jerkyboy

Well, she is finally all together. With so many peope hacking on the car over the years, the wiring harness was a disaster so I had the shop re-wire the whole thing. The car is sitting on the chassis dyno and they are trying to get the Accel DFI to work properly. The comuter is acting really wacky with the program taking commands sometimes and not others. One run the A/F is perfect, the next run it starts real rich and runs real lean. This is with no changes at all. I even sprung for the Accel A/F box. The owner of the shop was one of the original certified tuners with Eli from Accel. He and Eli have been on the phone for days trying to figure this out. Anyway, she sounds real good through the new corsas and I can't wait to get her back Here's a few pics:

Aurora40

Nice! Can't wait to hear the numbers.

Also, it's funny how the appearance and the performance of intakes seems to be inversely proportional. That thing looks like some kind of industrial appliance or something, but it probably delivers the goods. Whereas the TPI intake looks all kinds of good, but delivers like an industrial appliance...

Steve85

Very cool, glad to see it's coming along!

Sorry to hear about the DFI struggles. I recently discovered that occasionally, after about 15-20mins of running the A/F correction goes to full rich for no apparant reason. There are no indications that the engine is actually running rich at that point. Weird...

Interesting intake setup. I'm running the same manifold and was wondering how they were going to feed it and keep the stock hood. I may be calling them for part numbers...

Best of luck Dave, keep us posted.

DVNCI

LOL I agree - same with the LSX intakes. They flow nice but I don't like how they look.

Love the ZR1's intake though

BrianCunningham

Looks great

Looking forward to see how it runs.

jerkyboy

I just got a call from the shop. Eli from Accel was coming down from the Northeast and stopped in to try and figure this out. I have got the guy who created the Gen 7 DFI system working on my car. If he can't figure it out.....I am f'd.

Steve, what your describing is part of what's happening on my program. The shop has a big block camaro with the Gen 7 sitting there with the same problem. Keep in touch because this seems to be a program problem.

I know the intake looks like a Hoover but It seems to work well. The shop admits that their Superflo dyno is very stingy. It made 465 rwhp on the first few pulls. Operator said the last cobra they had in there made 460 to the wheels and went right over to a dynojet and it made 490. I am not gonna get hung up on the numbers. I want it to run right

Steve85

That's not funny, but it is.


I definitely will!
I was thinking of having the firmware updated but I don't know if that would do anything...

LD85

All I can say is good luck and congrats! and I am jealous as well

pologreen1

wow! great work, if it pulled 465rwhp on the first pull . wait until they get a grip on this thing!

tpi 421 vette

Nice work Dave. I am sure you will get it sorted out. Should be a strong runner. Gotta love big inch SBC's.

Crzyfrlss1

Nice looking engine, but why is the timing pickup on the #2 cylinder instead of #1...???

88BlackZ-51

looking forward to seeing some dyno graphs!

sweet!

mackeyred96

Pwnage1337

That's a good point..maybe they were using the timing light to make sure all the wires were getting spark or something.

ddahlgren

Just for fun make a pull without the banjo fitting gizmo on the throttle body connecting to the air inlet duct.. Dynoed an EFI Pontiac years ago and down on power and acted weird. Pulled it off put on a old holley velocity stack to straighten out the air and all was goodness in the world. Ended up with parts,top and base, from a regular holley air cleaner with a band of aluminum instead of an air filter and a hand formed transition from that to the duct. Does the power change when the AF ratio goes crazy or is it just indicating that it is wrong?

jerkyboy

They have tried everything. I actually sat in the car when they made a few pulls and watched the computer do some wacky things. For example, it would idle perfectly at 900rpm as set in the program, AF would be exact in the computer and the monitor on the dyno. After the next pull, the computer would have the car idle at 1300rpm and not respond to the computer at all. No other parameters changed. It's definitely the DFI doing something screwy. The shop didn't have an accel harness for the engine dyno and tuned the motor using their FAST system. The engine ran perfectly. Eli from Accel was working on the tune all day yesterday and the shop said it sounded much better. Unfortunately, the shop owner is getting a hernia operation and is out til next Wed. So again I wait.

jerkyboy

...and ddahlgren, to answer your question, the motor was tuned on the engine dyno with the velocity stack. This shop routinely will take an engine from the engine dyno and put it right in the car and put it on their chassis dyno. They have pretty standard calcs for the difference between the two and the pulls they have made where the computer is acting ok, have been dead on based on the crank hp. You can watch the computer throw fuel in down low and pull it up top. Next run, it's perfect as programmed. I should've listed to the shop in the beginning and pulled the Accel system, sold it and put in the FAST system. I'd have my car back by now

Bluewasp

ddahlgren

After reading this from beginning to end twice I can only come up with a couple of things that could do what you are experiencing and they all hinge around 2 basic ideas. Either you have tons of RF that the DFI does not like and the fast unit had no issues with. I have seen this a million times and more common than you might imagine even for the same ecm to act different in the car than it did on the dyno. On a engine dyno everything is usually spread all over the place for ease of use and easy to get to. In the car everything is packed in tight due to space limitations. In my humble opinion and close to 20 years in the efi biz personally if something does not act the same way twice in a row and the pc side is unresponsive tapping on the keyboard is not the answer either.. Ask yourself if not repeating the same twice in a row why would it repeat the new settings twice in a row what makes them so special? Do you have mag pickups on the engine and where is the wiriing relative to the plug wires? How many ohms are the plug wires per foot if under 700 you may have big problems no matter what anyone says. Same goes for unshielded ignition pick-up wiring next to secondary voltage from the ignition or the actual ecm location for that matter. Both metal and air(distance) make good rf sheilding under the hood of a corvette you have neither. The other thing is to data log each pull with all sensor readings and injector duty cycle / pulse width and ignition timing something has to either be changing or the ecm thinks it is.. BTW the rf will cause the input readings to change as well.

Not trying to be a wise guy or know it all just offering my years of experience to help you get your car running right and have worked on about every system made over the years. Problems like yours keep guys in my biz awake at nights. I do know that about 10 years ago I quit using mag pickups completly and everything has gone to hall effect and shield wires on igntion pick ups and life has gone from weid problems to trouble free for the most part... The only other thing I can offer is one golden rule I have stuck with.. everything that is going to be in the car is on the engine dyno so we know it all works right at some point in time and do not waste time and money retesting everything in the car...

jerkyboy

Absolutely not and didn't take it that way. I value anyone's experience at this stuff...that's why I come to the forum. I will take this info and share it with the shop. Thank you.