This is likely a giant shot in the dark, but I thought I would try telling my problems here. I've posted at every other LS1 message board, including LS1tech.com which I was sure would help me out, but to no avail.

The LS1 was running great in the 94 Camaro, until randomly, one day these problems occured.

Symptoms:
- Car will barely start, most of the time afterfires and shoots flames out the exhaust, but wont start up. Sometimes it will not start after 10 minutes of trying, sometimes it will fire right up.

- Tachometer doesn't work (it used to). When you turn they key on, the tach will move up a milimeter from the bottom and sit the entire time.

- *FIXED* Speedometer thinks you are moving. When I let the clutch out after starting the engine, with the tranny in neutral, the speedo goes up to 10 mph. If you rev the engine, it goes up thinking you are moving.

Things we've tried/checked:
- Ground wires on each side of the dash, and by the drivers seat are all good
- Main engine ground strap good
- Smaller 2 grounds on each side of the engine bay are good
- Every fuse inside engine bay and inside cab are good
- Unplugged and plugged back in all transmission wiring connectors
- Unplugged and plugged back in the 3 front and rear ABS sensors
- Unplugged and plugged back in ABS module connector
- Installed new crank position sensor
- Installed new cam position sensor
- Gone through every connector in the entire harness of the car

On LS1tech and everywhere else I received lame responses like (you've got your speedo plugged into your tach!) I don't know anyone else who has transplanted an entire drivetrain into another car and used the stock wiring harness. Seems like most transplants end up with a Painless harness or something else.

At any rate, the blasted car is ready to run... if it would just run. Everything else on the car is ready to let it move and drive!

/Cries for help

Frustrating to be so close and have these gremlins ...

I wish I were a sparky, so I could help ...

I don't have any direct answers... but just for the hell of it...

pull a wire from a plug or two and check for spark. just to make sure your getting a good spark to the cylinders...

along with that... now i don't know how difficult it is on the LS motors but pull an injector off and crank the motor to make sure its spraying fuel (you may want to do this to each injector to make sure that they are all spraying)

just make sure you have the fundamentals there (air, fuel, spark)

If you have access to a scan tool, run it for codes. I think if you go to Autozone you can rent one or they can scan it for you.


on a side note of that, i had a similar problem in my MX6 where the car if it ran at all ran like absolute garbage. turned out that on my VAF (mass air for those cars) a wire had severed from comming into contact with my cruise control. causing a pethora of codes to trip and thankfully i had access to a scanner to see what went on.

it's very time consuming but check all voltage's coming from/and to all sensor's and pcm.It just seem's to be something(a wire)has come lose or broken.Becuase all was fine at first.

keep us posted

What about the 2 grounds on the back of the heads? can you be more specific, on what the engine came out of and stuff like that. You also say the stock wiring harness. Is this the harness out of the donor car? Now I have seen some cars speedo go up when in park when reved up. Not at idle. How high does the speedo go. The more info you can give us the better. The stuff you have listed is a start. I just need more. I will try and help you the best I can. What connections have you spliced. Later John

Im sorry, I assume everyone knows about this project for some reason.

I had a 1999 Camaro SS that ended up backwards into a tree. Purchased a 1994 V6 Camaro to transplant everything over to.

Everything from the 99 car moved over, I mean everything. Inside and outside wiring harness, engine, transmission, rear end, everything.

The only spliced connections in the harness right now are for the drivers side oxygen sensor. I checked it out and it looked ok.

I will check the grounds on the back of the drivers side cylinder head. I had totally forgotten about those grounds.

Also, today we got the speedo to stop acting up. I got the car up in the air and put the driveshaft in. The speedo was going crazy until we turned the rear end over, then it sat at 0 like it should. I suppose either the speed sensor in the tranny or the ABS sensor in the rear end was in a dead spot and sending false signals?

So now the main problem is the no tach, hard starting, and bad running when the engine is on.

Have you checked for fuel pressure? There is a little cap on the fuel rail, if the key is on, gas should come out when you press in the valve.

its your grounds on the back of the head. you will have 2 separate bolts w/ grounds on the drivers side.

previous post

Yeah fuel pump is hot wired straight from the alternator feed through a 30 amp relay and has good pressure.

Glenn, I checked on my grounds on the back of the head. I have the 3 ground wires all going to one bolt on the drivers side head. This shouldn't matter should it?

When I put the harness on the engine before we stuffed it back into the car, we could not find the 2nd bolt for those ground wires. Because of this I grounded all 3 with one bolt.

I would definitely scan it for any codes. That could narrow it down fast.

