Dope

Feh, I went out and took a look today and doesn't look like I'm gonna be of any help. I don't see any such connector anywhere in the area. Here's a pic of what my car looks like:



Then the part that's shrouded in the shadows of the first pic:



Try hooking up the MAF? My car stalls if I don't give it gas with the MAF disconnected. That could be a start a least. Even if you just jury-rig it so that you have the MAF in front of the TB and nothing else.

Can you start the car with the throttle halfway to the floor and see if it holds a steady rpm or if it stumbles and dies regardless?

When the car runs, does it run like crap or idle smooth? You might have fuel pressure but maybe one of the injector harnesses is unplugged. Do you have an infrared thermometer? Try measuring the temps of each primary before and after you run the car a few times. Maybe one side isn't firing at all (it will stay cool).

Just kinda throwing guesses out there.

Have you verified spark in all 8 cylinders?

Dope

RoadRebel

That is the knock sensor connector. The other end will be behind the intake laying somewhere..get it plugged in.

THe P1637 is the generator circuit Lterm.

Phil

The L-terminal circuit from the generator is a discrete circuit (a discrete circuit has no splices and only one source and destination) into the PCM. The PCM applies ignition voltage to the generator L-terminal circuit. A small amount of current flows from this circuit through the generator windings to ground to create a magnetic field which starts the generator process. When the generator is at operating speed and producing voltage, a solid state switch for the L-terminal circuit in the generator opens and the PCM detects that the initial startup current flow has stopped.

The PCM expects to detect low voltage on the L-terminal circuit prior to the generator rotating at operating speed and conversely expects the circuit to be at ignition voltage potential when the generator is operational. When the PCM detects a fault (circuit shorted to ground, or circuit shorted to voltage), the Driver Information Center will display Charging System Fault.

Conditions for Running the DTC
The ignition switch in the ON position or the engine is operating.

Conditions for Setting the DTC
The PCM detects the L terminal as Active with the key ON and the engine not running or the PCM detects the L-terminal as Inactive with the engine running.
All conditions met for 6 seconds.
Action Taken When the DTC Sets
The PCM stores the DTC information into memory when the diagnostic runs and fails.
The Malfunction Indicator Lamp (MIL) will not illuminate.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
A message is displayed on the Drivers Information Center.
Conditions for Clearing the DTC
A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
Use a scan tool in order to clear the DTC.
Diagnostic Aids

Important
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A . Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems.

The following may cause an intermittent:
Poor Connections; Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
A mis-routed harness
A rubbed through wire insulation
A broken wire inside the insulation
DTCs P1637 and P1638 may set at the same time depending on the failure. Also, the L-terminal circuit can cause a DTC P1638 to set. This diagnostic table diagnoses both DTCs P1637 and P1638.
Use a scan tool in order to diagnosis the generator circuits. The scan tool should display Inactive for the L terminal and 10-40 percent for the F terminal when the ignition is ON. When the engine is operating, the display should indicate that the L terminal is Active and the F terminal is greater than 5 percent.
A generator fault, such as a shorted output diode, malfunctioning regulator, open or shorted rotor, or open sense lead or battery feed may cause a low battery charge. Refer to Generator Not Operating Properly in Engine Electrical for further information and generator diagnosis.
Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This isolates when the DTC failed.
For an intermittent condition, refer to Symptoms .
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.

This step verifies the fault is current.

Inspect the circuit for an open or a short to ground if the test lamp did not illuminate.

If the scan tool displays Active, this indicates the circuit is open.

This step tests the F terminal for being shorted to a voltage. With the ignition ON, the F terminal should display between 10-40 percent. If the F terminal displays greater than 40 percent, inspect the circuit for a short to voltage.

When the engine is started the L terminal should be active.

This step is testing the L terminal for an open. If the L terminal displays Active when the circuit is grounded, this indicates the circuit is open.

This step is testing the F terminal circuit for an open or a short to ground. If the F terminal parameter goes to 99 percent the condition is within the generator.

