JDM 4G63 won't rev past 3500RPM
 

Don't know which section to post this on, so here goes...

I recently changed the valve cover gasket on my 4G63T, while I was at it I installed a new cone filter. Now I'm having trouble revving the car past 3500RPM and I feel the engine stumble and shake. When I give it gas and let go the engine stumbles and dies.

I don't know what this could be, I never had such a problem before.

Help guys!

Is it smoking? What color is it? Does it smoke more or less when you rev it? Are you getting smoke from the engine compartment? Your belt is still attached and spinning? Any CEL or codes?

More info will help us identify the issue....

hey acidtonic, now that you mentioned it it does smoke when I rev it. It is a whitish/blue smoke and smells like unburnt fuel, I saw a slight smoke from the engine compartment yesterday after the valve cover gasket install but I thought that would be normal considering the oil spill around it. M belt is still attached and spinning, I have a CEL but no ccodes(i have no scanner)

Hope this helps

i believe blue means that it's running rich and/or burning oil, neither of which are terribly good.

if there's a shop near you, you should take it in and have them scan the codes for you

I would suspect the recent gasket work immediately, after that consider a compression check and leakdown.

I wouldn't drive it like this, you probably have inadequate cooling so any kind of strenuous driving might overheat and warp something. Check your coolant for oil, and your oil for coolant. Make sure your TPS is connected. On my mustang a rodent had chewed through the TPS sensor on the throttlebody. It threw a tps code, and started dumping huge amounts of fuel. It stank of fuel and I had to shut it down. After fixing the connection I had to flush the engine and change the oil.

Basically if it's running really rich like that and sputtering, you have a chance of washing the rings or diluting the oil and washing a bearing. Get it looked at if you aren't proficient since you have much to lose. Good luck.

(EDIT: also, sometimes a leaking PCV vacuum connection will make it want to die and shake real bad. You might have a leak too, but the smoking worries me)

Check the plug to the MAF sensor, you probably forgot to hook it back up...

did you put your MAF sensor on the wrong way?...sounds like it to me.

hey guys, I have tried almost everything regarding this problem and now I have managed to get the engine to stop dieing after hard acceleration buy changing the Fuel Pressure Regulator but I'm still getting rough idle and black smoke at 3500RPM. This is feeling like a fuel supply/pressure related problem now I am considering changing the fuel injectors and MAF sensor to see its reaction, I will let you know how this all works out.

I forgot to mention this before, but I had recently(before the gasket job) installed a Walbro 255 fuel pump.

plug mas in..

Maybe it doesn't like the filter you installed. Try the old one.

make sure your spark plugs are plugged back in as well

hey guys, I finally figured out why my Evo was choking and not revving past 3500rpm... Somehow the Simota Cone Air-Filter was restricting the flow of air to the engine, the MAF was not seeing enough air flow especially when the car was stationary. I removed the air-filter and switched the car ON and what do you know...its breathing again!!! Now I guess I will have to put back everything that I changed(including the injectors and fuel pump)...

Thanks to all for your help:cool:

glad you figured it out, piece of advice, when fixing something do it one thing at a time. If you would have done the valve cover gasket, then drove her around for a little and noticed everything was working just fine, then done your cone,,, you could have limited the factors down to one.

otherwise you go replacing things that arnt related to your fixes and mods