ECM questions

[tomtom72]

Hi guys, Please forgive the elementary Q's but I truly have no experience to draw on.
I have a 90 ZR-1 & I think there is a possibility the ECM may need to be replaced.
Is the "chip" called a PROM, that thing on the underside of the ECM?
Dose that come with a new ECM or is it bought separetly?

I tried "drilling" down at some GM parts sites & tried to find a part listing for a PROM but I couldn't.

Thanks for any help,
Tom

[Kevin]

The "chip" is the prom and is accessed by turning the ECM over and undoing the bolts and pulling the cover off. The Prom is not part of the Ecm package when you buy it from gm. My advice is to go after marker with the prom and go with mark haibeck or someone like that.

[tomtom72]

Thank you Kevin. I didn't want to be totally ignorant when I have my car scanned by a diagnostic machine & not know the correct terms.

Is it possible to tell by using a scan tool if the ECM &/or the PROM are faulty?
I don't know if that is a valid question? I wish I could find some reading material that explains electronic engine controls to non-tech persons like me.

Thanks for your time!
Tom

[Kevin]

Tom,
What is the car doing that you need to have it looked at

[Nick]

Do you have the service manuals?

[tomtom72]

Hi Kevin, Hi Nick,
Yes I do have the helm manuals for the car. I have little to no experience with electronic engine controls & fuel injected cars from a "hands on" aspect.

The car is sputtering and it seems to have a miss. I thought water in gas, so I added techron(big bottle) & replaced the fuel filter. No joy. I next pulled all plugs; even # plugs had clean, white center porcelians, which seemed odd as the electrodes were charcoal; odd # plugs electrodes & center porcelian were charcoal. No visable damage, no fouling, broken parts. I had my FR2LS plugs saved so I put them in & no change. Resting state battery voltage is 12.5, I knew I wasn't gett'in lucky!

I had no SES light but I used Gordon's jumper kit to look for codes in the ECM and the CCM. 12 in ECM and --- in CCM so I went to 6E section, and checked fuel pressure, 50psi on KOEO tests, engine cold & 48psi with engine running @ hot idle. I used my inductive timming light to check the wires & get a feel if there was energy in all wires, and I had good light pluses on all wires. I put a Vacuum gauge on it also & 15"hg @ idle speed, hot motor. I did all those checks while I was warming up the motor to get fuel psi w/ motor running. Book said KOEO PSI tests w/cold motor & hot motor for running PSI test. I found no fuel in pressure regulator hose & since the PSI w/ motor running was good I figured the regulator was good. I put 12" hg on it w/ motor off and it held vacuum. The MAP hose was on & since it was only $30 I swapped it, no change. I smells lean to me so I figured no vacuum signal to ECM for A/F adjustment. Just a guess. I should know better.

The rest of the stuff in book talks about a Tech1A so I figured I need to have it scanned. I was afraid of what chart A-7 said about looking for spark & the cats so that is why I used my inductive light. It always worked on my 72 LT-1 & it had GM C/D ignition and I also checked the FR2LS plugs for wetness after swapping them & the fuel filter because I could tell right away the "miss" or "sputter" was still there. Also the exhaust smells lean. I figure big vacuum leak or all the injectors quit at once? I hate to say this but I feel like blocking the T/B extension but usually a vacuum leak leads to high idle & mine is normal, 600 or there abouts. Oh and this throws me, it started to sputter or miss very subtly and by the time I went about 5 miles it was a full miss. I also turned on the power key and it was the same miss. That's why I thought bad gas because I just tanked it. I siphoned out about 5 gals worth & let it sit to check for water, no soap. With no codes I'm quite lost as I can't take the odds of all 16 injectors going at the same time, and I figure if the O2 sensors were N/G it would be in "closed loop" only? I guess if no sensors actually break I wouldn't see a SES light & codes. I just don't understand enough to be very effective at trouble shooting, guess I should have went to Gordon's school before buying a Z. :o

Thanks for the sincere inquires & the knowledge you all share with us rookie Z drivers.
Tom

[Kevin]

code 12 is a check code. to check the injectors get the car hot, pull the plenum and use an ohm meeter on the injectors. 12.5-13 is what they should be at..

