2.8 stalls under load?

[bimdub]

well...I cant give you compression numbers....but I suspect since the car does not smoke.....the fluids are not mixing.....and it pulls strongly (once in a while it does drive fine) the engine is probably good as a whole.....

[60dgrzbelow0]

With your technical background... supported by the best advice that you've encountered so far ...from CNCguy... to employ the two-wire ALDL reading method for getting a glimpse at all the dope inside the PCM-ECM and perhaps that line of thinking will prove more revealing when used in conjunction with the ODB I-II Data Sets as per suggestions from pocket-rocket and Robertisaar, using an inexpensive laptop interface and the Free Diagnostic Software suggested earlier. The logs you create could then be posted back to the forum and those with a deeper and abiding understanding of their arcane meanings can see what we are so far missing...and light the way... Yes?

[CNCguy]

Any updates?

[bimdub]

yeah, its not the ICM.....

[bimdub]

need the letters.... but i'm going to guess they are ASWH?

yes....

[robertisaar]

then that car did get the service recall done. the MAF isn't really a MAF...

[bimdub]

update, I rigged a way to trigger the injectors manually.....and I can keep the engine running fine if I am triggering them manually (not very good fuel control but it does verify the ECM as not sending the signal) I also have noticed the noid is flashing very dimly sometimes during cranking and when the engine is "winding down" where is the ECM grounded? I think this could be a possible area of interest?

I have also considered the possibility of a dead hole, causing the 02 sensor to lean the mixture beyond the point of running, however this happens both open and closed loop, I will order the "tuning cable" I have looked at the software and downloaded it. but my time with this car is running out fast. I have an operational Megasquirt ECM in hand and might consider this route as a last resort, however I have found I can replace the OEM ECM for around $90 and its sure to be less work.

[robertisaar]

the main grounds for the ECM are C6 and D4 on the ECM plugs. D10 and D12 are also mentioned, but i'm not sure if they are intended for something else.

alldata describes them as being at: rear of engine, below exhaust manifold.

[60dgrzbelow0]

One last...perhaps crazy question from me...Have you ever use any kind of Racing Motor Oil... Like Valvoline Racing Oil for example? The reason I ask...is that the ZINC and Phosphate additives (along with a lot more exotic and protective stuff) will coat the O2 Sensors over time to the point where they will no longer function ...the Platinum Screen in the CAT also gets coated enough to be ruined as well... Just an idea...

[bimdub]

update....

yeah its not the ECM....back to the drawing board....I am getting a code 33 again....and I think the TPS might be "glitchy" but even then....there is no reason for the fuel to be cut off completely? its also not a grounding problem, I have been all over the harness more than once. as for the O2 sensor....this should not be the problem at all.....remember the O2 sensor is for closed loop....this is occurring in open as well as closed loop operation.

cal pack? gosh I hope not.....that would be expensive.....honestly I have more time into this than I should. what does not make any sense is that is consistently does this at the exact same point....

[60dgrzbelow0]

update....

yeah its not the ECM....back to the drawing board....I am getting a code 33 again....and I think the TPS might be "glitchy" but even then....there is no reason for the fuel to be cut off completely? its also not a grounding problem, I have been all over the harness more than once. as for the O2 sensor....this should not be the problem at all.....remember the O2 sensor is for closed loop....this is occurring in open as well as closed loop operation.

cal pack? gosh I hope not.....that would be expensive.....honestly I have more time into this than I should. what does not make any sense is that is consistently does this at the exact same point....

Okay... I'm back to thinking it is something really mechanical vs. sensor related... Not knowing how your Fuel Rail is set up...is there even the slightest chance that the fuel regulating-vacuum apparatus built into it has INTERNAL damage of some sort that will show proper fuel pressure at the rail Schrader valve when hooked up to an external Fuel Pressure Gauge... but then only misbehaves under the variability of a running engine? Doesn't your engine's Fuel Rail have a Spring Clip releasable FPR that you can dis-assemble (after letting off the pressure first) and allow you the chance to inspect it inside? In a closed fuel system... something like this would be very hard to detect under normal circumstances. It might be worth a look...Yes?

[bimdub]

no, the injector signal does stop, its not lack of pressure, it has been verified that the injector signal stops.

