Hey guys (and gals maybe)

Total noob here trying to dive into DIY tuning. Let me start with what I am working with, what equipment I already have, and what specific questions I have. I expect a little razzing for not finding all of this info myself, I am sure it is out there, but I have searched and read until everything is so jumbled up I simply don't know where to go from here. It has been my experience with other things my questions don't last long and I start to become someone giving back some info, so please bear with me!

I have a 1995 Chevy truck, original 350 TBI with 4L60E transmission and 16192747 ECM. Pulled motor, stroked to 383, 9.5:1 compression, Comp Cams XTreme Fuel Injection 260 EFI HR 13 http://www.compcams.com/Company/CC/c...?csid=207&sb=0 , full roller, First fuel injection TPI set up, 30lb injectors, headers, true dual exhaust with x pipe and magnaflow mufflers, MSD direct fit ignition system. Fuel pressure now set to 39.2 per accel specs for their injectors. Base timing set to 6*.

I had someone "piggyback" a 7730 ECM onto the 7427 to control the engine, have since learned this may not have been the best way to do this, but now have no idea how he did it, so it may be near impossible to go back to the 7427. This same person burned the chip with my engine specs and I am having major issues. Idle surges bad, has no power except from dead stop, knocking terribly at cruising speeds, BLM never above 118, mostly around 108. Transmission shifts too soon, etc, etc, etc.

So I decided the only way to make this thing RIGHT was to do it myself. I purchased all of the necessary hardware from Moates, several chips, adapaters, G1 for the 7427, G3 for the 7730 (I plan to tow too). I have read countless hours on all of this stuff and feel comfortable delving into it but since this is my daily driver and I haven't been able to drive it since I tore into it last February, well I really need to shorten my learning curve if at all possible here.

First question: On the 7427 ECM, controlling transmission function only, can someone tell me or direct me to the information to turn off all of the things I no longer need in this ECM and to make the transmission shift better and firmer without destroying my transmission? I might add this tranny was built pretty tough using all Corvette parts to beef it up a little.

Second question: I am thinking since the tune that was made for me is SO far off, I could start with the factory AUJP tune, modify displacement and injector constants, and that should at least get me started. Any thoughts on this?

Anyone willing to take a look at the tune that was burned for me and give me your opinion? I am not ready to name name's yet, maybe the problem is on my end and not his.

Last question, how can I convert to WBO2? Is it worth doing this, and will the ecm be able to utilize that info?

I might also add I am using TunerPro and also have Datamaster for logging if need be. Would also be great if someone could tell me how to record my logs in TunerPro.

Thanks in advance guys,

Chris

 

And yes I realize this is my first post, I have been reading on here for months, just didn't have anything useful to add yet! Hope that is ok!

 

I would suggest ditching the '7730 and going back to strictly the '7427.

One major reason being that the PCM will then know what is happening with both the engine AND the transmission. No need to swap parts, or even datalogging back and forth between the ECM and PCM. The wiring will be simplified and have no shared sensors. Finally you will know what you're dealing with and that it is correct.

The '7427 is capable of running MPFI with a couple simple internal modifications, which have been documented, here and at www.gearhead-efi.com.

I'm not sure of what all would be needed to be changed in the '7427 bin (likely to be $OD), to have it happy to run just the transmission.

Yes, you can start with a stock bin and go from there, in fact it sounds like it might be the best way, if you decide to stick with the piggy back set-up.

I've tried to avoid piggy back set-ups as much as I can, simply because I like one PCM to do the job it was intended to do. This is one of those cases where one PCM can do it all.

 

You are not the first person to suggest this, and I am seriously considering it as shoehorning two computers into the small dash area of my truck sucks. My concern is that I didn't do the wire work on this conversion, and concerned I won't be able to get things back to the way they were. Thanks for the input six_shooter, really starting to lean this way.

Hate to come to thirdgen for help, but am told you guys are the best when it comes to TPI set ups, not to mention we are the proud owners of a first and second gen camaro, so I'm close to being family right? LOL

 

Most of the guys here are tolerant to other ECM and chip tuning if your nice. Now stealing a TPI engine and ruining a thirdgen... may want to add it was totalled or something?

You do have a wiring mess there now. I've never seen that done and can't beleive it was done because that PCM will do MPFI! So there is always a chance of one wire wrong and no one will know because it's never been done or not much... I would take the time to go back to one PCM.

That engine is not going to be an easy tune or an easy way to learn to tune, but yes you can!

