I finally have all the installation bugs worked out on my car, and I was wondering if anyone would be willing to lend a hand.

The installed system is an Accel DFI Gen 7, Accel wideband, Accel Pro Ram single plane EFI using a Dual sync distributor for sequential fueling. All this is on a 406 with a slightly aggressive hydraulic roller cam.

I have the car running and idling for the most part, but drivability is not there yet. It just backfires when I try to move. I printed out all the directions and tips for starting and I'm not afraid to tinker, but I was hoping someone with a little experience could confirm I'm not working backwards.

Much thanks for any one that would be willing to help!

Jeremy

 

Jeremy first and formeost, are you certain the engine crank position sensing setup is correct, such that the actual spark timing equals the commanded spark timing? Are you certain you have the distributor rotor phased correctly and no cross firing?

If so, then I'm guessing you have a lean tip in stumble, or otherwise when you open the throttle it simply moves into incorrectly programmed VE cells.

Any chance you could post some graph pics of your VE, timing and delta TPS accel enrichment maps? Or just send me the file and I can look.

TurboTR

 

Yes please make sure you have the Dual Sync installed correctly. I wouldn't mind looking at your ecm file as well. I am sure we can get you going in the right direction.

 

I'm sure we'll all try to help. Backfire typically indicates a lean condition. Have you checked with the WB what your idle mix is? And what is being commanded? I.e. do you have it set to 14.7? And is it adding or subracting fuel (O2 correction)?

I would change the idle mix to something more like 13:1 and see if that helps (after fixing the fuel table. Maybe a log of a few of the important things would help, such as showing us AF desired / O2 correction / Advance / Duty Time and that'd help.

I have a similar motor (though Ford) and likely can help guide you a bit. Also, the best bet is to get ahold of a known good tune and go from there. You can get in touch with the Accel tech line, and they can email you a good tune. Give them your engine type (like above), injector size, and approx. crank HP, and they'll likely have one that is 85% there.

 

Set your full air to fuel table at 12.75 to 1. This makes the engine run cool, you can lean it out later. Use the auto cal to set a few points on the VE table, I put the car on blocks and brake torque it for a couple spots around 1200 and 1800 RPM. It is a good idea to get a IR temperature reader to check your header temperatures. When I first started mine I caught the spark plug wires on fire because the headers were too hot. See if you can find a timing table from a similar engine. Start with something not quite advanced, if you have the knock sensor you can figure out how far advanced you can go later.

 

I had to put heat shields on my spark plug wires to keep from burning. What is the cause for this?

 

to retarded ignition

if distributor is set poperly and you have set ignition advance properly than copy stock 350 TPI ignition map, same for VE and then start tuning. With SparkAdvance and VE maps form stock 350TPI You will be able to drive with car

best regards

 

If the engine gets too rich it starts burning fuel in the exhaust system. With the DFI system you need to be accurate with the fuel pressure settings and injector size.