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Thread: No idea what to try next...

  1. #1

    Default No idea what to try next...

    I've been reading thru all the latest posts to find someone with similar issues but nothing has been close. Thanks in advance for any help with this, I've tried everything I can think of multiple times and I'm about stuck at this point.

    I'll start with my setup.

    - Everything is brand new except for the block and cylinder heads.

    - In a 1970 Mustang, 351 Cleveland bored and stroked to a 408.

    - CR should be about 10:1. Compression tested and varies between 180 and 195 across all 8 cylinders.

    - Edelbrock dual plane intake under the Atomic EFI.

    - MSD 8577 billet distributor with locked out 84211 adjustable rotor phased to 15 degrees retarded (rotated clockwise looking at the top of the rotor, dizzy spins CCW).

    - Comp Cams 283THR7 hydraulic roller cam with 107 degree lobe separation, duration @ .050" Intake = 227, Exhaust = 241. Timing gears set straight up.

    - MSD 6A firing a Pertronix Blaster coil, forgot these aren't new but almost, they were on the old engine and worked perfectly.

    I installed the Atomic EFI with latest updates and set it up to control everything. Here are my initial settings:

    - Set up engine size and # of cylinders.

    - Timing locked out and set to 15 degrees on the balancer with a Snap On timing light.

    - Cam type = Street/Strip but I've tried all 3 settings without any noticeable improvement.

    - Fuel Pump = PWM, no return. Shows approx. 40 PSI on display.

    - Timing Enabled.

    - Idle RPM Target set to 950 and Idle Timing is set to 1050.

    - No nitrous or boost.

    - All other settings are left at the default settings but I've tried adjusting numerous settings with very limited success.

    - I've set the IAC numerous times but I can't get it to stabilize. It will go from 0 to 30 or 35 and then back to 0 and the engine runs extremely poor when the IAC kicks in, it's a little better at 0 but still not running anywhere close to what it should be. The exhaust is full of carbon when the IAC is controlling and clears up when the IAC is at 0. I've noticed the IAC as high as 42 when actually driving and this seems wrong to me but I don't know for sure. I've seen other guys that had to replace their IACs so I'm wondering if mine is pooched too???

    - I've gone thru two new sets of spark plugs because they are getting extremely carboned up and I suspected spark shorts due to the carbon but the latest set of plugs didn't make any difference.

    - When I try to drive the car, it idles very poorly and when the revs increase to about 2000 RPM it starts to cough and hack with some backfiring so it's essentially undriveable.

    - This engine is just gulping the fuel down too so something is definitely way off but I don't know where to look any more.

    Holy smokes this got long-winded. Sorry for the info overload but I think I've done everything right and I'm going no place fast.

  2. #2

    Default No idea what to try next...

    So a few things, what you have listed appears that you have a good grip on what needs to be done.

    The only things yet to be discovered here are:

    • what are your timing settings?
    • Where is your O2 sensor?
    • Where is your fuel pump located in relation to the tank?
    • I assume you have checked for vacuum leaks since this will certainly affect this

    The O2 sensor would be my first guess. But lets see what the rest are set to first.

  3. #3

    Default No idea what to try next...

    I was hoping you would reply, you seem to be the resident expert on these systems.

    Answers to your questions:

    - My idle timing is set to 10 and total advance set to 34 @ 2500 RPM as per the default settings.

    - My O2 sensor is installed in the passenger side header collector about 20 degress above center.

    - My fuel pump is mounted right at the tank with about 9" of tubing connecting it to the existing tank outlet. It is below the tank as well.

    - My vacuum reads about 16" at idle, depending on the IAC action. I only have the PCV hose connected to the manifold outlet on the back of the EFI.

    I'm not sure how much carbon the O2 sensor will tolerate considering that my spark plugs have been well coated with carbon?? The display shows the AFR at about 13.8 with the setpoint at 14 so I'm thinking the O2 sensor may still be functioning properly but that's a hope more than knowing for sure.

  4. #4

    Default No idea what to try next...

