Blew a ring? Faulty coilpack? Buggy ECU? HELP!

[TBird713]

Well recently i've been having some major problems with my gts-4 with an rb20det that I THOUGHT ran good. Well now I've been getting a dead piston that only seemed to pop up after hitting like 5k rpm but now it seems to be all the time. My exhaust smells like an old golf cart and it sort sounds like a subaru >_< I'm almost positive it's a dead piston because the entire car shakes through the rpm range. When I slowly bring up the rpms you can hear it cut out and the car begins to make sounds resembling a chainsaw (but not so ear piercing). I was only able to test two coilpacks but the testing was not effective as the problem would cut out when i got under the hood and started up again when i sat down (gah) Some helpful hints would be lovely because I really need to know wtf is goin on before I end up doing more damage.

[evilgtr]

do a compression test.

[TBird713]

Doing that tomorrow hopefully so I'll post the results when I get em. What gets me though is that it runs smooth most of the time, but it'll **** out and kill a cylinder and IT decides when to work again. If anyone has a working RB26DETT /w trans that they don't want give me a hoot too :P (it's worth a try haha)

[DarkCaporaL]

Sounds like a classic missfire....figure out which cylinder stops working (by unplugging coilpacks when it's missfiring), check your plugs, check for airleaks.

There is a detailed thread on here called "Fix your hesitation", I would suggest going through it.

But yeah start with the comp test and go from there.

EDIT: This one: http://forums.gtrcanada.com/gts-tech...esitation.html

[TBird713]

Well didn't get much time this afternoon but i did test cylinder #1 and it gave me about 118-120psi. Car has 105,xxxkm on it so i dont think is really high enough. The battery is new and the engine was fairly warm. Only testing one at a time so it ran on 5 and tested on 1. Don't know if that advised or the easiest way but im no mechanic :P

[MarusGTR]

What's the whole board numbers? If they're all the same it's something else (even if yes, 120 is low)

[TBird713]

Well got 4 of em done now. So far it's 118-110(but got 60 the second time i tested so ill do it a third to make sure)-120-130-?-?. Seems like maybe the gasket is bad around 1 and 2?

[amnash]

should only take like 45 mins max to check them all, why are you doing the test in segments?

[TBird713]

A. I'm by no means a mechanic, B. There is a LOT of **** covering the coil packs and C. My car is 20 years old and is all stock. Everything is very stiff and some screws are almost rusted on. Did I mention I'm not a mechanic?

[cschepp]

Dude seriously don't let that bring you down! I'm no mechanic and will never be. I enjoy the simple fact of taking things apart and fixing them. Provides a sense of accomplishment. Anyways enough banter. If your either too lazy or just simply don't have enough time take it into a mechanic. They will charge you 100-150 for the job and then you will know wet and dry compression numbers.

[TBird713]

Well this thing has already cost me over 1000 bucks just to get it to this point. If I had a job that payed more than mine I would. But I don't. So I'll continue doing it myself. I just didn't want to be out there anymore cuz my legs were getting sore from my workout before. All I know is so far the numbers arent good.

[mob_skyline]

My RB25DET had less than your km you stated and when I did a compression test I had bad numbers as well. When removed the head, gasket seems ok but piston rings were literally broken and pistons broke as soon as they were out, right on time before damaging the walls. What really helped me is that smoke was coming out of the exhaust ....

[TBird713]

Hmmm. Well when I took out the #5 coilpack and tested it the resistance was 1.2ohms. normal right? What wasnt normal was the spring from the coilpack sitting in the well of the sparkplug. I think I have found my problem.

[MarusGTR]

Well got 4 of em done now. So far it's 118-110(but got 60 the second time i tested so ill do it a third to make sure)-120-130-?-?. Seems like maybe the gasket is bad around 1 and 2?

Make sure you warm up the engine first so that your rings expand and get seated. Then take each coil and plug out, make sure your injectors are unplugged (or your cas).

Do each systematically (really, if you did one I dont see why you cant do the others. 5 cranks each should be enough). And with all the plugs out you wont drain the battery much.

What wasnt normal was the spring from the coilpack sitting in the well of the sparkplug. I think I have found my problem.

Yeeeeeeeeeeeeeeeeah lol.

[TBird713]

Oh and my final results were 118-110-120-130-120-130 so I might get it opened up and get the rings looked at especially in #1 and #2 but as of right now it does run smooth and gets me places so im happy :P Cept of course when the spring comes loose and I lose i piston but i've already called nissan and requested the part