Page 2 of 2 FirstFirst 12
Results 16 to 25 of 25

Thread: how to accurately test ECM?

  1. #16
    LT1 specialist steveo's Avatar
    Join Date
    Aug 2013
    Posts
    4,007
    at high load, your o2 seems to be reading too much fuel, so your ecm is responding by removing quite a bit of fuel. this might be a symptom rather than a cause. just for fun, how does it run with the o2 unplugged (and reset the ecm by disconnecting the battery for a bit)?

    is there anything you might have changed/swapped that would increase fuel or restrict airflow, adjustable FPR, different injectors, anything like that?

    i would tend to look for a mechanical problem too, you have a lot of unburned fuel, not making a ton of vacuum.

    how intermittent is this thing anyway? can we see a log of it behaving normally under heavy throttle?

  2. #17
    Fuel Injected!
    Join Date
    Jan 2014
    Posts
    98
    When I first started having these symptoms, they were minor and intermittent. At that time I believed it was a fuel issue. I replaced the fuel sender and also changed to a new high flow fuel pump. MSD2225 high pressure external fuel pump. I also replaced the fuel pump relay as well. I even dropped the tank and checked for contaminants as well. I installed a new in line filter as well. After all this work, the symptoms stayed gone for about a week and then came back. At this time, I decided to inspect the TBI and broke it down and installed a TBI rebuild kit. Again, the symptoms stayed away for about a week and then came back.. at this point, I discovered a coolant leak around my front left water jacket. I found this using dye and ultra violet light. It was a very small leak. I then did an intake job. I was extremely careful doing this. I cleaned all surfaces surgically clean prior to dropping intake down. Torqued it down in three stages, etc... I currently do not have any water leak or vacume leak.. Test drive after intake job was great for about two weeks.. The other day I take it out to interstate, stomp the pedal, and it bigs down and will not go accelerate properly. Today when I was logging the symptoms were the worst yet and barely got the truck back home. Now I am
    Perplexed. I even tried using an OEM fuel pump as well and had the same symptoms as well. I unfortunately do not have a log under normal
    conditions to compare to.
    Last edited by Tyree; 05-01-2018 at 10:12 AM.

  3. #18
    Carb and Points!
    Join Date
    Apr 2018
    Age
    41
    Posts
    2
    I would suggest to do leakdown and compression test. I dont throw even AFR heads on engine without visiting on machine shop.

  4. #19
    Fuel Injected! MQQN28's Avatar
    Join Date
    May 2016
    Location
    Melbourne Australia
    Age
    76
    Posts
    65
    Tyree

    Something to check. I see that you think it may be a fuel problem. When I put the efi on the flathead I had a problem that came and went not all the time and was noticeable when I went around corners.
    At first I had no CEL no way of data logging and I hooked up a monitor to the o2 sensor and saw it was running rich.
    I finally figured out it happened when I filled the tank. I thought it was a good idea at the time to hook up the purge line to the emission outlet on the tank. This was a straight link without a purge canister. So full tank going around corners vac line sucked fuel and caused flooding. FIX.... disconnect this line.
    It maybe a long shot but check if your problem occurs when the tank is at a particular level, it could be a pick up level?
    I had people telling me all sorts of things, wrong octane rating, timing, coil, spark plugs, my age, wiring, it just wasn't going to work, put carbies on it, fuel filter, fuel pump.......

    MOC
    Ford 28 Roadster Pick Up
    Ford Flathead 51 8BA. Balanced, ported,3/4 cam, Edelbrock 59A heads, C4 trans, 8" diff 3.55 narrowed 40mm /side.
    Fuel injection by Flatattack racing, 60mm Holden TB.
    ECM Delco 1227808 160 baud.

