ok so today my truck decided to bog down, and when i gave it gas it did nothing. the rpms bounced from 0 to 600, and then it died.

I tried to re-start it and it would crank and crank. caught a couple times then died immidiatly after. So i thought gas was the issue.

Luckily the truck died 2 blocks from a gas station, and i ran ove and got some gas and put it in.

Tried starting again, and it would crank and crank again. I popped the hood, wiggled the plug wires, and went to go fire it up again. it cranked and cranked, and caught, but ran like it was misfiring.

after running like crap for like 5 seconds, there was a LOUD backfire, and all of the sudden my oil psi goes all the way up to 110 PSI. It stayed there for about 15 seconds, and then dropped to the line before the 110 mark. It was also running clean again.

Got the the gas station (with oil psi at the line before 110), filled up, and she fired right back up and now the oil PSI is back to normal (45 psi)

Is this something i should be prepared for? Does it sound like something's going to go on it? Do you think its safe? Its running fine now, i just dont know if that was a taste of whats to come. Anyone had this happen?

 

Maybe something really bad got sucked up through the tank and when it got dumped in the cylinders and fired, it created some really high pressures and the backfire. What RPMs was it at with the high oil PSI?

 

normal idle after backfire and rise in oil psi. idling at 6-700 pms

 

Could be a chunk of catalytic converter broke off, plugged up, then blew out. That doesn't explain the oil pressure, though-- that's weird.

 

There may be a reason for the spike in oil pressure due to where the backfire went.

Sounds like the oil pan was pressurized from the backfire thus the sudden spike in psi.

I don't think anything entered into the engine. The fuel pump has a screen on it for one thing, and, even at worst case scenario, it would just restrict the gas flow- it would never make it past the injectors so, that is not what happened.

Either one of two things:

A: Lost timing sync at the PCM level


In this case: PCM lost timing reference either due to a intermittent / OPEN CKT / GROUND at either the CKPS or CPS sensor level.

The entire EFI system as well as the ignition system is clocked by those master sensors.


B: CAT

If you have a seriously backed up CAT that is so clogged- it would die out without warning for sure and YES- it would backfire and build up serious back pressure into the engine

Symptoms: no power, sudden increase in engine temp but, if it's cold enough as it is in winter, it may not present that symptom.

Then, at that time, the exhaust backs up into the chambers thus snuffing out the spark thus it dying suddenly. Now, when starting it over and over, more fuel is entering the chambers along with more exhaust pressure- this exhaust pressure builds up and, may blow past the valvetrain thus entering into the lifter valley and either up and out the TB or, it makes it's way down into the crankcase either by passing by the rings or valvetrain thus pressurizing the oil pan.

This is probably what happened and, if your truck did this out of the blue- check your CAT ASAP. If it's something that has been ongoing, I would look at the CAT in addition to the CKPS and CPS.

CM

 

Has not been on-going. There is NO power loss at all. There was before it died, i drove it about an 8th of a mile with it boggy, then hitting the gas did nothing...then onto my original post.

The CAT IS original, and i had a bad plenum (now fixed with hughes) So it could be the CAT since its got 199608 miles

theres no rattle or anything either.


BTW thank you for that info cmckenna. I always learn something every time you post.

 

Your welcome.

As for CAT symptoms: It should have read: "sudden loss of power" or "gradual loss of power / bogging"

I have a feeling it's your CAT and, at that high mileage coupled with an OEM CAT-, time to R&R that thing.

CM

 

i just got my tax check today so i think ill get the magnaflow from summit.


ALSO

another thing that happened today. My ABS light has been on for 2 months (I melted the wire) The ABS HAS NOT been working. I just noticed the ABS light was off when i went to the store. and theres black ice and snow on the ground right now and my ABS is in fact working. how can this be?

 

To be honest, I don't have any experience with the ABS CKT nor the system functionality in general however, I do have a similar problem with my 4WD lamp where, it sometimes lights up and sometimes does not but, in all cases- 4WD is engaging. This is because there's a switch that is not working 100% and, this is separate from the mechanical function.

So, with that in mind, it may be due to that there's two CKTs at play with the ABS, one that triggers the dash lamp and, a separate CKT that controls the mechanical function of the ABS. I would have to see what sensor is on that line and what triggers the light to come on (assuming that the light coming on is a result of an error yes?)

This is just a logical guess so, until I were to research this issue as well as delve into those schematics, I'm afraid I can't be of much help in this case.

I wonder if I even have those schematic sets or not for that system.. have to take a look for you. Let me check that out and I'll see what I can do for you here.

CM

 

thank you

and yes the light was on due to an error that i caused. I went to jump my maxima, and my cables were worn, and the positive and negative were able to touch near the middle of the cables, and when i hooked it to my truck, a spark went and white smoke filled the engine bay. Then i found the sensor and ground that go to the brake master cylinder were melted, and in fact broke apart. when this happened the ABS light popped on, and i had no abs brakes. Now all of the sudden it works and the light is off? doesnt make sense.


Also i went for another drive, and the oil psi is relitivly high again. its at about 70 PSI when on the gas, and about 60 idle. it runs great. i hammered on it, and theres absolutly no power loss at all, so i dont know if it can be the cat....but with its age im going to replace it anyways. but my oil PSI, even though its high, is worrying me.