you need a compression check . In my case , same issue , it would start to smoke after idling , and a fair amount too , then , nothing after it was revved . I re-did the plenum , but , it never fixed the issue . A comp test showed 90psi in #5 , the rest above 130 . I figure the oil ring , or clogged/stuck rings to be the issue as a result of the failed plenum (it was bad) , wet test brought it back up . It drove great though , no other symptoms . I should have started with a comp test to know what I had .

I ended up ditching that engine for another , but could have been easily repaired . I also suspect the issue could have been with a valve , but there was no visual damage , I should have done a leak test with it before sending it to the scrap metal yard

 

ya, but it seems to have gone away since i cut my muffler out, maybe soemthign in there?

 

could have been oil in the cat/muffler but usually they dont stink and smoke untill they are real hot and the oil starts to burn....
My 2 cycle G1 golfcart as well as my old harley golfcart are known for this as unburned oil acumulated and plugs the muffler and smokes on long trips...the fix is to remove the muffler and barbacue it in a campfire with no one around to choke. But I dont think that will work on a bad clogged cat or muffler...

 

BUMP. Today truck shut off again, after replaceing the fuel pump, cleaning the crank sensor, but now i have another symptom, that i over looked before.

When it shuts off now the odometer flashes on and off 3-4 times (about as many as it does when changing the tune with superchips.) then it stops, and reads "no bus"

any ideas?

im leaning towards a faulty pcm.

I also learned that I DO have the deathflash, though its been removed by my 3815.

 

If the CPS is bad, cleaning it will do jack! Have you tried removing the SC program and returning the pcm to stock?

 

yep, did that last month, and tahts why i wanted to sell it, but then it died on me in the stock as well. and i know that if it is bad cleaning will do nothing, but i dont think its bad, as the truck runs fine, with no codes present.

 

I thought the whole point of this was the truck isnt running fine??
If its just dying randomly something electrical is flakey .... Mine did the exact same thing for two days like three weeks ago while I was running a can of seafoam through a tank of gas.....I got lucky and it seem to clear up on its own...no codes either....
It wouldnt stay running after stalling unless I kept my foot on the gas and when it died it would fire up for a sec when restarting and die right out....did it while driving at 30mph twice as well as in the driveway...

 

nope, my asd relay de-energizes, aand killing all power to my gauges, and the ladder. including the motor.

truck runs fine, except for the fact that it randomly dies while driving, or even sometimes idleing, and it just shuts off like i turned the key off, no suputering or anythign.

 

Looks like a lot of guessing going on here. Are you measuring anything? The only way to fix or actually, in this case, find the root cause is to start testing the electrical circuits from the battery to the power distribution center from the ASD relay to your fuel pump relay to the 12V feed to the PCM and so on.

Check all your grounds. Grounds from both heads to the firewall, from the battery to the frame, from battery to the body, from battery to block, battery to ALT.

Check all of your + VDC feeds and verify there is constant 12 VDC supply.

Check your ALT output and note the voltage output. Should be ~14 VDC. Check your battery w/o a load on it. Turn the headlamps on and note the voltage drop. While keeping a load on it, hit the starter and note the voltage drop. You will have to place the meter in the window in order to see the reading. It should drop ~2VDC and then come right back up quick.

Once you have verified that all those circuits are indeed intact, and, all grounds have been redone, checked and tightened back up, start checking your ASD relay feed supply. Same with your fuel pump relay. All those circuits should be seeing 12 VDC. If it's not reading 12 VDC, there's an issue with the supply.

When the feed supply is low, the entire engine management system, EFI system, timing system will go out of whack thus shutting down the system via PCM through the control circuit at the PCM.

Also, you need to verify your sensor voltages. Check the CPS first. This is very simple to do. If you would like to know how to check this, let me know and I will write it out for you step by step. Without that in circuit, the truck will not start or run (depending on the year). Some designs use that sensor for the timing while some use it as a monitor only. If the voltage does not fall within the upper and lower spec limits set forth in the program parameters in the PCM, it will trip the PCM to kill power at the PCM.

Same applies to the CKPS> it will kill all power to the vehicle. Your going to have to check every single harness and meter them out to find out whether you have a harness issue, you have a sensor low / high voltage condition / or, no voltage present (random drop outs in the rpm range), you have a fault in the ASD component itself, you have a fault in the fuel pump relay, fuel pump module (this will also kill power to the vehicle on some models as it is wired in series with the ASD so, if one goes out, it take the entire system down with it.

If you can not or, you do not possess the tools or skills to troubleshoot down to the component level, I highly recommend that you take the vehicle into a shop where they can fix it for you.

If your PCM was faulty, there's a code for that but, I can't recall it at the moment. Speaking of that, you mention a no-bus condition. No bus means no communication. That means that there's no power going to the PCM. Or, if indeed there is power at the PCM input, this means that there may be an internal bus error due to a bad flash. This is common. Poor connections, dealer flashed PCM coupled with a bad flash and, you wind up with a funky PCM. I have never had that happen but, I have heard about this happening a few times so, I thought I would mention it. But, usually, what that means is no power to the PCM. This is what you got off your flash / code reader correct?

When you got that, and the dash lights flashed, were you able to pull any codes through the OBD port into your code reader?

Now, if your feed from your batter TO the PCM is hosed, broken, intermittent, high contact resistance (low power) etc, this would also lead to low or no power at the PCM which would in turn cause it to display no bus found because there's no power to the PCM at which point, it shuts down and resets. This would lead to no DTCs being displayed as well as shutting down the vehicle. When the PCM shuts down, it takes the entire system down since it controls the engine management system.

IF your NOT getting any codes, check to see that the correct power is being applied 100% to the PCM. Place a meter across the appropriate pinout/s and note if there's a constant 12 VDC to the PCM. Check your schematics and wiring diagrams for your year vehicle.

If it falls below OEM specs, you have a supply problem. That will have a DTC code for "battery out of range" condition. If it's within OEM spec, we now have to start checking everything in that circuit and begin walking the path.

Oh, by the way, one last thing; if and when the CKPS or CPS starts to go out, both will trip a DTC.

 

thanks for the input cmckenna, but no codes stored, and no codes pending. and the only thing that flashes is the odo, when its about to go to no bus. and once again no codes. and i know the batt. to frame ground is ok, because i ran a second 8 gauge wire from the bat to the frame to reduce the strain on my alt. and batt with my system.

it is an intermitant problem. also sometimes it will start rigth back up, others it wont, and i have to swap relays, and recently i started pulling the connectors from the pcm, and i dont think its the fuel pump, as ive replaced that already as well.