JRENIGAR

iTrader: (37)

Will do. I did use a can of carb cleaner to spray all around the intake where it meets the heads and the injector bosses and no difference in idle quality so I thought It was good. Maybe the back of the intake has a map sensor leak.

JRENIGAR

iTrader: (37)

Im curious if a map reading at idle might give an indication of a vaccum leak? Anyone know how many KPA's there should be on a stock car at idle?

JRENIGAR

iTrader: (37)

All readings in park @ 600 RPM. MAP reads 35KPA and MAF reads 4.5-4.6 g/sec. Are these normal or outta range. I will also say that during warmup mode when I give it gas and hold the RPM around 2000 or so the LTFT's went way down to the +8 to +9 range until it switched over then they went to +25 again.

JRENIGAR

iTrader: (37)

Took the car to a ls shop and was told I have very noisy lifters that are probably gummed up and that the car needs a tune bad. I thought it was piston slap but they said definitely lifters. They make alot of noise on startup until the car is warm. BTW they dont make a knocking sound its more like a tapping or clattering sound. Is there any way noisy lifters could cause a miss feeling in the engine when its idling and a vibration when the rpm's are brought up to say 2000RPM? It still does this even after everything is all warmed up and they dont make the tapping noise anymore. Not trying to go against what the shop said but taking the heads off to replace lifters that are just noisy is alot of work. If it fixes the problem then so be it but if not I will be upset to say the least.

RockinWs6

HMMM my lifters tap a lot and I don't have a vibration, If its not miss firing I don't see how it could cause so much vibration. You say the vibration was gone before you welded the exhaust? Explain more, you also said it stopped afer you disconnected the convertor? Lets be clear about all this.

JRENIGAR

iTrader: (37)

yeah, exactly. Im sounding more and more like I dont have a clue because I guess I dont. Ok when I disconnected the converter in the driveway the front of the car was on jack stands. I was sure it was gone then. I took it to my friends shop with a lift and we replaced the converter while it was being replaced the rear seal cover gasket was leaking bad and it got replaced then. I cut the exhaust off right after the rear cats to remove the ypipe so I could get the trans out. After the trans was back in, before the ypipe was welded back on I briefly fired it up. I thought it was smoother than before but the car was up in the air on a 4 post lift so that might have had some factor in it. I thought the lifters would not have caused the vibration issue either but everything I have tried has got me no where. I hate to keep bothering you guys on here with my never ending vibration problem but damn this is turning out to be a real bastard.

RockinWs6

Ok is it a vibration that you are hearing or feeling? Is it a steady constant vibration or is it more of a unsteady missing type of thing? Really hard from here to help without actually hands on because what you call a vibration I might call something else.

Lets start over, when you put it on the lift and unbolted the convertor did you try it 1st then let it back down and felt it was gone? Can you only feel this vibration or is there noise like an exhaust rattling vibrating type of thing?

Do you notice this vibration while driving OR only when stopped revving it?

JRENIGAR

iTrader: (37)

I notice it while driving and while stopped in park. Its a real vibration that shakes the passenger seat back and fourth about an inch or so when going down the road. It feels like its in the floorboard more than anywhere else. The vibration I feel in park is noticeable like a small miss at idle and when held steady at 1800-2000 rpm its like a in and out series of vibrations like a bad ujoint at 50mph or something. It will shake about 20 times real quickly in about 2 seconds then taper off to smooth within the same amount of time then right back again. The vibration at speed happens around 40 mph and gets faster with speed. I can get up to 80 or so and throw it in neutral and let the RPM down to idle real quick and the vibration is still there until the car slows down. For the record I think I have multiple problems causing two different kind of vibrations but I cant quite tell. I have replaced so many things that should cause A vibration but hasn't fixed the problem until Im running outta thoughts and money to keep throwing at it.

RockinWs6

Ok before you do ANYTHING ELSE check or have a good shop check the CRANK SHAFT END PLAY<<< should be .04 to .08 but maybe higher. If its too high it will cause the vibrations you are feeling. The lifters wouldn't do this.

