EFI screenshot of TPI running

Discussion in 'High Tech Retrofits' started by kik_start, Dec 20, 2008.

  1. kik_start

    kik_start BANNED

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    Here are some screen shots of the engine running...maybe you can see something here ULTM8Z...

    The idle speed is high....I need to go back and adjust it again it looks like.
    The O2 reading was all over the place...from 800+ all the way down to 200, it was changing so fast that I really couldn't get an average.

    What is timing suppossed to be at idle?


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    The O2 was reading rich until the temp started going up then it was going back and forth between lean/rich...real fast.



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  2. ULTM8Z

    ULTM8Z Veteran Member

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    Your target AFR is set at 11.05:1. That's pig rich. Minimum I'd run would be 12.5:1. I'm actually running 13.8:1 on start up. My hunch is that if you lean out that cold AFR by a point and a half, you'd see an improvement.

    The bottom screenshot shows closed loop. I take it that was captured at a different time than the top screen shots? The top looks like it's in open loop.

    Any rate, in open loop the O2 sensor voltage will be bouncing around like crazy and you should see the cross counts increasing rapidly. This is normal since the ECM is constantly making fuel trim adjustments to keep it centered around 450 mV. It'll overshoot and then have to correct in the other direction, it results in very wild swings of the O2 voltage.

    Your idle timing is ok. I'm running about that much too.

    43.5 kPa manifold pressure. You must be running a decent sized cam. What are the specs?

    5°C air temperature? Yikes, makes me glad I'm in SoCal! ;)

    Can you give me the same top set of screen shots but with the car running at full operating temperature?
     
  3. kik_start

    kik_start BANNED

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    Mike, here is the cam info...I'll go warm it up and get some more posted in just a minute.

    How do I change the target AFR? I guess I'll have to buy a burner? I've been putting it off...because the one from moates cost about 300 bucks.

    [​IMG]
     
  4. ULTM8Z

    ULTM8Z Veteran Member

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    Did you say you had a 406? That's a REALLY small cam for that engine size. IT's even a small cam for a 350.

    I'm surprised you have such low manifold pressure with that cam. Hmmm... it's probably due to the really rich open loop AFR. I'm curious to see what it is in closed loop.

    Yeah, you'd have to burn your own chip to change the open loop target AFR. And even then it's not as simple as plugging in 12.5:1. The cold start enrichment has two tables that the ECM references- % enrichment vs MAP and % enrichment vs coolant temp. The two combine via a complicated formula in order to produce the enrichment vs any coolant temp and RPM. What happens is that for every coolant temperature (as your car warms up), the ECM will vary the enrichment depending on the manifold pressure. It reads what you programmed and uses that without any feedback from the O2. Essentially the ECM is just throwing in fuel per what you told it and it doesn't care how the engine runs. Once you get into closed loop, that changes and it'll start adjusting fuel based on how the engine responds.

    Don't worry though, I'll walk you through it once you're ready to start. Once you do it a couple of times, it's actually pretty straight forward. I created a Microsoft Excel tool that you can use to set up your AFR's, at which point you just copy and paste the values into your Tuner. I'm running Tunercat and it's very user friendly (especially for when I was a beginner).
     
    Last edited: Dec 20, 2008
  5. kik_start

    kik_start BANNED

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    Yep, it's a 406. I've never liked the performance of this engine...kind of why all this is going on in the first place.
    The cam was recommended to me by the machine shop...I took his word for what I needed. The guy said it should be good for torque, I use this to pull my 75 to the track.

    I'll go warm it up...
     
  6. ULTM8Z

    ULTM8Z Veteran Member

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    Oh I wouldn't doubt you've got some torque with that thing! ;)

    It'll be a very efficient car at low engine speeds with that cam and EFI. Should have a silky smooth idle too.

    BTW, not sure what you mean by you "never liked the performance". But if you're looking for 406-ish power above 3500 rpm, don't count on it with that cam and TPI. The cam will choke that engine off above 4000 and so will the TPI. The TPI was designed around a 305 and runs out of oomph at 4800 on a 350.

    But, if all you're looking for is an efficient running engine with decent gas mileage that really only sees low to mid-range engine speeds, I think you should be happy once this engine is dialed in.
     
    Last edited: Dec 20, 2008
  7. kik_start

    kik_start BANNED

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    Idle is terrible...right now. I'm sure there is something wrong...may take a while to sort things out but I'm going to stay with it till it's right...in to deep now to quit. hahaha

    As far as the performance statement goes, I really figured this engine with a carb would have been like a small big block...but it wasn't...it is just another small block. ;) , it'll do fine for what it's use is.

    pics coming up.
     
  8. kik_start

    kik_start BANNED

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    These are screen shots of the top and bottom of the same window...it won't fit all in one screen. The first two are as soon as I started and the second two are after it reached 83C... I have a 180 t-stat. (I replaced the thermostat and that fixed the heating up issue)

    Why would the AFR change?

    start up 1

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    start up 2

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    warm 1

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    warm 2

    [​IMG]
     
  9. ULTM8Z

    ULTM8Z Veteran Member

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    Ok, I think you may have a vacuum leak somewhere. Three reasons: Your idle steps are zero, your actual idle speed (750 rpm) is higher your programmed idle speed (700 rpm), and your idle manifold pressure is way too low for the engine combo you're running. Zero steps means the ECM has closed the IAC motor completely. It's seeing that you have air coming in from somewhere else and it doesn't need to provide any additional air with the IAC motor. ECM wants to bring the idle speed back down to programmed 700 rpm, but it's run out of adjustment with the IAC motor since you're at zero steps.

    Also, you're running way rich. BLM is at 96, should be at 128. It's saying that the ECM is trying to pull fuel out like crazy. For instance, if your BLM was at 150, I'd say you were running lean. Below 128 => Rich. Above 128 => Lean. Stock bottom limit for the BLM is 108. Which means if you're at 96, your chip guy changed the limit. Your cross counts are also low compared to engine run time. It could be that the engine is seeing the low manifold pressure and adding more fuel. In the fueling table, the lower the map, the more fuel the engine will add. BLM of 128 is ideal but typically on a well tuned engine, you could be hovering between 124 and 132, which is fine.

    Only thing that may contradict what I'm thinking...

    Have you played with your idle stop screw at all? It may be set out too much and opening the blades to far. Re-adjusting the stop screw could correct the IAC steps and the idle speed, but it wouldn't affect the idle manifold pressure (which again, is too low). I'd expect to see around 60-70 kPa @ 750 rpm with your combo.

    Also, the target AFR will change with temperature. For a given manifold pressure and RPM, the higher the engine temperature, the higher the numerical AFR number will go.
     
    Last edited: Dec 20, 2008
  10. kik_start

    kik_start BANNED

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    That actually makes sense...I think there is a vacuum leak also...I haven't been able to locate it though.
    The crazy part is the idle is lower on start up and as it warms up idle speed gets higher...up to over 1K...and goes back down to under 800...up and down like shutting the key off and turning it back on...but when in drive it stays right at 800 rpm and steady but has issues when coming to a stop light...it wants to die and hard to start back up.

    I'll look for a vacuum leak tomorrow, it's dark and getting colder now. I hate cold weather too...:(

    Steps I took to set idle...

    1. jumper A and B terminal for 30 seconds with key in the on position and unplug the IAC
    2. start engine and set idle to 450, 500 rpm with the stop screw (I think it was closer to 500)
    3. adjust the TPS to read .5v at rest...checked at full throttle and it reads 4.97v
    4. Set timing to 6* btdc

    What exactly is "BLM"...not sure I've ever read anything about that.
     
    Last edited: Dec 20, 2008

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