My first thought when I started reading was crank or cam sensor. But if you swapped those out, then that almost eliminates those... (unless there is a bad connection)

The afterfires and shooting out the exhaust sounds like a car that has "jumped" time (timing chain). Except you said it starts and runs fine sometimes, so it's probably not the timing chain, and I keep coming back around to thinking it's a bad sensor. The pcm will try to find the right firing cycle if it gets a read from the crank but not from the cam...

The three grounds to one bolt should be ok.

Ok the more info the better. So one thing is fixed..

Now onto the drivabilty complaint. You said your tach worked, is this before the swap or after. Can you relate the tach not working to the bad running? Now to the bad running, Once the car is running is it smooth, ruff, other. You say its hard to start does it crank over normal or is it normal cranking then does it act the timing goes way wrong. Will it idle without being on the gas. Also you say it shooting flames out of the exhaust, which side, and is the flames while the car is running.

Sorry for all the question, but if the car was at my shop I'd ask you the same and possibly more depending on your response to the above question. John

Tach worked after the swap for a couple weeks. One day we went out to start the car and the problems began.

Once the car is running, it seems to run ok, but still a little rougher than it used to with this cam (TR224).

The car only afterfires (blue fire from exhaust) when trying to crank the car over. It cranks over perfectly well, but it just wont start. Fuel accumulates in the exhaust and you get obnoxious bangs that sound like a shotgun, accompanied by lots of light and fire from both headers.

The weird thing is, you can leave it for 2 minutes, and it will fire right up. Then you can turn it off, try to start it again, and go through hell with the afterfiring.

Again, no fire or flames when the car is running, just when trying to get it to start. If this was a carbed car, I would look straight to the timing for such a problem. But with the LS1... who knows.

Thanks for all the help folks!

That sounds like an open lop closed loop thing.

Isn't that controlled by the O2s and engine temp?

Had ( have:) ) a friend who had a similar problem. His was with a LT1 car, but found a bad o2 sensor that was causing all kinds of problems. It would run fine then act like it was out of tune, then fine...... you get the picture!.This was AFTER putting in a new one (it was bad) Also check wiring to the o2 sensors, if bad ( broken) they will give a false reading to the PCM and cause more problems.

Hope all works out

Gary

I have two extra O2 sensors, I will also swap those out in the morning. I will also comb through the O2 wires again and make sure they havent been heated up by the headers lately.

I just had a nice thing typed out and hit a wrong key. I guess im the only one that goes to work at 11:00 on a Sat to help a perfrect stranger.

You need to put the car on a scanner. Beg Borrow or steal one. You need to see what the computer is seeing. The tach signal wire is one wire coming form the Pcm so if it was cut it shouldnt casue a complaint. The computer controls spark and fuel based in inputs from different sensors. If the computer is getting wrong info from something thing will be off. So spark and fuel might both be off together. Is the check engine light working or funtional. Is the OBD 2 port working. I cant say this enough, you need to put this on a scanner.. Are you 100 % that there is no issue with the cam gear sprokets, and chain. You do say that the car is not running like it used too. Can you do one thing for me, Disconnect the MAF sensor and try starting the car that way and see what it does.

Oh there another ground in the area of the starter and Crank sensor.

While typing I saw a cuople people post about o2's. If he is starting the car they wont give you a starting complaint that way. If the signals were wrong you would see that on the scanner which hasnt been mentioned yet I assume it hasnt seen one. If you could answer some more info and will go from there. John

PS wait till he get the bill from me for this

Well you can try the o2's, but they wont fix your starting complaint. You could start the car with both of them disconnected and it wont make a damm until the car warms up. Im going to bed. Later Super cricket

Thanks for all the help Ojust and everyone. Tomorrow I will disconnect the MAF and start her up. I also understand the O2s arent used until after the car is warmed up and changes loops, so I suppose that wont help the starting problem either.

The car "should" be able to drive, but I'm just not sure about getting it down to an Autozone without insurance on her, and I don't have a trailer. I do have a friend who works down there, so I will try to get him to borrow the scanner on his lunch break or something.

Will report back in the morning with the results.

I hope you just mean that you spliced in an extension cable ....

would the flames in the exhust mean excessive unburnt fuel? Maybe your injectors are leaking fuel into the manifold while the car is off?

well it could be that, or it could be that the ignition is just really out of whack and its sending a spark when a cylinders exhaust valve is open. there is plenty of unburned fuel in exhaust to ignite it when given a spark.

Yup, just an extension cable, and this was about 1.5 years ago when it was in the other car.

The other wiring is for my switch panel (fuel pump, fans, ignition, pcv pump, etc.) and is all proper and tidy.

From the sounds of the afterfiring and the nice whooshes of flame that come out, it does seem like it's getting spark when an exhaust valve is open.

