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L99 4.3 to LT1 swap issues..

9K views 31 replies 4 participants last post by  jsw396 
#1 ·
How's in going everyone? So i have a 1994 caprice, it first had the 4.3 l99 in it an I spun a bearing so I purchased another caprice an took the 5.7 along with the tranny an posi an swapped it in. Although havent put the posi in yet only the motor, tranny, an pcm. Wired everything up correctly, even threw new opti, plugs, wires, ECT. -no start- ... Not even trying to crank. I've read that you can start the 5.7 with the L99 pcm so I switched that back thinking maybe vats was kicking in from not changing the keys that went with that specific vehicle. Nothing. Although I do have the steering column an keys to the donor car just havent put it in yet (mine won't turn brights off lol).. I'm stumped. I tried to turn they key on an jump the starter aswell. Only the solenoid engages but dosent engage the starter-(brand new) just makes that winding spinning sound. I'm stumped.. Please helpppp
 
#2 · (Edited)
First off, what year engine and pcm did you install in your caprice. If another 94 or 95, either pcm should start car. If 96 pcm, it is an obd 2 pcm and would need some conversion work.

Does your security light come on when you turn key on, then go off after several seconds? If yes, that is normal. If security light stays on, then you have a security problem whick disables starter & fuel injectors from opening.

Your 94 and the 95 models have a tdm (theft deterrent module) The key code of key is stored in tdm and the correct key needs to be used to start engine. However, if the pcm you installed is a 96, 1st it's an obd 2 system, and security is in the bcm of 96 & later cars. So if you installed a 96 or 97 pcm in your car, it's looking for input from a bcm that your car does not have.

Next, you may have not connected something correctly or broken something that is keeping engine from running. So go back and double check your work.

You can read up on vats security at shbox.com
#25 in how to section.

And welcome to the forum.
 
#3 ·
hey cocobolo, appreciate the response and thanks for the welocome. So yea the pcm and engine are both out of a 94 caprice as mine is. Its weired. No security light comes, not even for a second when I turn the key. The lights radio ECT cut on, just the beep from turning the key an nothing else. Except when you turn the key you can hear the pump engage, fuel is getting to the motor at least at the Schrader valve which i though security stops. An like I said when I jump the starter it just spins an makes that whinding sound. The flex plate looked good before I put it in from what I could see an the starter is fairly new. I do have another one in case. It's just weired it won't engage from key and from starter just whinds. This is where stuff gets really writes although I don't know much about o2s, when I was jumping starter, I noticed my o2s were gettin quite warm. Without the car running. Is that normal, so do they do that when trying to start a vehicle. I'm not a complete expert though I do enjoy learning. Again thanks for the we'll come, and help. If i missed anything as far as info please ask.
 
#4 ·
I'd pull the starter off and have it bench tested just to rule it out. Directly jumping it should obviously get the motor turning over. There must be wiring issues going on as well, most likely vats related.
 
#7 ·
Thanks bolo, this will be my left side getting done, had right side done July 13. Sucks 2 replacments at 28 y/o but my right side already feels so much better. Anyhow sorry for the wait guys. Just had starter tested today. Bad news is it tested good.. Not sure where to start now. Any tips appreciated. So battery tested good, starter tested good aswel. Still no cranking an no security light. Little overwhelmed here lol. Couple questions, where should I start now, is it normal for the o2 sensors to warm up without the car running ( some thing I noticed when trying to jump the starter under there, not sure if it's from jumping starter or just having key on ) again thanks guys.
 
#9 ·
Ok guys better news I suppose. I don't know what the neck happen. I put the starter back on, although I did switch a ground at the coil. Turning over now. Buuuutttt no start just cranks. So far. Fuel shoots out shrader valve, I also pulled a plug an saw pretty good spark. Not sure if it's a timing issue. Anything I'm missing. Also I will add that now all of sudden the pass key light blinks on for a second as it should. Shoot...
 
#10 · (Edited)
You need to pull the fuel rail out so you can see if injectors are spraying fuel while engine is cranking. Of course, have a fire extinguisher at hand while doing this test.

