99 Tahoe advice

[Stinky_Hooker]

I am a pretty decent mechanic as is my dad thats been helping me on my Tahoe but I need some outside opinions.

Over the past few months I have been battling some strange "shudder/vibration'. My truck is a 99' 4x4 tahoe with 5.7 and Auto tranny.



I have replaced the following:

Truck has 202K but we completely rebuilt the engine at 169K

Both front CV alxe assemblies, were worn and needed replaced

Pulled the front differential and replaced carrier and axle shaft bearings...all were worn.

Inspected all U-joints, they are in good shape.

After this took to a mechanic that said the shudder I was still feeling was the torque converter when going into overdrive.

Pulled tranny, t-case, etc...replaced torque converter, service tranny with new filter, pan gasket and fluid.


It was running good for about two weeks and this weekend on the way home from out of town the shudder is back. Only thing different is it seems to be less intermident and more steady. It also doesnt stop when I shift from 4th down to 3rd now as the mechanic suggested trying before to see if it was the overdrive. It it steady now around 40-65 MPH but not 70mph plus.



Any advice would be greatly appreciated, Im about to loose my mind over this. Im worried maybe the tranny is going out and its hunting season.

[ssiredfish]

You guys know way more about this than I do but we had a similar problem with a vehicle turned out to be bad motor mounts, You couldnt notice them until the engine was at higher revs. We replaced them and the shudder went away.......

Or--

Your Tahoe caught wind of the election results and just said, "Ya know, F' it..."

[Blue_Runner]

Stink I had an incident recently with mine and it turned out to be plug wires. Only did it around 60mph. '96 w/ 240k rebuilt at 183k.

[Stinky_Hooker]

Blue, forgot to mention I changed plugs and wires when this first started too. Last year it did something similiar and it was a wire but didnt help this time. I guess Im gonna have to try and change em again.

[THEFERMANATOR]

Does it only do it in lockup, or does it do it all the time at those speeds? If it does it only while in lockup, then my next question is did you upgrade the valve body when you did the converter? 4L60E's from 95+ sufferred from lockup bore wear in teh valve body that causes them to slip or drop out of lock-up many times throwing a P1870 code. The most common aftermarket fix is to replace the PWM lockup valve with an on off style valve to eliminate the pulse width modulation lockup function(soft lockup feature), and makes it like another gear. GM and SONNAX use an oversized lockup valve in the valve body, but they suffer from the same issue down the road. Another VERY common issue that causes missing going down the road at cruise is the injector pod assembly. If it is the origanal non multi port updated set-up this could be your issue. Also make sure your cats aren't plugged, the EGR is working and not hanging open, and O2 sensors are NOTORIOUS for giving driveability issues in these without coding or for throwing misfire codes. Also make sure and put a PREMIUM quality cap and rotor in it as the crab caps are BAD about cross firing internally.

You need to narrow it down to wether it is a driveline binding issue, lockup kicking out, engine misfire, or loading up. Then go from there. And yes, I've worked on a FEW of these animals and the early V8 VORTEC can give you nightmares trying to chase issues in them as the OBD2 in them SUCKS.

[THEFERMANATOR]

Blue, forgot to mention I changed plugs and wires when this first started too. Last year it did something similiar and it was a wire but didnt help this time. I guess Im gonna have to try and change em again.

ONLY, and I repeat ONLY use AC DELCO platinum or iridium plugs in these engines if you don't want misfires and studders. Also most wiresets you buy now are JUNK! I use teh CARQUEST premium 8MM silicone wires, or BOSCH from AZ. The DURALAST wires are garbage, and most of teh time run worse than 200K mile origanals.

[Stinky_Hooker]

Thanks FERM. I THINK I went with ACdelco on the plug. Wires were whatever advanced auto had. Im thinking Ill get some better 8mm next and double check my plug. I Havent done the rotor/cap in a while so that will be the first step.


Its after lockup at a steady speed.


and No we didnt fool with the valve body. What do you think ...it could be that?