RoadRebel

The question I have Is does the car start and idle fine or run rough?
And is it stalling out or does it seem like its just shut off.

Phil

ABNVET.I

When it starts it sounds like a new car it sets there and idles fine. Then after a few seconds it starts sounding rough and after a few seconds of that it dies. Like I said this is a new motor put in by a GM dealership in NY. They had it 6 months and evidently this is what was going on with them after the new motor install. The guy got a lawyer after them to fix it and the Ins company instead paid the guy off and the car was salvaged. But what I have found in a lot of areas is I dont think they was much of mechanics. I have found plugs like the one shown disconnected the TAC plug pulled off and a few other things. So this is a nightmare in progress. One more thing the 1637 code was cleared witht he installation of the belt that was off. Thanks for the reply!

RoadRebel

Getr your knock sensors plugged back in....The wire come out the back of the engine between the intake and valley cover. It will be the mating connection to the one your found.

What happens, when you start it up..and hold the idle up. Will it stay running?


Phil

ABNVET.I

Looking for the hook up to the knock sensors now. The plug shown in the picture I posted goes under the intake correct? Now the problem I have it where is the other end of it? I dont even know which direction it goes and cant seem to feel it in the back of the intake.

Doczo6

At first it sounded like it was going into the anti-theft mode ( maybe since it is a new engine) not sure of the sequence of resetting. But I had the same thing happen to me but it was when i was using hptuners and my battery voltage went low. Same bcm/pcm loss of communications, I tried all the reset procedures. The only thing that fixed it was a new pcm/bcm.

WKMCD

They replace the mechanical parts - pins and such.. What I really liked about the last dealer - Pohanka - was that the tech ask me if I had a bypass installed yet and recommended one. I had one at home and dropped it off. HE installed it for me while he was in there.

ABNVET.I

OK here we go I finally said heck with it and pulled the intake. I found no connector for the Knock Sensor back there BUT I did find 2 wires to no where with no plug on the end. I figured these are it but they are different colors. It looks like LT Green and Blue. Could these be the ones to the plug that are Lt Blue and Drk Blue? So thestory goes on

Ralph Restart

Thought I'd through my experience in although it may not help much.

A few months after purchasing my 2001 (new) it began stalling while driving occasionally – Right before it happened it seemed to me like the DIC would dim or go out along with the clock (radio) display – then it would seem to kick a bit and go dead. It would usually start again on the first try and be fine.

I took it to the dealer numerous times but was not able to reproduce the problem. As time went on, it began to happen more often and I had cases where it does exactly what you describe – starts fine, runs for a few seconds, then becomes very rough and will stall unless you continuously ‘pump’ the accelerator – which would keep it running but it was still very rough – seemed on the verged of backfiring. There was no chance there was enough power to engage the clutch without having it stall. This would happen with cold starts, or immediately after driving and parking (and still while driving too – causing some embarrassing and dangerous situations).

I also had electrical problems with the car at that time: The turn signals would just quit working for a random period of time (This was finally traced to a bad hazard-light switch). When I exited the car and locked the doors (using the key fob) the ‘alarm’ would sometimes go off (horn/lights). I would have to open the door and lock it before closing it to avoid this when it happened (this was never directly resolved but hasn’t happened in years).

Anyway, when the ‘rough idle start’ happened I would try all sorts of different things to get it started again. I’d also had the common steering column issues and knew that it was supposed to cause something like that sort of operation so I would crank the steering wheel the full range in both directions while keeping the car running then stop and restart it. I tried manually setting off the alarm system since I’d had issues with that too. Eventually the car would start again and run fine and I had know idea what changed or if any of my fumbling did anything.

Finally, one day (the day before Christmas of course) it just gave up and wouldn’t do anything but the rough idle. I called for a flatbed and had it dropped of at the dealer. They never really told me what they did during the next week but called and told me to come pick it up – I figured I’d find out what they found when I got there. Turns out they didn’t find anything wrong – in fact the car started and ran fine the entire time it was there – until the guy went to get it from the lot for me. He came walking back and said it wouldn’t start - all I could do is laugh.