    I don't consider myself an expert, I have just made a lot of mistakes so I had lots of opportunity to learn.

    I fear your next step is going to need to be a call to Tech Support.

    Other than fiddling with the blade adjustment to get the IAC setting down to where it needs to be, there is nothing out of the ordinary with your setup to my eye. Perhaps it is a bad MAF or other sensor throwing off the mixture. I've been very lucky, being one of the original purchasers of this system, I have not had any failures to know what sensor or system could cause this.

    Sorry I could not be of more help.

  5. #5

    Default No idea what to try next...

    Darn, I was hoping you might be able to save my bacon on this one.

    I didn't think I had many any mistakes on the installation because I was super careful to follow the installation instructions to the letter. That's why I've been so stumped on my issues with this install and I went back to instructions numerous times to make sure I had everything right. My other unknown was the fact that this was a fresh build from scratch with everything new and not just a swap out/in with the comfort of knowing what was working well prior to the install. I'll give the MSD techies a shout Monday to hopefully get some help with this.

    Thanks for taking the time to read thru this and respond to my dilemma.

  6. #6

    Default No idea what to try next...

    This really bites cuz I live in a city of about 250,000 and I don't know of anyone that has an Atomic EFI system. I go to alot of car shows and know quite afew car guys and they're all waiting to see how mine works to make the decision on their own cars so I'm the test mule that took the leap, unfortunately my chute hasn't opened up yet.

  7. #7
    Join Date
    Sep 2017

    Default No idea what to try next...

    Is your car stick or automatic, stock converter?

    On the Atomic dashboard, what is your water temp?

    Where is the Atomic ect sensor installed?

    What have you set for A/F targets?

    What does the dashboard shown for A/F and timing?

    Does learning say on or off?

    How far from the exhaust port is the oxygen sensor?

    What are your firmware levels?

  8. #8

    Default No idea what to try next...

    Hey bdud,

    My car has a manual transmission.

    I always wait until the engine is warmed up and the EFI is in learning mode so the water temps are around 185.

    The ECT is installed in the original temp sensor location so it is in the block and seems to work well there.

    The AFR settings are as per default settings so they are: Idle = 14.0, Cruise = 14.0 and WOT = 12.8.

    At idle the dashboard shows AFR around 13.8ish and the little bit I have tried to drive it, looks to be about the same when driving. The timing bounces around from 2 to 10ish at idle (depends on how crappy it's running) and does increase when driving.

    It does go into learning mode at about 160 ECT and I don't adjust anything until learning mode is on.

    The O2 sensor is in the header collector so it's probably about 2 to 3 feet from the closest and farthest exhaust ports.

    I did the firmware updates about 6 weeks ago so they are the most current.

  9. #9
    Join Date
    Sep 2017

    Default No idea what to try next...

    You could try using a higher setting for idle and cruise to see if that makes a difference, maybe 14.5.

    You also could try increasing your initial timing to 15, 10 might be too low for your cam.

    What is your power valve setting?

    You have checked for crossed or bad leads?

  10. #10

    Default No idea what to try next...

    I've tried setting the AFRs leaner and fatter and nothing makes any difference, it still runs extremely rich judging by the fouled plugs and the fuel it's going thru.

    I've tried initial timing settings all the way from 6 to 16 degrees and this hasn't helped either.

    I think the default pump squirt is @ 25 and the power valve is @ 19. I still have not figured out what these values are in the grand scheme of things. I've read differing explanations of these on the forum that don't make any sense to me either.

    I'm using my newer MSD plug wires that I had on my other engine and they worked perfectly on it. I've checked and traced the wires back and forth from the distributor to the plugs make sure they're correct many times. I also have wire separation looms that keep the wires from crossing over too much. I have checked each spark plug wire with the timing light to confirm each plug was getting spark and they are.

    As a side note, if I crank the throttle blades open enough to get the RPMs up to the 2000 range, the engine runs really nice and smooth but that's not of much use other than knowing the engine can actually run smoothly at some point.

    Thanks for trying to help with this.

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