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91 testarossa KE jet

Discussion in 'Technical Q&A' started by Dannytestarossa, Oct 31, 2019.

  1. Dannytestarossa

    Aug 13, 2017
    9
    My name is Danny Coll and I live in Key West Fl, and have a 1991 Ferrari Testarossa with KE jetronic, CISFLOWTECH rebuilt both my fuel distributors and EHA,
    I was never able to get it to run decent so its been sitting, the LAMDA system has been disconnected, thats the way I bought the car, when connecting the LAMDA control units, the warning lights go on, SLOW bank 7-12 and it runs terrible, when connecting O2 sensors it runs terrible, the only way to get it to idle is adjusting it with a 3mm tool like we did on the older K jetronic. It would idle great but under a load it's hesitating just like the old K jet with a warmup reg pressures to high when cold.
    for some reason just yesterday I went for a drive and after it reach operating temperature (fan come on) it started running great like never before,
    after a while I started feeling the same hesitation and the fuel pumps making loud noise like there was an obstruction, finally it die, after a while I took the gas cap off and there was a lot of pressure, when I got home I checked the venting system and sure enough the the venting valve up by the right/rear hatch hinge was totally plug, I was sure this would help the problem but it did not. again is there anyway to run this car with out the O2 and the control units? Please Help!!!
     
  2. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,395
    Texas
    Full Name:
    Steve Magnusson
    If by "Lambda control unit", you mean the two KE-Jet ECUs mounted on top of the RR wheel well = yes, those really need to stay connected as they operate the EHAs (to function like the WURs on a K-Jet model) to add enrichment during cold staring and cold running (in addition to the Lambda function they provide during warm-running).

    However, when you say "the LAMBDA system has been disconnected", if you mean those two KE-Jet ECUs were physically unplugged = you would need to readjust the mixture screws lean if you plugged them back in (i.e., if the mixture screws were adjusted such that the engine ran reasonably well when warm with the KE-Jet ECUs physically unplugged, when the KE-Jet ECUs are plugged in, the engine will be running very rich = this would cause the slow down warning lights to come "on").

    I wouldn't be too hopeful that you could just plug the KE-Jet ECUs back in, retweak the mixtures, and all would be fine as it sounds like a lot of desperate modification was made. However, if you want to try this, the initial steps you could take (with the KE-Jet ECUs plugged in, and the single sensor wires of each O2 sensors unplugged) are:
    1. Measure the DC voltage between the single unplugged O2 sensor wire of each bank to ground (like the bare engine block or bare cylinder head) at warm idle,
    2. Turn the mixture adjustment screw on the fuel distributor of the bank whose O2 sensor you are measuring,
    3. Confirm you can "swing" the output voltage of the unplugged O2 sensor from lean (0.1~0.2 V DC) to rich (0.8~0.9 V DC) by turning the mixture screw CCW/lean and CW/rich.

    if you can get this to work, a reasonable mixture screw adjustment would be to set each unplugged O2 sensor output to be 0.6~0.7 V DC at warm idle (with no air entering the mixture adjustment screw openings).

    If that can be done, you would then plug in the the single wires from the O2 sensors, and confirm the voltage between the plugged in single wire of each O2 sensor and ground is "wandering" every few seconds from rich to lean and back again. (One thing to confirm here is that you've got the right O2 sensor connected to the right KE-Jet ECU -- the O2 sensor mounted in the 7-12 exhaust stream should be connected to pin 8 of the forwardmost KE-Jet ECU, and, likewise. the O2 sensor mounted in the 1-6 exhaust stream should be connected to pin 8 of the rearwardmost KE-Jet ECU).

    Try chewing on some of that (or let me know if I'm not understanding you post correctly).
     
  3. Dannytestarossa

    Aug 13, 2017
    9
     
  4. Dannytestarossa

    Aug 13, 2017
    9
    Steve, first I want to thank you for all this information, I truly appreciate your help, so the plugs that are disconnected are two oval 4 wire (plugs look like trailer light style) they are by the fuel accumulator right side, (they are marked red and green)when those are connected the warning light go on (Slow down 7-12) and not the KE-Jet ECUs, but the O2 sensor wires and the heater are all disconnected, I will follow your steps this morning and report back. I will check for voltage of the green O2 wire and see if it switches. do I need to get to operating temperature (closed loop) to check for voltage? and what are this oval plugs that were disconnected?
     
