Hey Tanker, is the miss missing?

[markelectric]

Just wondering how you were progressing on your miss/ lockup problem. Mine is getting worse with no time in sight for me to look at it. I was sort of hoping your success would give my mechanic a target to shoot for. Let us know!

[tanker]

Yes mine still does the skip or miss, or converter unlocking. :rolleyes: Towed my trailer for 165 miles on Saturday, and it still did it. I don't seem to notice it as much solo in the cold weather, but it still does do it. Time? yes I have not had much time to really look into it. It seems like something electrical cuts in and out real quick. Going over a bumping highway does not seem to increase the problem. I also have a "BD" torq-Loc and it still does it even when locked, but it still could be unlocking. I should go and check the electrical connections, just in case its a plug comming apart.
I too was hoping someone on the forum had this and found a cure. Will post if I find something. smile.gif

[HowieE]

Tom
I don't have my BD manual, but called BD and they refreshed my memory.

Remove the transmission connector and make sure pin S, brown wire, is clean and looks good.

Attach an analog voltmeter to the TCC lockup wire, pin S on the trans. You should also be able to locate this wire were you teed in the blue wire coming out of the BD box. However the closer you get to the connector on the trans the more of the electrical circuit you will monitor

While driving if the meter jumps while the TCC apply signal is on and the convertor should be locked your problem is electrical. You can place your meter connection closer to the computer in stages and check see if the problem disapears. If so you have located the problem point between the last 2 points you monitored.

If the voltage fluctuate at the output of the GM computer I would look at the speed sensor voltage output next. However if the problem were on the input side of the computer I would think a code would have been set.

[LanduytG]

My 95 is doing the same thing but it gets worse the colder it gets. Once temps are up to 40 or so it goes away. To cold to crawl under it now so its going to have to wait for warmer weather.

Howie
Did you get the lines put on yet/


Greg

[CareyWeber]

Tanker,

I was having a issue with my trany too.

I finally in plugged the big fuse in the engine compartment fuse box for the Anti-Lock Brakes, and mine has not acted up since that.

When I was asking about the issue some time ago here someone mentioned that the ABS wheel speed sensors get corrosion between them and their mounting pad and that it affects the signal they provide.

I

[markelectric]

I think I have found the "miss". After a discussion with a transmission rebuilder I was told to replace the throtle position sensor. So I went to see my freind at the GM garage. He tried to laugh me out of the joint, saying my 95 is fly by wire. So I went back to the tranny guy and he tells me that the gas pedel has a multi zone rehostat and one of the zones controls the tranny. He cannot explain how this will fix the problem while on cruise but assures me that this has worked in the past. By this time my wife is real annoyed with the miss and wants something done. So I went back to the stealership and ordered the "gas pedal". Big ouch when the bill came. The day after installing the assembly we went on a weekend trip. That days driving was about 475 miles. I felt the miss probably a total of 3 times. I did not feel it on the return trip. I have not felt it again and a month and a half or 2500 miles more have passed. I hope this helps your problem. Bad news is I have felt it on my 94 1500 pickup a few times. I really do not want to spend that much again.

[MTTwister]

marc - have you searched and looked intot he 'cleaning' of the APP? Drill a couple of holes in the circular 'black box' - not Dead Center - and spray with contact cleaner - slosh and soak, drain - plug holes. I read about it around here somewhere. Possible fix, and cheaper than a new one, if the cure works. Good Luck

[markelectric]

I had thought about that but......It is the daily driver for the wife. I could see me running a drill into it and bits of copper falling out. I then could imagine the phone call about needing to be picked up a couple of days later. The Suburban is rapidly approaching 325,000 miles. I guess in the big picture this is just a small bump in the road.

[john8662]

I too have been trying to track down the intermittant "miss" its more of a tick or jump that it does once in a while, The colder it outside the less it does it though. I had hoped that it might be related to my ignition switch, but now that its changed, it still did it, but the switch change did fix other problems. My list is growing on things I have tried to get rid of the miss with

- Lift pump (maybe low fuel pressure, nope)
- OPS (maybe low fuel pressure, cause tick, nope)
- Ignition switch (low voltage to IP and tranny?, nope)
- Fuel filter housing "o" ring change, (checking for air leaks, nope)
- Fuel filter (of course, goes with the territory)
- Tranny flush and re-fill with synthetic, (no change either).


