93 mtx blackbox question

[petrol]

Hello all, I've been lurking for a long time on here, but never needed to post until now. ( so I finally made an account)

I have a 1993 MTX, and I just swapped the motor for another mtx3.0 because my original one threw a rod out of the oilpan.

Anyway,

I am troubleshooting why the motor wont start on its own...I am not getting good power to the injector harness. It will start briefly with a quick dose of starter fluid (although I am EXTREMELY sparing on this stuff because I dont want to risk any ring or other damage). I'm going to doublecheck my ground tonight, and make sure I got all that right, but my -actual- question in this post is... WHAT is that black box on the core support, above the radiator? This is the one that the other end of the engine harness plugs into. The reason I ask, is that its buzzing loudly for some reason. I didnt notice this before the swap...but I never took the rad cover off, or really listened to the engine bay with key-on engine-off.

Thanks!

 

[Phoenix]

CCRM is that box. It's not a computer , it's only a bunched up relays-in-a-box.

It drive the AC , fuel pump and some other stuff I dont remember...

Point is , it's looking that the CCRM is toasted , do you hear the fuel pump prime when key on? , If not , that' probalbly your problem.

If you change it , There's a big letter on top of that module , you need to find another CCRM with the SAME letter.

 

[CPUNeck]

Well if it's big, read a little small than a 8.5x11 sheet of paper with lots of wires going into it, then it's your ABS module. If it's in the center of the core support with only 2-3 wires going to it, it's for the SRS. (airbag)

-C

 

[petrol]

I think its probably the one that Phoenix brought up... Its attached to the actual core support with a couple of nuts. Its generally above the ABS equipment though. About the size of a wide/thick pack of cigarettes. The harness bolts into it.

I can hear the fuel pump prime when the key is started, so at least that part is working ok...and I do have pressure in the rail. I dont get any (or an occasional faint light) light to the "noid" light though.

I thought about it on the way into work though...(kicking my ass all the way for not thinking about it before)...but I bet I have a crappy or nonexistent ground to the motor. I have the battery just sitting in the engine bay at this point...and I dont recall any ground straps or other good source of ground to the engine itself. So maybe thats it?!?

Thanks for the fast replies though guys... I love the fact that people are always on here, helping.

-scott

 

[Phoenix]

You should have a flat braided wire from the intake to the chassis in the upper left side of the engine. If that wire is missing , it wont start.

What bugs me though is that it starts with starting fluid , that should mean there's no fuel (pressure or whatever).... So technicaly it has spark...

Ummm

 

[petrol]

I agree.

I havent revved it or anything with starting fluid. Maybe it just barely has enough spark to start up.

I'll throw on a ground tonight and hope for the best. I'll update this thread around 630-700pm this evening...hopefully with good news. Feel free to post other thoughts, suggestions, etc in the meantime though. I'm online alllll day.

 

[petrol]

And by "starts with starting fluid"... I meant that it'll start up for about 5-6 seconds before the ether burns off. The injectors just wont fire.

I pulled the upper plenum off last night, and had a friend crank the motor...none of the injectors put out so much as a drop of fuel.

I'm still semi-hopeful that its the ground.

 

[petrol]

by the way... after reading some of your other posts about the CCRM, etc... Do I NEED to have the 02 sensors hooked up for it to start? I havent reattached the cat-section to the car yet...thus the o2 sensors arent installed. I assumed it would just run in open loop and at least start.

-shrug-

 

[SASHO91]

I would double check your connections under the T-body. There are two black connectors that are IDENTICAL and plug into each other. However, the wiring is different.

Don't ask how I know.....


And no, the car will start without O2's.

 

[petrol]

Cool, thanks Josh.

One thing that DID throw me off pretty bad when I swapped the motors... the injector harness had the opposite gender connectors on it than my motor did! I had to pull it all back off, and swap my original harness in there so it would connect. What kind of dirty trick were they playing...changing the connectors like that.