[bimdub]

what about oil pressure sender? is this tied into the ecm somehow? I am so stumped by this.....its silly....I have checked every wire, replaced the ICM ECM MAP MAF rotated coils checked plugs, wires, adjusted the TPS, cleaned the EGR passages and the IAC passages, I tested each injector (talk about a PITA) there simply does not appear to be anything shorted or grounded that is not supposed to be.

in short, I replaced the CPS....and it idles so much nicer, but it still dies...so still trying to sort it out, I need to pull some trouble codes now, but I think they may be from me tweaking the TPS.

[bimdub]

ok...I think I got it....and its almost embarrassing, the owner had the plugs and wires replaced.....before I got to it.....the car was not driven for a year after that......so they had no idea until recently that the car had problems....I like a moron assumed the job was done correctly, it was NOT! the plugs were all wrong both heat range and type...the gap was not even close either......and it turns out the back three were never changed at all....so after a set of plugs the car suddenly has full rpm range.....what troubles me is that all the work I did everything made it run smoother, and before I even bothered with the plugs it actually was not missing at all, it really ran very good up to 2000 rpms......and then would just quit.....you could actually watch the injector pulse stop with a noid......the only thing I could figure is that somehow the plugs could not keep up at that RPM and the wasted spark would fire through the cylinder with no load, this caused a rich (excessive) read at the o2 sensor and the computer pulled the fuel out? after I changed the plugs to the correct type and heat range it still died a few more times then started going up the RPM range higher each time (learning?) once it had run for a few minutes it smoothed out and it looks like its going to be fine.....

on a side note.....in the changing of the plugs I could have easily jostled some wires that had issues around and this made all the difference, as you can all imagine those back plugs are miserably a PITA to change.....I wish I had my old engine analyzer and four gas when I got this car brought to me.....would have made this a bit easier to discover I am sure......but the moral is.....NEVER ASSUME.....the total bill has been around $250 for a $12 set of plugs......but either way this was a pro bono job from the beginning....

I never would have thought about the plugs as reasonable as the car ran at idle.....might be a good idea to check those every now and then...


oh yeah....and what to do with the GM service manual now?

[60dgrzbelow0]

ok...I think I got it....and its almost embarrassing, the owner had the plugs and wires replaced.....before I got to it.....the car was not driven for a year after that......so they had no idea until recently that the car had problems....I like a moron assumed the job was done correctly, it was NOT! the plugs were all wrong both heat range and type...the gap was not even close either......and it turns out the back three were never changed at all....so after a set of plugs the car suddenly has full rpm range.....what troubles me is that all the work I did everything made it run smoother, and before I even bothered with the plugs it actually was not missing at all, it really ran very good up to 2000 rpms......and then would just quit.....you could actually watch the injector pulse stop with a noid......the only thing I could figure is that somehow the plugs could not keep up at that RPM and the wasted spark would fire through the cylinder with no load, this caused a rich (excessive) read at the o2 sensor and the computer pulled the fuel out? after I changed the plugs to the correct type and heat range it still died a few more times then started going up the RPM range higher each time (learning?) once it had run for a few minutes it smoothed out and it looks like its going to be fine.....

on a side note.....in the changing of the plugs I could have easily jostled some wires that had issues around and this made all the difference, as you can all imagine those back plugs are miserably a PITA to change.....I wish I had my old engine analyzer and four gas when I got this car brought to me.....would have made this a bit easier to discover I am sure......but the moral is.....NEVER ASSUME.....the total bill has been around $250 for a $12 set of plugs......but either way this was a pro bono job from the beginning....

I never would have thought about the plugs as reasonable as the car ran at idle.....might be a good idea to check those every now and then...


Oh yeah....and what to do with the GM service manual now?

Print this information from the very First Reply to this Post as a Book Mark and slip it inside the cover of that GM Shop Manual and put it on your bookshelf in the Den...

Pull the plugs and read them... Greasy, black and gummy? Bad Valves and/or Bad Rings ...or even both (mileage on the car?) A big drop in compression will cause an early stall. A compression test first without a few drops of oil in each cylinder and then with...should reveal the bad rings side of this issue if there is a big difference between the dry/wet tests.. But if the plugs innards are a nice, "Fried Chicken Brown and Tan" ...then check for a bad, loose (or off) plug wire(s) at the plugs and at the coil plug connections.