  5. #20
    Fuel Injected!
    Join Date
    Jan 2014
    Posts
    98
    MOC, I appreciate this reply.. my tank is an aftermarket under bed tank.. brand new from LMC truck. It only has an inlet for for fuel pump supply through sender and a single return line.. at this point, I am open to all suggestions at this point. :(

  6. #21
    Fuel Injected! MQQN28's Avatar
    Join Date
    May 2016
    Location
    Melbourne Australia
    Age
    76
    Posts
    65
    Quote Originally Posted by Tyree View Post
    MOC, I appreciate this reply.. my tank is an aftermarket under bed tank.. brand new from LMC truck. It only has an inlet for for fuel pump supply through sender and a single return line.. at this point, I am open to all suggestions at this point. :(
    Tyree
    Some other things to check.
    I had forgotten that I had to change a coil in both the hot rod and daily driver. The daily driver would crap its self coming home from work and the first time felt like it was running out of fuel. The next two times were more violent and I figured it was a coil pack. Replaced and all was fine. The coil in the hot rod was less obvious but died in the drive way and was easy to diagnose.
    I also had the battery deteriorate in it and it also gave indications of fuel problems.
    It may well be worth checking Coil, battery, and alternator as these can fail slowly with intermittent symptoms that the ECM tries to correct and give the impression that there is a fuel problem.
    The alternator can develop problems that the ECM sees as falling battery voltage and try to compensate giving an impression that something else is happening.
    At this stage you may have to eliminate devices before you find the problem. Going back to carbies may not fix the problem.
    It is very hard to find an intermittent problem when it fails outright and you get to it you know.

    MOC
    Ford 28 Roadster Pick Up
    Ford Flathead 51 8BA. Balanced, ported,3/4 cam, Edelbrock 59A heads, C4 trans, 8" diff 3.55 narrowed 40mm /side.
    Fuel injection by Flatattack racing, 60mm Holden TB.
    ECM Delco 1227808 160 baud.

  7. #22
    Fuel Injected! tamperedchevy's Avatar
    Join Date
    Mar 2014
    Location
    Missouri
    Age
    37
    Posts
    69
    do you have catatlytic converters?

  8. #23
    Fuel Injected!
    Join Date
    Jan 2014
    Posts
    98
    no converter

  9. #24
    Fuel Injected!
    Join Date
    Jan 2014
    Posts
    98
    I somehow, someway came up with the hypothesis that my coil or some component within the ignition system was not performing under load. This was my best guess at this point because I was confident in the mechanics of the engine and the fuel system/wiring harness was working properly. This was really tricky because the symptoms would not reveal themselves consistently. I pulled the ignition module off the distributor and the pins connecting to the pickup coil were rusted and had green corrosion. I also decided to replace the coil as well. Took it for a test drive and it ran great. No issues. I cannot say specifically which component was failing. I ran the truck through city blocks and also on interstate without a single hiccup. I hope that this has resolved my phantom issue. I will know more after a few more test drives. Again, thank you to all of the contributors and suggestions on this post.

  10. #25
    Fuel Injected! MQQN28's Avatar
    Join Date
    May 2016
    Location
    Melbourne Australia
    Age
    76
    Posts
    65
    Tyree
    Great you worked it out. Theres nothing better to nut out a fault like that to success.
    Never give up

    MOC
    Ford 28 Roadster Pick Up
    Ford Flathead 51 8BA. Balanced, ported,3/4 cam, Edelbrock 59A heads, C4 trans, 8" diff 3.55 narrowed 40mm /side.
    Fuel injection by Flatattack racing, 60mm Holden TB.
    ECM Delco 1227808 160 baud.

Similar Threads

  1. ECM Test Bench
    By Six_Shooter in forum Other EFI systems and related topics
    Replies: 54
    Last Post: 04-15-2016, 06:34 AM
  2. test bench
    By ericjon262 in forum OBDII Tuning
    Replies: 16
    Last Post: 02-02-2014, 04:06 AM
  3. Replies: 78
    Last Post: 01-11-2014, 02:38 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •