'93 Camaro OBD1 swap

[ForcedFirebird]

Finally, a day without rain (so far) and I was able to get the ECM temporarily in place. I tinned the wire ends with a soldering iron and shoved the tips into the stock connectors to make it easy if there was something out of place.

Here is the very first start up. It sounds bad because I missed the MAP sensor wire, but once I got that connected it ran OK. I used the stock $a1 code/chip (from a FWD Lumina '7727 ECM), so the idle was high, and I may have a fan wire crossed because it never turned on and started to over heat - might need to be on the secondary fan pin instead of primary, but I will have to look at the .bin on the chip to see for sure...




Here's the spaghetti mess I started with...



and during the "swap"...





Not that alot of this means anything to you guys, in the end I guess I just wanted you to see what I was going through to get here :jest:

Next I will pull the pins out of the '7727 connectors and solder in the wires directly from the car harness and iron out the bugs. Once I have this one in and running properly, I will disassemble the stock '93 ECM and use the connectors so that I can offer up the adapters. That way whoever buys the adapter will send their old ECM to me so the next guy can have one made and so on.

One other thing I have to iron out is the difference in the way the A/C turns on. The "older" ECM's only had a request signal and a clutch control. The F-body uses a different turn on function than the more common OBD1 ECM's, but that will be overcome between the next couple days.

My datalog cable took a dump on me, so I couldn't datalog this first startup, but the new one should be here any day.


Any suggestions on the fan and A/C conditions I am experiencing?

[fleenor]

No suggestions, but good luck and I will be keeping an eye on this thread!!!!!!

[ForcedFirebird]

Got the ECM hard wired in, burned a $A1 mask chip, and was able to connect to the laptop fine now. Only thing I can think is that perhaps there was a V8 chip, or bad PROM in the 2 ECM's I had. I put another known good knock circuit section on my adapter and it is reading/running good - best so far actually.

I am still having a couple flags (error codes). One being coolant temp too low, open loop (or o2 absent), and checksum (PROM error).

The o2 sensor may because I hooked up only one sensor (OBD1 uses 1 o2 vs the two in the car previously) and may have reversed the ground and am actually hooked up to the signal side of one o2 and the ground on the other lol. Could be a bad o2, or may be having problems with the rich tune in there now.

Temp being too low may be because for some reason the coolant fan kick-on temp was set at 107* and the iron heads like to run much hotter than that. The only other thing I can think of is maybe there is a difference in the temp sensors themselves, but I have examined the 3.4 and 3.1 sensors and they appear to be identical (maybe someone can verify?).

Not sure what to make of the PROM error unless maybe there is a wire I left off that needs to be hooked up to sum correctly. The '7727 ECM has two 5v out's for the sensors and the stock '93 f-body ECM had only one for all the sensors, and a matching ground. Might have to pair the 5v out with the other and send the loose ground to ground.


Start today. Running rich as mentioned, checking for codes, making sure all the sensors were working, along with fan etc. All good except after warmup (as I mentioned the codes above)...



Started installing the wires one at a time. At first I started pulling the pins off the wires, but it took like 20 mins to get the first one done and decided to solder/heatshrink the pigtails from the ECM instead...

[IsaacHayes]

Checksum would be error internally with the PROM I would think. Is everything seated ok?

Re-pinning sucks and can be un-reliable if re-using pins. Soldering and heatshrinking the wires together is fine if you can solder well. That's what I would do. And it's quicker and easy (for me). Just got done soldering up more diodes and capacitors at work on some LCD monitor inverter power boards that the bad power in the building fried. Out of warranty now and for $40 for a bulk order of parts we have saved a bunch of monitors and room for more from the dumpster... And I work for the government, so I'm saving our tax dollars. I do get funny looks though when soldering on stuff.... LOL

O2 error, you might be on the right track for that one.

CTS maybe a ground is missing too?? Check the sensor too with a DMM and see what the resistance is.. it could be bad even... Not sure which way cold/hot is so maybe if it's open with no ground it would read as super cold...

You're making progress though!

[ForcedFirebird]

Today I wanted to load the $88 mask as it is closer to the 3.4 tune than any of the stock $a1 masks, but the $88 .XDF doesn't have the option for cylinder offset, and am not completely understanding the definition-writing tutorial on Tunerpro. I could translate all the fuel and spark data to the $a1, but that would end up being a lot of time consumed

http://www.tunerpro.net/tutorials/CreatingECUs.htm

Any help/suggestions?

[robertisaar]

5 minute solution:

copy/paste all of the important tables into excel, then paste them into a A1 BIN... i've done it a few times.

[ForcedFirebird]

Thanks, Robert, but I feel that may have taken longer than just using the $88 with a cylinder offset mod



Well, I burned a new chip using the tables from the $88 iron head v6 tune (stock). I wanted to use the $88 mask all together to make things easy, but there was no cyl offset in the definition so adjust for the 59* offset in DIS, so $a1 was used.

The car started and ran much better, no more black smoke

BUT! Still had the o2 and MAP flags, so I went back over the wiring diagram. Even though the 5V+ shouldn't matter, it did. I moved pin C12 (5V+ ref) to C7 and the MAP issue went away. Then I was curious if the ECM would like to see the sensor grounds in the correct place. The pinout diagram I had didn't specify what grounds were what, so I cross referenced with a '9396 ECM (similar to the '7727 with a couple diff pins) and saw that A22 was actually meant for the o2, so I swapped A22 with C5, and what do you know! Works great now.

I didn't like the lower idle of the 3.1 tune (~750-800) since the cam in the 3.4 seems to like an idle of about 950-1000 - or it sounded cammed and would like to bog when the wheel was turned or the brake pedal depressed, so I bumped it up to 950.

A little later when it starts getting dark, I will post a pin swap guide with the new changes for future reference.

As far as the A/C goes, I was chatting with a GM rep at Scoggin Dickey (gectek) and he explained to me how ALL the GM A/C systems run off the low side sensor and he just go done doing an LS swap in a truck using the new A/C system and OBD1 ECM. He told me if I ground the compressor clutch relay through the low side sensor, then the system will kick on/off like it should independent of the ECM, so that is next on the agenda.

[robertisaar]

so you just used a stock 3.1 FWD $A1 tune?

[ForcedFirebird]

so you just used a stock 3.1 FWD $A1 tune?

No. That's what I started the car with after the ECM swap to test. This time I used the $88 iron head values in the $a1 mask. I have tried the 3100 $a1 tune in a 3.1 iron head in the past and it ran/started, but drove horrible, so I knew it would let me know if everything was hooked up correctly.

[robertisaar]

"This time I used the $88 iron head values in the $a1 mask"

thats what i said earlier about copy/pasting the iron head values into the A1 tune...

[ForcedFirebird]

Thanks, Robert, but I feel that may have taken longer than just using the $88 with a cylinder offset mod



Well, I burned a new chip using the tables from the $88 iron head v6 tune (stock). I wanted to use the $88 mask all together to make things easy, but there was no cyl offset in the definition so adjust for the 59* offset in DIS, so $a1 was used.

Sorry if that sounded confusing haha.

[ForcedFirebird]

One of the first starts (not running great, some stalling etc, repost)...



After some changes...



Now...





This is with the idle about 850-900. 750-800 sounds awesome, but will bog on P/S and P/B action...

This is stock everything except 3" cat back and Magnaflow cat. Including stock log manifolds

[robertisaar]

can never complain about that 660 growl...

[Iyyob]

so is it 100% and wats our price i also have the 95 obd 1.5

[robertisaar]

possible problem there:

if its a manual tranny car, no problem

automatic: issues
the stock PCM in the 95 uses a PWM solenoid to control line pressure, meaning you'll need to swap to an older tranny, or somehow retrofit a modulator on the one you have now.

or.......

you could use the stock PCM to control just the tranny and have a tuneable ECM for fuel/spark.

price: i wouldn't know, john would have to answer that one