hey guys well car is pretty much stock. I was on the dyno from one second to another the car started knocking during regular driving and WOT.

i checked the engine lights

p0351 until p0358 wich it is coil issues. I am using efi live, i did a full pcm flash with the program and it did not pass correctly it failed becuasej the labtop turned off.

Is my PCM screwed up, I redid it and working fine it reflashed and passed without issues.

Guys please help it sucks driving a car that knocks all the time. I am not sure what the hell is going on


thanks,

Ed

 

I can't understand your description of your problem ... other than you say you have an engine knock ...... .... I'm starting to believe we need an ESL forum on here .... with translators .....

What codes are you getting .... a P0351 means there is a problem with the ignition control circuit for Coil 1 .... a P0352 means for coil 2 .... and ... guess what a P0358 means ..... hey, you got it ... a problem with coil number 8 !!!!!

So which one is showing the problem ????

It is one of 3 things ......

* A bad wiring connection between the PCM and the coil

* A bad coil

* A bad PCM

Connect a Digital Multi-meter (DMM) set for DC Hz, between the Ignition Control (IC) wire from the PCM and the BROWN Low reference wire back to the PCM. We are looking for between 3 to 20 Hz. The IC wiring will be the wires that are different colors to each coil .... each coil has a PINK, a BLACK, and a BROWN wire .... we want to test the OTHER wire.

If a coil shows out of range for the DC Hz test, flip the DMM to DC Volts and check the voltage on that same wire. If the wire shows more than 1 volt there is a short in the wiring.

If it passes those tests, check for continuity of wiring between the PCM and the coil on the IC circuit.

Test the IC circuit for a short to ground.

Inspect the wiring connections at the PCM to ensure they are clean.

If ALL the wiring tests pass ..... your PCM is trash.

 

I am sorry for not making any sense. I am getting the codes for 1 all the way through 8. I just changed my spark plugs. I will do the test and if that works will any pcm from an LS1 work on my car...

When I reflash the pcm it test OK. can the pcm still be bad though.

thanks,

Edgard

 

ALL 8 are throwing the code ?????

That is NOT a good sign .....

No, the PCM really should be from the same model year ... and also match on issues such as whether it is programmed for a manual or automatic transmission. Also I believe vehicles made for EXPORT (Initially sold in Europe, Japan, etc.) are also programmed differently for things like smog control. Once the PCM is installed it has to be updated with the correct vehicle VIN, and some procedures have to occur (such as Vehicle Theft Deterrent Password Relearn) to integrate the PCM with the other computers in the car.

What Model Year (if you're not sure post the 10th digit of your VIN) is your car, is it an Export vehicle ?? What transmission do you have????

What spark plugs did you put in ... they shouldn't cause the codes you're seeing but MAYBE if they are WAY OUT of the correct heat range they are confusing the PCM ... what brand and type of plugs, and what gap were they set too ????

In general, a failure during a PCM flash puts the PCM at great risk .... let's hope that is not the cause of this problem.

 

ok it is a 99 frc with manual transmission. I changed the plugs becuase i thought it could be the issue. I think my PCM is wacked out even though I can still flash it. What do I need to do now to get a new one.

thanks,

Ed

 

Where are you located ??? You should fill out your user profile .... go to "User CP" in the red/brown bar at the top of this page, and then on that page select EDIT PROFILE from choices on the left.

For a 1999 the GM part number is 9354896 ..... the good news is that the cost isn't bad, about $300.00 from a dealer for the part. The bad news is .... the PCM is completely blank, no programming in it.

Effectively this means that a dealer will need to do the install because after it is connected to the car a Tech2 is used to "connect" the PCM to the GM TIS service, and based on your VIN, the correct software is then loaded to your PCM.

The dealer should be able, with a Tech2, pretty much verify that the PCM is "blown" before they replace it.

After the new PCM is installed I'd take a "snapshot" of your new "stock" tune to your EFIlive product, so you have a "clean" base to start from again.

 

blackz06 thanks for the help, Well I really think it is the PCM becuase it is hard for all 8 coils to go in a few minutes. I just do not understand how the car still runs and idles fine and I can still read and write to PCM if it is blown... I am wondering if something else could also cause issue.

Tomorrow I will take the car to Breathless performance here in south FL. My budd said they are good. If he can't help I am going to take the car to the dealer and get it cheked out.

Thanks for everything and wish me luck lol...

Ed

 

I don't know if this is possible .... but thinking about it ... is it possible the "tune" you have loaded has incorrect parameters for ignition timing .... in other words, could your Knock Retard tables have incorrect data so that the PCM is being "forced" to fire the fuel in such a way that you hear it as a knock ???? Because it is ???

A simpler way to say it .... a computer does what it is programmed to do ... is it possible the new "tune" is causing the knock ??

Can you put the PCM back to its "original" program ???? If so, I'd try that.

Steve

 

that was the first thing I did, I put the stock tune once I started having the issues. Right now I put the stock tune I downloaded originally from the car. I will download it again from on line and redo it and see.

thanks,

Ed

 

ok after doing some research on line i found that it could also be a ground problem. I am going to check that tomorrow. Also can you tell me where the ignition relay is and where is the PCM located.


thanks,

Ed

 

I said in post #2 that you gotta check the wiring .....

The PCM is located roughly directly under the battery. If you remove the front pasenger side wheel from the car there is an access panel that you can remove should you need to get to it.

The Ignition Relay is in the Underhood Fuse Block. It is Relay #42

 

thanks for all your help, next time I am in Cali Im going to take u out for drinks man.

Ed

 

LOL ... we may meet yet ... I have an investment property in Naples .... I'll be down in a month or two to do some work on it (love those "maintenance run" write-offs .... change 3 light bulbs and spend the rest of the day in the pool with cold beer ... tomorrow is "replace a sprinkler head" day ... ) so ya never know ....

 

errrr well in 1 month I will be eating sand every day in IRAQ. LOL

 

Just to do a quick sanity check. Have you checked the Ground connection on the back of the drivers cylinder head?? Thats the ground for all eight coils. There will be TWO black /white stripped wires in an eyelet which is bolted to the rear side of the head with a single nut.

Another thing that can cause the same issue is wiring harness damage. There is a black metal bracket at the rear of the drivers side of the engine. The wiring harness for the injectors. coils MAF alternator etc.... bend around that bracket and the wires for are all that stuff are in that harness.

On some C5, that harness contacts that bracket and rubs through to the wires and shorts them out!

Also see the safety retainer clip on the fuel line connection cut through the same harness.
The harness in that case was not run back in the stock location after some MODs.

Seen it a hand full of times. It's an easy quick painless check that may just cure the issue.

Let us know how that stuff checks out.

THANKS FOR SERVING!

Bill C

 

well guys good news I found out it is not the PCM. I was driving around and the car started bucking so i started messing with the harness and boom the car turns off... so every time i jiggle the harness it turns off. So it is eighter the harness or that ground.

now the question is how the hell do i get to that ground >?????? i can't reach it from the top so DO i have to reach it from the bottom of the car.

Also can I just cut them and connect them somewhere else in the chassis ???


thanks,

Ed

PS: No problem I love serving for this wonderful country

 

updates

Ok guys well i tool the intake manifold off. i fould the ground off the bolt. I have a 99 so i have the air tubes runnig back there and there is no room to work. I am going to rerun that ground to somewhere in the chassis. I will fix correct once I have the head installed.

Tomorrow I will finish the reinstall of the intake mani and drive it around, then if all good go back to dyno and see what I can get off my stock C5.

thanks all for the help.

Ed