acceleration knock

[iBoostDSM]

Last night I went for a little cruise and while accelerating in 4th gear it sounded like something popped off, it was right by my house so I got home opened the hood and it was idling really bad. It would drop down to 500rpms or so, wideband would read --- and DSMlink read 20.0 afr. Then it would save itself and go back up to 1500rpms. When it dropped down I could hear a knocking pretty loud and knock very fast. Found out that the honeycomb in the MAS fell down. Fixed it and it was fine, didn't drive it again that night.

This morning went to start it up for school, perfect start up and idle. Got on the street and the acceleration was horible, plus the addiction of a knock, did not get faster with rpms though, at least I don't think so. DSMlink read 12 deg of knock. Got back home right away, didn't knock at idle light last night with a perfect idle. What is it?

 

[BigBeans]

Could the maf have been damaged?

What are you getting on the wideband when you're seeing all this knock? Are you hearing a mechanical knocking noise, or the sound of detonation?

 

[iBoostDSM]

The wideband was reading around 17.0. Sorry a little noobish but what's the difference in the sounds of a mechanical noise and detonation? It was more of a clunking. I'll check the maf when I can, I'm at school.

 

[Tanro]

I don't think your going to hear knock (detonation) the ecu will pull timing before it gets to that point.

Are you having any noticeable performance issues? That would indicate the ecu is pulling timing.

If your hearing a banging noise it would be hard to identify without a video/audio file.

Sounds to me like you have a massive boost leak, or you MAF is ####ed if your running lean enough to knock that bad.

 

[iBoostDSM]

My logs have been showing my timing going wacko. For performance just horrible acceleration and stuttering. Didn't do much becasue of that so didn't find any other performance issues.

I do have a little video I will post when I get home along with a log.

Ironic because I was just fixing a boost leak, but it did sound like something popped of while I was driving. I'll test today. My MAF has always been fine. Any ways to identify if it's bad?

 

[BigBeans]

If you're wideband is reading 17.0 under heavy acceleration you are WAY lean (should be in the 10s on a stock tune, no leaner than 11.5 on pump gas), which will cause knock and engine damage.

Do you have DSMlink? If so what were you seeing for airflow when the car was healthy? Now?

At first glance, it seems like something threw your MAF way off.

 

[iBoostDSM]

I didn't dare go to heavy acceleration, highest was about 30% throttle.

I do have link but got it about a week ago. Not sure what airflow was and is now. My care has never been fully healthy , always had leaks I can't seem to find.

 

[BigBeans]

I didn't dare go to heavy acceleration, highest was about 30% throttle.

I do have link but got it about a week ago. Not sure what airflow was and is now. My care has never been fully healthy , always had leaks I can't seem to find.

Was the car starting to make boost when it was starting to knock or no?

Can you post a log?

 

[iBoostDSM]

I guess my log didn't save or I can't find it, anyway I never got into boost so no.

In all my logs it shows my timing going crazy! One second it's at 5* then 12* then 6*.....so on and so on, and sometimes it gets really high. Could that be causing this? I took of the cover today and found my timing marks appeared to be a little off, I didn't make them top dead center but I could tell they were off.

I also checked for leaks, and the only one I found was a little one coming out the dip stick.

Whatever happened it's fixed, for now. I did a boost leak test found a little leak in the dip stick, fixed that. No more I could find. Went to drive it and it was bogging and stuff for about 1.5 miles or so will 12.7 deg of knock showing up in every gear then all of a sudden it was gone and pulling hard. I did change the TB yesterday, maybe it needed a little break in I don't know but it's gone.....for now.

 

[BigBeans]

I guess my log didn't save or I can't find it, anyway I never got into boost so no.

In all my logs it shows my timing going crazy! One second it's at 5* then 12* then 6*.....so on and so on, and sometimes it gets really high. Could that be causing this? I took of the cover today and found my timing marks appeared to be a little off, I didn't make them top dead center but I could tell they were off.

I also checked for leaks, and the only one I found was a little one coming out the dip stick.

Whatever happened it's fixed, for now. I did a boost leak test found a little leak in the dip stick, fixed that. No more I could find. Went to drive it and it was bogging and stuff for about 1.5 miles or so will 12.7 deg of knock showing up in every gear then all of a sudden it was gone and pulling hard. I did change the TB yesterday, maybe it needed a little break in I don't know but it's gone.....for now.

When you do a boost leak test, you should rotate the engine to 30* ATDC so all the intake valves are closed, so no air goes through the engine, because you're only trying to test the intake system.

If it comes back, record a log and it'll be easier for members to help you.

 

[iBoostDSM]

Never knew about rotating the engine, how would I go about doing that?

Drove to school today and it still had a little bog and it showed 12 deg of knock right after I got passed 2500 rpms. I also had an idle of 17.5 to --- afr. I'm guessing that could be some sort of leak somewhere. Also my front o2 sensor is dead. It doesn't cycle and reads 0 volts. Got a new one coming soon.

I'll get a log on the way to school tom.

 

[BigBeans]

Never knew about rotating the engine, how would I go about doing that?

Take a 1/2 inch ratchet w/ a 6" or so extension, turn the steering wheel all the way to the left, and you can put the extension right into the crank pulley in the wheel well without removing anything.

Use the timing marks to guesstimate about 30* ATDC. It doesn't matter if you're off a little, all the valves will be closed.

Try to get a log when the car is running well and when it's having issues so we can compare.

 

[gho5tone]

Don't forget to rotate only clockwise.