I have a 97 ws6 t/a. I have a rebuilt engine with about hundred miles. The mods are hot cam and bbk headers. I have gutted the cats due to them being bad. I have a new msd opti, new msd wires, new ac delco coil, new spark plugs, checked the icm when it was hot and it is good. The ses light came on and it blinked and stayed on. I had it scanned and it has multiple cylinder misfire which was in 6 cylinders. I have checked the wires and I made sure that they cannot be burnt in any way. The car starts up everytime and drives but at low rpm, when I back up or take off, the car will bog/ buck really bad until it gets to a higher rpm. The car drives alright when its driving but not taking off. I had an exhaust leak at the egr pipe off the header, but I fixed it a couple days ago. I still have an exhaust leak somewhere, but dont know where. I also had a low reading for the bank 1 position 1 o2 sensor so I replaced it and no change. When I start up the car when its cold it still drives the same as when warmed up. This problem is at all times. The car is also running rich. The coolant light is also on, dont know it that effects the pcm anyway towards timing. It seems like something is retarding the timing. The knock sensor also was setting off the ses light when there was no knock, I unplugged and it the light went away for awhile. Now the ses came back on and blinks and then stays on. I resetted the pcm but the ses came back on. I know its an electrical problem and not a fuel problem because im getting too much fuel..unless somehow there something with the injectors. Another thing is that there is not change in idle when I unplugg the MAF. I have tried 3 MAF units on the car and none of them have a change in idle. I know the post is very long but I wanted to mention every detail. Please help me im very frustrated and am tired of spending time trying to figure out myself. Any help is great. Thanks

 

I have a similar problem and if I unplug the vacuum line off the EGR VALVE the cars runs pretty damn good....it will take you 2 seconds to unplug it and see if the problem goes away....if it does then I would say you have a vacuum leak somewhere...also at idle you can press with two thumbs on the egr valve and if stalls then most likley your EGR valve is OK....

I'm not a mechanic, but these are EASY QUICK ways to possibly solve your problem or get you on the right track...if not, no harm done....you can easily plug your egr valve vacuum back on.

 

I took the vacuum line off the egr but there was no change in idle, I havent put my fingers on the back of the wholes yet...I believe that if theres too much exhaust air or not enough going into the egr will throw the pcm off and it could retard the timing and cause the car to run bad. Thanks for the reply

 

Sorry you misread or I mistyped...

try this

At idle with the vacuum line ON press both thumbs on the egr valve towards the interior of the car...you have to apply some pressure, the car should start to die and then stall as you press further. If the car stalls with the vacuum line ON and thumbs pressing in on the egr valve your egr valve is probably working just fine,

now if your egr seems fine UNPLUG the vacuum line on the egr valve and drive the vehicle...see if it seems to drive better...if your bucking/bogging go away or lessen significantly then you likely have a vacuum leak somewhere.

If neither of these options show anything then I can't hep you and you'll have to wait for other people who are smarter than me to help. But I think your bogging and bucking may be the same as what I call hesitation/surging.

 

When I say bucking, it almost feels like im dumping the clutch with no gas

 

Ok...I have put pressure on the egr valve and nother happened. I also switched out the egr silonoid with another one and yet its still the same..lt1's r junk

 

The low coolant sensor does not connect to the PCM and has nothing to do with ignition timing. But.... see next quote.

If the knock sensor circuit was faulty, and turning on the SES light (did you verify this by pulling the code?), unhooking the knock sensor would not turn the SES light off. It would pretty much guarantee the SES light would be on all the time for the incomplete knock sensor circuit. And when the code sets for the faulty knock sensor circuit, the PCM pulls timing almost constantly, up to 15 degrees, to protect the engine.

By "no change" do you mean you still have the code? Or that the code went away but there was no change in the "rich" problem? Did you check for a wiring problem? Swap the pre-cat O2 sensors side to side, and see if the problem follows the sensor (sensor problem), or stays where it is (wiring problem, or engine problem affecting only one bank).

With that attitude, I'm surprised anyone would even try and help you

 

Ok that makes sense about the knock sensor, I will plug it back im and see what happens, and yes the knock sensor through a code when it was plugged in before. My engine is shaking alot causing a vibration which is probly throwing the knock sensor off.

Well I replaced the o2 sensor but havent put it back on a scanner yet. I know that the o2 sensor is not my problem anyways but I just wanted to mention it. Yes, my car is still running rich after replacing the bad o2 sensor.

Im sorry, I dont like being negative but Im so frustrated with this car. Thanks for the help

 

What if I plug the knock sensor back in and the ses stays on due to the vibration? Can I just put a resistor on the connector so it will keep the ses light off? Thanks again

 

Ok I plugged the connector back in to the knock sensor and the ses light went off right away but the car is still driving the same. Do I need a tune for this cam?

 

Ok so I know this cam isnt big, but big enough to cause the ses light to come and for the multiple cylinder misfire code to come on without a tune...so im going to tune it and the car should drive really good, so thank you guys for helping out

 

a good man with the right program will maqke the bucking go away. On his lap top he will set air fuel ratios at all RPM bands and he'll see the if the knock sensor is retarding the spark. He can tell if the 0 2 sensors are working properly and if all sensors are working. This will either fix your LT1 problem or tell you what to do. At the end of it you'll have more horses and a smoother engine.

 

Yes im going to get a dyno tune, im sure the car will drive good if I do. Thanks