If no fuel from injectors, you will need an oscilloscope for next test. You can buy a pc based scope for about $70. Get on ebay, amazon, etc.

Get a wiring diagram for caprice. You need fuel injection diagram. Get one at www.bbbind.com

You are looking for the fuel enable signal which originates at tdm (theft deterrent module) and goes to pcm. You need to splice into the dark blue wire that is fuel enable signal, and hook positive scope lead to it. Then hook scope ground lead to good ground.

Crank engine and see if 50 hertz fuel enable signal is being sent by tdm to pcm. The signal should be a nice square wave occurring 50 times per second. If signal is not present, or not the correct square wave, pcm will not open fuel injectors.

If signal gone or not correct wave form, you can buy a 50 hertz vats bypass module. You can find them on ebay. There's one for about $20 and one for about $40. Both of them work well.

There's also the option of having your pcm tuned and eliminating vats and the fuel enable signal.
 
#12 ·
Guys thanks for the quick responses.. So bolo should I start with the tests or do you think I should try to completely disable vats first to eliminate? Forgot to mention no fire up with starting fluid as well not even a change in cranking. Not sure if the car will still fire up with the fluid an no injectors spraying fuel. But if i did disable vats do i have to disable from the pcm? What the easiest reliable was to rid this security system?
 
#15 ·
Yes, the bypass module will allow injectors to open. But, as shoebox pointed out, the starter disable part of vats still needs to be bypassed.

To do so, you must find the tdr (theft deterrent relay) It is tucked way up under the dash. It's a starter relay that doesn't allow starter to operate unless tdm supplies the ground.

So after locating the tdr, you will look for the small yellow/black wire that tdr has. You cut the wire. Then splice in another wire to side of yellow/blk wire that goes to tdr. You then run that wire you spliced in to a good ground. As long as relay works, starter will work when you turn key to start.

TDR has 4 wires going to it. On F-body cars, there are 2 large yellow wires, a large purple wire. And the target small yellow black wire. You can tell by the wiring that you have the correct part to bypass. Even if caprice doesn't have the large purple wire, 3 wires will be large diameter, Target wire is small diameter and yellow with black stripe.
 
#18 ·
Good information guys, i will most likely order that bypass module, and i will look at everything you told me to check. Hopfully i will get it done within the week if not il get to it after the surgery next week. Probley about 3 weeks after the surgery il be able to back to it. Il update..
 
#19 ·
Well up for surgery tmmrw. Part didnt get here in time. Il mess with car in a few weeks when i heal up a little. Got one question tho, so if vats is screwing with my car an its not getting the correct signal wouldnt it still start the starting fluid an shut off but at least start?
 
#21 · (Edited)
Yes, if vats or something else is stopping fuel injectors from opening, spraying fuel into intake will run engine. That is if ignition system is working.

If you have silent codes 16, 41, or 42, fuel injectors get disabled also.

So, have you checked to see if you have good spark? And have you put an obd 1 scanner on the car to check for codes?

Code 16 which is low resolution opti pulse missing can be checked by observing tach needle while cranking engine. If low res pulse is present, tach needle will move slightly while cranking. But oscilloscope is only 100% method for checking low or high res opti pulses.

Codes 41 & 42 are icm related.

Scope can also be used for checking that 50 hertz fuel enable signal is present.

You can buy a pc based scope for around $70 on ebay, amazon, etc.

If you don't have an obd 1 scanner, you can get the pc based obd 1 scan program "scan9495" at www.mediafire.com/?0elo4c935uc5s

Get the newest version from the lt1 v-8 folder. You will also need the microsoft net framework, which is in another folder or available at microsoft site.

Scan9495 scans for regular codes, abs & sir codes. It does running sensor scans and will log info to a file for later playback. It also tests engine & auto trans actuators.

But you will need a 12 pin obd 1 aldl to usb port cable, to connect car to pc. Get at www.aldlcables.com
 
#22 ·
I also suggest investigating why security light does not come on when key turned on. Previous owner of car, could have removed bulb. Or it could be just burned out.