[Aurora40]

Short answer from someone only mildly informed. The ECM can detect errors with itself to a degree. Obviously depending on how it is flawed, it might not do that. I suppose diagnostics could help narrow this down. Another way would be to just swap the chip. If your car had the recall done, do you have the original PROM? Would be a quick way to rule it out.

Also, just to clarify, by "check code", that means that code 12 is always there. It means nothing except that the code checking procedure is working. You will always get 12, next code, next code, etc. So if there are no codes, you'll just get code 12.

Edit: just a quick also, each code will flash 3 times. So make sure you are waiting through 3 instances of "12" to see if there is a next code.

[tomtom72]

Thank you Kevin for the ohms readings. I must have missed that in Sec. 6.
I read on CF that there is a way to check the ohms thru the ECM connector, but the post was a bit over my head. Anyone ever do it that way? How is that done? I'm not garaged so I want avoid the plenum for now as I'm in the process of securing a rented space to do that work over the winter. Thanks for your help! :thumbsup:

Hi A40, Yea I have Gordon's book & jumper modules & he explains the drill so even the non-EEC people can read codes. I waited, in fact I did the ECM & CCM. The local independent tech I spoke with laughed when I told him about my troubles. He said..."Those EEC systems from back then are retarded. The ECM might have lost a ground or it could have quit on you, outside it might be the MAP, but I doubt it. Did you check the grounds?" I couldn't say much because I don't know much. I have all the paper from the orig. owner & it seems not. I don't have a dealership receipt for that. I can say my guess would be no it wasn't done because it has the symptoms. Thanks for your time! :thumbsup:
Tom, I should have done GK's school.

[Kevin]

I'm not sure how to do the ecm test on the injectors but pulling the plenum is quite easy.

[tomtom72]

Kevin, Thank you for your time and effort on this! I've read so much about pulling the plenum that it almost seems less daunting! I've started buying parts for under there already. Just small stuff but I think , RC if I'm correct, I'll just go on & replace all the injectors as a pre-emptive measure. I have the sort of luck that whatever I don't replace under there, will bite me soon after I close it up.

There is a guy on CF forum that says you can check the ohms on any primary by using the pins in connector A, primary injectors are all there; and the ECM 12 volt feed in connector B. I did that & got 18 ohms for the complete circuit on all the injectors. I just wish I knew if my results are valid. I figure if the injectors should be between 12 - 15 ohms, then all the wire & the pins = 3 ohms. It sounded reasonable to me but then what do I know.

I also wounder if the "limp home mode" is a myth or fact? If fact what would the car run like in that mode? If it goes lean on all cylinders so as not to go rich & ruin the cats? Just too much I don't know & what's worse I can't find anything to read to educate myself. Should have gone to GK's school before buying this car.
Anyway thank you & everyone else for the generous help & advice!
Tom

[Kevin]

I'm more of a hands on guy, I'd rather yank the plenum and do it with an ohm meeter. 12.5-13 is normal for the injectors. When they start to go bad they run rich. And I'm happy to help in anyway i can.

[tomtom72]

:handshak: I agree with your method! The car is for sure not rich!

Besides I hate anyone I don't trust touching anything I care about. I know it's not normal but well I'm not normal. Gotta get me garage space I can work in for that, i'm trying. Just ordered some stuff for the secondary vac system & made some on line inquires about some of the other parts under there. I figure if I'm going to do it I'm renewing everything under there I can get.

Thanks again Kevin & to all Z owners who offered input to my education.

:cheers:
Tom

[Kevin]

If they get to bad then the car goes lean.

[Patton]

Every time i see ECM i think Electronic Counter Measures.... I have to demilitarize my mind.

[tomtom72]

:sign10:

I like that, Patton! Everytime I see ECM I think DTC code 666...then the LCD dash goes blank, a :thumbsdo: appears and all the lights on the DIC come on, a little door opens on the DIC where the SES light used to be and a little guy with a chute gets out & :hello: only it ain't hello & then he jumps out the window.

Any one know if the 90 ECM part number is still good. I checked a few on line chevy parts sites & found a 92-93 ECM, P/N 16163993 is still a good # & I was told it replaces the 90 ECM. Pete Bernard told me about the ECM deal.