Just woke up. Headed out to test some things. Thanks for all the help folks.

It kind of seems to me that we have a timing/intermittant spark issue. Especially since the tach was involved. I would say that the ECM is having trouble reading the cam sensor, or the ECM is having trouble firing the injectors/spark plugs at the appropriate time once it does read the cam sensor signal? I guess I'd vote for having someone try to pull the codes before you start to beat you head on a wooden desk

Unplugged the MAF and it still had trouble starting up. Still no tach, still running a bit rough.

so you wired the fuel pump diretly to 12v via a switch? isnt there a sensor that stops the fuel pump when a sertain pressure is reached while the motor is not running? if i go out to my car, turn the key, i can here the pump run for a few seconds and then it will quit. is it possible that you are overpowering the seat in the injectors and flooding the cylinders? you may have already killed the O2's from repeated fuel fouling. the computer may have gotten the fuel trims so high (due to the foulded O2's) that is just freaking the computer out.
does this make sense?

The still running rough is what has me bothered. Beside the hard starting. Cricket you have a vac gauge available.

Now this is a rant. I've worked on repairing cars for yrs. There are certain thing I do that others do also. Im not a 'Parts Replacer', I find the problem through diagnosis and fix it. I try to help people as much as I can, This Particular community(Frrax) I will go out of my way, when I can help someone. But when trying to help someone there are cetain things that should of been checked long ago before it got to this point. Then someone has to go to the internet. Do this, hit or miss info, replace this or replace that. Most professional's wont touch, do internet diagonsis for some of above said reason. I assume basic info has been looked at and it has not. There are lot of variable's invloved here. Cricket if you want my help and of others you have to answer question's about certain things. I don't mind helping you but you have to answer questions that were asked. Let me know how you made out today. John

Glenn I understand what you are saying, and I wondered about that a long time ago when we originally wired the pump that way. I believe the PCM signals the fuel pump when you first turn the key in order to prime the lines and build up pressure before you try to start the engine. I've had it hooked up this way for about a year now when it was all in the SS and it worked great. I just make sure not to leave the fuel pump running constant while the engine is not running. Also in theory the intank fuel regulator should keep the pressure at the norm no matter how long the fuel pump is running without the engine going... in theory.

Ojust, just about everything that has been mentioned so far has been done before I posted here. The only thing I didn't do was verify the grounds on the back of the drivers side cylinder head, but I checked those yesterday and they looked good.

Before I posted this thread we started from scratch, not one sensor was hooked up to the engine really. This meant no O2, no MAF, no idle air temp sensor, throttle position sensor, idle air control valve, fans, coolant temp sensor, etc. The engine exhibited the same characterisics as I am stating now. We hooked things up one by one to see if its behavior changed, but nothing made a difference.

The only sensors I could think of that might control ignition and timing were the crank and cam sensors. Those were replaced one at a time as well. First we replaced the crank sensor above the starter, and it still had hell starting up. After that we did the cam sensor and it had no effect as well.

Also the battery was unplugged during both sensor changes to make sure the computer reset.

We did hook the vacuum gauge up after the cam sensor change to make sure the intake manifold seated properly and we didn't have a leak. It pulled the norm, so that looked ok.

Maybe I should have gone through every single thing I have tried in my original post, but I have the tendency to create large novels. On most other message boards if I go past a paragraph or two I get posts saying "that was too long, didn't want to read" etc.

At any rate, I am working on getting an OBD-II scanner over to the house to see if we can read what codes it has thrown. If my friend can't swing borrowing it, then I might just have to get it onto a trailer and take it to Autozone.

Again to summarize what I did today:
*Started vehicle without MAF and with, no difference in starting or running behavior

*Replaced O2 sensors with spare set. Removed wiring loom and checked original splices, they all looked great. This also had no effect.

I'm just really confused about the no tach issue. Like I originally said, the tachometer needle moves up about 1 milimeter when you first turn the key, and it holds there the entire time.

Anyway, Ojust I fully understand where you are coming from. I am a computer/network technician, and I definately know that while replacing parts all day long until it works may solve the problem, it's hardly the best way to do it. In the case of the car, I suppose diagnosing its woes requires getting a code scanner on it. I'm trying as best I can.

Thanks for all the help!

Well onto the tach. Think it about it this way. Out of the PCM there is a signal wire that goes directly too the tach. The PCM take's the signal from the Cam sensor and converts it to a signal that the tach can use and if the tach has power, the tach will work.

So with that said, if the PCM is seeing wrong info, is converting the info wrong, or is missing some info. The car will have problems. Like I said before If you can 100% say that the tach stopped working at the same time the car is having problems. Then we can narrow your problem down.

