MarcR94v6

So recently I had trouble with my car, noticing that the warm idle oil pressure has been dipping lower and lower in warmer days after long drives, though still technically within spec. Then it started stumbling, missing, and backfiring and nearly dying. I pulled over for about 30 minutes then decided to try to make it home, I kept the revs up in neutral at stop lights just in case, not knowing if that helped any, as it happens worse under load when moving from a stop. It did it once on the way home about 4 blocks away at the very first stop light, I powered through it as it stumbled and backfired from the engine, i'm not sure if it did from the exhaust, it almost all my backfires are up front. It sounded like a 6 cylinder as I pushed through it and then cleared up and didn't do it again and hasn't since as I've been testing it but haven't driven it to work or anything. Just testing, trying to recreate the problem.

When I was home showing my dad, it would not do it, but my dad noted the slightly surging idle and I noted the unusually loud, higher pitched fuel pump that was also surging with the idle. I always hear the pump prime and occasionally during driving, but this was like it was working really hard and was pretty loud. Pump is a Granatelli changed out in 09 after running the car out of gas. Had about 2-3 gallons left in the tank at the time. I scanned it with my auto x ray and got no codes. I checked the fuel pressure several times and was all within spec, except once recently where the pressure went up after engine was off for 20 minutes to 51 psi. The next couple nights of testing the fuel pump was a normal sound level, barely noticeable with my exhaust unlike the evening of the original problem. I pulled a plug and some part of it was coffee colored but most was covered with black carbon build up and the plug smelled very much like fuel.

It should be noted that the engine has about 35k miles and 20k ago I blew a head gasket and replaced nearly every sensor that hadn't already been replaced during the rebuild. I recently read where crimping wires could cause problems versus soldering them, and it has worried me, there have been a few occasions where connections to maf wires and such have pulled apart but they always gave codes and I was able to track them down easily. I also have a fairly bad oil consumption issue.

I have no clue where to start. If I change plugs they'll just foul again, and it'll take me all day just to do the passenger side with my shortys. A hotter plug seems like a band aid in my mild build. I'm leaning towards getting the oil consumption sorted and getting a dyno tune, maybe the mail order is too rich? If I throw parts at it such as new 02 sensors, how will I know if the rich problem has been fixed?

Injuneer

Check the oil for a fuel smell. Running rich can cause fuel to bypass the rings and get in the oil. That might explain the dropping oil pressure.

When you checked the fuel pressure, what results did you get idle, with and without the vacuum line connected to the FPR? Was there any pressure variation that corresponded to the idle surge and the sound change in the fuel pump? Did you also check the fuel pressure under load, out on the road?

MarcR94v6

All pressures were 2-3 psi within spec for the test, but this was the day after. I wrote them down somewhere I'll have to find the paper at my parent;s house. I could also do it again later today, I just got back from vacation yesterday and haven't messed with it. The engine was too hot for me to attatch the gauge the night of the problem, I find it difficult and was too upset to try. So unfortunately, I won't know about that. I left it on while driving but found that the gauge hose wasn't long enough to stick out of my cowl hood to see anything. Which is funny because I remember being able to snake it out on my stock hood and just barely read it as I was driving. I suppose I could find a longer gauge and try that test again.

I will check those and update you.

MarcR94v6

It got dark on me too quick so so far all I ahve to report is the 02s in closed loop both jumped around between 100 or under to 800, except the left 02 only would get as high as 598. I don't know if that means anything. I think I'll have to break down and get a data cable and start data logging so smarter people can see all the numbers, because I have no idea what the learned idle steps and block values mean.

Also, on a test drive I got a SES light. "yes!!! Finally", I said. But it turned out to just be TPS too low. Likely unrelated, but I have had trouble with the crimping of sensor wires of the maf, tps and iat coming off and setting codes. I think im going to go through all tof my crimped wires and solder them.

MarcR94v6

fuel pressure result: 30 psi prime. 38 engine start. 42 w/ fpr vac line pulled. pump held pressure for a while after. I checked it a few days later and it's prime was higher like 35-37.

I hand wrote scanner results as I dont have an ALDL cable just yet, plan to get one from moates or somewhere. This was after I took off and inspected the tb and sensor wires, which appeared to be crimped very well so I didn't know what the problem was. I cleaned the tb and re-installed everything and there was no more TPS code. I'm, thinking that I adjusted it back to normal voltage while re-installing it.

Here are the results for closed loop.

map sensor 1.48-1.54
throttle sensor 0.74
barometric pressure 4.82
left 02 105-682
right 02 101-888
block learn cell 16
left block learn 134
right block learn 131
Left integrator 132
right integrator 129
left injector pulse 3.7-3.8 (after letting it run a while it went to 3.3)
injector pulse 3.6-3.8 (3.1 after running a while)
maf 8 gr/sec
idle air mtr pos 21 steps (24 warm)
learned idle pos 37 steps (24 warm
spark advance 27*
knock retard 0*
knock sensor 213 (150 warm)
EGR duty cycle was always 0%.

Now I don't know if any of that does you guys any good, you might be better off looking at a datamaster file or something huh? Well if yo see anything strange please let me know.

Injuneer

Appears it was idling. What was the RPM? What was coolant temp? Most things look normal. Injector pulse widths look a bit high. Spark advance looks a few degrees high, but that might be the result of high RPM. Was it indicating "closed loop"?

What does this mean:

"knock sensor 213 (150 warm)"

There are two "knock" values - knock retard and knock count. Since you are saying the knock retard was 0*, are you saying the knock count decreased as the engine warmed up? Not really possible, since this is a field that only increments upwards, and then resets to 0 when it reaches the maximum value for the field. And that in the 10 thousands, not in the hundreds.

MarcR94v6

After driving a while i rechecked the values and some were lower or higher, thats what the "warm" means. This was checked at idle in closed loop, indicated by the scanner. It's at about 870 rpms. I forgot to record the coolant temp, it wasn't running hot that I can remember, I'll hook it up again tomorrow.