EGA's, DMM's, Dwell meters, and duty cycle are all completely foreign to you, this might be best left to someone who understands the system and how to tune it. If you want to learn more, a good place to start is "Bosch Fuel Injection and Engine Management" by Charles Probst. This book is pretty good start for both the theory of how these systems work, and how to diagnose and repair them, but this (and most other) book(s) still assume a somewhat basic understanding of how to use the tools to test and set up these systems. It is very easy to make things much worse in a hurry if you do not know what you are doing. HTH, Jeff
Thank you for the info! I am going to buy the book that you listed so at least I understand it better.
My Ferrari Mechanic sent me instructions: 1 - Get him on the phone 2 - remove air filter housing 3 - disconnect lamba sensor (black/green connector) between frame and air filter housing 4 - Warm engine to full temp. Remove plug from Fuel Distributor. Use long 3mm alan to lean out turn counter clockwise.
The 3mm plug will adjust the fuel for idle only, after that the WUR and the feedback from the O2 sensor take over. carefull not to go to lean, the adjustment should be made with a CO reader so you now what you're doing. also it's not a simple turn and set, you have to go past then back. plug the hole becouse it's a vacumm leak then measure the CO and readjust until it's right. also once you make that adjustment the idle will need to be reset and then it's the game of 'roundy round' the WSM has the specifics for setting idle and adjusting the CO. I second the Probst book and match that to the WSM and you should have no trouble setting it up.
Can someone help me with my 85 328 rough idling. I have done pretty much everything, trying to adjust the fuel mixture and no difference but when I disconnect the 02 sensor, blue wire the idle is smooth. I did not drive on the road to see how it runs. Any suggestions?
Hi: I have recently gone through the entire process of adjusting the mixture on my US 308QV (1984) without using EGA, hence duty cycle, etc. One important thing I learned was that simply tapping a duty cycle meter to the 2 wires going to the frequency valve IS NOT going to give you the duty cycle measurement you are looking for. This is a myth. The duty cycle output needed is actually on PIN 17 of the Bosch ECU, which in the Ferrari application is not extended into the harness. You can modify it if you wish. link below After much research, primarily on BenzWorld, the best way to address this without an EGA is to get a cheap oscilloscope, and "tap" into the 2 wires going to the frequency valve. Then, with the scope set to 10V/Div vertical, 2ms/Div horizontal, and HF Reject on the trigger (source BenzWOrld) you turn the mixture screw a VERY TINY BIT at a time until the break in the baseline (indicated by the blue arrow) is centered between the pulses, and, oscillates back a forth a tiny bit. You will find that when you unplug the O2 sensor and lock the unit at 50%, the oscillation will stop and the break in the baseline will lock itself right in the middle because the system is now locked at the 50%. I would like to credit user: "Myndex" on BenzWorld for his excellent posts on the matter: Hope this helps and saves you some time and frustration Image Unavailable, Please Login https://www.benzworld.org/forums/r-c107-sl-slc-class/2182425-k-jetronic-lambda-overview-adjustment.html https://www.benzworld.org/forums/r-c107-sl-slc-class/2189370-1980-1985-ecu-mod-correct-duty.html
Do you happen to know what size bolt is used to plug the access hole to the 3mm plug? Mine is missing (has some goober stuff sealing it) and I'd like to replace it. I've tried a couple of different threads, but I'm hesitant to try and force anything in there.
