more lt1 issues...frustrated....

[piston]

this is driving me nuts. first off some of you know i have a 94 caprice lt1 t56 swap into a 75 280z. ok, i finished my exhaust the other day and took it for a test drive. my lights dimmed out and my car came to a stop in the garage and never fired back up. alternator is bad and batery is drained (brand new batery). so i had to throw down some cash and pick up a new alternator and batery. questions...

 

my lt1 alternator was wired f terminal to indicator lamp along with a ground onto neg side of idiot light. the other end was wired to starter switch wire. then for no reason my L wire on the connector was wired to constant hot. wtf? i already know this was wrong cause it sucked the hell out of my alternator and batery.

 

ok, after searching and reading old posts, it looks like only the f terminal is being used on the connector and bat 10gauge goes to contant hot along with fusable link. is that true? i have two wires comming out of my connector and one is label L and other F. F i understand is field output which is ignition hot along with 470ohm resistor or idiot light. now, with the light used, the f goes to the ground side along with the ground wire and the other side of the light goes to ignition hot along with 5amp fuse right? if this is correct, how come my idiot light doesnt go off? im using the light because i cannot find anywhere a 470ohm resistor. not even radioshack. plus the light tells me if its charging or not..

 

other problems...my car idles at 2k and if i tap the pedal quick 50%, why does it move so fast to 6,300 redline within a blink, seriously! then the rpm slowly comes back down very slowly and then revs back up by itself to 4k or 5k rpm and comes back down and almost stubles but doesnt die out. then my fan turns on out of nowhere after not even being on for a minute. then the engine starts to kick in late like its not getting enough fuel or something. then after its been on for about 30 seconds or so, i rev it and it takes a second before the rpm actually revs. it acts real slow and hesitates when i give it gas. i have power on all my injectors and they all work when i use the 9volt batery trick. its not clogged since the fuel pressure drops everytime i test each injector. the passenger side exhaust runners are way hotter then the driver side. its only obviouse because they are almost gold color by now and the driver side is still chrome. the only thing i can think of is the pcm.

 

could it be because i only have one knock sensor? the pcm, is a 95 camaro pcm and the caprice k/s sensor is the same as the one on the f body im sure. but the caprice uses 2 sensors. i deleted one and use only one since the f body uses only one and the pcm was program to run i guess one.

 

i didnt want to test it and try to see whats up with the rpm and run the engine so long since im not sure if the alternator is charging or not because my indicator lamp stays on. can someone please shim in on their thoughts and experiences please because i can no longer do anything to it until i get a straight anser. thanks....

[jbc3]

The fans turn on because the SES light is on. The computer throws a code, it turns on the fans. Get Datamaster, Diacom, Autotap... and read the code.

Check the throttle position sensor and make sure it is right. Check all of your vacuum lines to make sure all are connected. Something is not connected right or your throttle cable is not letting the throttle body close.

As far as the knock sensor, you need to make sure you have the correct resistance sensor for the year PCM. I don't know about the caprice set-ups, so I can't shed any light on which one to use, but I suspect the one you are using is right because if it was wrong, the SES light would set immediately and the fans would turn on right away, not 30 seconds later.

 

Get something to monitor the computer. It will save you from guessing.

[80LS1T]

Is there any modifications done to your motor? I had to modify my TPS sensor when I installed the 58mm throttle body on my engine because it would read too high at idle and throw a code. I ended up enlongating the mounting holes to turn it down into the proper voltage range(about .3V if I remember correctly).

 

Do you have anything for editing the PCM software? If so have you done anything to the PCM? I don't know if the MAF sensors are the same from the Camaro to the Caprice? MAF sensors can cause real weird issues

when dirty/going bad...

 

Guy

 

P.S. Did you get my email?

[piston]

jbc3, the throttle is functioning good but im not sure how to check the tps. all the vacumm is hooked up and i have no vacumme ports open anywhere. the rpm, drops down and almost stubles to a stop once a while but climbs back up to 2k and stays there. now after starting it a couple of times, i notice my fan turns on right away...somethings up for sure...i dont have anything to tune or edit my pcm...my pcm was progrqamed by some guy from pcmamerica. basic tune and edited out all the emissions and stuff i didnt need like a/c egr and stuff like that.

 

guy, my engine doesnt have much in it, its just a stock 94 caprice lt1 with lt4 cam, spring and 1.6 rr. and thats all i can think of for internal mods. i need to get tuner cat or someone to monitor or check my pcm. its acting crazy and i dont know what the hell is wrong with it. i havent looked into what editing software is availible for the pcm but i heard of tunercat and datamaster. how hard is it to work these programs, im sure it no different from hondata, since i use to do ecu mods for hondas...price wise??? how much? man, money, money and more money...by the way, where do i buy these software program or editing devices from anyways???

 

ok, now what about the indicator light set up and wiring??? why does my light stay on? with the light on, it throw me off to not run it so long cause im gonna fry the alternator, without it wired correctly, i cant check anything.

[mark]

Also check the idel air control valve.

