Were swapping in an L98 out of an 89 Trans Am into my GF's 91 RS. We have fuel pressure at 40 PSI but after cranking and cranking the plugs are bone dry. I sprayed some gas in through the TB with a squirt bottle and it fired right up for 2 secs then died. Fuel pressure was still at 40 PSI. Any ideas? The ground behind the head are all in great shape and all tight.

 

Are you using the wire harness out of the trans am for the engine? I ask this because I don't know if you have a wiring diagram for the bulkhead connectors. I can tell you there is a big wiring difference.

 

I had a buddy that just went though that. Spray fuel into the TB and it would fire up and try to run so... he discounted the ESC module in the distributor as being the problem.

After much trouble shooting and trying another ECM, he discovered he wasn't getting the reference pulses from the module. Changed the module and it ran fine.

If the ECM doesn't see the pulses on the purple and white wire out of the four pin plug from the distributor module it won't fire the injectors. Odd thing was, it was firing the plugs but not sending the pulses. I'd never seen one fail this way either and not saying yours is bad... just suggesting you test for pulses on that wire.

 

Yes we are using the wiring from the TA. Ignition Module is BRAND new Surprisengly everything works ok except the gas guage, ACC fuse blows and thats about it. . Anything else to look for?

 

Are you using a VATS PROM with that ECM and not a VATS ignition key?

Do a search for VATS if you don't understand. But, if you made that swap you probably know about most of that.

Are you using the same '91 VATS ignition key and '91 module to the '89 ECM? Did the '91 have VATS?

Are you getting a pulse on the purple/white wire from the module in the distributor?

Do you have power to the injectors when the key is turned on? Should test 12v on one side with key on.

 

Did you use a wiring schematic for the bulkhead connectors on the passenger side to make sure the wires connected to what they were supposed too. I mentioned this in my last post because the wires at the bulkhead connector on the passenger side are different for a 89 and 91 model. Also, are you using the ECM from the 89 in it? It also doesn't matter about the VATS as long as you have the old VATS key and module. It appears that you do since it cranks, the injectors just don't work. Also check the injector fuses in the fuse panel.

 

This is Mkos1980 working on Erin91RS's car. We have power to the injectors. The test light turned on on both sides of the terminal. Is this right? The noid light did not flash when connected. I'm thinking why would both sides be positive? Also where do I hook up the noid to test the module?

 

You will have 12 volts on both wires when you turn on the key. The injector drivers pull one side to ground to fire the injectors. Check all grounding wires, especially the black wire attached directly onto the ECM plug. This is the injector ground connection. Check the link below. You will find ECM drawings for all F bodies. There are many differences based on year and model. Find your application and check wiring. Some model even require a signal from an oil pressure sending unit to allow the injectors to fire. ECM Drawings Hope this helps.

 

What changes (if any) did you make to the 15 pin I/P connector and the bulkhead connector on the firewall? As everyone else is saying, there are changes from 1989 to 1991.

One important correction to an above post
The engine will crank even if vats is the reason the motor is not running.

Where are you located? I'm in Erie, PA...30 min from the PA/OH border. If you're close to the border, I might be able to swing by with some service manuals and a memcal with vats disabled. Can't promise I'll make the trip, but it all depends on your location. I'm currently building TPI harnesses and am very familiar with the system and several of the harness differences throughout the years.

 

Didnt do any yet but the injector pnk/blk wire is at the same plac as he one on th TA harness

 

I have a similar problem as Mkos's. Putting an L98 into my 91 RS, spent 3 or 4K in nice shiny go-fast parts, plugged it all in and got it running . . . . barely. It's only firing on 7 cylinders, generally running like crap and runs really hot which (I'm told) says that it's running lean. I'm going to replace the injectors in hopes that it will, if not cure, at least help the problem.

What injectors are on a stock L98? Any brand/flow recommendations?

10:1 355 CI, LT4 cam, Ported Edelbrock heads

 

What year is your harness? I'm using the 89 one. 22lbs came on L98's.

 

Mine is actually the stock 91 305 TBI harness that I sent to Howell's to be converted. Seems to work pretty well. Had some issues with wire lengths but overall no complaints.

 

Out of curiosity, what did Howell charge for the TBI to TPI conversion?

