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Bucking and jerking not running right

13K views 105 replies 12 participants last post by  tommyboy8072002 
#1 · (Edited)
HI I have a 1996 Chevy C3500 5.7 manual transmission. I let the truck sit for 4 to 5 months to have my transmission rebuilt. Drove the truck for the first time after all of the work was done. Broke down and was running like crap so I changed the following Plugs, wires , rotor , cap , fuel flitter, Ignition control module and coil ... I also put fuel treatment in the gas tank and went with high octane with non ethanol fuel. Still not running right bucking and jerking when under a load. with high rpms runs fine. NO CODES. I don't understand ran fine the day I parked it
:confused:
 
#32 ·
Hi Guys just wanted to let you all know. That my truck is still running like crap. But it did bring up 4 codes. But nothing for a miss fire. I did notice that I am going on my 3rd set of plug wires. Some reason 6 and 8 burns them up melts them. Not sure what causes that but anyways.
Here are the codes.
p102.
P113.
P137.
P1406.
 
#33 ·
P0102 is a MAF sensor circuit/range problem. Could be the fuse (ECM 1 I think) The wiring harness could also be the problem.Check for 12 V + at the sensor.
P0113 is intake air temp sensor circuit low.
Both of those could be caused by having them unplugged with the key on.
P113 is bank 1 sensor 2 (bank 1 downstream O2) circuit low voltage
P1406 is EGR circuit trouble of some kind.
 
#39 ·
Yes a failed EGR will cause pinging. The injection is programmed to deliver the correct mixture for the air bearing oxygen present in the intake system while the EGR is also putting in an amount of inert exhaust gasses. If the EGR is not putting the inert exhaust gasses into the intake that space becomes occupied by air with oxygen. The computer has no way to know this so it continues to fuel as if there is a mixture of fresh oxygen bearing air and inert exahust gas rather that a lot more fresh air and no exhaust gasses. This causes the mixture to fall lean which will result in pinging and back firing.

Bogie
 
#36 ·
If the transmission was out I would be willing to bet that you have grounds that go on the bell housing bolts that are not connected or broken. The other think to check is to make sure the harness is not pinched between the engine and bell housing. I have seen a lot of these type of issues after a tranny was out and back in.
 
#38 ·
Bucking

Yes...a broken ground strap will cause it to run like sh##. Had a buddy tear half his engine apart trying to fix his...it would start, backfire, pop, stall and then start right up and do the same thing. I went out to help him and found the ground wire from engine to frame broken...ran a jumper cable from the engine to the frame and it started right up and ran great. Easiest way to check it.
 
#41 ·
You can unplug the EGR motor's connector and see if the issue remains. You can remove teh 3 bolts and clean the EGR as well to make sure the pintle valve isnt stuiuck with carbon.

Bad running can be caused by a bad O2 sensor causing bogging and teh engine to "load up" with fuel when in closed loop. If the issue clears up at WOT, O2 sensors can be the issue. At WOT the PCM doesnt read the O2 sensors, so better WOT running can be indicative of O2 sensor problems.


If its the popets here is the CSFI to MPFI conversion from GM.

CSFI to MPFI - Vortec Engine Fueling Fix - Fuel Injection - Off-Road Magazine
And here is some cleaning info
http://www.acdelcotechconnect.com/pdf/tsb/tsb_05D-105.pdf
peace
Hog
 
#43 · (Edited)
It also an excellent idea to seperatly ground each head. The extremely high energy ignitions used to jump .060 plug gaps dump a lot of energy into the heads searching for a ground path. We have passed the point where one can assume this energy will find its way to the battery ground by hoping the head bolts and other accessories are providing an adaquate path to the block where grounds usually originate from back to the battery.

I highly suggest a good ground one that can be verified from each head to the block or from each head to the chassis or to the battery's negative terminal be established. This does not need to be a huge wire as there is not much amperage involved. So a number 8 or 10 wire with suitable terminals is sufficient.

For those of you who are loosing MSD boxes and MSD tells you you it's high voltage getting into the box, this baby is the source, it ain't an overcharging alternator.

Bogie
 
#44 ·
I found only one ground wire on this truck it goes to the motor to the battery.
I am going to do like bogie said and run two ground wires one to each head. Then to the frame. Also going to clean the egr and see if that helps. But I was thinking on going with to big ground wires. Just because there are no other Grounds. I was looking at the wiring harness I didn't see any ground wires. I hope the heads will work.
 
#47 ·
When you clean the EGR (a dentist pick works good for that)get a screened replacement gasket from the help section at your local auto parts store.I will prevent carbon build-up from getting in there again.No grounds codes aren't in there,so it is reasonable broken ground would cause this.Keep in mind that first code is normally causing the others.So after fixing the ground issue,be sure to clear all the the codes.
 
#48 ·
well I ran new ground wires on both sides. Little bit of difference. But not much. Egr looked good cleaned it anyway. still not running the way it should I checked so see if I have any wires in the bell housing Not a thing. You Guys think that the cats would be the issue. Would that make the tac jump when its idealing
 
#51 ·
bucking

Maybe unplug the negative cable at the battery to clear the codes, then see if they come up again when you start it up . If they do, I'd recommend pulling the MAF and cleaning it with a sensor safe cleaner...they have a cleaner specifically for MAF sensors at any auto parts store. See if that helps
 
#52 ·
P0102 is actually a Circuit problem. Cleaning the MAF...although a good Idea wont fix it.
I have seen wiring problems as a broken connector, blown fuse and such cause the issue. It will also affect the transmission shift points and throttle pressure as it is controlled by readings from MAF and engine rpm/load and throttle position.
Also , unhooking the battery wont clear codes on OBD 2, it will clear the radio memory.
 
#53 ·
bucking

Latech, so you believe it is either a bad wire, a short or a bad connector? I've run into that in the past. I just questioned the MAF because I understood it was running fine when parked 4-5 months ago due to trans problems. You are probably right though...these modern electrical issues are not my forte.
 
#54 ·
That is what the P0102 is refering to...a circuit problem.
Certainly is an avenue to pursue first.Blown fuse, broken wire( B+ pink to MAF I have seen several times) , Defective MAF.
Cleaning the MAF is allways a good idea. Contamination will register a lean reading.
As long as the code is bonafide and not accidentally induce by technician, that would be the place to start.
 
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