Also inspect the lower engine pulley , its the harmonic damper for the crank shaft. Look to see if its rubber parts are coming apart or if the center bolt that holds it on is loose and while its running if it turns steady without shaking around or wobbling.

Also try running the engine without any belts for a short time to see if that changes it.

JRENIGAR

iTrader: (37)

Already looked at the balancer while the car was idling and couldn't see any wobble. I looked at the rubber layer between the two steel layers while it wasn't running and it looked even with none pushing out or rotted out. I used the crank bolt to turn the engine over when I removed and installed the converter bolts and it felt tight but I didn't actually lock the engine down and put any real torque on it. I have another stock balancer that came off one of my other fbody cars from a while ago that I know is good but didn't see the need to change it. I removed both belts and no difference that I could tell. How do you check crankshaft endplay with it in the car? I understand what it is but not sure how to check it. Good ideas, keep em coming.

RockinWs6

Mount a machinists dial indicator on the block and indicate the off the frt of the crank or inside the rubber on the steel part of the pulley then use a large screw driver to move the crank in and out. If it worn it will move easily.

Also did inspect the flex plate for cracks when you changed the the convertor?

JRENIGAR

iTrader: (37)

Sounds doable. Thought something like that would work but wasn't sure it would be accurate enough with all the crap mounted on the engine. Ill do that tomorrow and report back. You say .004"-.008" is ideal but how much more would start being a possible cause of the vibration like Im describing?

RockinWs6

If it gets any bigger than .015 you may start to notice it, If its worn enough to shake you get a reading like .020 on up. Its a place to start, do you know the history of the car? People do dumb things when they want to get rid of a car.

I had a similar problem on my 99 ta but it never got bad enough to worry about. I never really dug into it but I'm sure it was a worn thrust bearing on the crank. The oil pressure would drop as I give lite throttle then come bk up too. It caused by the crnk walking back and forth. Soor y for the poor spelling I;m tired.

JRENIGAR

iTrader: (37)

I don't know the history as I bought it from the 2nd actual owner and he got it from a car lot that got it from another lot that got it from the original owner. Whew, long story.

JRENIGAR

iTrader: (37)

Crank endplay is 0.006"-0.007" checked about 10 times to be sure. Swapped in another set of stock injectors that I know to be good just to see and no difference.

fasteddy

Is it an intermittent or constant vibration at 2000rpms?

I had (have) the same thing on my 02 Z28 with 124K and I've felt it on other high mileage 4th gens....even the v6s too.

1. I rebuilt the trans (but it needed it)
2. swapped the TQ converter twice (but I wanted a lower stall)
3. Put in a built LQ9 (great upgrade for these cars)
4. Rebuilt the rear end with 3.73s
5. Replaced all the accessories and pulleys except for the belt tensioner and the PS pump.

The car is almost fully restored now and it still has that intermittent (but consistent) vibration at 2000rpms.....very faint but its still there.

The guy who installed my engine thought it might be the exhaust....cats and / or muffler......but who knows.

Next will be the main belt tensioner....but the thing is eating belts so that needs to get done anyway.


Let me know what you find......

Good Luck

JRENIGAR

iTrader: (37)

Its an intermittent vibration that comes and goes within a few seconds at a time. Its more like a thud or miss at idle and intensifies with more RPM's. Its the worst between Id say 1500-2500 RPM. As luck would have it my crusing speed to work is 55-65mph and that is around 2000RPM with the 3.23's.

fasteddy

One of the things I did before I replaced the engine was I replaced harmonic balancer......that took care of a lot of the vibration...the inner rubber layer on mine was cracked.....as was just about all the rubber on the 124K mile car.

The balancers are hard to inspect and hard to install.

JRENIGAR

iTrader: (37)

I might as well install the extra stocker I have off my other car just to say I did it and that's not the problem. I will have to make another tool to install it though as I lost my other one.

jks67ss396

iTrader: (1)

any updates?