Kevin, I'm ordering injectors also, from RC. I heard that their injectors are stainless. Just hope they answer my Q about which ones I need for 90Z.
Thanks guys!
Tom

Forgot something. Has anyone done bussiness with P & G chevy in PA? They seem to have a lot of Z parts that I need.
Thanks again,
Tom

[Jeffvette]

ECM's are not swapable.... to a certain extent. You can use a 91 in a 90 as a bare minumum running system. You'll lose a couple of functions.

[Kevin]

I think you can go to mid America or places like that and get a new 90 ecm.

[tomtom72]

Thank you Jeffvette and Kevin for the heads up on the ECM's. The P/N for the 90 ECM that I took from the parts CD that I got from KWR doesn't come up at those GM sites. How do I know which one to get? Are there #'s on the one in my car that will help me get the correct one?

Thanks guys!
Tom

[Kevin]

Call around and see who has one in stock? Try mid America, ecklers etc.

[tomtom72]

Thank you Kevin for the advice!

Secondly, just got off of the phone with Bill at P & G chevy in PA. These people are very cordial and helpful. I called with the old P/N from the parts CD and Bill chased down the part thru three P/N changes and didn't like what was up. He took my e-mail & phone # and is getting back to me when he is satisfied that he can get me the correct part.

Maybe I expect to little, I don't know. I can only say that P & G makes you feel like they care that you get the right parts the first time! Kudos to Bill and P & G chevy!! :thumbsup:

Just thought I would pass this along. Oh and their prices seem reasonable also.
Tom

[Kevin]

While I have had some bad experiences with other parts of the dealer I am going to list, the parts guys have always done me right. Try Tom Henry chevy 724 443 1575 tell them you are with the net/registry (although they will probably figure that out) and they give you a 15%(I think) discount. And try Pete @ 781 953 2034.

[tomtom72]

Kevin and everyone else in this fraternity, Thanks! Truly it is the people and not just the car. The car is nice, we all know that. I learn every day that the people involved with the car are first class and that makes the ownership experience so positive!

P&G got back to me & there seems to be a lack of 90 ECM's in the system for now. I ordered one from AutoZone, they use the original GM P/N's to verify which ECM you need, $266.00 w/tax & free shipping. I'll let everyone know how their stuff is. Oh, GM's new P/N for the 90 replacement ECM is P/N 88961373. I didn't ask the price but I'm sure it's easy to find.

I'm waiting for a reply from RC but I understand their #205 injector is the correct replacement for both 1* and 2* injectors on a 90Z?

Also I have a Q about ingnition Sys Replacement Parts:
OE coils = 40K volts or Jegs has a coil at 45K volts. The pricing is par between the OE & Jegs w/ tax & shipping. Which would you choose?
OE wires vs Magnecor?
I may also R & R the electronics for the ignition system, for preventive reasons, any thoughts on this?

My only reason for all these parts being R & R'ed is I don't have a garage where I can work. If I do this myself I figure to make it a one time event, as much as humanly possible. I understand electronic parts quit when they quit, no warning. I just figure new parts may be more reliable than my 16 year old ones. I'm looking for a garage where the owner would allow me to do this type of minor work; if I don't find one I have to buy labor from one of the local vette shops. Either way, I have to make this count. My own house is a few yrs off yet $ wise. Anyone's opinion would be welcome on any of this!

Thanks again,
Tom

[Aurora40]

Hey Tom, I just want to say, $266 for an ECM just to see... That's about 1/2 way towards Tech-I. Also, this is the whole ECM, right, not just a PROM?

Also, the coil packs are GM/ACDelco parts. You might be able to find a local AC Delco dealer that will sell for the "jobber" price vs. full price. I think they were about $30-40 each from my local place. Part #D545. I'd also be glad to pick them up and ship them to you. The plug wires are AC #628D in case those are cheaper than from GM sources.

Edit: You don't need to pull anything to swap the ECM or PROM, so perhaps you should do these after.

Also, I plan to pull my plenum in the coming weeks/months to swap out wires, get the injectors rebuilt, and patch up the secondary vacuum system. I thought about coil packs, but it doesn't seem like a maintenance item really.