Things I haven't tried, maybe swapping in my spare new FSD on cooler, the APP, new IP (stealer will have to do that one). I don't know if its the tranny or the engine cutting out. I wonder if having a scanner on board when it happens will tell what the problem is. Otherwise, the problem continues, but the rigs still runs (for now...) Is this reported on 96+ trucks, or just 94-95 rigs (mines a 95)?

Maybe I can get the IP model number and see if we all have that in common, who knows..

[tanker]

Hey guy's, mine still does it :rolleyes: , I've checked about everything, and I'm still leaning towards the throttle position sensor, as stated above. Would like to find a used one, just to try. It does seem to (skip-miss-flutter :rolleyes: ) at about 1/4 throttle position, but it could also be at other times. Sometimes its worse than others. I'll see what comes in the way of a borrowed unit. ;)

[gmctd]

PCM cycles the 4L80E line pressure solenoid regularly to prevent sticking - supposed to happen quickly, not interfering with 'driveability'.

Today's trend to have the trans 'back-flushed', rather than dropping the pan for fluid and new filter, has never 'set' easy with me.
Particularly with the high mileages being accumulated rapidly in today's fast-paced world.

Truck may only be a year old, but a hundred thousand miles is still a hundred thousand miles.

GM strongly recommended several filter changes in that interval, at one time - more if towing or heavy duty service.

And, iirc, a small screen filter is in the supply fitting on the inj pump - try removing the supply hose, blowing that fitting out with an air hose.

Far as the APP module - the manuals state lose any one input, truck will run, with Check APP indicator. Lose any two inputs, PCM wil switch to 'limp home', trans will hard shift.
It appears to be an algebraic function, rather than simple division.

[ 04-26-2004, 04:25 AM: Message edited by: gmctd ]

[G. Gearloose]

Originally posted by john8662:
Is this reported on 96+ trucks, or just 94-95 rigs (mines a 95)?I feel it bump while cruising once-twice a week on my '96.

It also since new used to fart occasionally on decel, when rpms are up from engine braking but throttle on idle, like a full -throttle pop for a revolution, but hasn't done that for a few years now.

[Bobbie Martin]

On the APP, it has 3 differently scaled outputs the PCM uses for transmission & engine control. It uses all three all of the time. Its not like one for the transmission and two for the engine. Trust me, I have lots of experience on the operation of the APP. Basically, the APP gets 5 volts and sends three outputs to the PCM. The PCM compares the APP inputs and if one is out of range, it ignores it and sets a code. If two are out of range, it goes into limp home and you will definitely know it. I can't remember if one or two out of range outputs lights the "service throttle soon" light, but I think its one. If you don't have a code set, the APP is probably OK. I always had an intermittent miss when we had a DS4, I think its normal.
If anyone is interested, I have the rheostat portion of an APP I could send you. This is the only part that goes bad, but GM sells only the complete unit. You will have to remove yours from the throttle pedal assembly (not really too hard) and install this one. While experimenting with my DB2 conversion, I enlarged the mounting holes. But, it should work, at least for testing. Email if interested.

[whatnot]

Originally posted by Bobbie Martin:
On the APP, it has 3 differently scaled outputs the PCM uses for transmission & engine control. It uses all three all of the time. Its not like one for the transmission and two for the engine. Trust me, I have lots of experience on the operation of the APP. Basically, the APP gets 5 volts and sends three outputs to the PCM. The PCM compares the APP inputs and if one is out of range, it ignores it and sets a code. If two are out of range, it goes into limp home and you will definitely know it. I can't remember if one or two out of range outputs lights the "service throttle soon" light, but I think its one. If you don't have a code set, the APP is probably OK. I always had an intermittent miss when we had a DS4, I think its normal.
If anyone is interested, I have the rheostat portion of an APP I could send you. This is the only part that goes bad, but GM sells only the complete unit. You will have to remove yours from the throttle pedal assembly (not really too hard) and install this one. While experimenting with my DB2 conversion, I enlarged the mounting holes. But, it should work, at least for testing. Email if interested. One APP signal out of range didn't turn the light on in my truck, just stored a code. (it fixed itself :D )

The intermintant miss you had must have been something in the IP because it moved to my truck when I installed your old pump. (It didn't have it with the old pump)

[Bobbie Martin]

The intermintant miss you had must have been something in the IP because it moved to my truck when I installed your old pump. (It didn't have it with the old pump) [/QB]IIRC it was every DS4 we had, not just that one! You are correct, I checked and it takes two APP sensors to set the Throttle light. But, it reduces power at the same time, so its not like you wouldn't know it. Seems like it should set with one sensor out so you would know something is wrong. Oh well, another reason to change to a DB2! ;)

[LanduytG]

Mine is getting worse. I have decided its not a miss because under full load it still climbs in rpm. It starts to act up around 50 mph and will quit about 65 or so. I am leaning more toward the speed sensor. If you have a dirty ground you could have a of problems as well.

Greg

[rjschoolcraft]

Mine still does this occasionally. It is much less frequent after installing a new FSD on a heat sink! Prior to that, the miss (or skip or slip or ????) kept getting worse and more frequent. Was worse when towing than when solo. Then the FSD died. Correlation? I think so.

[tanker]

Well member Howie E. loaned me(sent me a new Throttle pedal assy), but then it stopped its skipping etc. So a few weeks later I went to Jersey and paid Howie a visit and returned it. However it did do it again, but only a few times. Hmmmmmmm? I towed, and did not skip a beat. But every other day or so it does it, but nothing like before. Sooooo! Who knows.
We're going up to The Canadian maritimes in July, so we'll see how it goes.
I also moved my FSD cooler to the front bumper to the right of my intercooler, to get it away from all the under hood heat. Bought a 6ft extension harness from John Kennedy, so I'll see how that goes as well.
Thanks for asking, and will post any news. smile.gif

[LanduytG]

Any body have a aprt number for the throttle gizzy?

Greg

[markelectric]

I would save your money on the throtle gizzy ( go pedal}. Mine is back to doing it again. In the mean time we have also replaced the timing chain and crank position sensor for other reasons and the miss is still there. I now feel like it may be the computer as GMCTD mentioned above but do not have the disposable cash right now to test the idea.

[rjwest]

I had a skip/ miss, like a spark plug miss-fire.
This problem was noticable under very light throttle load and just after tcc locked up: about 1600 rpm in OD. This condition lasted for a year. Just did'nt feel right when TCC locked at light throttle, Power was ok, more throttle caused shifts at higher RPM, above 1700 rpm could not feel the " miss"
Went through 2 FSD fails for " no Starts, Quits at all rpm's etc. Finally it got worse.

When going down hill and closeing throttle and quickly steping on brake, I would get a " engine "
quit with imediate restart (You gotto be quick in the mountains in Tenn, with no PS and Brake boost.)

I thought this to be another FSD, it was not.

Than the engine would quit after 20-30 minutes warm up from 30-40- or so overnight temperatures.

Than lots for " eng quits. Swapped in another good FSD, no fix, Called GOMER's in MT, was on trip in area ) He said that it was most likly the pump.

New pump fixed all problems to date, including
the stubborn " Miss " at low power, low speed.

I believe the Miss was present at 1600rpm , but needed TCC lock up to feel it..

Through all this, only set code 1 time,Inj pulse to short.....
Do not know if this applies, thought I would share it.

GM did pay for the pump after I called them 10 months latter.

[markelectric]

Working on the third pump in the space of 20,000 miles and the miss has been with each. What fun?

[Shotuscnc]

i have the miss... and then some... just completed a 7,000mi vacation... and the 6.5TD was the worst part of the trip... nursed the thing thru at least 5,000 of them..

began as a 'skip' or 'stutter' and became a stall with limp-home state if restart at all..

had mechanic replace $1500 fpump and problems cleared for almost a day... then similar symptoms.. flutter, stutter, now appearing more frequently and at idle infrequently.. eventually stalling.. and then only running in limp mode..

codes.. consistently thru 17,18,35,36,54,78

was told by two 'experts' that the fpump was required to clear 35,36... codes continued..

now have 19, crank position sensor.. the suburban barely got me home... stalling at the most improbable times.. running in limp-mode only.

anybody got ideas... i am not a proud owner and have been thru all normal filters,lift pump, OPswitch, remote FSD, another FSD..

thanks.