7747 on a Ford 400 - still not getting a backfire issue sorted

I think I fixed it! Looking at ony's post about the MAP values again, I realized that cruising at low rpm the Ford 400 does not produce a lot of vacuum, leading to MAP values in the sixties. Checking the logs, all the backfires resulted from high MAP-to-WOT transitions. Thus, I bumped all the values in the MAP PW table up by one column, i.e., the 49 value in the 20 column and the 20 value in the 0 column. Two longer test drives confirm that the backfire is mostly gone. I had one smallish backfire, but that was more fart-like, unlike the huge booms before, so I guess I am working in the right direction and just have to up the values a bit more.

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Originally Posted by buddrow

If you are interested, I have been building a stand-alone transmission controller for some GM transmissions, I could easily put together one for the E4OD. I could set you up with a complete package from transmission to controller and everything in between. Just a thought.

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Thank you! But first things first - I gotta find a way to ship an E4OD to Germany without getting bankrupted by shipping cost. ;)

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Thank you! But first things first - I gotta find a way to ship an E4OD to Germany without getting bankrupted by shipping cost. ;)

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I work with a girl who has family in Germany.
I can find E4OD transmissions.
I am interested in parts used on certain Opel vehicles that have no equivalent here in the US.
At some point it might be beneficial to work together.

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Originally Posted by 1project2many

I work with a girl who has family in Germany.
I can find E4OD transmissions.
I am interested in parts used on certain Opel vehicles that have no equivalent here in the US.
At some point it might be beneficial to work together.

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As the owner of a late-70s Opel I an pretty good at acquiring Opel parts. Shoot me a PM what you need and I'll look around :)

Finally getting there! After lots of dabbling with the AE settings, she's running mostly great, with an AFR under AE between 12:1 and 13:1 - but the WB o2 tells me that starting from a standstill and accelerating at low rpm, I hit 10:1. I can feel her hesitating a bit, even.

As I am a bit lost as to how MAP AE and TPS AE work together, I can't really tune that behavior out. A log and the bin's attached, and I am glad if someone can help me out!

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Originally Posted by Dr_Grip

Finally getting there! After lots of dabbling with the AE settings, she's running mostly great, with an AFR under AE between 12:1 and 13:1 - but the WB o2 tells me that starting from a standstill and accelerating at low rpm, I hit 10:1. I can feel her hesitating a bit, even.

As I am a bit lost as to how MAP AE and TPS AE work together, I can't really tune that behavior out. A log and the bin's attached, and I am glad if someone can help me out!

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Gotta bump this. Still at a loss. Any ideas?

Too much AE will cause a bog/hesitation also. There are several threads here on the forum with info on tuning AE.

http://www.gearhead-efi.com/Fuel-Inj...1647-Tuning-0D

Here is one from another forum that describes tps and map ae

http://www.ifsja.org/forums/vb/showthread.php?t=149344

HTH
Brian

Thank you for the input! So basically, I have to check TPS AE in the affected TPS % range. Will do and report back (my girl told me to take the next weekend off from wrenching, so it'll take some time, but I will report back).

Reporting back - getting there, even if tuning the TPS AE is a real PITA and involves more trial and error than I generally like. Thank you all for your input!

So glad to see someone else had the same idea as I did to convert a Ford 400 to gm efi! I just started my conversion, had no idea anyone else had tried until I googled for ford 400 knock sensor and your posts popped up. I'm a bit of a greenhorn when it comes to tuning but if i make any progress with mine, ill let you know. Perhaps we can work on it together. Im planning on using ebl flash. The only downside is my 400 is a 79, so it might tune different. Im still assembling mine at the moment, planning to start tuning in a month or so. I think your build is awesome BTW. Its really cool you took a full size car and went racing! :D

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Originally Posted by 400_Fordman

So glad to see someone else had the same idea as I did to convert a Ford 400 to gm efi! I just started my conversion, had no idea anyone else had tried until I googled for ford 400 knock sensor and your posts popped up. I'm a bit of a greenhorn when it comes to tuning but if i make any progress with mine, ill let you know. Perhaps we can work on it together. Im planning on using ebl flash. The only downside is my 400 is a 79, so it might tune different. Im still assembling mine at the moment, planning to start tuning in a month or so. I think your build is awesome BTW. Its really cool you took a full size car and went racing! :D

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Always glad to help and let's work together wherever it helps! The backfire issue is mostly MAP AE vs. TPS AE, so tedious, tedious woring with the wideband o2 sensor to tune it out without going too rich. Additionally, the stainless steel cam gear on my $49 aftermarket dizzy ate up my stock camshaft, so I had to do some rebuilding work anyways and decided to stick a set of 1971-style flat top pistons into the engine to boost compression to 9.sometihng:1. I also decided to go for an Edelbrock cam instead of the stock one while I am at it. The rebuild hopefully will be done during Febrary. Then I'll be back at square one with my fueling tables anyways, so I'll let you know how it goes!

Final post on this matter - after the ECU gave up, I in turn gave up on fighting 30-year-old tech. So I bit the bullet and got a Holley Sniper. It basically is the same as the GM TBI with a touchscreen controller and an SD card instead of burning chips and worrying about ALDL cables. Also, the injectors are not dang in the middle of the airstream down the venturis, which is a plus. Final plus point is that it supports a WB o2 natively, so you can have target a/f rations other than 14.7:1 in your fueling tables.

Cars runs pretty much perfect now.

EDIT: The only thing I miss is TunerPro. Holley's software is sub-par compared to it.