1995 OBS 1211 code on hard acceleration
 

So I guess it's time for me to introduce my self and ask for some help/advice. My 95 OBS is COMPLETELY STOCK and new to me, a friend of mine used it as a farm truck and said come get it one day! So I rescued it from a horrible death as a yard ornament on his farm or worse, the junk yard! It has 256k miles and is throwing three codes 0107,0603 and 1211. The one that is getting on my nerves is the 1211, I've looked at the normal EASY stuff. No oil in fuel, reservoir full.I have not pulled the VC and looked at the injectors or around their bores for leaks yet though. I've connected a manual high pressure gauge to the head. It reads around 485lbs-575lbs at idle, 1465-1590lbs at wot (no load in neutral) and that pressure remains constant suggesting no aeration in oil. I've also ran the truck with the gauge attached while driving but the pressure has never climbed above 1650lbs before the CEL set and lost power. We also looked at ICP and IPR with a scanner today (no raod test yet). ICP confirmed above manual pressures, IPR was at 14% at Idle and 34% at WOT in neutral. It was getting late so we did not run scans while driving, however when driving it will sometimes set CEL at about 21-2300 rpms and loose power until you kill it and start over. But it will set the CEL if you accelerate hard right about 2300 rpms and looses power same as above. Correct me if I'm wrong but the HPOP pressures and IPR duty cycles are close to spec. The truck acts like it wants to run strong right up to the point it sets the CEL. I just cant get it to run hard long enough to check the pressures and duty cycles under a load.

All the reading I've done (100's of threads) leaves a lot on the table to be discussed, I even found a thread that a fella solved a similar issue on a 99, his cause was rust in the tank. Don't see how' that would set a HPOS code but it proves I've done my homework:)!

I'm just wondering if any of you have had a similar issue on a NON chipped truck? I know that chipped truck can throw this code due to commanded pressures being higher than the PCM likes.

Any help or advice is appreciated, kinda stumped

The code is a reference to Injection control pressure and it being above/below desired. Your pressure is way low.

At idle it should be around 500psi.+/- 20 or so. Duty cycle should be 10-15% at idle.
At Wide Open throttle your psi needs to be atleast 1800 minimum, with your duty cycle not above 65%.

So its pointing to injector leaks or bad HPOP?

I'd probably say that your HPOP is weak. If your fuel filter is black you have one or more bad injector orings.

Fuel in bowl and filter is clean, so I guess the injectors could be leaking to the topside around the bore or top of injector. I guess that is the last check other than ohm/volt checking the ICP and IPR. I'll try and get to that ASAP, but the weather sucks right now! Us Texans dont like the cold/rainy weather! I have a Fairly large shop to work in but I hate being cold when working on vehicles.

I also forgot to mention that a buzz and contribution test was run, both seemed good.

I changed the oil today, Delvac 15/40 and Lucas oil stabilizer, It improved the the HPOP pressure to:
At idle:
750psi at start up
580-600psi at temp

WOT in neutral:
2700psi with brief WOT flicks at about 130*
1650-1700psi at temp (but that’s the highest it would produce even when cockroached)

Took it for a spin, while temp was at 130-150* it ran pretty well, would produce and hold 2800psi and never set the CEL. But it would not pull past 3000-3100rpm.

When temp reached full operating temp, it ran ok, but wouldn’t pull more than 20000psi, would pull to 2500-2800rpm before pressure would start to fall of to 1700psi and it would set the CEL and loose power. This a major improvement from what it was doing prior to oil change.

I haven’t pulled the VC’s yet but that is a must at this point since I only found 1 half ass working glow plug and it was 10ohms resistance, the others all showed infinite! There is also oil in all the connectors at the VC. So I’m sure there is another $300 for the gaskets, UVCH’s and glow plugs.

Which brings me to another point, the PCM is not sending the negative signal to the GPR to energize it. It is always hot on the A side of the plug. I’m thinking the BARO code 0107 I got from the scanner probably has something to do with it. It functions if I remove that terminal an manually supply a ground.

It would appear that the ICP and IPR are functioning correctly, So if you guys have any more suggestions please speak up. If you think I have been a dumb ass, and missed something, say so!

I changed the oil today, Delvac 15/40 and Lucas oil stabilizer, It improved the the HPOP pressure to:
At idle:
750psi at start up
580-600psi at temp

WOT in neutral:
2700psi with brief WOT flicks at about 130*
1650-1700psi at temp (but that’s the highest it would produce even when cockroached)

Took it for a spin, while temp was at 130-150* it ran pretty well, would produce and hold 2800psi and never set the CEL. But it would not pull past 3000-3100rpm.

When temp reached full operating temp, it ran ok, but wouldn’t pull more than 20000psi, would pull to 2500-2800rpm before pressure would start to fall of to 1700psi and it would set the CEL and loose power. This a major improvement from what it was doing prior to oil change.

I haven’t pulled the VC’s yet but that is a must at this point since I only found 1 half ass working glow plug and it was 10ohms resistance, the others all showed infinite! There is also oil in all the connectors at the VC. So I’m sure there is another $300 for the gaskets, UVCH’s and glow plugs.

Which brings me to another point, the PCM is not sending the negative signal to the GPR to energize it. It is always hot on the A side of the plug. I’m thinking the BARO code 0107 I got from the scanner probably has something to do with it. It functions if I remove that terminal an manually supply a ground.

It would appear that the ICP and IPR are functioning correctly, So if you guys have any more suggestions please speak up. If you think I have been a dumb ass, and missed something, say so!