If I had you go out to a properly functioning car, find the wire coming out of the pcm that sends the signal to the tach and have you cut it right at the pcm. The tach will stop working, but the car will function normally. I hope this explain's for you. That why you need to get some form of scanner on the car to see what the computer readings are. I have not said this before because alot of people would go right out and find one and put one in. I have seen PCM's go bad. I had 2 chrysler mini van come in for bad pcm's(No start complaints) on one car it had 2 defective pcm and the other one had 1 defective. These PCM were right from chysler.

My question is does the check engine light turn on when the car is in the run position? You also say your switch panel is wired OK, What does this mean, Have you gone around the factory wiring to run cooling fans, fuel pump, and what else. Please let me know. John

Ojust, I understand what you are saying about the tach.

Well today I went and bought a code scanner, which I am about to immediately return ($175). I grabbed the codes from it, cleared them, and made sure those were the only two that came back.

P0342 - Camshaft Position Sensor A - Bank 1 Circuit Low Input

P0405 - EGR Circuit Low Input

The EGR is fine, I yanked that around 3 years ago. I searched around LS1tech.com for that code, found a couple threads but not much info. Found a guy with a truck who replaced the sensor and keeps getting the code too.

I replaced the cam position sensor and it didn't change anything. Maybe I got super unlucky and got a bum sensor?

Gotta take the scanner back now. Will work on the car more tonight. I'm going to check continuity between the cam sensor connector and the PCM, make sure everything is cherry.

The cam sensor, the plug, or the wiring between it and your ECM is your problem. A cam sensor is nothing more than a "hall effect" type sensor. It creates an AC voltage as the "tone wheel" spins past it. You can actually measure this voltage with a Fluke meter or similiar. I never hear of them failing in the LS1 world, but in the trucking industry replacing them is about like changing the oil. Since you just did a swap I'd suspect a connection before the sensor itself.

1. You can do an ohm reading on the sensor and compare it to a known "good" sensor if you have access
2. You can check the AC output on the sensor to ECM return wire also.

Good luck.

Now were getting somewhere.

Cricket, You should be able to check the connection between the Sensor and the PCM with a Ohm Meter. Im not at work right now do you have a fax number that I could send you the Diagnosis info too. John

Thanks for the help everyone! It lives again!

I pulled the intake off and headed straight for the camshaft position sensor again. I removed the connector, it looked great. I grabbed a multimeter and tried to get continuity between the CPS connector and the connector for the PCM. I went through the 100 connections on the PCM well over 5 times, and never got anything for all 3 of the wires going to the cam position sensor.

Frustrated I cut all the loom and electrical tape off the wiring harness for this side of the engine. I followed the cam position wires and to my amazement, they entered the loom for the passenger side fuel rail. I follow them more and ended up at a connector up by the throttle body! Apparently GM in their wisdom send wires from the back of the engine up to the front, put a little connector there, and send them back down to the back of the engine to the PCM.

I can only guess this connector is so you can unhook the connection and test the camshaft sensor without having to remove the intake manifold?

At any rate, this connector was buggard up. I yanked all the wires out, redid this connection, and put everything back into the looms. Everything looks much more neat and tidy now.

Got the intake back on. Went in, flipped my row of switches and she cranked right up. Tach came up, sounded mean as hell, and it's running great.

I wish I would have driven the 10 minutes to Autozone for the scanner in the first place, instead of replacing and removing random things on the car. Lesson learned. It really is like working on computers!

So thanks for the help everyone. Can't wait to get the racecar on the track.

-Kyle

the best lessons learned are learned the hard way. we all knew it was something simple. all the things we told you it was are the things we learned the hard way ourselves. glad it worked out. i bet it was all worth it once it fired right up!

Kyle I guess the Ls1 Gods over hear helped you!!!

Congrats on getting it fixed. Can you answer one question for me, How many wks have you been playing around with this before coming here?

Oh yeah Where do I send the Bill too. Even better yet how about a donation to FRRAX to keep this GREAT SITE going!!!!!

Enjoy John Oliver

John,

The problem has been going on for 2 weeks, but mind you I haven't worked on the car that much. With Christmas, New Years, etc. going on, I had an afternoon a week or so to head out and work on it.

I just can't believe GM put a connector in the middle of the wiring and had the wires run to the front of the engine and then back to the PCM. All that time they were hanging there I swore it was for the air conditioner I had previously ripped out!

Thanks for the help. Would you accept a Darton block for the bill? I have one sitting in a crate thats been there for 8 months.

-Kyle

Nothing needed

Glad we could all put our heads together and get you fixed up.

Enjoy John