Topic: Alternate Injectors (Read 940 times)

cellulararrest · « **Reply #15 on:** May 04, 2009, 09:45:19 PM »

http://www.d-90.com/forum/showthread.php?t=16057&highlight=4.2+ecu

Well that's a bit of a surprise to me I guess, however I certainly trust Mark Adams over any other internet guru.

Swapping a 3.9 EPROM with a 4.2 EPROM seems to be common advice for a slight performance edge. It seems that is debunked.

junkyddog11 · « **Reply #16 on:** May 04, 2009, 09:50:50 PM »

I'm not sure I'm following what you're not following. I wasn't talking about the 4.2 "chip", but was instead refering to the "chip" that Mark Adams developed and that is peddled by RPI and JE who also lay claim to it. Who will also agree that there is very little difference with the 4.2 chip........other than they designed it to handle the slight need for a little extra fuel at start up and to very quickly lean out.

cellulararrest · « **Reply #17 on:** May 04, 2009, 09:57:58 PM »

Quote from: junkyddog11;17370

It took quite a bit of development and I'm fairly sure they, Mark Adams (Tornado systems), Chris Crane (RPI), John Earles (JE Engineering) have it fairly well protected.

Yes I have no doubt the rather high price tag is a measure of the effort it took to reverse engineer that thing. It certainly would be a fun project though.

whatroad · « **Reply #18 on:** May 04, 2009, 10:02:19 PM »

Quote from: junkyddog11;17373

I'm not sure I'm following what you're not following. I wasn't talking about the 4.2 "chip", but was instead refering to the "chip" that Mark Adams developed and that is peddled by RPI and JE who also lay claim to it. Who will also agree that there is very little difference with the 4.2 chip........other than they designed it to handle the slight need for a little extra fuel at start up and to very quickly lean out.

Ah, I was talking about earlier in the post somewhere about swapping a stock 4.2 ECU on Ethan's truck.
Mark's "chip" isn't what I was talking about....hey man, it's late and I only work on Vee Dubs, so what the heck do I know... ;-)

junkyddog11 · « **Reply #19 on:** May 07, 2009, 07:42:27 PM »

hey, I mostely work on oil burners so have to completely twist my head off to get back into things that need a spark......

cellulararrest · « **Reply #20 on:** May 07, 2009, 07:52:11 PM »

I think if I were to do any real modifications down the line I'd end up going megasquirt. It's right up my alley.

junkyddog11 · « **Reply #21 on:** May 07, 2009, 09:00:29 PM »

you'll twist your head right off with that.......unless you enjoy endless fiddling, which I'm sure has it's charms. Personally I'd rather just drive my junk. leave the laptop at home.

cellulararrest · « **Reply #22 on:** May 07, 2009, 09:56:36 PM »

Quote from: junkyddog11;17423

unless you enjoy endless fiddling, which I'm sure has it's charms.

Haha. That's the problem... I do.

whatroad · « **Reply #23 on:** May 08, 2009, 03:33:23 PM »

If you like "fiddling around". Find some late 70's Vovlo and retro fit the mechanical fuel injection system from any 242 GL etc. No wires, but works great. You'll need to get creative because they were 4 and 6 cyl. , not 8. However, minor set backs.

cellulararrest · « **Reply #24 on:** May 20, 2009, 07:12:35 PM »

I got Ethan's truck all tuned up and it runs quite well. It no longer feels tired

. I guess the power upgrades can wait for a bit. Maybe the GM ignition module, however. His is getting a bit touchy although I'm pretty sure it's just the connector.

Follow up post:

Oh here's another question for Matt/Carey. What have you guys had most sucess with timing wise? I have both my trucks around 9 BTDC as that seems to be where they're happiest. However I have read that the marks can be off significantly. Have you ever run into this? Where's the sweet spot you've found, if any.

Greatdivide1 · « **Reply #25 on:** May 20, 2009, 10:37:37 PM »

I have run mine a 13degree for the last 20k without an issue.As for the marks roll number one to tdc and see where the pointer is should be at or dam near 0 on the crank

cellulararrest · « **Reply #26 on:** May 20, 2009, 10:47:46 PM »

Alright. Maybe you have low compression? Ethan's truck was at 11.5 and didn't feel so great. I backed it off to 9.5 (Shop manual says 6 +- 1) and it feels better. However I did a bunch of other stuff at the same time (unfortunately breaking scientific method). Maybe I'll put it back and see if it pings. Ideally I think you want to be just advanced enough that it doesn't ping.

On the 90 I get some stumbling when I'm near 13 BTDC.

It's so hard to tell without being able to quantify it with a dyno or something so I'm not too worried about it. I'm mostly just curious what the guys who do this for a living on these engines have figured out.

Ethan noticed a difference when I gave it back to him, so that's what matters I guess.

junkyddog11 · « **Reply #27 on:** May 21, 2009, 09:27:22 PM »

7-8 deg is where I've found them to be happy. Never liked anything much more than that and you shouldn't need it unless the advance is shot.

cellulararrest · « **Reply #28 on:** May 21, 2009, 09:29:52 PM »

Quote from: junkyddog11;17586

7-8 deg is where I've found them to be happy. Never liked anything much more than that and you shouldn't need it unless the advance is shot.

Perfect. Thank you, Matt.

whatroad · « **Reply #29 on:** May 22, 2009, 04:30:13 PM »

Quote from: cellulararrest;17575

Alright. Maybe you have low compression? Ethan's truck was at 11.5 and didn't feel so great. I backed it off to 9.5 (Shop manual says 6 +- 1) and it feels better. However I did a bunch of other stuff at the same time (unfortunately breaking scientific method). Maybe I'll put it back and see if it pings. Ideally I think you want to be just advanced enough that it doesn't ping.

On the 90 I get some stumbling when I'm near 13 BTDC.

It's so hard to tell without being able to quantify it with a dyno or something so I'm not too worried about it. I'm mostly just curious what the guys who do this for a living on these engines have figured out.

Ethan noticed a difference when I gave it back to him, so that's what matters I guess.

You're not checking the timing at base idle are you? We set about 5-6 , but not at idle.

Author Topic: Alternate Injectors (Read 940 times)