 

How are you making out on that injector problem? Also, you might find that the alternator will not charge. In 89, the brown (or brown/white) wire on terminal f of the alternator (also tied into the fan relay) went through the I/P harness under the dash (cavity D). The 90 harness (don't know about 91) has this wire going through the bulkhead at the firewall in cavity G8. In the 90 car (again, don't know about 91), the brown wire in the I/P harness at cavity D is going to the instrument cluster to deliver a signal to the speedometer from the ECM. That's another problem, the 89 harness is not set up to go into a car with a VSS in the tailshaft of the tranny.

 

they came out with vss in 88 I think. My 89 has it. I also found the fan problem you were already talking about

 

It was a while ago, but i think it was about $350-$400. May as well just get a painless from summit for the same price and not deal with the extra shipping costs. But they went and burned me a custom chip for my new cam while they were doing it and threw in a new aux. fuel pump. Like I said though, it was a while ago.

 

Thanks. $350 or so isn't too bad considering the amount of time involved.

 

I did the same exact swap a few months ago and ran into the same problem on my 92 RS swap. The system was from a 91 Transam with 350. I bought a noid light from Autozone and verified a signal to the injectors. The problem turned out to be the injectors were seized. Injectors have a tendency to seize up when they've been sitting for a while with no fuel in them. I removed them and squirted some carb cleaner and let them soak overnight. I reinstalled them and had my wife crank the engine while I tapped the injectors which freed them up and the engine started without any problems.

 

does anyone know where we can find the wiring schematics for the 91 SD bulkhead on the drivers side?My car was originally a 3.1L. We're trying to repin the connector to match the 89MAF coming from the engine. Can't seem to get the dash apart to reach all the wires and see where they are going. A diagram of the bulkhead connecter would be really helpful.

I'm Mkos's GF, he's workin on my camaro

 

Yes

 

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not supposed to

the VATS kills the starter via the "starter enable relay" in the drivers kick panel and it kills the injectors via a signal(or lack thereof) to the ECM

 

thank you Trickster!

 

Hey Trickster hate to bug ya again but do you happen to have the schematics for the 89 TPI bulkhead connector? All my wires are worn out. Can't tell the difference between oranges and reds, tans and yellows etc.

i found this ftp://ftp.diy-efi.org/pub/gmecm/manu...9-165v8MAF.jpg which is good we needed to see the ALDL but we need the schematics for that bulkhead connector where it plugs into the remaining SD harness on the drivers side.

I checked out the library and they don't carry any reference books for 89 and older cars

Thanks

 

Of course I have them, enjoy!!!

 

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Because I've been using my motor on a test stand for quite some time now, I didn't consider that I'm using a separate circuit for the starter, so it's not tied into the VATS system at all. Sorry.

 

Hi Matt did you get the car running yet??? If so, post what the problem was as I am curious to see what it will be. I think those are my injectors you are battling with. Keep me posted

 

thanks again trickster :hail: hehe

 

matt bought those injectors for my car lol.Those bad boys better work! Hopefully we will be able to get it running after repinning these connectors.

 

Yeah, I would really doubt the injectors are to blame. I used them last year when I thought my LS1 injectors were no good. I even put them in my fuel rail and checked for leaks. I also hooked up each injector to a nifty little gadget that fires the injector either one time or has a setting for 100 cycles as well. Each one misted fuel out very nicely I hope the re-pinning does the trick!

 

Oh no, i'm not blaming the injectors. There's something wrong with the wiring.

I spent a couple hours comparing the 2 bulkhead connectors. Now i stared at and compared these schematics for hours and what i got out of it was nothing had to actually be repinned. I might have lost my mind while staring at all of this but i think i am correct. There was wiper pins on the MAF harness that I ignored because there's a seperate little harness for the wipers and lights already coming from my car. The 91 and 92 SD cars had the mini harness correct? When i had the ignition on, my wipers and lights worked so i don't believe that was a problem. However, i'm going to have to rig in a fan wire into the MAF connector because there is none. The 91 SD harness has a fan pin. So i'm guessing once a pin is correctly rigged into the MAF connector the ECM will recognize the fan right? Why doesn't the MAF bulkhead connector have a pin for the fan?

I forgot to test my grounds so i'll have to do that tomorrow.

Now, i'm sure i'm going to get this wrong so i'll probably need Matt to post but i have the schematics for the 91 Speed density ALDL but not the 89 MAF. We need to know what wires are going into the 89 ALDL connector to repin it correctly.