[tomtom72]

Aurora40, Yea I hate to trouble shoot this way. That said I just got a reply from GMpartsdirect.com..."ECM is not in stock. You may have to seek an aftermarket vendor to fill that order..." I don't know what that means except to say I got the same answer about the 1990 style right front LTPWS sensor awhile back.

Anyway, all that B.S. aside, the EPROM is not included with the ECM, and that's from anyone as I understand it. EPROM is a separate P/N at additional cost. I don't remember if I searched the price on a TECH1-A, seems I went to Vertronx's web site & didn't see a Tech1-A, only a TechII or something like that. As I said I bid on one on e-bay & bailed after $750; I think it went to $800+ but I can't say for sure. I figure if the ECM is the problem then I'm okay and if it's not then the injectors I'll order as soon as I call RC.

The other stuff, well when I get my package from P & G Chevy and another vendor I'll have every part of the secondary port throttle vacuum system in hand & brand new. I get the 16 injectors and the ignition coils and wires and maybe stop there; or maybe I buy the "brains" to the ignition system also, heck it's only two more parts. It's alot of $ but then that's new also along with everything else under there. To me having all the parts means only doing the plenum once. In theory I figure another 15 yrs or 13,000 miles of not having to go back under there. Ofcourse I intend to put more use on it so maybe I don't get 15 yrs but I'm banking the new parts will live for some time & milage close to what the OE stuff gave me. I'm not saying my thinking is 100% correct but I think it holds some water?

I figure I can autopsy all the parts after & see what failed &/ or the condition of them at TOD. I know it's not a real mechanic's way of doing things but I'm not in that trade. I'm just some backyard hack!

:mrgreen:
Tom

[Kevin]

Did you try and contact mid america and places like that?

[tomtom72]

Hi Kevin, Yes I ran thru the on-line catalogues & found one of those guys selling ECM's. Them & autoZone were the same except AZ don't want a core.

I did the on-line order w/AZone, no core charge & free shipping. Both were like $260 - $270 range, so it was a toss-up.
:thumbsup:
Tom

[Kevin]

I just checked myself. I thought they were less

[Chedberg]

There was something floating over the Net about Lucas Injectors. How do they compare with the RCs? I thought the secondary injectors were different than the primary ones?

[tomtom72]

Hi Chedberg, I do not know much about the injectors, or the rest of the car for that matter! I'm under the impression that 90 injectors are different from the 91-95's, but like I said my lack of knowledge...

I just hope that when I call RC to order the injectors THEY know which ones I need because I sure don't.

RC injectors are made from stainless steel so they don't have rust problems and as I understand the coils are resistant to ethanol mixed in with the gas. The 90 injectors were not designed with ethanol in mind. If I understood what I read the ethanol softens the insulator around the coil and intrudes into the coil's windings. BUT don't quote me on that as I'm probably not correct. All I know for sure is 90 injectors are different. I can see some of the injector pairs in my 90 and I see that the 1* and 2* sit differently in the injector housing, 1* are in further, I think. That's all I know for sure. Also for what it is worth, depending on what grade of S/S is used they will resist deposit adheasion & rust to a large degree. The main advantage of S/S is that it is stable from a molecular and chemical point of view. The metal will not willingly enter into a chemical reaction, therefore deposits & rust will be easier to remove as they don't get a good hold of the metal, they just sit on it. In order to get S/S to react you need a strong reducing or oxidating agent; but that's on marine & surgical grade S/S. The ratio of non-ferrous to ferrous metals in the S/S determines the grade. Ferrous metals, like the OE injectors, do not resist reactions well at all.

Whish I could comment about injectors better but if you go to Mark Haibeck's site there is a paper about ZR-1 injectors. Also in the NetRegistry maintenence section there is a write up also. Sorry but I just don't know enough to answer your Q about the Bosch injectors.

Kevin, I was a little surprised at the results of my search, I would have thought the vette sites woul have been better price wise.

Tom

[Jeffvette]

90-92 injectors are two different kind on the primaries. Primary have the nozzle tip shaved off and the secondaries are the same as the 93-95 injectors. The 93-95 cars use the same injector for all 16 ports.