[piston]

yeah, i was just looking at bartmans old post about how he had to swap out his idle air control valve. ill be doing that check, and also, i was at work looking through our catolog and notice that the knock sensors on all the lt1s are different and some used in 94-95 only and at the same time, the lt4 knock sensor is also tha same as the 96-97 camaro. it goes back and forth, these are delphi parts and ac delco parts im looking at. anyways, the one i have on right now is only compatible with 94-95 caprice, and the ones in the f body camaros are different part# but in 96, the part switched to the same one as on the 94-95 caprice, but the oem part on the lt4 is the delco one and its also the samne as the 96-97 camaro.

 

i can get anyone for 20 bucks. whats the recomended one?

[piston]

anyone??? specific indicator lamp wiring anyone???

[wheelman]

Do you have an SES light hooked up?

I tried to run mine without one but the PCM detected it was missing and would throw a code as soon as the engine started. This would cause the fans to come on. Other than the fans my engine ran fine, but the SES code was the only one being set. I used the "choke on" light as my SES so now the PCM is happy.

 

The Camaro and Caprice MAFs are different. Camaro and Vette MAFs are 3.5" and B-Body MAFs are 3". I switched to a Camaro MAF and had to edit the calibration table to get things back to normal. Something to think about, especially if you're using a Camaro PCM and the Caprice MAF.

Did you send the PCM away for the tune?

Did you let PCMAMERICA know it was going to be used with a Caprice engine?

Where did you get the PCM? Maybe it's bad and nothing you do will fix the issues until it's replaced.

 

The cam, springs and rockers should not be causing the issues. I put an LT4 hot cam in mine and it runs fine without having to tweak for it.

 

Wheelman

[piston]

yeah, the guy tuned it for a camaro im sure, since i just told him it was an lt1 t56(not specific.). suposebly at the time, i thought it was all the same. i didnt know the maf was different also. ill look into that and measure it, if i recall, it was 3 1/4 when i measured a while back.

 

i dont have the ses light hooked up, but i will be doing that also. ill be checking the idle air control valve also.

 

i bought the pcm from them programed through them. i dont think it was programed to run the caprice since i thought it was all the same at the time. ill be swaping all the differnces i guess but first ill have tp see whats really up before changing everything. hopefully its nothing big. what sofeware are you using to programe your pcm? i was wondering if worst comes to worse, you think you can check out my pcm if i ship it to you? itll be great is you can.

[80LS1T]

I dont know for sure how to hook up the charging light because I dont have one in my car, I am just using a voltmeter instead. If you hook up a 12V+ Ignition to the "F" terminal your alternator will charge unless there is something wrong with it. From looking at this diagram I dont know for sre if you can hook it up like the Camaro without some way of making the circuit that is in the cluster of the Camaro. Just unhook the other wire for now so you can worry about the running issue. Low voltage at the PCM can cause weird driveablilty issues too.

 

 

I am using Tunercat for editing and Datamaster for scanning codes. I like Tunercat so far(haven't really got to use it alot though yet because since switching over to a 95' ECM & harness I havent actually driven the car anywhere ).

 

Are you using a Caprice harness on your engine or a Camaro harness. The IAC motors may be different from one car to another so the wiring may be different too. I know that when I bought my engine(93' out of a Camaro) and put the harness and PCM that I bought from Darius(yes the one and only Darius!) in my car the IAC was one thing that was not the same. I just had to wiring it correctly and it was ok. You shoud be able to do the same. I had idle issues like your describing and thats what it was. I know other guys that have had the same exact thing happen when swapping harnesses.

 

Here's how I would tackle your problems....

 

#1. wire up the alternator F terminal to 12V Ignition

#2. check that IAC wiring from the PCM is correct for the IAC that is on your engine(the IAC has 4 wires labled A-hi A-low, B-hi B-low) those need to be going to the correct pins on the IAC connector, if not it wont work correctly.

 

#3. If those don't fix your problems then you need to hook up your SES light and read the codes out with it generic scan tool or use Datamaster and a laptop to get the codes out of your PCM. I think Datamaster is free if I remember correctly but I don't have the website for where to download it.

[wheelman]

The wiring harnesses are different but the pinout of the PCMs is identical so a Camaro harness should work assuming you have the power and ground connections that integrate it into the Datsun correct.

 

I can't help with the Camaro harness as I robbed the one I'm using from the Caprice donor car. I used a PCM pinout listing for a 94 Camaro and everything works so I know the pinouts are good.

 

I use Tunercat as well and agree with 80LT1, hookup the SES light and resolve the alternator wiring problem then if things are still wierd dump the codes from the PCM. Without the codes it's more difficult to diagnose the problem.

 

Be sure to post tomorrow and let us know if the alternator is working, I have a Caprice alternator and it works fine but I can't remember how I wired it right now. If you can't get yours working I'll strip the tape off my alternator wires to see where I hooked them up.

 

Datamaster is also a very good tool to have assuming you have a computer and a cable to communicate with your PCM. You can use it for free but it will only record data for 30 seconds. It will show the trouble codes that are set and allow you to clear them though.