Does any of that sound remotely correct? I don't mean confuse you guys, i'm confused myself lol.

 

Hey Trickster, do you have the wiring diagram to the 91 C207 connector?

 

Yep!!!!!!!!!!!!!!!!

 

Ah, Trickster you are a wiring guru! lol.

Do you have any idea what pin D(gray wire) does? We're having trouble trying to figure out where that wire goes.

I'm comparing the 89 connector that you posted a while back and the 91 connector and it's confusing lol. This might be the last connector i ahve to repin to get my car going.

 

But of course, that gray wire goes to pin "C" of the Throttle Position Sensor (TPS) and is the 5 volt reference signal to the ECM.

 

So thats goes into Pin c which is the service engine soon , ignition and tach on the 89?

 

AHHHHHHHHHHHHH NM i figured it out. That wire goes to the gray wire connected to the TPS right?

 

Right!!!!!!!!!!!!!!!!!!!!

 

Dam wires. I threw a fit tongiht and ripped her whole dam harness out and teared it apart tyrng to find an answer

 

OK last few questions.Pin M on the 89 C207 B/W wires goes where? I'm thinking it gets connected to the aldl? Pin P on the 89 is empty but the 91 is showing the VSS sensor. Where does the red wire on the 91 side go too and last one is. That 5v referance goes into the ECM? or out to the TPS? Thanks

 

Pin "M" is a ground wire that goes to Pin "D1" of the ECM and Pin "A" of the MAF sensor. That 5 volt reference signal goes into the ECM at pin "C14". The red wire is not required, the VSS is handled through Pin "K" on connector C207 and is a brown wire and will go to pin "A10" on the 89 ECM. Are you using the 89 ECM or the 91 ECM? Sorry, I forgot to ask earlier.

 

We have a 91 RS V6 and putting in a 89 350 TPI. So were using the 89 ECM. OK I understand everything but this "Pin "M" is a ground wire that goes to Pin "D1" of the ECM and Pin "A" of the MAF sensor" Basically the ECM gives out a ground to the Pin M then goes out to the MAF?

I'm still not liking the ALDL, when jumped I cant get the SES light to blink.

 

Ok, here are the wire codes and wiring for the ALDL.

A= blk/wht ground
B= wht/blk pin A9 ECM pin E C207
C= brwn air diverter pin A2 ECM pin A C207

D= SES light
E= orange DATA pin A8 ECM pin J C207
F= tan/blk TCC pin A7 ECM pin H C207
G= red/blk fuel pin E6 C100 pin D fuel pump relay

M= orange DATA pin A8 ECM pin J C207.

The reason for Pin "E" & "M" going to the same location on C207 & the ECM is because of a splice in the wire before the ALDL. Also remember Pin "A" of the ALDL is a black wire with a white stripe and Pin "B" is a white wire with a black stripe. Here is a picture of the ALDL with all the functions listed, some of which don't apply to the 89 ECM.

 

So you can take the orage wire off of Pin J and splice it into 2 and connect them to E and M? Its so weird that the ALDL looks completely differant on her 91 V6 as it does on my 89 TPI

 

You don't have to splice anything, it already has the splice in it from the factory. The ALDL looks different on hers because in 1990 they added airbags and anti-lock brakes which go to pin "H" & "K" on the ALDL and do not apply to the 89 ECM.

 

Just hooked up normally should I have at least a blinking SES light when jumped? Way in teh beginning we hooked everything up and I tried to get it to flash but we got nothing. Is there a specific wire which we need to wire in differantly so that he ECM can read the aldl? I'm sorry about these tupid questions but i'm confused.

 

When you jumpered pins "A" & "B", did you have the key turned to the "ON" position so you would have power to the ECM? Do you have an orange wire going to the ECM at pins "B1" & "C16"? These are the battery connections for the ECM.

 

"Pin "M" is a ground wire that goes to Pin "D1" of the ECM and Pin "A" of the MAF sensor. That 5 volt reference signal goes into the ECM at pin "C14". "
(This is matt)
Ic where pin m goes to the split which goes to the maf then to the ECM but where the the other side of PIN M go to (black pin M) Her car had a orange ACC wire in Pin M and I'm wondering what the ground goes to in her car or if I should let it be. On the grey 5 volt referance. we have the C14 grey wire going right to the TPS, but where does her grey wire in Pin D go to Her Pin D grey wire is the 89's Pin D tan/white coolant wire.