[tsubaki]

Have you looked at the driveshaft? Or is this not the vibration type you are experiencing?

[Skools Out]

stink i've had best luck with the MSD cap and button or the blue marine cap and button with brass terminals. Wires best luck with Delphi or AC wires. plugs best for me have been either AC Platinum or Denso Iridium plugs.

[THEFERMANATOR]

I like the blue marine cap as well. have yet to have one of them fail me, but many of the black ones give all kinds of grief. ANYTIME there is a torque converter issue with a 95+ 4L60E the valve body should be teh FIRST thing addressed. Most any trans shop knows this, and I'm surprised one told you to do a converter instead of the lockup valve. It wouldn't hurt to put a TRANSGO SK or HD2 shift kit in teh valve body. Lockup will be alot firmer, but it will eliminate the possibility of converter slippage from a control issue which is a semi common issue on 95+ 4L60E's. And it wouldn't hurt to put a fuel pressure guage on it while it is doing it to make sure it is holding pressure. If it still has teh central unit with poppets on it, they NEED at least 42 PSI to open the poppits properly, but prefer 46 or better.

[Skools Out]

ferm would this kit fix Stinks and mine as well? mine does it slightly time to time, it's a 99 as well...

http://transgoonline.com/products.php?prd=SK-4L60E&homeinclude=catalog&category_id=97&parent_id=31&product_id=182&countdisplay=1&start=0&addcountview=Yes

[THEFERMANATOR]

ferm would this kit fix Stinks and mine as well? mine does it slightly time to time, it's a 99 as well...

http://transgoonline.com/products.php?prd=SK-4L60E&homeinclude=catalog&category_id=97&parent_id=31&product_id=182&countdisplay=1&start=0&addcountview=Yes

That's teh SK kit which is a good kit for daily drivers. If you tow alot or want really crisp shifts go with the HD2 kit. Also chances are your seperator plate will be WELL worn where the checkballs seat against it. The TRANSGO plate is a hardened plate and holds up a bit better than teh stock one does. The SK kit is designed for the professional, so the directions may not be that clear to follow for the average DIY who isn't real familiar with how a valve body works. The HD2 kit is a drop in kit with good directions, and you can buy a video for it as well. And being you both have 99's, the accumlator piston in the valve body should be swapped out for an aluminum one(GM put a plastic one in it, and they stick and crack which will cause a pressure bleed off).

[Skools Out]

took mine to the trans shop today they said they would rebuild the valve body, replace all solenoids, and add shift kit, plus service it for $385

[Stinky_Hooker]

Well I talked to a mechanic I really trust, they are top notch folks and he quit building trannys but gave me a number to someone he uses. Im going to take it to him the next couple days to let him drive and pull any codes. Im pretty depressed and thinking my hunting season is pretty well shot as we are pretty tight on $$ right now.


Also noticed this doing some looking. Anyone use anyone online they trust for a newly built one?

http://www.transdepot.net/product.asp?itemid=195&gclid=CKeNq5XZzrMCFRRbnAodJEoAgA

[THEFERMANATOR]

Well I talked to a mechanic I really trust, they are top notch folks and he quit building trannys but gave me a number to someone he uses. Im going to take it to him the next couple days to let him drive and pull any codes. Im pretty depressed and thinking my hunting season is pretty well shot as we are pretty tight on $$ right now.


Also noticed this doing some looking. Anyone use anyone online they trust for a newly built one?

http://www.transdepot.net/product.asp?itemid=195&gclid=CKeNq5XZzrMCFRRbnAodJEoAgA

Theres not many online places I would trust to rebuild a trans, and the one in your link will not fit yours Stink. Yours is a 2 piece 4L60E as GM went to a removeable bellhousing in 96. Yours is basically a 98 trans even though it is in a 99 as teh GMT-400 tahoe was a carryover for the drivetrain. If you get a 99 it may cause issues as the newer body style uses slightly different valve bodies in them.