[yellowz]

hey tom did you check for a bad coil that will do it also:happy1:

[tomtom72]

Hi Jeff,
Okay I'm not getting something about the injectors. "90-92 injectors are two different kind on the primaries. 1* have nozzel tip shaved off."

The 93-95 injectors are all the same, 1* & 2*, and the 90's use 93-95 injectors as secondary injectors? I think I'm not clear on what to tell RC. If I order by application, 1* & 2* injectors for a 90 Z they will know what to sell me? Or should I just get OE injectors :cry: For the amount of cash involved in injectors I would just as soon buy the S/S RC injectors. Help! I thought this would be simple, obviously I'm mistaken.

Yellowz, I have spark on all the plugs. I'm buying all of the parts that go under the plenum so I only do this once, hopefully for another good while. So far santa brought: Vac hose, vac solenoid & filter, actuators, tank, breather hoses, top end gasket set, magnecor KV85 wires. Next on the list is spark control module, Ign control module, 16 injectors, 45,000 volt coils from Jegs, starter & alt. rebuild parts, & anything else I find under there on my parts CD. If I can find space that will let me work I might even send some stuff to Mr. H for some fix'in. If not I need to have all the parts so this is done in one shift as I have no garage.

It ain't purdy but it all I've got. I've reduced it to the simplest form of work...parts changing.
Thanks for the shout!
Tom

[Aurora40]

Hi Jeff,
Okay I'm not getting something about the injectors. "90-92 injectors are two different kind on the primaries. 1* have nozzel tip shaved off."


Here are some pictures of them I found on Delphi's website.

Primary: http://go.delphi.com/del/epc_images/Products%5C3045p_Primary_IMAGE.JPG


Secondary: http://go.delphi.com/del/epc_images/Products%5C3050p_Primary_IMAGE.JPG


The 1993-95 injectors look pretty much the same as each other

Primary: http://go.delphi.com/del/epc_images/Products%5C3120p_Primary_IMAGE.JPG and secondary: http://go.delphi.com/del/epc_images/Products%5C3125p_Primary_IMAGE.JPG

[tomtom72]

Thank you Aurora40 for the info. Looks like the secondaries on a 90 could use the injectors from 93-95. The 90's primaries look unique to me but I don't know what to say beyond that. Looks like I'll try Delphi.com & look around to see what I can learn.

Thanks for the effort, much appreciated!! Z owners are the best!

:thumbsup:
Tom

[Aurora40]

Thank you Aurora40 for the info. Looks like the secondaries on a 90 could use the injectors from 93-95. The 90's primaries look unique to me but I don't know what to say beyond that. Looks like I'll try Delphi.com & look around to see what I can learn.

It's sort of a cool site, though ultimately doesn't seem to help me find a good price on anything... :-\

Anyway, try: http://go.delphi.com/default.asp?Language=English

the injectors for 1990-92 are FJ10004 and FJ10005. For '93-95 it's FJ10019 and FJ10020. I got this info from the mailing listserv. You can see the vehicle application list on the delphi site for each injector, though.

Also, their initial page on MPFI injectors would suggest they are all now compatible with ethanol fuels.

[Kevin]

fyi the secondary is an lt1 injector.

[tomtom72]

Thanks Kevin! I see there are alot of choices for the secondary replacement injectors. What is with the primaries? I see the machined part of the nozzle(?) necked down but what is the reason? Where does the O-ring go on a primary?

Was that something to do with the "air over" theory in the injector housing? It seems to me that the injector housings must be different on a 90-91-92 motor comparred to a 93-95 motor?

This stuff makes me wish I spent less time learning my holley & more time paying attention to FI developments. :icon_scra

Thanks again for your help! :thumbsup:
Tom

[Jeffvette]

O ring is in the injector housing further up the neck on the injector.

And yes the injector housings are different 90-92 and 93-95.

[wdo-mkr]

Thank you Aurora40 for the info. Looks like the secondaries on a 90 could use the injectors from 93-95. The 90's primaries look unique to me but I don't know what to say beyond that. Looks like I'll try Delphi.com & look around to see what I can learn.

Thanks for the effort, much appreciated!! Z owners are the best!

