I experienced some bogging @ WOT around 5K rpm, then it got a bit smooth, then more bogging right around 7K rpm. I bang 3rd gear, and more bogging, accompanied by a audible "pop" that was not coming from the exhuast, but from somewhere in the engine bay.

I pulled over @ a gas station to check things out, and smelled a hint of coolant. Temps outside are close to freezing point(0 degrees F, with the wind chill into the negatives). Checked for leaks, and found nothing. Checked my oil level, and it seems fine. Checked the coolant level and it seems fine, although I didnt open up the tank, just a quick visual look @ the marker.

Mods include turboxs mbc running about 20 psi @ redline although there were spikes to 21/22 when I punch the gas before it settles @ 19/20, dynoflash, and rmr cone filter.

Im wondering if its a case of bad gas. One person I talked to suggested it maybe the stock bypass valve going bad. But if thats the case, would the loud popping be coming from that too?

I had a friend stay behind my car while I punched the gas to see if there is any hint of burning oil. He said that when I went WOT, it was black smoke coming out. Possibly bad plugs? Its very late, so I figure to ask you guys what the possibilities are before I do some checking up tomorrow.

TIA.

Ken

 

you popped a hose somewhere

 

oops double post

 

I hope that is true. The reason Im still up in the air about it is that I drove home after doing the WOT tests, and it was a good 15 miles back to my house. If I drive regularly at partial throttle, or even 75% throttle, it seems fine.

Ken

 

I popped a sensor hose once .. and it stutters and bucks and spew black smoke once the boost hits around 0.5bar didnt even dare to go WOT after that ..

then I popped the IC piping .. car just bucks and jerks and refused to move faster than 10mph

 

Hmm sounds like timing retarding... overboost? Slightly blown gasket?

 

No apparent overboosting problems that I notice. How can I check about a "slightly blown headgasket"?

Ken

 

ok... is this what you feel when you are accelerating..

3rd or 4th gear, RPMs moving up rapidly.. then pausing for a moment and continuing to move up again...

If yes, it sounds like your engine is retarding ignition timing (due to knock).. i get the same problem...

If no.. is this how it does it?

same gears, RPM moving up rapidly.. then suddenly shooting up (like its being declutched) and coming down to resume its upward movement?

If yes.. sounds like your clutch is slipping...

Other than that... the only other thing i can think of is that you are running too rich... (one of the reasons why you hear the pop in the exhaust as unburnt fuel gets pass the CAT and exits the exhaust)... try run the car on a dyno with an A/F meter and see what readings you get... most stock evos run as rich as 10.9:1 at the high RPMS.. are you getting the same or higher (lower number) than that?

 

A slipping clutch is definitely out of the question.


Yes, as you described regarding timing retard sounds similar to what is happening. But I still wonder what the popping noise I heard is. I was thinking it may have been audible detonation, but it was more of a pop, than a sound of marbles as some may have described.

Btw, when I got tuned by Al with the Dynoflash, he tuned my A/F pretty conservatively. Here is my dynosheet and A/F.



Im wondering of a combination of bad gas, cold weather, and 19/20 psi @ redline is causing my headaches.

Ken

 

Sounds like you're running really rich to me. Are you sure the pop was not the exhaust? If you're sure it was under the hood, sounds like an IC hose? Are you still boosting?

 

High resistance in the the secondary ignition coil.

 

Ah ha!!

From your dyno charts.. you are retarding timing.... a perfectly tuned curve is even (almost smooth) and does not have the dips... those dips are caused by the ECU retarding timing when it detects knock.... look at mine.. and from what you are describing of bogging at 5k and at 7k.. its consistent with the chart u put up... better tell your tuner to redo it... get him to do a smooth curve... if not, you keep experiencing the same thing...

 

This is my boost and a/f

 

Where is Al when you need him. Hopefully it's not the tune cause it wouldn't be good for Al's bussiness. Call Al and see what he thinks.

 

Kenny,
stop using those octane boosters, sometimes they create deposits on the plugs. Your problem sound like its a misfire, if you hear popping then its misfire. A timing retard is almost not noticable, in other words it will feel less powerful but not a dip at a certain rpm. Also, you may have water in the tank. Change that pump asap, its cheap insurance . Laterz slowboy, lol,lol.