another blown KA

[esahuque]

Well i blew my motor tonight, need some opinion's

Lets start off by giving you the history. 95 240sx, bought the car with a cracked head and swapped the motor out with a 96 motor with 62,000 mi on it. Did a compression test and got 170ish across the board. So I went ahead and turboed it with a sweet t3/t4 turbo, 550cc injectors, enthalpy tuned ECU and a SAFC NEO all dyno tuned ( 11.5 at WOT). This morning i started my car and it had a slight miss to it (sounded like i was driving a VW) and it was idling a little lean, about 16.2 when i usually idle a 14.7 to 14.9. tested a few sensor's did a boost leak test and check plugs and wires (PLUGS LOOKED PREFECT) couldn't find anything wrong. The only thing i wasn't to sure about was the voltage test on the n62 maf, wasn't sure what the voltage should be. It was 0.7v with the car off, 1.0v with the car at idle and 2.15v at 4000 rpm's. anyway i went ahead and took it for a spin, it was running at about 13.5 to 14.1 under light load and about 12.5 to 12.9 at WOT. So after i did my pass i let off the gas to stop at a light and it killed. It took a good bit to get it started again. after that it wouldn't hold an idle, so i limped it home and popped the hood just to find...........Oil all over the motor, I getting BAD blowby out my breather on my valve cover. I'm going to hopefully rebuild the motor, if i can but my Question is

How can i tell what caused this? i would hate to rebuild the motor just to find out that my tuned ecu caused this or bad maf ect ect... and blow the motor again.

just looking for some advice as in what to look for when i open up the motor in what may have cause this healthy motor to go out this fast. i only put 2000mi on the turbo

sorry for the long post, thanx in advance

Modified by esahuque at 10:31 PM 11/18/2007
Modified by esahuque at 11:06 PM 11/18/2007

[480sx]

It sounds like you leaned out a bit, probably because of the cold air and dammaged your rings. Your afrs were right at the brink of being unsafe.

This is why im going to run Meth..

How much boost were you running at the time?

Also you really should keep the PCV system intact. On your next build make sure you get an oil catch can, and hook that system up, its important.

[boznuttz]

What was your timing setup and how much boost were you running? If timing isn't retarded enough, higher afr's and stock or advanced timign can lead to higher egts and predetonation.

It's always sad to hear about a blown motor. Hope you get back on the road soon!

On a side note, how much can the PCV system affect a boosted setup?

[Florida240sx]

What psi where you at? Sounds like blown HG not rings. because oil is everywhere...I'm looking to order a new crate motor for mine. Had 2 engine build go bad so $2000 pissed away and 1 year of downtime I'm tired of sh!tty builders.

[480sx]

Well if your rings are cracked it will send the pressure that normally would be compressed into your head/block into your crank case, and then into your valve cover. Since he seemed pretty sure that the oil was coming from his breather, i made the assumption that he probably cracked his rings.

Boz, a PCV system is way more important in a turbocharged car than in a NA. Since your dealing with higher cylinder pressures, more gas can escape the rings. These gas's will wreck havoc on your oil, causing it to break down much faster than it normally would. Its so damn easy to run a PCV system, theres really no good excuse to not have one.

[boznuttz]

Except that it's easy as hell to replace on a SOHC as opposed to a DOHC. -.-

[Florida240sx]

I missed the part of oil coming out the breather. Yup cracked ringlands or rings bad. I blew 1st and 3rd out on mine

[esahuque]

yeah, i know i cracked my ringlands. the next thing is to figure out why i ran lean before i rebuild. it was dynoed tune with an enthalpy ecu and a safc, so it wasn't my tune. oh and to answer everybody's Q's i was running 12psi of boost, steady.

[coolbone28]

What fuel pump and injectors do you have? Also have you done a compression test? That will give a little more info.

[esahuque]

Walbro Fuel Pump with 550cc injectors. Did a compression test on a cold motor due to the fact that i cant start it, 75psi on all four cyl. spark plugs all look the same, no oil on any of them, just a little white from running lean.

[Jookmasta]

ur MAF thing intrigue's me....................

[Florida240sx]

IIRC mine was close to 4.... in upper rpm 19psi though...

[spooled240]

75 across the board is very low so i'd say your rings are gone aside from the oil coming out of your pcv system. can you test the maf to see if it's actually giving a signal?

about the pcv system, i just have a vented hose hanging, there's no oil coming out tho so i don't see how this could be problem for the oil??

[esahuque]

well, I'm ging to rebuild the motor with wiseco piston's 9:1 bored .20, felpro head gasket set and arp head studs.I'm on a small budget, do you think it will be ok to go oem on the rest of the build, main and rod bearings? I'm only pushing a little under 300hp at 12psi.

[esahuque]

i haven't pulled the motor apart yet but i know i cracked at least two ringlands from running lean. just looking at the motor i can tell i have oil leaking out ALL the way arounf the head gasket, which tell's me i ALSO must have a blown head gasket on top of cracked ringlands. i know that a blown head gasket can cause a rough idle and miss during driving (with i had signs of before i cracked my ringlands) but....can a blown head gasket cause me to run lean at idle all the way through to WOT?

and no i don't have water in my oil or oil in my water.

[480sx]

No, a blown HG will not cause you to run lean.

