Whose got a hose diagram?

Maybe I just scan her with the dang things conected and then remove the ruber elbows and cap them check valves shot with a ruber piece and scan her again ?


MMm I will do that on my day off.


Marvin

 

Guess I'll chime in since I'm having the SAME problem, on almost the exact same setup.

I have new O2's and EGR along with a fuel filter on the way, but I don't think that's the fix.

Can't find anything wrong still. May be going to Jay Fisher Pontiac later next month if I can squeeze in.

Marvin, good idea on the pump. It's something to check, that's for sure.

 

My AIR is deleted and the holes plugged in the headers. Plus, the problem happens in open and closed loop, which suggests its not a leak in the exhaust since the O2s are ignored in open loop.

As for what the miss feels like. At idle, it randomly dips or hesitates, you can feel the engine dip slightly in RPM, and the vacuum gauge shows it drops an inch of vac each time it does this. At 1500 to 1800 rpm, it is extremely rough, vibrating, like a classic miss.

At part throttle cruise on 4th gear the car bucks slightly, and at WOT it cuts out like you are hitting a rev limiter, but it is not at one specific RPM, it does it the whole way up to redline.

t is not completely intermittent. It doesn't ever go away and run fine, but it is not one single cylinder that is dead. I say intermittent because at idle it hits randomly rather than being rythmic.

And last week it died on my twice at idle, just cut off like somebody flipped a switch.

All 8 cyls are getting spark and fuel, the only thing left is that the spark is too weak, which is why I'm going to check the ignition switch.

 

Here is the thing. Yesterday morning I scanned my firts WOT run.
I stopped on the side of the Highway, a straight line shot. I could see far away and horizontally leveled. The B.i.t.%%C spun the tires for a whole second from Idle to 2125 RPMs. This is something she never does... She went from block learn cell 4, to 8, to 15 **Never went to open Loop* for the entire run, it says **loop status = closed**... I got the log.

The first Second she spun the tires, on the second "second" she bogged down a bit... she spend the next second as follows....

RPM=2125, Map=4.42 volts, MAF=92 gr/sec, Knock retard=9*
Rpm=2450, Map=4.80 volts, MAF=108gr/sec,Knock retard=9*
RPM=2525, Map=4.82 volts, MAF=109gr/sec, Knock Retard=8*

Then she took off like a bat out of hell....


Again she never went into open loop per data log , she never locked the torque converter and The oxygen sensors went to 940 / 946 mV. the entire run while she was on Block Cell 15.

The only thing that changed was the BLMs and Integrators that were locked into 128. From the scan it seems as if she was still reading the O2s but the fuel adjustment (BLMs, int's) were ignored.

another weird thing is that with the key On and engine Off the scanner reports the pcm reading 50 RPMs.

So are you sure the PCM ignores the 02's? or just the Fuel Trims?? I am looking at my fuel injectors pulse for both left and right and they were being adjusted for the entire run. Right about pig rich readings 17.90 to 18.60 mS. for the entire run.

So is this what you guys see in your scans or is my car special? (retarded)

 

The 02 sensors are how the PCM calculates the fuel trims. If the fuel trims are not being used then the O2s are not being used.

It may be best for you to post you problems in a new thread, I think our situations are pretty different.

 

Amen....



I didnt mean to steal your post. My apologies


Marvin

 

i sure hope someone comes up with a fix. I have a skip prop also, my not be same, but i am just as aggrivated. If someone came up with a fix it would give me more hope. I am going to try again to fix this prop this weekend. If i have any luck i will post a thread.

Good luck!

 

Well guys the ignition switch didn't do squat for me.

With all the things I've checked or replaced, including 3 optis, and the fact that an osciliscope showed no abnormalities with the ignition on any of the cylinders, I am wondering if this could be caused by an out of balance harmonic balancer or torque converter.

 

That is an interesting idea. I hope it doesn't come down to where you have to tear down the motor. Keep searching. The answer has to be there somewhere.....good luck.

 

OK, I've been watching this post from the begining and wondering the samething myself. Last year I had a simuler problem with my 95 Mustang right after I changed clutch and I racked my brain looking for a miss just like you with no results.Then I started thinking it was a balance problem and not a miss so naturally I suspected the clutch and after changing it again problem was still there.I was about at my wits end and was checking the plug wire again and the only way to get to the #1 was under the car and that's when I noticed the
rubber ring in the Harmonic balancer had seperated and was sticking out. The outer ring had spun and the thing was out of balance,not a miss.
The symptems seemed to be a bad miss at 1200 rpm then a sporatic miss while accelerating.Although I had looked at the balancer from above it was only visible from under the car.Intstalled new one and that was it.
I don't know if that's what you have but ever since I've been following your your post I've wondered if your problem might
be the same.
David

 

Thanks for your input, it is truly helpful. The only thing that causes me to second guess it could be the balancer is the LT1 is internally balanced and the balancer should be neutral. But it needs to be ruled out either way at this point.

Going to see if I can source a known good balancer and go from there. I think I have a buddy who's car is down I can borrow from.

 

I hate to throw another $.02, but I didn't see any mention in the thread of a possible EGR problem. I have been having a similar (very similar) performance problem that's got me all but ready to give up on the car. But after doing a little more reading, I'm starting to think EGR.

Also, have you though of hooking up with a smog sniffer, and then analysing the emissions alongside the scanner data?

Just a thought.

 

Just a thought, have you replaced your battery cables. Take your car to someone who specializes in automotive electrical. They can check for grounds. Just think how many circuts and how much wiring we're talking about here. You could chase this problem for ever and never find it. It might cost you more to have a pro look at it, but it looks like you've all ready invested quite a bit in your car, so it will be worth it.

 

My high rpm miss and rich condition ended up being a partially busted ringland. How is took this long to start puking smoke from the valve cover i'll never know. That just drove me crazy! It's ok.....that was an excuse to get a 383 with ported musser heads lol....and the bottle. No more blower for me.

Joe

 

EGR has been removed from the car.


The idea about the automotive electrical specialist is a good one. Hadn't thought of that.