Problem 1, Situation:

Cruising on the freeway in 5th or 6th gear at a low RPM. No boost built up at all. If i go WOT right away (floor it) from around 2-3k RPM the car will hesitate VERY bad and jolt and i guess "sputter" about 4 times then will be fine to redline. If i slowly go WOT instead of just floor it, the car will be fine and not sputter but thats like 5 seconds of rolling on the throttle until i achieve WOT. What can this jolt/sputtering/backfire be caused by??

Problem 2, Situation:

Another problem I am having is my RPMs staying up when shifting. When i shift at a low RPM when i am not boosting the car will shift fine. When i shift around 4500-redline when boosting the car will rev up in between shifts. I have tried so many different ways of shifting but it is a problem that cant be fixed unless i let off the gas for about 1 second, then push clutch in, shift, and gas again. If i dont let off gas for a second, and clutch/ get off gas at the same time it will rev up about another 1k rpms. What would cause this?

to help out my current mods are:
2005 Evo 8 MR, JIC titanium catback, RMR 3inch Downpipe, Stock Cat (for now), APS twin vent BOV.

I thought these problems were caused by the BOV but it does it with the APS twin vent BOV and the JDM evo 9 BOV.

Any input would be very helpful. Thanks.

UPDATE:

I couldnt take the problems anymore so i decided to put the stock DP and stock BOV on and problem went away, well most of it, still back fires a little at WOT through all gears. I guess the DP was just causing over boost or fuel cut and that was causing the miss fire. The clutch was checked out and IS bad! Currently being replaced at the dealer.

 

Problem #1 is from your engine knocking from the high load and most likely pulling timing. I've logged this myself and low rpm/high load is a bad combination. Try a lower gear or like you said, gradually tip into the throttle to avoid this.

 

sounds like your maxing ur fuel pump and hitting fuel cut- most likely
could also be your plugs are gone or need to be gapped tighter, or your cat is clogged

 

also the hanging rpm can be caused by the clutch delay valve which u can either remove or by a cheap stainless steel clutch line - or your clutch is going

 

For problem 1, its either fuel cut or misfiring. Im gonna go with misfiring.

 

Problem 1: First i would check your spark plugs they may be fouled or not gapped right, that could be the reason your misfiring

Problem 2: I have the same problem with my Subaru, when i shift sometimes the rpms jump a little. Your clutch could be the problem, but before you go spending money check your clutch out by going on the highway getting in the slow lane and putting your car into 6th gear drop the rpms down to 2-2.5K and then floor it. If your rpm climb steady your clutch is if not your clutch is .

Before you do the clutch test check your plugs and also look to see if any hoses or your I/C pipes are not connected right or leaking

Hope this helps
Tom

 

car seems to keep getting worse and worse at WOT so i am not even going WOT anymore until I get the car in to get checked out. Any other input on this problem??

 

1) change plugs (i would also get better wires as stock ones suck).
2) obtain larger fuel pump.
3) get a 3" cat.
4) TUNE that ****!!!!!!!!!

 

Bump. Thought some people might be curious to what the problem was and what happened.

 

same thing happenend to mine and it was bad plugs!!

 

I just had a similar problem with my Evo. My car would stutter at around 3-4K until redline. I thought it was bad gas from on base, but it wouldn't go away. The next thing I did was check to see if I had any leaks and I didn't. So the last thing I checked was the spark plug gap. I never even thought something so small could have caused my car lose so much power. Well it was too wide ( .045) it was supposed to be between .020-.023, after I fixed this all the power came back and it runs as strong as it did before.

 

bump for final result. So basically, the spark plugs fixed everything? im having the rpm jump problem after i put in the aps dv bov

 

anyone still dealing with rpm hang problem? Im beginning to think its my clutch but it holds strong at 5th gear full throttle at 3k rpm upwards. inputs anyone? could it be the clutch pedal engagement point?