Finally Back together...Bogging under boost now

[240sxOwner]

Well i finally put the engine back together and got the thing running good. No more overheating!!! Now i have a new problem. When i am at about 5K rpm in everything but 1st gear, the car hits a brick wall and bogs bad. I thought maybe the plugs were bad since the headgasket had blown 1 week earlier...so i went and got some NGK's that are 1 step colder and gapped them to .032. Went on a test drive, and it stilled bogged....I thought maybe the spark was jumping to my oil feed line, so i insulated it....still no go. The plugs are at .030 now....nothing....Wires are fine, plugs are brand new, cap and rotor are good. The only thing i can think of is that i am running really rich due to my bad 02 sensor...

SetupRevhard ManifoldT4 on center, .58 A/R turbine, .60 A/R compECU FlashedJE Pistons, ARP Studs

Any ideas?

[deviousKA]

Sounds like its going too rich into boost.

What ecu flash is it? Have you run it previously?

[PencilShavings]

im still new to this, but i thought under boost plug gaps were run even smaller?? like .020-.025?

how much boost are you running, and do you run well in boost before 5k? or does that t4 just start to climb around there?

[DammitBobby]

Plug gap of .032 is fine for boost up to 12 psi. I had the same problem and it turned out to be a bad stock fuel pump. Problem is hard to diagnose without a wideband and fuel pressure gauge. Right now all you can do is just guess.

[david200095367]

i had the same problem, and i found out it was a boost leak. so i was running to rich. one of my couplers came loose. But i say you put it on a wideband and check it out.

[Kenrik]

Sounds like its going too rich into boost.

What ecu flash is it? Have you run it previously?

Devious can you flash turbo Ecus? I would pay you good $$ to flash me a chip for 370cc injectors and a map for a boosted KA

[deviousKA]

I sell hardware and on the spot tuning only, no mail order turbo tunes at this time.

You can buy a daughterboard from a variety of places for $50-80, and then a burner for $50. You can then burn the file that redss has set up for ka24de-t and posted over at eccs.hybridka.com. Thats your most affordable solution, and very easy to do.

A daughterboard installed into an ecu with any given tune is going to cost you twice to three times as much, and doesnt include the equipment to RE-tune it like the option above.

[S14tat]

yeah how much boost are you running? if your running 10 psi, it shouldn't be a problem if your running a S14. but i know the S13's stock ignition is not as good as the S14's. if your running like 13 psi, then you should gap them down to .27" atleast.

[PencilShavings]

I sell hardware and on the spot tuning only, no mail order turbo tunes at this time.

You can buy a daughterboard from a variety of places for $50-80, and then a burner for $50. You can then burn the file that redss has set up for ka24de-t and posted over at eccs.hybridka.com. Thats your most affordable solution, and very easy to do.

A daughterboard installed into an ecu with any given tune is going to cost you twice to three times as much, and doesnt include the equipment to RE-tune it like the option above.

do you have any links to sites with more information about this? might be something i want to look into in the future..

[240sxOwner]

i am running 7psi.....MSD 6AL, but stock coil. The fuel pump was upgraded but im not sure to what. I think i am running really rich, my 02 sensor is bad. Not to mention since i swapped the motor into my car, the air/fuel gauge has not given me a reading. It stays all the way on lean but very dim on last led. It also does not do it everytime.....just most of the time.

[240sxOwner]

im not sure who tuned the ecu...there are no stickers on the case or antything....but it has to be flashed or else the car would blow up. The turbo starts to spool at 2500 and hits full boost at 5K or so. In second gear it pulls hard and usually breaks loose at 5500 or so. Thats is on a 60 degree day with 245's on back with helical LSD and 3/4 of tank! It pulls very hard for 7lbs

[PencilShavings]

what injectors? what maf?

have you pulled your plugs yet to see what they look like?

[240sxOwner]

stock maf...i think 370 injectors (not sure).....the plugs are brand new...and they look fine

[PencilShavings]

I dont have personal experience with this, but i hear the stock maf max's out at around 270hp (some people claim around 7-9psi on a t3/t04e). Im not sure how your straight t4 compares to that, but it seems possible.

[WDRacing]

Best way to check for spark issues over 5000 is to have a friend get the rpms up to about the trouble rpm point while your holding the end of the wire that goes over the plug...you'll know if there is enough spark right away...lol.

[240sxOwner]

Ill pass on that WD...lol I forgot to mention that it does not happen all of the time. This just started recently and usually only happens when the car is warmed up. Any way that the o2 sensor could cause me to run real rich under boost? Maybe gap is too small?

[Jookmasta]

just go replace the 02 sensor...............30 bux. u need to change it anyway so might as well eliminate that as a cause.

[WDRacing]

At WOT the O2 sensor isn't used.

[240sxOwner]

i adjusted the distributor today and retarded the timing some more...no more bogging. BUT, now abouve 5K i have a rattle and it sounds like timing chain popping...but everything is brand new...I remember on my last ka...when the timing was advanced for a little extra kick, it did the same thing...Any Thoughts?

[PencilShavings]

dunno what else..you might have to start slowing working on possible causes..

could you turn the boost down a few psi? if it still boggs then, maybe it would rule out MAF?

maybe try some more ignition crap? theres some good stuff here.. zerothread?id=127078like the alternator secondary ground, and the ignition relay

have you tried a smaller plug gap at all? just for starters?

I guess these are just things to try that are free, and its where I would start if it was my car..

what have you actually tried so far?

[PencilShavings]

what was your timing at originally? how much did you retard it?

[240sxOwner]

i retarded it about half the length of the distributor arc. I don't what the timing was set at originally....i i will see if i can check it out. I have put the gap from .036 down to .030 same problem. I have a deltagate Mark II ....with a 7lb spring...how do i adjust it? I though it couldn't be adjusted w/o another spring

[PencilShavings]

I though it couldn't be adjusted w/o another spring

Yes im pretty sure you're right..anyone else know how to kill a few psi of boost off?

[Florida240sx]

Nope.You can only increase boost.Not decrease it. However if you have a nipple off your hotpipe or mani it will yield a couple psi less than at your fpr. Because it doesn't have the system eff. loss.

[240sxOwner]

boost is running from a tee at the FPR

[2FourTee]

Is this an aftermarket FPR????

[240sxOwner]

yes....but the stock one is still bolted onto the fuel rail.

[2FourTee]

OK, but it is definitely not a Rising-rate FPR, correct??

You haven't tried a wideband on it yet, have you??

There are really just too many unknown variables here. You aren't sure about timing, don't have a wideband (at least I didn't see it mentioned), and you are not sure what kind of ECU reflash has been done.

ALso, the reason I asked about the FPR is because if it is a Rising-rate FPR and you also have a tuned ECU, it could be feeding way too much fuel when you hit boost.

I would take it to a dyno, or borrow/buy a wideband, check timing, check for boost leaks with a leak tester, and then try to diagnose what's happening. Otherwise, all the people replying are really just guessing.

[240sxOwner]

not a rising rate....I am going to borrow a wideband if i can....Is it possible that my stock maf could be maxing out at 7psi?

[PencilShavings]

not a rising rate....I am going to borrow a wideband if i can....Is it possible that my stock maf could be maxing out at 7psi?

That still what my guess is. Is the bogging consistent with the weather or any other variables?

EDIT: better yet, wouldn't it be possible to spice into the maf wires, and have a voltmeter in the cabin with you, so you can monitor the maf voltage and see if it maxes out?
Modified by PencilShavings at 3:28 PM 4/6/2006