And SKOOLS, for $385 I doubt they are using OEM quality solonoids as the last set for a 98 I bought cost about $185 for just the solonoids. I've used aftermarket ones, and everytime they have failed and took the trans out with it. I only use AC DELCO OEM's now.

[Stinky_Hooker]

OK, took it to a good mechanic to get it scanned. Found a few codes that shouldnt have anything to do with what its doing..minor stuff. He drove it and felt the shudder and talked about seals at the convertor that probably needed to be replaced when I did the convertor that could be allowing blowby and fluid getting past? Ferm this make any sense to you? Around the input shaft?

[Skools Out]

stink it's the valve body, that fixed mine, just need your valve body rebuilt.

[Stinky_Hooker]

Im taking in to the tranny guy next, just wondering, never heard of this.

[THEFERMANATOR]

Did he tell you what the codes were? I need to know what the P code numbers were to tell you what they might mean. And the codes for a 99 5.7L are HORRIBLE for telling you what the problem actually is. RARELY have I seen them throw a code for a bad O2, the ywill normally throw a misfire code when an O2 sensor fails. If there was a P1870 code in it, then the valve body needs to be done first before you go any furthur.

[ssiredfish]

Did he tell you what the codes were? I need to know what the P code numbers were to tell you what they might mean. And the codes for a 99 5.7L are HORRIBLE for telling you what the problem actually is. RARELY have I seen them throw a code for a bad O2, the ywill normally throw a misfire code when an O2 sensor fails. If there was a P1870 code in it, then the valve body needs to be done first before you go any furthur.

Best thing we ever did was buy one of those code computers. At $50 a read it doesnt take long to pay for itself......

[Stinky_Hooker]

There were no Pcodes. Its was low effeciency through caty convertors which he said was waaay before I started having problems, a fuel level sensor (which I knew, cause my fuel gauge doesnt work) thats it. I was hoping for a trans code but nothing.

I only took it to him cause he is really honest and wanted to see A: if there were trans codes and B: if it may have been an engine issue before concluding it was the tranny, which it obviously is. He gave me the # to a tranny guy he trusts and Im going to call him this afternoon when I get off work (left the number at home). If they work tommorrow I may run it by today, if not Monday. I been driving it in 3rd only 40 MPH or so to keep the shudder down to hopefully not cause any damage. I only drive 5 miles to work each way. No driving it otherwise.

[THEFERMANATOR]

There were no Pcodes. Its was low effeciency through caty convertors which he said was waaay before I started having problems, a fuel level sensor (which I knew, cause my fuel gauge doesnt work) thats it. I was hoping for a trans code but nothing.

I only took it to him cause he is really honest and wanted to see A: if there were trans codes and B: if it may have been an engine issue before concluding it was the tranny, which it obviously is. He gave me the # to a tranny guy he trusts and Im going to call him this afternoon when I get off work (left the number at home). If they work tommorrow I may run it by today, if not Monday. I been driving it in 3rd only 40 MPH or so to keep the shudder down to hopefully not cause any damage. I only drive 5 miles to work each way. No driving it otherwise.

The 2 conditions you describe would have both been a P code. The ECM reads out trouble codes for the powertrain(engine/trans) as P or powertrain codes. The cat efficiency code can EASLIY cause the problem you describe from it as I have SEEN it happen on 99 5.7's. This is why I said we needed to know what the P codes were to go off of, and NOT to trust the diagnostic trouble codes given for this engine as most of teh time they can lead you on a wild goose chase if your not familiar with the system. As for seals on teh input shaft, I find it HIGHLY unlikely the teflon seals have gone bad unless somebody pulled the trans apart and put it back together dry with a sledge hammer. Since the late 80's GM has used teflon sealing rings and they are VERY resiliant and hardly ever need changing even during a rebuild.

I haven't ever used one of these, but I have read good things about this for the P1870 repair for alot less money. Supposedly it will work better in valve bodies that are severely worn that the tRANSGO kit won't fix.
http://www.teckpak-fitzall.com/spgm.cfm?id=A74741Q

[Stinky_Hooker]

Well crap, to eliminate the cats starting to get clogged what do I do short of replacing them for alot of $$.