  5. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,395
    Texas
    Full Name:
    Steve Magnusson
    Those 4-pin oval plugs are just for the slowdown warning light ecus and have no influence at all on how the engine runs -- and often malfunction (so are often unplugged). If the self-test isn't always working properly, or they do something crazy like turn on the warning light immediately (when the cat couldn't possible be hot) = it, or they, are bad.

    Yes, the engine needs to be warm as the output from the O2 sensors is valid only when they are warm/hot. Measuring the voltages on the green O2 wires (relative to ground) when plugged in to see if it "switches" (or more accurately "wanders") at warm idle is good, but also measure it when unplugged at warm idle, too -- and the even more informative test is to see if you can "swing" it when unplugged at warm idle by turning the mixture screw -- make a note of where it (the wrench) is before turning it - it shouldn't take large adjustments.

    Good Hunting!
     
  6. Dannytestarossa

    Aug 13, 2017
    9
    Steve,
    I checked the O2 sensor wires (relative to ground) at first I could only get the right bank to respond when adjusting the CO, CW rich CCW lean, could go from .02 to .08 but the left bank nothing, I took both O2 sensor out and clean them with an air mass sensor spray, they were both fouled (black with carbon) and I already ordered two new ones, but after reinstalling I got both sensors to respond the same way .2 to .9 but they are not switching or hunting or wandering, the wires from the K-jet units are reading .54 disconnected from the O2s.when you connect the O2 to the KE Jet ECU there is fluctuation .2 .4 .8 .5..8 on both banks.
    It idles perfect but when going for a test drive it's starving for fuel, tremendous hesitation like riding a bronco, I drove the car with CIS gages on system pressure is 5.5 bar, when I got back the good idle was gone and had to readjust CO on the left bank significantly to get my Idle back, also when disconnecting the gages the port I used (center of the fuel distributor that feeds the cold start valve) was spiting fuel for a few minutes (just traces of fuel but significant residual pressure,
    As I've mentioned before the fuel distributors and EHA were rebuilt by CISFLOWTECH a year ago, the car never run right, so I parked it, just installed new fuel filter and checked the input filter to the fuel distributors and it's clean as new also all new bosch injectors. Let's keep Hunting my friend LOL
     
  7. Andy 355

    Andy 355 Formula Junior

    The very 1st thing to do is to make sure the fuel pump/s depending on the cis system, is to make certain they have adequate fuel supply reaching them.
     
  8. 335s

    335s Formula Junior

    Jan 17, 2007
    826
    SF Bay Area
    Full Name:
    T. Monma
    I have a couple of BASELINE questions to ask-especially since you live in South Florida....

    Have you been setting the car up with a gas analyser?
    do you have a mercury column to establish proper throttle balance between the two banks?
    Does the car have an OE COMPLETE catalyst system on iktr-if not, whats there?
    Have you-or previous work orders indicate IF: the base throttle positions HAVE BEEN SETUP PER SPECIFICATION?
    At FULL operating temp-at idle-with BOTH O2 sensors DISCONNECTED, and the CO concentration set at 1.5%- BOTH sides, at EACH sample tube(exhaust question above): is the car running reasonably "normally"?

    NEXT: What happens when you plug in the O2 sensors???? Gas concentration wise? Does the CO skyrocket/steadily creep UP after plugging the sensors in?
    For the sake of argument, allow them to get hot-3-5 mins, unplug and see what its doing....

    IF when hot-and assuming balance is correct-AND baseline throttle set up is correct, AND sensors are now hot: what does the car do when you plug them in?
    Does the post cat numbers drop, OR, do they go up-counter intuitive I know-but there is a reason for me asking-there is a notorious grounding circuit for the lambda function of the ECU which goes bad-if this car is bad, how it behaves as described will tell us-its a 15 minute repair!
    let me know how and what its doing...
     
  9. Veedub00

    Veedub00 F1 Rookie
    Silver Subscribed Owner

    Jun 30, 2006
    3,468
    Troy, Michigan
    Full Name:
    James
    what's the grounding circuit?
     
  10. Andy 355

    Andy 355 Formula Junior

    Sounds to me like the main cis pump is starving for fuel. All the voo doo in the world wont help if it's 5.5bar of air. Op needs to check basics 1st. Often the cheapest and easiest.
     

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