They kept my car for the next three weeks. According to them they pretty much removed and replaced every electrical part that could have any effect on the problem. I stopped in once for visitation rights and they had the entire dash/console/door panels/hood laying all over the floor. They finally called in a couple ‘experts’ from somewhere and they worked on it for a while too. In late January, I got a call telling me they found the problem. There is apparently a grounding strap/wire on the fuel tank, didn’t tell me which side of the car, but they claim it was not connected well and was causing the computer to keep the car from running.

I guess I really don’t know if that was the real problem or not but the car has not had the problem since I got it back. Sorry for the length of the post.

SpeedyZ

Does those two wires without a plug come up out of the center of the valley pan just below the intake and head out the back under the intake? If so they are the ones that go to that plug with the little metal clip on the side of it. I don't have a car or a diagram in front of me so I don't know which one goes where. It may not matter, I don't know it the PCM looks for knock on each end of the block or not.

Looks like you really got a mess there! Another reason to never take your car to a dealer!

Good luck!

ABNVET.I

Found the wires for the Knock Sensor and put a plug back on it. Here is the kicker. Evidently the dealer who had it tore the plug off and so what they done is cut back the insulation on the other side plug and soldered it right to it. That is why I never got a Knock Sensor code from it. Ok now I get in start it up it starts great runs great fingers crossed DIES. I go to diag immediately and it shows PCM PO351,PO352,PO353,PO354,PO355,PO356,PO35 7,PO358
After it runs I go back and they are gone no more codes. I didnt reset them but poof gone. So I start it again. Same thing. There isnt one other code in the car at the end of the scan. Also it smells like it is running rich very heavy exhaust smells.
The codes are Ignition Control #1-#8 circuit

RoadRebel

Ok..Again..start it up and hold the idle up with the gad pedal..will it stay running.

Phil

Bill Curlee

You are getting DTC's for ALL of the ignition coils. The COMMON point for all of the coils is the ground G-107. There is a ground wire on the back of the drivers side head. It will have two black/white stripe wires connect to one ground eyelet. If that wire is not hooked up, the same symptoms will happen.

LOOK CLOSELY at the center of the picture near the top of the coil. You can see the two black wires that are molded together.

They should be grounded to the head with a bolt.



Please let me know what you find.

BC

ABNVET.I

Bill Curlee YOU ARE A GENIUS!

That is it kind of. Ok I went out looked at the ground wires it was on the painted side of the bracket so I’m thinking it isn’t making contact. So I put it on the underside of the bracket so it is now metal to metal. Start it up and yes in a few seconds it dies. So I’m thinking Bill maybe onto something here. So I take a jumper wire and run it from frame to the bolt with the 2 blk/wht wires. Start it 1min 2min 3min go by still running! So where ever them 2 ground wires go to they are not grounded I would say. Bill you are the man! Thanks a million for everyone’s help on this. But I can see now the C5 is a grounding nightmare.

Bill Curlee

There should be a 13 mm bolt on the back of the head. The ground eyelet should bolt DIRECTLY to the head.

If need be I can get a mirror and take a pic of the bolt and eyelet.

Good job! If I were you, I would go back and check every connection and bolt that those BONE HEAD service department people touched!!

So far their track record id severly lacking!!!!!!!

ABNVET.I

Will do Right now it is actually on a pained bracket you see in the picture. To think the insurance company trashed this 1999 58k corvette out because of a bad ground wire! There was a lot of short cuts made on this car by the dealership and when I talked to the original owner he was heart broken he had to get rid of it. So I can say one thing this car or my 90 will never see a dealer again! Agian Thanks all and check them grounds!

runamuk

Dang, Bill beat me to it. As I was reading thru this it occured to me that these are the same symptoms alot of people have after doing a head/cam install in their own garage.

Dope

Bill is the fuggin MAN.

Dope

Railfan

Thats what is was when a similar thing happened to my car.