pinging/chattering after cleaning out EGR

[porschpow]

This is weird, I took off and cleaned the EGR put it back on now I hear it pinging (especially right after gear changes under a load). I have read a few threads about this and it always seems to tie back to the EGR system. I tested the EGR diaphram by blowing into to it to see if it still keeps the vacuum, and it does.

Any idea what gives?

On a side note, I also changed the crescent valve and even though it works now, I still hear a little hiss coming from under the dash (if I put my head under it. Is that normal???

[sly]

it may be leaking air at the EGR gasket or possibly some build up in the EGR channels fell off and is holding the EGR open.

The crescent valve should leak in P/R/N and seal in all forward gears to pull the brake release.

Also, check the other vacuum lines to make sure nothing got broken/disconnected in the process.

edit: check your MAP sensor first. read your other post and that is most likely the issue.

[porschpow]

10-4 on the crescent valve

That's what I have been doing. Looking for leaks, and I got nothing?!?!?

Ill slap on a new gasket, but I tightened the old one down pretty tight!

I took off the valve and was pressing it in and out, doesn't seem to be stuck or close wrong. Closes ok!

[porschpow]

Perhaps its a bad MAP sensor, how do I test the MAP out?

I did have a code 22

[sly]

well... apparently oldfuelinjection.com is down because the guy isn't paying attention to his domain (nothing new there)... so archive.org it is...
https://web.archive.org/web/20131229...tion.com/?p=27

If you have a multimeter with a Hz setting (like mine has) or an oscilloscope, you can backprobe (poke the pointy part in next to the wire through the rubber guide down to the contact) the map harness and see if the reading changes from key on engine off to key on engine running and see if it's in the ballpark of what it should be. If it doesn't change or is erratic, change it. Or just change it and see if it works better with a new one.

[nfldfordltd]

Sorry to thread jack here, but where can a guy get a new crescent valve? I need one for my 88 Town Car. It reminded me when I was reading through the thread, lol.

[sly]

I got my last one at Autozone. I know Rock Auto has them.

[porschpow]

yeah autozone.


My car has still beeen doing the pinging, nto as bad as it used to, still under the same conditions??

Could it be the coil? The timing chain???

[gckeene09gm]

Pinging is caused by higher than normal combustion temperatures. The EGR operation assists in reducing these temps. Therefore your valve is probably not opening now. Check the valve's control system.

[porschpow]

it's more of a chattering noise if anything.

I cleaned out the valve and tried opening it. It does open, what else could I check in the system?

[sly]

if it's the normal valve train chatter, ignore it. the stock rockers and valves and lifters and such make a little noise after a good while, but they don't go bad unless something really bad happens or they get oil starved.

you should hear my 88. damn near sounds like a diesel engine first thing in the morning.

[porschpow]

WOW, lol but mine doesn't do that until i have been driving a lot (20-45 mile drive)...this chattering fiasco

[sly]

hmm... that's different.

[porschpow]

yeah, it's weird. I narrowed it down to timing chain or EGR

[gadget73]

check it for codes to see if the egr is working now. It may not be. The computer adjusts timing based on EGR function though. If it detects the valve opening, it advances the timing more. It has no idea if there is actually any flow though. If the passages are plugged but the valve opens, it may do this. Apply vacuum to the valve and see what happens. The engine should stall or run very poorly. If it barely makes a difference, your EGR system is plugged up and not working. Only fix is either pull the intakes and try to clear it out, or cap off the vacuum line so the ECM doesn't try to open the valve and over-advance the timing. Pinging will melt the pistons, so you don't want it doing that.