I was driving on the highway to break-in some more mileage on my rebuilt motor. The car was fully warmed up and I was crusing in 5th gear around 3K rpm.

Now all of sudden, the exhaust noise suddenly changed tone and the engine was bogging on me around 3K rpm while the exhaust pops violently under slow acceleration. I let go of the throttle and slowly made my way towards the nearest exit, the bogging was really bad under 3K rpm, the car hesitate to rev up & felt like something is choking up the exhaust.

From the wideband reading, the A/F suddenly became very lean (16 ish) under 3K. This is strange because my car has been street tuned for 14.5 partial throttle and settings have not been touched since. I double check my fuel/ignition map on my EMS and confirmed the settings are the same.

However, it drives normal again when giving it about 30% more throttle and bring the revs higher. But with lighter throttle like 15 % or less it starts laging/popping/backfiring pretty badly. The noise is rumbling like what you hear from a washing machine.

It sounds to me like fuel related problem. The things that came in mind are fuel filter (which was replaced 8 months ago), cap & rotor (with less than 20K), plugs (heat range -7 w/ just over 2K), injectors (RC with less than 10K).

Im kinda loss as to what may cause this, if anyone else has run into the same problem would probably have different setups as me.

From memory, one time when the motor was cold, sat outside for 3 hours or so, it bogged down heavily under acceleration, until it fully warms up. So I knew from that time to let the car warm up first, and so i did. But now it looks like there's more related into this problem.

 

Any chance it is timing related? Could be the distributor, wires or plugs.

 

Your exhaust could be plugged.

 

Im running standalone so timing shouldn't altered. Plugs are new, don't think its the wires. Distributor has 120K, should still be in good shape.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hu &raquo;</TD></TR><TR><TD CLASS="quote">Any chance it is timing related? Could be the distributor, wires or plugs. </TD></TR></TABLE>

 

Funny you mentioned that, my sard muffler has an internal silencer which I thought might have clogged up for some reason. Im gonna try some WD40 to see if that makes any differences.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by amckee &raquo;</TD></TR><TR><TD CLASS="quote">Your exhaust could be plugged.</TD></TR></TABLE>

 

are you throwing a CEL ?


Sounds to me like you might have a vac leak. Did the exhuast note change considerably and sound more like a boat? pop the hood and fire up the car and listen for a loud hissing, or have a friend rev it and hold it at 3K while you check things out.

Usually with a large enough vac leak the car will throw the IACV code.

 

Would AEM EMS even throw codes though?

 

There's no CEL/code as Im running AEM EMS.

You're dead on about the exhaust note, it changes tone all of a sudden and sounded like a boat.

Vac leak is a possibility, I'll double check and see.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98TypeSH &raquo;</TD></TR><TR><TD CLASS="quote">are you throwing a CEL ?

Sounds to me like you might have a vac leak. Did the exhuast note change considerably and sound more like a boat? pop the hood and fire up the car and listen for a loud hissing, or have a friend rev it and hold it at 3K while you check things out.

Usually with a large enough vac leak the car will throw the IACV code.</TD></TR></TABLE>

 

You would have to have a pretty big leak to cause that kind of performance issue.

 

Last night I checked the four vaccum hoses connected to each runners on the ITBs were still intact. I would have to look elsewhere tonight for a possible leak. Which location would be a good start from this point?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by amckee &raquo;</TD></TR><TR><TD CLASS="quote">You would have to have a pretty big leak to cause that kind of performance issue.</TD></TR></TABLE>

 

Some guys spray choke cleaner around hoses and and gaskets and look for the engine to stumble. I like to start with a cold engine and run my hand around everything and listen for a change in pitch. If you have a leak you should be able to hear a distinguished hissing . You might want to just unbolt the exhaust manifold at the first joint to rule out a cat or muffler blockage.

 

I can rule out the cat because Im not running one. It could be the internal silencer in the muffler so I will check that out, along with the possible vaccum leak.

I will get a fuel injection cleaner as well just to make sure the injectors are not clogging up.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by amckee &raquo;</TD></TR><TR><TD CLASS="quote">Some guys spray choke cleaner around hoses and and gaskets and look for the engine to stumble. I like to start with a cold engine and run my hand around everything and listen for a change in pitch. If you have a leak you should be able to hear a distinguished hissing . You might want to just unbolt the exhaust manifold at the first joint to rule out a cat or muffler blockage.</TD></TR></TABLE>

 

You are running ITB's correct? So the thought of an intake manifold gasket leaking is out, along with the IAB gasket or TB gasket. No IACV or anything else that can cause it...... This is a toughy. Do you have some type of VAC manifold ? Try spraying some carb cleaner or something that wont hurt wires/vac lines in the suspected areas. If you see excessive bubbles or hear gurgling thats the problem. An exhuast leak after the header would not cause any sort of bogging. It would just be loud and you would see a loss in performance as well as a lean condition ( maybe, not in all cases ) the bogging/hesitation is leading me to believe its a vac leak from a line in the enginebay some where. retrace all VAC lines and double check nothing is getting pinched,torn, or is disconnected.