:thumbsup:
Tom

One other thing to take notice of is the locating key that is on the bottom side of the connector for the wiring. The keyway is offset on the secondaries vs. the primaries. Its nothing that a quick pass with a grinder won't fix, but if you are thinking about having the machine shop grind down the primary injector boss at the bottom of the injector, then have them sand the black plastic locator boss on the electrical connector as well.

[tomtom72]

Jeff thank you again for helping me out! :thumbsup: Now I realize what I saw in pictures of injector housings, it was the primary O-ring in the bore, not on the injector. The secondaries have the O-ring on the injector. I'm sorry I'm so dense but I've never actually seen an LT5 until I bought one.

wdo-mkr, I would not even know where to begin to do any modding to an injector. I guess if RC has direct bolt on replacements I'll be okay. If not I'll just get OE primaries from GM. I don't have any knowledge or experience with FI systems so I'm not qualified to mess with the parts. I guess if I can't figure this out I'll ask more Q's.

Thanks guys for the help!
Tom

[wdo-mkr]

wdo-mkr, I would not even know where to begin to do any modding to an injector. I guess if RC has direct bolt on replacements I'll be okay. If not I'll just get OE primaries from GM. I don't have any knowledge or experience with FI systems so I'm not qualified to mess with the parts. I guess if I can't figure this out I'll ask more Q's.

Thanks guys for the help!
Tom

Tom, I just wanted to make you aware of the issues that need to be considered if you decide to move something from the primary to secondary position on a 90-92 style lt5. Its not a big deal and one could remove the locators on the connector side in a couple minutes per injector. I am a bit puzzled though. Why not just order the entire set of 16 from RC and be done with the project? I personally like driving the car more than I like working on it and pulling the plenum is not hard but still a pain if you have to. With the RC injectors being all SS, why not put this part of the maintenance behind you and go from there? Just a thought. Ask all the questions you like. That's how we all learn. Having pulled my plenum and couple others several times, its now not all that exciting for me anymore. :sign10:

[tomtom72]

wdo-mkr, I e-mailed RC with my request for injectors, all 16, and they said that they were out of stock on "OE primary injectors" till end of Sept.
Not being up on all this stuff I took them for telling me the only injectors that they sell were the secondaries. They thru me for a loss when they said "OE primary injectors". Of course I figure now that they meant "OE style replacement Primary injectors". They kind of confused me with the e-mail response.

I'm gonna get 16 of some one's injectors and change all in one sitting. I know it's kind of a waste if you only have two or three bad ones. I have a vacuum leak that is slowly gett'in worse and I figure to get all the stuff under there so I make this a one time restoration, instead of a repair type operation.

This may make me sound very ignorant of an LT5, well I am, but I completely missed the point you were making. The thought never crossed my mind that it would be possible to switch electrical connections from a primary to a secondary. My lack of experience & knowledge shows! I think when I do this I'm gonna do one side of the motor at a time. This sure ain't nothing like my 72 sb C3!

Thank you for sharing your knowledge :thumbsup:
Tom

[wdo-mkr]

wdo-mkr, I e-mailed RC with my request for injectors, all 16, and they said that they were out of stock on "OE primary injectors" till end of Sept.
Not being up on all this stuff I took them for telling me the only injectors that they sell were the secondaries. They thru me for a loss when they said "OE primary injectors". Of course I figure now that they meant "OE style replacement Primary injectors". They kind of confused me with the e-mail response.


Ah, now I see your issue. I thought you were just going to do the change the secondaries thing and then go back under there again later and deal with the primaries later. Personally I think its a small pain the you know what which is why I was recommending that if you can afford to, go ahead and change them all while you have the fuel rails out. Don't bother trying to clean the old ones. I had a set done and then when I put them back in, they just stuck and or leaked immediately. Not worth the time, loss of weekends, etc IMHO.


I'm gonna get 16 of some one's injectors and change all in one sitting. I know it's kind of a waste if you only have two or three bad ones. I have a vacuum leak that is slowly gett'in worse and I figure to get all the stuff under there so I make this a one time restoration, instead of a repair type operation.


