knocking problem under acceleration

coogs · #1 03-31-2007, 04:59 PM

99 Lesabre.. 150K knocking problem under load - upon acceleration but not necessarliy from a stop? and its only intermitent. I run the bronze unleaded fule and havent tried a higher octane.. plugs are pretty new and she runs well. Any sugegstions?

maxwedge · #2 04-01-2007, 08:45 AM

Make sure your egr system is operating, number one cause of pinging on accel in these cars.

coogs · #3 04-01-2007, 10:40 AM

thanks .. now... I'm pretty mechanically inclined and know what an EGR system is but i'm a liitle sheepish on the best way for me is to go about testing/cleaning or otherwise replacing a component as reg maintenance. I dont belive this system has ever been addressed or looked at.

Only other piece of info is... sounds like when it she does the old 'pingaroo' it's coming from under the hood psgnr side... Again- this issues is intermitentaly as in... slowing down to about double idele speed and then accelerating from there- that's where the problem is..

thnks

maxwedge · #4 04-01-2007, 11:51 AM

Tough to say what exactly you are hearing, a tech should reasly listen to this or you could go off on a tangent. If the egr passages are carboned up/blocked and /or the egr is inop this usually sets a cel code. The noise could be some rattle from the exhaust or such also, someone on site should listen to this for you.

Scrapper · #5 04-01-2007, 11:59 AM

i'm asuming this is a 3.8 or 3800? i'd check harmonic balancer as these are bad on them..

good luck.....

coogs · #6 06-15-2007, 07:36 PM

well the pinging /knocking is definately an engine as opposed to something loose. I had it itn the shop and no error codes. Could I still have a bad EGR with no Error codes?
thanks

ChemMan · #7 06-15-2007, 10:31 PM

Quote:

Originally Posted by coogs

well the pinging /knocking is definately an engine as opposed to something loose. I had it itn the shop and no error codes. Could I still have a bad EGR with no Error codes?
thanks

Absolutely. If one of the egr tubes is partially/completely clogged and the egr valve is still functioning properly, you will not get a code. How is the computer supposed to know a pipe is clogged? Pull the valve off and check the tubing and valve for excess carbon build up. Clean the valve and tubing with carb cleaner, and then reinstall the valve with a new gasket. A can of carb cleaner and a new gasket shouldn't cost more than $15 and the whole job should take 1/2 an hour. Not a hard job.

coogs · #8 06-15-2007, 11:06 PM

ok thanks - will do.... I have another problem if you're interested... major violent front end shaking clunking - like the engine is coming apart upon left hand turn from a stop upon hard acceleratioon- usally happens when the light is changing from a amber to red on a left hand tunr in an intersection. It'll do every time. wont do it on a right hand or stariaght out of the gate.If I take it easy - no issue The dealer said it is likely the tranny and was thinking it muight be due to the oil pick up when the fluid shifts.. Persoanlly I think thats BS as the tanny shift beaut and is 130K. Its like something is brioke in there- alos I'd say something sounds loose when I dive over a man hole cover with the left tires... Only other thing I;d mention is the car took a very hard hit on the right side a couple years ago which resulted in the lower and upper arm being replaced... suggestions?

maxwedge · #9 06-16-2007, 09:00 AM

Quote:

Originally Posted by ChemMan

Absolutely. If one of the egr tubes is partially/completely clogged and the egr valve is still functioning properly, you will not get a code. How is the computer supposed to know a pipe is clogged? Pull the valve off and check the tubing and valve for excess carbon build up. Clean the valve and tubing with carb cleaner, and then reinstall the valve with a new gasket. A can of carb cleaner and a new gasket shouldn't cost more than $15 and the whole job should take 1/2 an hour. Not a hard job.

Actually the pcm does know if the egr is not able to function, as the exhaust enters the combustion chamber o2 readings change and a code can be set, plus the map drops slightly for the same throttle and load.

spinne1 · #10 06-16-2007, 03:06 PM

Quote:

Originally Posted by coogs

ok thanks - will do.... I have another problem if you're interested... major violent front end shaking clunking - like the engine is coming apart upon left hand turn from a stop upon hard acceleratioon- usally happens when the light is changing from a amber to red on a left hand tunr in an intersection. It'll do every time. wont do it on a right hand or stariaght out of the gate.If I take it easy - no issue The dealer said it is likely the tranny and was thinking it muight be due to the oil pick up when the fluid shifts.. Persoanlly I think thats BS as the tanny shift beaut and is 130K. Its like something is brioke in there- alos I'd say something sounds loose when I dive over a man hole cover with the left tires... Only other thing I;d mention is the car took a very hard hit on the right side a couple years ago which resulted in the lower and upper arm being replaced... suggestions?

It sounds like your CV joint on the left side. Have that diagnosed at a garage. If it was simply fluid shifting, why wouldn't all LeSabres do this? Wouldn't the fluid shift the same in all cars?

Another possibility is one or more of your motor/transmission mounts are bad. Look at them and look for signs of failure (rubber coming apart, etc).

coogs · #11 06-17-2007, 06:47 PM

I asked about the VC and the shop forman said the boot was intact and no obvious signs fo any problems there... I thougt bad CVs click aorund tghe conrners.. this my man is a likfe there's a guy under the hood with a sledge wailing away when I accelerate.... bang bang bang bang

maxwedge · #12 06-18-2007, 03:28 PM

So if he drives it he says this is a fluid change issue, find another shop. All the recommndations here are on target, you must now follow up on them however you see fit.

coogs · #13 06-18-2007, 10:14 PM

good advise and I agree... Tires are due to be rotated and I deal witha good shop for front end rubber so will ask them to have a look..

coogs · #14 06-18-2007, 10:19 PM

can I go back top the other issue.. I took off the Linear EGR... looked ok but blewe er out with carb cleaner and did the same on the tubes.. didnt see anything obvious - in fact all looked really normal.. some carbon but I;d expect that.. re-installed with a new gasket and .... same pining at 50-60 and then acceleration... I belive it only does it in second gear actually...It sounds just like the timing is out but I understand this is all governed by the overhad cranfshaft and MAF.... not the sort of thing you get out the timing light for and I guess I'd have a hard time finding the distributer.

so... can you point me to something else... my gut tells me if I ran the expense gas... or the MORE expense gas that would fix it...

what about the MAF - is there something there a pretty handy guy can clean or have a look at...

thanks my man- Im appreciate it

Greg from Langley BC Canada...

ChemMan · #15 06-19-2007, 11:01 PM

MAF is easy to clean. Remove the 4 screws holding it in the throttle body and inspect the little wires that make up the sensor for dirt, contamination, etc. I've used a little spray of carb cleaner to remove gunk from the wires. Then just reinstall.

Just out of curiosity, does the car use oil?

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