 

I could try to work with your PCM but I'd have to build a harness to provide power and communications. I experimented with mine in the car so don't have a bench harness. I know how to build one but haven't and would rather you pursue all other options before I try anything. I don't want to accidentally zap your PCM testing a new harness.

 

Have you talked to PCMAMERICA yet?

Do they provide any kind of warrenty or trouble shooting help?

It would be better to see what they can do before I try to look at it.

 

One other thing. It is extremely important to have good grounds in all the PCM circuits. Bad grounds will cause all sorts of weird behavior and could be the entire problem for you.

 

Wheelman

[piston]

yeah, im going to hook up a ground block on my neg bat post and go straight to the engine in variouse places. hook up a check light. quick Q on the ses light, the ses wire from the pcm goes to bulb pos then the other just goes to ground right? stupid question but thought i might ask anyways.

 

also, i hear if i dont hook up an idiot light to the wire, it wont charge right and it will shorten the life of the alternator? from what it sounds, you guys are saying is to just hook up the wire to ignittion hot and itll charge?

 

ill be looking into the iac differences also. the harness i know is pretty much similar. i checked colors on the wires and the color connectors before i loomed it up using the camaro pinouts and everything matches.. i think its just some of the sensors that are different.

 

i havent talked to pcm america yet, the guy lives in newyork and im in cali. far away...im going to try to trouble shoot it first before i send it out anywhere, if all comes to worst, like said, ill rather ship it out to a hybridz member that knows what their doing instead of someone just basic tunning pcms.

[piston]

im at work right now and looking at the IACs and it looks like the difference is the oil cooler! lt1s equip with an oil cooler has a different IAc from non oil cooler lt1s. im wondering, what the hell does an oil cooler have to do with IAC??? i have an oil cooler factory on my lt1, what if i run the non oil cool IAC on my engine, whats that going to do or how is that going to effect my engine??? it looks like f body equip with oil cool has the same IAC from 94-95 lt1 as on the caprices. ill barrow my buddies non oil cool IAC from his lt1 and see what happens. this is crazy, ther is so many little differences in the lt1 that i never thought of. ill let you guys know whats up when i get the chance to do the IAC swap and see whats the results.

[piston]

by the way, where do i buy tunercat from and how much and what do i need???

[wheelman]

Tunercat is availble from Tunercat.com.

It's been a while since I purchased mine but Ithink it was $60.00 for the program and 1 engine profile.

You'll also need an ADL cable which can get from AKM electronics www.akmcables.com

 

Got to go, I'll check back in later.

 

Wheelman

[piston]

another short dumb question before it doesnt work and i start getting worried. the wire that comes out of the pcm to check for trouble code is the adl link wire or something like that correct. i just hook that one up onto the obd1 port and wire up a negative and port is ready to go right?

[wheelman]

That should work for the ADL cable, there is also a field diagnostic wire you may want to hook up but it shouldn't be required for a code reader. I don't have mine hooked up and can communicate fine. This circuit is also pretty sensitive to ground issues so make sure you have a good ground here also.

 

To answer your question about wiring the SES light, you need to provide 12V to the light and the PCM will provide ground if it wants to light the bulb. Thats partly how the PCM knows it's there, it measures for 12V on that input pin. I took the 12V from the choke light circuit but any fused 12V, ignition switched source would be fine.

 

Are you having fun yet?

 

Wheelman

[piston]

so the ses wire from the pcm actually connects to the neg side of the bulb and the other side pretty much just goes to ign hot right?

 

one more thing about the alternator wire. which wire needs to be wire, im getting L wire and some say its the F wire. if its F wire for example, this F wire goes to the neg side of the indicator lamp correct or splices into the ground wire on the bulb,the other side of the bulb then connects to ignition hot? im still lost.

[wheelman]

Piston,

Yes to your description of the SES light. Use a fuse in the circuit though.

 

Here is how I wired my alternator.

 

P - not used

L - Fused 12V, ignition switched

F - Not used

S - 12V non-switched, it's hot at all times, no fuse, this is the charge level sense line.

Battery Post - Positive battery terminal

 

EDIT: Put a 35 ohm (5 watt) - 500 ohm (1/2 watt) resistor in the line connected to the L pin to prevent current over draw. Here is a link to a page with lots of good info on these alternators http://oljeep.com/gw/alt/Alternator_Theory.html#Section_3

Look at the section on the CS-130, CS-133 and CS-144 alternators.

 

I'm not using a charge light, that's why I used the L instead of the F connection.

The documentation I have says the S connection is optional but it wouldn't work without it.

I believe you could substitute the F for the L and use a charge light if you want, don't connect them both, it won't work.

 

If you do connect the F pin the alternator provides the ground so you connect the other side of the bulb to a fused ignition switched 12V source.

 

Hope this helps.

 

Wheelman

[80LS1T]

Sorry those pics I posted changed from last night(links must have changed! LOL) I will save them to my computer and load them up on my site so they don't change!

 

Guy