asking help for my cousins qr25de...

[Roger_cha]

as the title says my cousins bought a sentra ser spec v with a qr25de 6 speed. he has a straight pip with no cats. it seems like his engine is burning oil because its blowing black smokes out of his exhaust and he has to top off oil every 3 or 4 days. we add the no smoke with stop leak in it no help did compression check on each cylinder and its good he gets 215 on all cylinder, can someone help us because its getting worst please.

[Roger_cha]

any tip will help thanks.

[spec_v03]

How's the coolant look? If level drops it could be HG, but QR25s are known to guzzle oil, mine drinks ~2.5qt every 3k-4k miles. Black smoke is unburnt fuel, mine shoots out a puff when i stomp it too, they run rich from the factory. If that bugs you get a SAFC and correct the a/f mix yourself.throw a peice of cardboard under the engine overnight and see if its dripping oil.if not, i would guess he suffered from precat failure, headgasket on its way out, or piston rings, those are the most common oil burning problems with specs.also, redo the compression check just to be sure. perfect comp for the QR25 is 180ish, dunno how you'd be getting 215...

[Roger_cha]

there is no oil leak we checked it and coolant is good.. it doesnt have the 2 cat, it has an aftermarket ebay header with straight pipe no cat and it has an ebay intake. the thing that i can think of now is probably the valve seal is bad, but not sure, it blows out alot of black smoke like its burning oil. like i said he have to top off about 1 quart of oil every 3 or 4 days, now thats alot of oil..

[eddlc15]

Im guessing your cousin bought the car used?? i agree with the precat failure with the past owner(s) and maybe yr piston rings are going out...

[Roger_cha]

well ill do the compression check again to get an accurate reading... yea he bought the car used from a private dealer and that dealer is a s*** hole cause he back down his word on fixing the car. i know it can't be the piston rings cause the car runs fine and has alot of power just like my friends spec v which is stock but only thing is his is blowing out alot of black smokes.

[VMPhil]

the engine may be toast on the account of either the Precat failure or an eaten butterfly screw. either one of these can cause scored cylinders and oil consumption. I would talk to a Lawyer about this.

[Roger_cha]

well i did the compression again and this time i get a reading of 180 across the cylinder, when we first did it we didnt warm up the engine up completely we just let it run for 5 min and just did the compression this time we let it run for almost an hour before we did the compression...

but now we run to another problem he accidentally miss shifted and redlined and now the car wont rev pass 2500 rpm, the engine check light isnt on too so im thinking that it might be the throttle body that is bad but not sure

[Roger_cha]

his car dont have any of the 2 cats in it when we bought it, it has a dc header and a straight pipe. we check the screws on the butterfly they are all tights and not loose now my only option is that the valve seal is bad but i havent check inside the intake to see if there are any oil in it.

[nametakennow]

The ECU is in safe mode. That's why you can't go past 2500rpm. I suspect you could reset it by leaving the battery unhooked overnight, but grab the FSM and take a look at the official procedure.

When did he buy it? Did he buy it with the header and straight pipe on or did he add them afterwards? Could be that the precat failed and, rather than replace the engine, the previous owner covered it up by replacing the header.

[Roger_cha]

ill tell him to give it a try to see what happens on the ecu. as for the header and straight pipe yes he did bought it like that he bought it like a year ago from today from a private dealer which it didnt pass smog so the dealer order the stock header that has the cat on it and it pass smog then after that we put on back the ebay header.

[Roger_cha]

well we try to reset the ecu over nite and left it unhook for 12 hours and no go still the same is it possible that the ecu might be bad. we swap out the throttle body and still the same wont rev pass 2500 rpm.

[xru5tyx]

i would check the maf, same thing happened with my 240

[spec_v03]

I agree, B15s, especially 02-03s, are notorious for having the MAF crap out.try using spray MAF cleaner, and reset the ecu and do the idle relearn. if that doesnt work replace it.have you checked the butterflies? you say it happened when you redlined the car, butterflies open right before redline, its possible you ate a screw.

and the proper way to reset the ECU is to use a consult II, or use the pedal dance to get into diagnostic mode, then hold the accelerator pedal for 10 seconds until the CEL holds steady.

[Roger_cha]

well we found the problem it was the maf and the throttle body, we replace all that and it works fine now.