There is a documented way to run an engine control ECM with a trans controlled by stock PCM, it's also a SWEET system for tuning built engines you may want to consider changing your tuning path now? Ask these guys.
http://www.dynamicefi.com/

 

Ok so I have mentally committed to removing the 7730 ECM and bringing everything back to the 7427, now just to do it. The guy added 2 or 3 wires running from the engine side through the firewall, everything else appears to have been done under the dash, so maybe undoing won't be too large of a task.

Then it will just be a matter of figuring out how to tune the whole thing. I will have many questions when I get to that point. I have been reading up on it for months, but have yet to find some of the info I need, particularly the bpw offset vs. battery voltage for the accel injectors. Starting to wonder if I need to go with a different injector that has this info readily available. Tech support at Accel has no clue.

Thanks for the input guys, will move forward as soon as possible and keep you updated as to what I find.

 

Something just hit me, I am wondering if the extra wires running through the bulkhead are for the MAT sensor, and if so, will the 7427 have an input for it? Any one here know?

 

The '7427 does not have a MAT sensor, nor input for use of it.

There is information on here about the MPFI '7427 mod and what it takes.

 

Before I went EBL I was going to go the '7427 route and according to my research you can run an IAT sensor (aka MAT).

 

Sorry it has been a while, just an update.

I attempted to make a go of the current set up. Through a member's help found out the memcals (2 of them) this guy sent me were v-6 memcals and they had not been modified for v-8. I soldered in a jumper for v-8 cylinder select (hope I am saying that right), changed dispacement and injector values in otherwise stock AUJP and motor fired right up. First thing I noticed, it idles 200% smoother. It still had a little flucuation, but was only 50-150 rpm, not 500-800 rpm. Worked for a few days on the VE, realizing that as soon as my cam kicked in (1500) everything went lean, after several tries and talking with a couple of different people, realized I would be better off to get rid of the 730.

Today I tore into the wiring mess I had. It really wasn't as bad as I expected. I printed a pin out of both ecms, figured out what wires were missing from the 427 and found them on the 730 plug, unplugged, rerouted and replugged. Pretty simple really. Did that until all of the empty slot of the 427 were filled, then went through the remaining wires from the 730. About 5 or 6 were tapped into original wires of the 427, simply cut those off and taped up the original wire. That's when I found it, a wire for the CTS input of the 427. It went straight to ground. Untaped it, and there was a resistor between it and the ground. Maybe this is why the 427 would only show 199* when datalogging? Long story short, I am 99.9% positive I have everything back the way it was. The only wires added were 2 wires for the vss to the 730 and a ground wire for all the grounds of the 730. Looks like he used original EGR wire (gray) to send the MAT sensor data.

Tomorrow I will go in and make the modifications to the 427 ecm and memcal. Then it's back to tuning! That's where I will need some serious direction. I think I understand a lot of it, but not most of it. I am very thankful for boards like this one that allow a person to learn and ask questions. You guys are awesome.

Oh and Eaglemark, this isn't a factory TPI system, it's an aftermarket, so no Camaro was sacrificed for the aquisition of it!

 

Just to make sure, have you made all of the modifications needed to the ECM, hardware wise to run MPFI?

 

Six_shooter, no sir not yet, that is my first order of business tomorrow. Since I have already done pretty well the exact same modification to another memcal, I feel pretty confident in soldering in the jumper. My issue is with the ecm modification. In the word doc posted by 93v8s10, he mentions using some wire out of an old piece of electronics. I wasn't sure how old that writing was, do you guys have any input here as to what wire I should use? I am a bit more nervous about making that modification. I have a cousin that is an EE that solders on circuit boards all the time, I may see if he can run by and do that for me, but I would probably still need to know what type of wire to use, if it even matters.

 

Type of wire won't really matter, as long as it's not "resistor" wire. Chances of you coming across resistor wire is pretty low, unless you cut it out of the engine harness of a 70's or older GM vehicle.

You can use some of the wire that you cut out of your harness if you wish.

It just needs to bypass the sense resistors.

I'd likely just solder the wire across the existing resistors if I was doing the modification. That way it would be easy to revert to the original configuration, if need be.

 

I wondered about just leaving the resisitors there and soldering right to the "legs" of the resistor. I just wasn't sure if leaving them would cause an issue. I will attempt to do it this way today. I would feel more comfortable doing it that way vs trying to solder direct to the board. Thanks six_shooter!

On to the next order of business. Can someone direct me to the most updated xdf and adx for the $0D bin? The xdf I have is 0D_TPV5_v250.xdf which I downloaded from TP website. The adx I have is A217_0D_v250.adx also downloaded from TP website. I have since been told those files haven't been updated in a while so want to make sure I am using the best available.

I should have my internal mods made by noon today. Any direction other than the tbi-mpfi docs to tell me what mods I need to make to the bin to start with?