I Give Up! Need LS1 Gods... Options

[mjf454]

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

[68 Camaro]

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.

[SuperCricket]

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

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.

[Racehead]

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 (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif)

[SuperCricket]

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

[GlennCMC70]

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?

[Ojustracing]

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

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

[SuperCricket]

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. (IMG:http://www.frrax.com/rrforum/style_emoticons/default/blink.gif)

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!

[Ojustracing]

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

[SuperCricket]

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.

[Racehead]

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.

[Ojustracing]

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

[SuperCricket]

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

[GlennCMC70]

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!

[Ojustracing]

Kyle I guess the Ls1 Gods over hear helped you!!! (IMG:http://www.frrax.com/rrforum/style_emoticons/default/2thumbs.gif)

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. (IMG:http://www.frrax.com/rrforum/style_emoticons/default/rotf.gif) (IMG:http://www.frrax.com/rrforum/style_emoticons/default/drink.gif) (IMG:http://www.frrax.com/rrforum/style_emoticons/default/beerchug.gif) Even better yet how about a donation to FRRAX to keep this GREAT SITE going!!!!!

Enjoy John Oliver

[SuperCricket]

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

[Ojustracing]

Nothing needed

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

Enjoy John