I know this is basic mechanical knowledge BUT i am having one hell of a time here with my PFC AND i'm am so close to having my rebuild complete. Problem is when PFC is plugged in to EM harness and IGN is ON, the four fuel injector wires on the #3 EM connector heat up the 10ohm resistors and continue to get hot. Now this means the wires are getting to much resistance correct?

My OEM ECU and HKS F-CON do not heat up the wires when plugged in and the ignition turned to ON.

The PFC forum has been little help and Apexi just bench tested my unit and said it checked out good.
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I have already checked on the four fuel injector leads : for continuity, 12V present when IG is ON, Stray Voltage when IG is OFF. == All checked good.

On the two fuel injector grounds I checked for: continuity and resistance. All where good.

On the PFC Banzia adapter I checked for possibly touching prongs, continuity= all checked GOOD

QUESTION is: can anyone else tell me if I need to check anything other then these. Can a fuel injector fry and cause these issues?

I am really stumped and completely out of ideas. Thank you for your time and it is appreciated.

-Sean


PS= I might just try another EM harness If there is no luck. If anyone has a S4 TII EM harness for sale in good shape PM me. Thanks!

 

Anyone? If there is no stray voltage WHY ARE THE WIRES GETTING HOT?

 

post a pic of how you soldered your resistors. remove the tape.

 

A shorted injector wire would pop the EGI fuse or ...depending.....cause the injector to spray constantly and fuel would literally pour out the exhaust after, oh, maybe five minutes or so.

I assume when you say *fuel injector grounds*, you mean one of the wires from each injector that goes to the *computer* and not a fuel injector wire that is going straight to a gnd.

 

Hailers: The grounds I am talking about are 3G and 3A on the EM harness. These two grounds go from computer striaght to the block. I rewired these completely last year and they worked great with my F-CON. I am under the impression that these are the fuel injector grounds(Aaron cake thread).

arghx: hey man, I am going to put in new resistors just because it is another eliminating factor in the trouble shooting game BUT yes the solder is a bit thick due to the large gauge wire that was sticking out of the Radio Shack resistor. I had a hard time getting the solder to stick to the wire strands AND the resistor(resistor wire just wouldn't get hot enough to suck the solder through the wire strands. It very well could be a cold solder joint BUT if it was wouldn't the voltage checks have been different? I am unsure and would think no because it is a open circuit until the PFC is connected right?

I get the PFC tomorrow or WED so I will plug in and go from there.

I wonder if anything inside my alternator is fucked due to it being the location where the big sparks happened?

 

My original 88 OEM harness was in really bad shape when I bought my PFC, so I ended up going with a used, relatively uncut 87 T2 emissions harness and used the OEM resistor pack. I never had anymore bullshit resistor problems, plus the OEM injector clips on the 87 harness plug right into my Greddy/Denso 720's and Bosch 1600's.

That being said, before that I also had some luck with resistors from here: http://www.mouser.com/search/Product...key71-RH10-5.0

Those are 5 ohm resistors. The factory resistor pack on the 86-87 1/2 cars is 5-6 ohms, something in that range. You can also try the FJO injector driver, but that's getting expensive.

Your alternator isn't running while the car is off and it doesn't appear to be blowing any fuses, so I wouldn't worry about it just yet.

 

**********Hailers: The grounds I am talking about are 3G and 3A on the EM harness. These two grounds go from computer striaght to the block. I rewired these completely last year and they worked great with my F-CON. I am under the impression that these are the fuel injector grounds(Aaron cake thread).
************************************************** ************

Those grounds are for ALL the circuitry in the ECU. Includes the fuel injector drivers and what not.

 

I am going to go the new harness route if I can't find the problem. As for the alternator I HOPE nothing is messed up when the engine actually starts.

Hailers: thanks man, I didn't know that. I need to check the wires coming from the main relay TO the fuel injectors again.

 

little update:

So I wired in 4 new 10ohm/10watt resistors with solder with core flux. Nice and pretty with good readings all around.

PFC won't arrive til tomorrow.

I wanted to check continuity of all four EGI leads with the fuel injector clips ATTACHED to the injectors. WHile I checked continuity(all good by the way) I probed the battery lead, 3J on #3 EM connector and the end of one of the resistors on the fuel injection wire. CRAZY thing is I get a quick continuity beep then it doesn't sound of the multimeter. I checked it numerous times with all four resistors and again, got a quick beep on my multimeter for continuity on all four wires. The beep went on for only a split second each time. ?? Of course once I disconnect connector FEM-02 the beep no longer occurs.

Any thoughts?

I will check the engine side of my harness. I checked the main relay for any visual defects, worn wires, ect+ nothing.

I have been studying the FSM wiring diagrams 50-22 and 50-25 non-stop

The only things I have altered on the EM harness since the last time the car started is: I snipped the AFM, variable resistor. I accidently snipped the pressure sensor conector but re connected everything(verified with continuity check from connector to ECU).

I Also mooded the trailing coils.

man, what a headache.

 

I got the PFC in yesterday. Plugged it in and got the same results.

I ended up going stir crazy last night and when my Wife and daughter went to bed I stayed up til 3AM checking for everything and anything.

I basically removed anything that I modded or added to my car electrical wise since the start of the rebuild to see if the problem occured because of those.....nothing, still hot resistors. Even tried a friends extra TII harness and the PFC still didn't work.

I have my harness completely stripped and no damaged wires. TRIPLE checked for 12v present on BATT and MAIN RELAY leads to PFC.

What ever is causing the resistors to heat up is also inhibiting the PFC to power up. I have yet to be able to get the commander to illuminate.