You can check fuel injectors for opening with a noid light or 2 lead test light. When key is in on position, all fuel injectors have power on the pink wire. It's pink on F-bodies. Hoping it's the same on caprice.

Pcm supplies ground for injectors on other wire. It is the pcm supplying the ground that opens the injectors. When using noid or test light, hook both leads to injector. Have assistant crank engine and see if light flashes on and off quickly while cranking. If yes, pcm is supplying ground for injectors. If no, pcm is not supplying ground.

You can get many of your car's wiring diagrams at BBB Industries- Premium Alternators, Starters, Power Steering Products
 
#23 ·
Whats going on guys. Long time.... Just been recovering, actually my hips are starting to feel great man. Feels good to be able to walk all around the scrap yard and not be in pain. So heres the scoop on the caprice, shes running. Not so well sad to say. You guys might laught or sigh. The retard i had helping me work on it had put the opti on wrong. Yup it happened. Got new opti because it was under warranty and after it started it ran rough and the part on the opti that spins on the crank sounded horrible, so i replaced it. The car currently starts up every time, nice quick starts. It idles nice and strong, but stumbles at low rpm and ide say around 2k it straightens out and revs strong (no over reving), although crackles a little more out the exauhst. It does not drive good. I pulled out of the drive way got through the stumble it picked up speed pretty nice at 1/4-1/2 throttle, then i went to turn the corner and it barley drove, even featheting the gas nothing. So i looped around around took her back home and popped the hood. Manifolds were hot. Turning red. I shut it off and havnt drove it since. Passenger side a little more red than driver. I have no cats, and o2s not too old. My uncle is saying its running way too lean, but im not sure. Ive checked for vaccum leaks, nothing to my knowledge. Before i started it after new opti i blocked all hoses that go to and from egr. A.i.r is gone as well. Also after we let it cool down i let it idle again in the dark, i noticed very tiny arcing by plug wires at least 3. You barley could catch it doing it. I went and got new wires today as they were under warranty, gotta wait for the rain to slap them in. What do you guys think. Timing at crank is on with new timing chain, and opti is is new as well. Thanks.....
 
#24 · (Edited)
Several things can cause exhaust manifolds to glow red. Very lean mixture is 1 of them. Another is very retarded ignition timing. And finally crank and cam timing being set wrong with retarded timing there.

The 1st 2 reasons can be checked out with an obd 1 scanner that does real time sensor data. The lean mixture can be verified with fuel trim readings. The retarded ignition timing can be checked with spark advance and timing retard data.

The timing chain being off has to be checked by looking at timing gear position.

Also the type 1 opti with splined shaft can be installed in the wrong position, thus creating retarded ignition timing.
 
#25 ·
Thanks for the response bolo, so im gonna order that adapter and see if hooking laptop shows some valuable info. Car running much better at throttle since i swapped wires. No stumble or hesitation at throttle just idleing not that i was reving it crazy but as soon as you put in drive an hit the gas still bogs and doesnt really go. Ide say it doesnt go over 1-1.5k. Got a few questions.. What all would cause a real lean mixture, and i forgot to ask you do i need the lt1 fuel pump or should mine that came with the l99 4.3 be good enough to run and drive the car. They look identical, i believe they are the same psi but they deff got different part numbers? My uncle is the one who did the timing chain and he swears the dots are aligned properly. Also i watched him put opti on right spot. It just seems to start and idle too good for timing to be off but idk i know they can be tricky.
 
#26 ·
Lean mixture can be caused by vacuum leaks, clogged injectors, too low of fuel pressure, and mechanical problems with engine.

Can't say if ls style fuel pump will work or not. But ls engines use higher fuel pressure than lt1 engine does. But regulator is what usually controls fuel pressure. Get a fuel pressure tester and test your fuel pressure. Test at key on prime, engine idling, and other driving conditions.

Have you put an oscilloscope on your opti low & high resolution signal wires to see if they are working as they should?

Have you misted plug wires with water and run at night to check for spark leakage?
 
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