Ah not exactly. Its not a waste at all. As others here have mentioned. Often times if you have one injector thats either shorted out, stuck, leaking, failed, then the others are not far behind. Its just sound preventative maintenance IMHO.


This may make me sound very ignorant of an LT5, well I am, but I completely missed the point you were making. The thought never crossed my mind that it would be possible to switch electrical connections from a primary to a secondary. My lack of experience & knowledge shows! I think when I do this I'm gonna do one side of the motor at a time. This sure ain't nothing like my 72 sb C3!


Not at all. Look at the photos again. On the secondaries for both models you will notice a small tag on the connector where the harness connects to the injector. If you look at the 90-92 injectors, the main differences between the primary and secondaries are two items.

On the 90-92primaries, the bellows around the bottom has been shaved off and the bottom of the injector has a taper on the seat of the part that fits in the housing.

Next if you look at the photo of the 90-92 secondary photo below, you will notice a little locating tang on the bottom side of the connector that the harness plugs into. Its centered in the middle of the connector on the injector. If you try and plug the secondary into your injector harness (at least on both of my 91s it was this way) the edge connector will not allow you to plug the harness into the injector if a secondary injector is in a primary position with the tang still in place. The tang will need to be ground off first.

http://go.delphi.com/del/epc_images/Products%5C3045p_Primary_IMAGE.JPGhttp://go.delphi.com/del/epc_images/Products%5C3050p_Primary_IMAGE.JPG

The same thing applies if we look at the 93-95 injectors for the primary and secondary. The primary injector for the 93-95's now has the locating tang on it. Its also offset from the factory secondary injector. Why they did this, I have no idea, since the primaries and secondary injectors are supposed to be the same here.

One could again, just as easily grind the locating tab off the connector and you would be set and the primary and secondaries could be interchanged at that point.

Not owning a 93-95 car, I have not seen a an injector harness up close from this model year to see if they have both of the slots in the injector harness connectors to allow for this, but as I mentioned, one could just grind this tab off and you will be able to connect the harness to either injector and move them around. Something to think about if one is trying to flow balance a set of injectors. Perhaps someone with more knowledge than I could comment on the 93-95 injector harness.
http://go.delphi.com/del/epc_images/Products%5C3120p_Primary_IMAGE.JPG http://go.delphi.com/del/epc_images/Products%5C3125p_Primary_IMAGE.JPG

Glad to hear you are doing the lines, secondary actuators, cleaning up the valley area under the starter and coils, and swapping the injectors at once. Its best if you can do it all at once. I would also purchase a set of injector housing to head gaskets, and a center crankcase gasket as well just to be safe. Most times the cover that the two hoses that come from the block to the injector housings are loose and the oil blows back and fills the area in the block under the starter with lots of nice oil, dirt and what ever else the local rodent population can store underneath there. My white car with 65k miles on it at the time had a couple half eaten pecans under the starter and about 1/4 inch of oil,dirt slime mixture in it. All of the bolts on the crankcase cover were loose as well. Its a great way to get a peek inside your lower end of the motor with this cover off as well. (item 2 in the photo below) credits to the corvette action center for this great photo.

http://www.corvetteactioncenter.com/tech/c4/zr1/images/vac04.jpg

[tomtom72]

wdo-mkr, I have said this before but it bears repeating. Yes these cars are special but it's not just the car. The people that own them are what makes owning a ZR-1 special! The willingness to educate the rookies so that they can carry on and hand down the info to the next rookie. That's what makes owning a Z the real deal! It's the people. Thank you & all the members!! :thumbsup:

Yea the pics are of Rob's 90. It's so clean it hurts to look at it! :notworthy

You see it the same way I do, why not just do it all if the plenum has to be pulled. I mean my car is going on 16 yrs old and things don't last forever. I figure to get all the injectors, 4 coils, both ignition modules, rebuild parts for the alternator & starter. The Actuators, vacuum line assembly, solenoid & filter, tank, breather hoses, magnecor 8.5 wire set and a "top end" gasket kit I found on the net are inbound. I'll wait a bit for the finances to recover & start collecting the rest of the parts so I will have all of it before I take the plenum off. It's extreeme but it would be like a new car to me and then I could drive the new off of the parts.

Thank you again for being generous with your knowledge!
Tom