So I have decided to send the PFC and the S4 Adapter to Banzai Racing and have them test both of the items out. Being in Montana I am limited to finding anyone with a FD, or even a S4 TII(buddies is torn apart and been down for a while), otherwise I would use those as a determining factor.

I have a feeling Apex might have bullshitted me(better not have, I paid 50.00 to have the bench test done) So this is why I am sending it to Chris at Banzia. Hopefully he can test the PFC and check to see if the adapter is in working order.

Man, my efforts and "build" are completely haulted here until I figure this out. I have a feeling winter will be here before I get this done due to time constrigencies with work and my family.

If Chris does say evrything is OK, I am going to replace both my engine harness and EM harness.

As for the wierd continuity check with the battery lead and the resistors(last post) I couldn't determine why my multimeter beeped for a split second?

 

Draw a very simple diagram of how you wired the resistors in the harness. The resistors cannot get hot because you have batt voltage coming into one wire on the injector and the other wire coming out goes to the small ECU plug and that plug is not connected to anything. I assume the resistors were getting hot when the ECU plugs were not connected to anything.

3J............I mean, key ON and see if 3J has batt voltage on it or not. 3I is what powers up the stock ECU. It should have batt voltage with the key ON.

 

No Hailers, the resistors get hot when the injector clips are on the fuel injector AND the #3 EM harness connector is plugged into the PFC. When the PFC is not plugged in, the resistors stay cool, ALSO the resistors dont get hot when the injector clips are not connected to the fuel injectors but EM harness is connected to PFC.

I already verified voltage present with 3J and 3I with the IG on.

here is your simple pic. Again, they were wired like this when I ran my F-CON with no problem.

Thanks for the concern though.

 

Yeah. I just kinda screwed up. In your original post you said the plug was on the PFC. Sorry 'bout that. I'm clueless why they get hot when connected to the PFC. Clueless because I don't know anything about the PFC.

It would be interesting though, to hook up the PFC and then go to the injector plugs and pull them off one at a time. IF the injector clicks/shuts off, then for some reason the PFC has pulsed them open. Actually it's almost a given that they are being powered ON. Probably not pulsing or you'd have heard the clicking. Probably just ON/full open. MIght just connect a spare injector to one of the wires and watch its ???pintle as the plug is pulled off/on.

I'll drop out of this thread. I know not PFC.

 

It is crazy isn't? If the Power FC checks good at Banzai that is what I am gonna have to do is test out some other injectors that I have laying around.

My 4 injectors are the only thing I haven't tested and I have talked to numerous technicians that say it is very difficult to fry injectors, usually caused by an insulation break on the body of the injector.

to be continued...

 

It's not likely the injectors themselves. Prove it. Take a fuel injector. Hold it in your HAND. Put the connector on it. Plug the PFC in and apply the key to ON. IF it gets warm, it isn't the fuel injector. I mean, It's in your hand and cannot short out. Use a spare fuel injector.

For some reason It SOUNDS like the PFC thinks the engine is running. Got me why. Injectors should not pulse unless the CAS is turning over imho. Very humble opinion.

EDIT: and if it was the fuel injectors shorting to gnd, then they'd get hot with the plugs off the ECU/PFC. Ain't the fuel injectors themselves. I'd hold one in my hand and key ON and all connectors on the PFC. See if it's pulsing.

That might not turn out good, so the LAST thing I can think of is to go to CONTROL UNIT in the FUEL AND EMISSIONS seciton of the FSM and compare your readings at each pin of the ECU with the readings in the CONTROL UNIT page.

EDIT: from memory and because I'm lazy, I think you questioned the pinouts on a plug in your first post or two. You read the plugs from the wire side of the connector. Just in case.

 

I will have to try that when I get the unit back.

As for the 4B section of the FSM, I have used the CPU pin layout for years and am well aware of its intel.

I took out my EM harness today a removed all the snipped/not needed wires from the harness connecter(actually removed the female pin from connector). Inspected wires from the injector clip to the ECU connector for any faults. ZERO, hell even tripled checked all the wires for any faults. No biggy, because I really wanted to replace all that old crispy black insulation around the entire harness anyway.

My harness is pretty bare bones now with all the emissions and AFM/var resist/ ect wires removed. I guess this problem got me to take care of some stuff I needed to do.

I DID however find something interesting....as you know I ended up cutting the old grounds in the harness and actually routed two new wires from pins 3G 3A to the block. Well, I was looking over the EGI and EMISSION (50-25) wire schematic and noticed that the ECU ground 2R actually is spliced into 3A(ground 2C does as well further down the wire).

Now obiviously these grounds worked for the MAP sensor and TPS or I wouldn't have been able to drive my car last year. BUT I wonder if the PFC needs these grounds to be interconnected to operate......it is a long shot but right now I am desperate.

I think I will slpice them into the 3A/3G wires I have. Wouldn't hurt right?

 

The PFC and harness tested out perfectly fine and are being returned to you today.

You need to verify that you have grounds at 4A ,4B, 4C, 4D and 12V power for the 1A and 1B on the PFC. In your other thread you state that the commander does not light up, these are the bare minimum that you need to power up the PFC and have the datalogit and commander work.


PFC grounds connector #4

4A = S4 3A
4B = S4 3G
4C = S4 2R
4D = S4 2C

12v PFC connector #1

1A = S4 3J
1B = S4 3I

Check your main relay for power

 

Thanks for the help Chris. I am soldering in 2R and 2C to 3A and 3G. Again, your patience and help is appreciated!

 

when you figure this out, it's going to be something really stupid. it always is.

 

Murphy's law

 

enough said

Thanks everyone for the help

 

I take it it was the two grounds that you had cut, that we discussed?

 

I had 2R, 3A and 3G connected. Good old 2C was cut. What good fun, ha ha. Thanks Chris.