I'll try re-connecting the other black and grey connectors too, and see if that makes a difference at the injectors. I wish there was a way to identify them easier.

This isnt a problem (yet)....but once the injectors Do start spraying... which side to the black vs. white connectors go on?

noob FTL.

-scott

 

[SASHO91]

White=Front Black=Rear... If I recall.

The grey connectors can't get miss-matched. But the black ones can. Also, (some more bad news) I had to swap EEC's as I believe I "fried" the one that was in there while the two connectors were mated wrong.

One way to check this, is grab a DMM and check for B+ @ the Red/Lt Grn wire anywhere at the following locations: Coil pack, DIS, CPS, CID, and noise capacitor (mounted to the coil pack). If you do not have B+ (aka 12v) at these, then you'll know where your problem is.

Allthough, that troubleshooting is up to you. If you just want to dive into the harness(not that hard, just remove the air box/tube) and double check the connectors then that'll work too.

 

[petrol]

Great! Thanks for all the good information.

 

[AREA 91]

I would NOT run the car without the Y pipe installed. Too risky! Melted wires, fan, etc...

 

[petrol]

I wasnt going to actually be running the car like that. I was just excited about finally finishing my swap that I wanted to hear it run and get the top side all buttoned up. I havent reconnected the shift linkage yet either.

 

[petrol]

Well.. last night... from 7pm until about 2am, I finally got it running.

Wow did I feel dumb though. It was the ground (or lack thereof). I put a good ground to it, tightend up the others. Reconnected the exhaust and shift linkage, etc. Good to go.

The only thing I need to get a definitive answer on is the daaaaamn firing order. I found 3 different specs out there, all with their own shoddy drawings. I'm going to search the forums and see if I can find something here set in stone, but aside from that I'm pretty good to go so far.

I really appreciate everyone's help, and answers.

-scott

 

[Phoenix]

Well.. last night... from 7pm until about 2am, I finally got it running.

Wow did I feel dumb though. It was the ground (or lack thereof). I put a good ground to it, tightend up the others. Reconnected the exhaust and shift linkage, etc. Good to go.

The only thing I need to get a definitive answer on is the daaaaamn firing order. I found 3 different specs out there, all with their own shoddy drawings. I'm going to search the forums and see if I can find something here set in stone, but aside from that I'm pretty good to go so far.

I really appreciate everyone's help, and answers.

-scott

Glad you got it running bud.

There you go :

The chilton manual have it wrong I believe.

 

[petrol]

Absolutely awesome.

I did my anti-n00b search, and found the page with all the technical drawings, wiring diagrams, etc. Great.

I appreciate you including the pic as well...

-Scott

 

[SASHO91]

Ah, yeah a bad ground will sure do that.... I thought you allready checked them though.

Glad to hear you got it running though.

 

[petrol]

The motor is running like the good ol' days now...I couldnt be happier. EXCEPT!

Apparently something popped a hole in the radiator core....So I get to replace it tomorrow. But that's a cinch at least.

One more question!! Along the firewall, I have a thick, soft rubber vacuum line (with a red stripe on it)...that doesnt appear to have a home. I originally thought it was the intake vacuum line, but eventually found the right hose for the intake folded back under there. I cant find any hose-less connectors left in the engine bay, so I plugged the hose for the time being.

Anyone know what this goes to???

-Scott

 

[92inPA]

One more question!! Along the firewall, I have a thick, soft rubber vacuum line (with a red stripe on it)...that doesnt appear to have a home. I originally thought it was the intake vacuum line, but eventually found the right hose for the intake folded back under there. I cant find any hose-less connectors left in the engine bay, so I plugged the hose for the time being.

Anyone know what this goes to???

-Scott

It's most likely either the vacuum to the brake booster or a windshield washer fluid line.

This might be handy for you to have:

And in case you want to learn a little about the "black box", CLICK HERE.