[Stinky_Hooker]

Ferm I miss understood what you were asking about the p codes.


I just picked it up from the shop and I have a list of the codes Standby till I get home I'm on my phone.

[Stinky_Hooker]

Here ferm

http://img.photobucket.com/albums/v721/bbingsuperman/2012-11-16_15-46-54_862.jpg

[THEFERMANATOR]

From what I see I would find a new shop to go to. Your truck only has 2 cats, NOT 3. Bad vibration from the torque converter? How did he come to that conclusion? I hate seeing receipts like these as most of the time it means they didn't really check anything. The P0420 and P0430 both being in there concerns me the most. I would check the fuel pressure on it to make sure it is up to par. If it was one or the other I could see a bad cat, but both at the same time normally means a fuel delivery problem or an injector issue. How does it start cold? How does it start hot? Do you have problems restarting it hot after it sits for about 10 minutes? To remove the cats there are a few different ways of doing it, but all of them are pretty illegal and the EPA is out for blood here lately over emissions equipment tampering. PM me for ways to disable them for "testing" purposes if you want. Also the P0440 could be the cause of your P0420 and P0430 codes. If the evap purge solonoid is stuck on, then it can cause a rich fuel condition causing it to surge or buck as well as throw cat converter efficiency codes.

[Stinky_Hooker]

I was assuming the third cat was the 3 of 4 oxygen sensors?


I have a guy that will cut my converters off and weld them straight. I had it done on a 2001 s 10. It cause the light to come on but what will it do to my tahoe will it run right? Hell for that matter I can straight pipe it...what will happen?
Would that be what you would do next?


Also I think he came up with the vibration from the torque converter based on driving it and I told him I replaced it.

Thoughts?

[THEFERMANATOR]

This is a 350 or 5.7L engine with a distributor correct? I have never seen one, but I have heard some 99's came with the 4.8 and 5.3L engine. I just want to make sure. As for your O2 sensor, there is one after each manifold, and one after each cat. If you straight pipe it it will go into engine protection mode and limit the timing WAY back. I do NOT reccomend doing it as CAT's aren't that expensive if you get aftermarket MAGNAFLOW universal ones(last ones I bought were $65 each). With the P0440 code, there is a GOOD chance your WHOLE problem is nothing more than a stuck open evaportive emissions valve venting fuel vapors to the engine and fattening out the mixture. This will cause it to be off on the timing tables and show both cats as having poor efficiency.

[Stinky_Hooker]

Well Ferm, I thought I would update you. Took it to the transmission guy and dropped it off two weeks ago, (I got it back last tuesday). On the way over there to drop it off it started getting real bad.

He called me the day after I dropped it of and said it was definately loosing pressure and they found a good bit of dust from what he thought was the 3rd and 4th gear clutches wearing out and thats what I was feeling on my way over. Anyways, he offered to go into it and try a few different things to figure wear the pressure was being lost. It may have been overkill but with my several months of frustration and missing over a month of hunting I told him to give me a price and just rebuild the damn thing!!

Anyways, long story short and $1900 later she's running like a top. I felt good about the decision because of the piece of mind I FINALLY have, the motor only has 40K on it and he gave me a 12 month/12K mile warranty on the tranny.

The truck might be an old 99' but I love her and she's worth it to me...and PAID for. :beer:

[Stinky_Hooker]

Also, does anyone have an extra grill emblem laying around or where to get one reasonable. Mine disappeared!


http://img.photobucket.com/albums/v721/bbingsuperman/2012-12-11_08-27-56_433.jpg

[smokeonthewater]

http://www.ebay.com/itm/1991-2005-CHEVROLET-BLAZER-S-10-BOWTIE-GRILLE-EMBLEM-NEW-OEM-/121036309704?pt=Motors_Car_Truck_Parts_Accessories&hash=item1c2e5384c8&vxp=mtr

[Stinky_Hooker]

Awesome thanks!


I wonder if someone stole it. Never had one come off before.