 

You're right, there's no IAVC and the only gasket I have on the intake side is the hondata IM gasket.

Im using golden eagle vac manifold for the ITBs & brake booster, I'll double check on that & the hoses with brake cleaner later on.

And there's only one O2 sensor for the EMS, so there're only a few things that is causing this. I cannot relate any previous threads to my problem because none had the same setup as me.

Hopefully its something simple.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98TypeSH &raquo;</TD></TR><TR><TD CLASS="quote">You are running ITB's correct? So the thought of an intake manifold gasket leaking is out, along with the IAB gasket or TB gasket. No IACV or anything else that can cause it...... This is a toughy. Do you have some type of VAC manifold ? Try spraying some carb cleaner or something that wont hurt wires/vac lines in the suspected areas. If you see excessive bubbles or hear gurgling thats the problem. An exhuast leak after the header would not cause any sort of bogging. It would just be loud and you would see a loss in performance as well as a lean condition ( maybe, not in all cases ) the bogging/hesitation is leading me to believe its a vac leak from a line in the enginebay some where. retrace all VAC lines and double check nothing is getting pinched,torn, or is disconnected.

</TD></TR></TABLE>

 

id advise against the brake cleaner on VAC lines or any electrical wires. A little bit to harsh for normal rubber lines... carb cleaner would possibly be ok.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98TypeSH &raquo;</TD></TR><TR><TD CLASS="quote">id advise against the brake cleaner on VAC lines or any electrical wires. A little bit to harsh for normal rubber lines... carb cleaner would possibly be ok.</TD></TR></TABLE>You really have to pay attention to the chemicals in each particular brand. Gumout brand brake cleaner, for example, is identical to carb and choke cleaner. Vac lines will be resistant to any of the sprays but the wiring and wire wrap would not be if they are PVC based and that would apply to the carb cleaner as well if it is methylene chloride based.

 

I can't seem to find any leak anywhere, the only possibility now is the exhaust internal silencer is acting up and choking the exhaust gas at times. I will get a new muffler welded later next week.

However, tonight as I was checking up my spark plugs I found something strange.
Here are the pics: https://honda-tech.com/zeropost?cmd=fshow&id=4

I'm thinking now the ignition has something to do with that.

 

i dont see any pics. what color is the tip?

 

i seem to be having the same problem as you as at the moment. i changed just about everything dealing with ignition. still rides like crap and my idle sucks. my engine code came up and showed a code 4. crank angle sensor. dealing with the dizzy. i think its time for me to get a new dizzy. most likely the reason my car has been misfiring and backfiring alot. fixing this thing tomorrow and i'll see if my car still bogs out or messes up cuz we could be on the same boat here.

 

I can't see the pics, but IF your exhaust is plugged it would probably cause the plugs to look a little funky. Maybe you ought to crack one of the exhaust joints loose and go for a drive before you buy a muffler (unless you were going to get one anyway).

 

I have rehosted the pictures again with a different server:

The plugs have only been used for 2500km.

From left to right, the plugs from cyc #1 & #2 is identical. But #3 seem to have coroded, where as #4 is totally rusted.

Also the #4 wire is covered with yellowish dust. It looks like water has went in there and causing surface rust on the bodies of the #3 & #4 plugs. Could this be it?

 

Doesn't look good. What does that stuff smell like?

Looks like you don't have the metal "gasket" on the spark plugs from cylinders 1 and 2 - 3 and 4 you have them on though.

 

^The metal gaskets are still intact, just the corrided so badly from the moisture that you couldn't tell.

I still wonder how water could get in like that. Yes I have washed engine bay before, but it would be pretty hard for the water to leak under the plug wire cover then go in again from the wire cap and leak down the plugs.

Does it look like the moisture have fouled the #3 & #4 plugs enough, so it started to misfire and bog out on me?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by VSBB6 &raquo;</TD></TR><TR><TD CLASS="quote">Does it look like the moisture have fouled the #3 & #4 plugs enough, so it started to misfire and bog out on me? </TD></TR></TABLE>

Bringing this back cuz I'm pretty much having the same problem. Did you figure what the problem was?

My car bogs until it completly warms up and then drives fine. I got new wires/plugs/cap and rotor and waiting on a new distributor. And my gas mileage is suddenly horrible from this.

 

checkt the egr valve and it might be clogged up with carbon thus making it stick open.