While you might have had your car professionally tuned, that doesnt mean they did it right. Enthalpy tunes come with a built in buffer zone for a safe AFR. What that dyno shop most likely did is take that buffer zone out to squeeze the extra 10-20 hp out of your engine. This is all fine and good until the temps change(you got your car tuned in the summer?), air gets denser than when you had it tuned and your car leans out. Your not the first person to blow an engine with Enthalpy and a SAFC. I think that Sunnys14 did the exact same thing as you pretty recently. IMO, Enthalpy knows what hes doing, and you probably should just keep his WOT values intact. Im using the SAFC simply to lean out light throttle/idle for better fuel econ.

[Florida240sx]

Reason why I have enthalpy, safc, and full time wideband. Florida weather chnages every minute either rain, heat, or cold front.

[myRed240]

Sorry to hear about your motor!

This morning i started my car and it had a slight miss to it (sounded like i was driving a VW) and it was idling a little lean, about 16.2 when i usually idle a 14.7 to 14.9.

I've had this exact sound and issue with the afr's. It turned out I blew out my wastegate gasket and the sound was from an exhaust leak.

Maybe you had a leak at the wastegate and it didn't open at the right pressure and you had a serious case of overboost??

[esahuque]

good idea, i'll have to check that out when i start pulling the motor this weekend.

[sunnys14]

13.5 afr's at WOT is just asking your motor to be blown. i blew mine instantly right after a 4th gear pull, the car smoked all the way home.

my engine is fully built again (#2!!!) with everything running strong. only 11psi on a gti-r t28 and i ran a 13.5 @ 107 with a 2.4 60' foot last week. im going to try to go again this week before the track closes for the season.

[esahuque]

13.5 afr's at WOT is just asking your motor to be blown. i blew mine instantly right after a 4th gear pull, the car smoked all the way home.

my engine is fully built again (#2!!!) with everything running strong. only 11psi on a gti-r t28 and i ran a 13.5 @ 107 with a 2.4 60' foot last week. im going to try to go again this week before the track closes for the season.

11.5 is what i was tuned for, believe me if i knew it was going to lean out that bad i wouldn't have got on it like i did. All it takes is one time, i guess i learned the hard way

[480sx]

Glad to hear that your back in the game so quick sunny.

Maybe this will be the engine that lasts... ?

[sunnys14]

my car doesnt like stock motors for some reason. my built one has been taking a beating, check out my thread about my runs at the track tonight.

[bruinbear714]

It's all in the tuning folks. Get it dyno tuned, not mail ordered tuned. The factory setup is finicky about getting the proper AFR and timing.

My setup costs about $1100 for the power fc with 3 bar map sensor and around $600 for a dyno tune... engine still strong after a few dozen drift & autox events.

[480sx]

Its funny that you bring that up, because the guys with mail order tunes arnt blowing their engines(enthalpy ftw!). However, this guy, ran a dyno tune and blew his.

Infact, the highest stock block HP that i know of for a KA was done with a mail order tune. 500 hp on the dyno at 25 psi. With the same tune the same guy ran 29 psi of boost. (enthalpy, lol)

Its not about the type of tune you get, its about the knowledge and experience the tuner has with engines.

[david200095367]

13.5 afr's at WOT is just asking your motor to be blown. i blew mine instantly right after a 4th gear pull, the car smoked all the way home.

my engine is fully built again (#2!!!) with everything running strong. only 11psi on a gti-r t28 and i ran a 13.5 @ 107 with a 2.4 60' foot last week. im going to try to go again this week before the track closes for the season.

?

i thought this was ur 3 or 4th ka-t?

[neverlift]

thought that was the total.... and afc advances timing.... unless you let enthalpy know your were going to dyno tune it with an afc,the tune would have less error room imo. I know if I had an afc involved I would take out extra timing,unless a btm was in the setup.

[2FourTee]

It's all in the tuning folks. Get it dyno tuned, not mail ordered tuned. The factory setup is finicky about getting the proper AFR and timing.

My setup costs about $1100 for the power fc with 3 bar map sensor and around $600 for a dyno tune... engine still strong after a few dozen drift & autox events.

Although a mail order tune is rarely going to be "100% perfect" out of the box, there are many, many people running mail order tunes, and their motor's are doing just fine and their AFR's/timing are perfectly acceptable. Most mail order tunes run a little rich, but that's what keeps them from running dangerously lean when the temperature drops. A good majority of the problems you read about with mail order tunes are user error, not the tune.

[bruinbear714]

I agree with that, mail order tunes are generally "safe"... however, every tune has very little safety margin for additional timing and/or higher AFRs in the event a piggyback is installed.

I would bet that the motor would have been fine with just the tuned ECU, no piggyback.

Although a mail order tune is rarely going to be "100% perfect" out of the box, there are many, many people running mail order tunes, and their motor's are doing just fine and their AFR's/timing are perfectly acceptable. Most mail order tunes run a little rich, but that's what keeps them from running dangerously lean when the temperature drops. A good majority of the problems you read about with mail order tunes are user error, not the tune.

[spooled240]

I think so also, mail order ecu tunes are pretty conservative in general for the average joe who wants a turbo. I know my jwt tune is in the 11.5's at WOT which is a little on the rich side..