Rb25det Chug Chug

[wgoos]

I have an R33 RB25DET, in the last 2 weeks or so its been making a 'chug chug chug chug' noise and losing quite a bit of power on and off (sometimes it runs fine) this mostly happens when excelerating but still does it on the freeway etc, its much worse when excelerating tho, anyway my first thought was i need a new ignition lead, so i started up my car & let it idol till it started chugging then pulled each plug out of each coil pack one at a time while it was still chugging & it would lose a little bit of power each time, i got through all 6 of them and realised it lost power every time i done it so it is certainly not my lead, coil packs or spark plugs otherwise there would of been one that didnt lose power, i dont really know what else it would be, the chugging sounds exactly the same as when u disable a spark plug (when its running fine) does anyone have ANY ideas?

[lachlanw]

air leak

[wgoos]

oh yeah i can see how that would happen, where should i look? and how can i tell where an air leak would be?

[Panko]

Vacume lines maybe cracked such as boost vacume lines, also there's a vacume line from the intake manifold to the fuel regulator diaphram, that need to be check as well.

[wgoos]

i pulled appart all the piping and re-aligned everything, done the pipes as tight as i physically could, car was running like a dream for about 20 mins then i brought it home let it sit for a while then started it up & it was shaking again, this time i checked the vaccum line that is connected to the BOV that seems to be working fine i tested the suction with my finger, im not sure where to find the other vaccum line? where is the fuel regulator located & where does the vaccum line connect to the intake manifold? if you have a pic that would be really helpful. thanks

[wgoos]

i found another 2 vaccum lines on the front & side rear of the head that run under the head past the radiator and into a plastic unit near the pod, these 2 vaccum lines and the vaccum line that goes to the BOV are all working good and have no holes for boost leaks, all my piping is tight i went through and pulled it all out and put it all back in again tighening every hose clamp i could find, i also inspected every rubber elbow to see if there was cracks or anything, alls good. so im still questioning whats wrong with the engine i've ruled out an electric problem and a boost problem. any other ideas?

[On Edge]

i wish my 33 actually was a v8 lol

[wgoos]

ha yeah, but that doesnt help me with my problem unfortunately.

[HEKT1K]

can you hear any loud hissing noises that sound like an air leak? for your car to be running so poorly it should be fairly obvious when you listen under the bonnet with the engine running.

check your boost gauge line, on the back of the inlet manifold (the one held in place with clips).. i've circled it for you

it's probably not your fuel pressure regulator (below and to the left of your oil filler cap) because your car would be running much worse if this line was broken.

good luck!

[wgoos]

i've been trying to hear air coming out but its just the sound of the engine chugging away, i've checked all the vaccum lines that go to the back of the inlet manifold there is 2 nozzles one has been blocked by a screw and the other one goes around to the BOV, there is one vaccuum nozzle going into the side of the inlet manifold (on the inside) that goes around to a plastic gadget between the pod & radiator & there is also another nozzle at the front of the inlet manifold that also goes to the plastic gadget, i've taken every vaccum line completely out and tested them for leaks, im pretty sure there is no leaks im starting to think maybe the car has a different problem..

its fairly obvious that the car is not running well from the rear all i hear is putt putt putt like there isnt a constant flow of exhaust it sounds more like its coming out in sections, when i rev the car it does the same thing but faster and the whole engine shakes, then if i leave the car for a few days it will run completely normal and after about 20 mins it will start doing it again backfiring from time to time.

im not sure if i've already checked the boost line with the clips as you say, i'll have to check this out tomorrow im pretty sure everything that has air flowing through it i checked today tho..

thanks for all the info.

[wgoos]

i checked out everything, still couldnt find anything, i did however let the car run for bout 20 mins, it was running alright, not shaking so i took it around the block, when i got home it started shaking on idle, i got back in the car & revved it a little and noticed the oil pressure guage was going up and down when i was revving it is this normal? is there any change i could of blown a head gasket? i have found traces of oil inside my air pipes.

[Socrates]

Oil pressure gets higher as you rev faster, happens on my car.

[wgoos]

yeah but my oil pressure doesnt sit in one spot, my oil tank is completely full because i changed my oil this morning so it should be peaking but after 20 mins of the car idling the oil pressure dropped from 3/4 up the guage to not even a 1/4 it constantly drops when i rev it goes back up but slowly goes right back to the bottom again.

[Kujotk]

on my car ive had an air leak (when i forgot to but a large rear pipe back on after pulling it appart) and a coil loom that wasn't clipped in properly after a mechanic changed the spark plugs. in my experience and depending which hose is faulty the cars idle will not be smooth, feels like stalling when in idle for a while. running on 5 cylinders makes the car sound like a wrx and it looses heaps of power, car will shake a bit aswell. Have a look at the coils, the connections, spark plugs, if it only does it sometimes it sounds like something is loose (without looking at your car or whatever, make sure the connections for the coils are not just connected with the clip, but make sure the mettal parts inside the connection are actually touching properly)

[wgoos]

on my car ive had an air leak (when i forgot to but a large rear pipe back on after pulling it appart) and a coil loom that wasn't clipped in properly after a mechanic changed the spark plugs. in my experience and depending which hose is faulty the cars idle will not be smooth, feels like stalling when in idle for a while. running on 5 cylinders makes the car sound like a wrx and it looses heaps of power, car will shake a bit aswell. Have a look at the coils, the connections, spark plugs, if it only does it sometimes it sounds like something is loose (without looking at your car or whatever, make sure the connections for the coils are not just connected with the clip, but make sure the mettal parts inside the connection are actually touching properly)

I know what you mean, I had the car running in the "chug chug" state and pulled each of them clips out then back in again one by one and the cars power would drop a little bit more each time, so it would go from low to lower (almost to stalling point), they all dropped more power while the car was running bad so this tells me that it has to be another problem otherwise one of the clips wouldn't of changed the power. Hope that makes sense.