5000rpm Timing Retard

[boostedfe3]

Guys I have a Series II rb25det in a S14 240sx. I cannot get this thing to run correctly. Everything is completely stock except a front mount intercooler, 2.5inch downpipe and 3inch exhaust and a walbro 255hp fuel pump. After driving the only code I get is 21 ignition circuit. Feels like antilag. I have already tried a different afm and a different cas and no change whatsoever. Any help would be appreciated. I do know about the rich and retard and I have no knock sensor code. I have bought the resistors to bypass rich and retard but I have not tried it yet. Thanks in advance for any help.

[SLY33]

Going back years, but i had a prob like you describe when i first got my series one. Although your car is mainly stock, boost will rise above stock due to the cooler and exhaust, and when the ecu see's up to a certain level it will pull timing, which on mine occured as you describe. When it was cold weather i would get what sounded like rev-limiter like pop sounds as it went through that flat range. Anyone correct if thats wrong.

I threw on an FC and got a tune which sorted everything out.

[Don Dada]

Guys I have a Series II rb25det in a S14 240sx. I cannot get this thing to run correctly. Everything is completely stock except a front mount intercooler, 2.5inch downpipe and 3inch exhaust and a walbro 255hp fuel pump. After driving the only code I get is 21 ignition circuit. Feels like antilag. I have already tried a different afm and a different cas and no change whatsoever. Any help would be appreciated. I do know about the rich and retard and I have no knock sensor code. I have bought the resistors to bypass rich and retard but I have not tried it yet. Thanks in advance for any help.

how much boost?

[JonnoHR31]

had the same thing with my s1 25, running about 10-12psi the power curve would take a dive then when u hit 6200 it was like hitting vtec. just the stock ecu going rich n retard. put it on the dyno at the time to make sure it was running safe -

http://i224.photobucket.com/albums/dd251/J...17052008009.jpg

[SS8_Gohan]

error 21 can include coilpacks, a very common problem.

my car did the same thing, seems to be a common thing with the RB25's. Trent at Status was able to take it out with a remap, so it was prob the ecu pulling timing.

considering it's an ignition error, what you checked the coils/spark plugs? how new are the plugs and what are they?

if you're in melb, take it to Trent @ status

[boostedfe3]

error 21 can include coilpacks, a very common problem.

my car did the same thing, seems to be a common thing with the RB25's. Trent at Status was able to take it out with a remap, so it was prob the ecu pulling timing.

considering it's an ignition error, what you checked the coils/spark plugs? how new are the plugs and what are they?

if you're in melb, take it to Trent @ status

Thanks for the replies. Boost is around 9.5 - 10 psi. I am using NGK BCPR7ES plugs that didnt change the problem so the plugs are a week old and are gapped at .8mm or .032. The thing is the car will do this with part throttle and sitting still. If I go full throttle sitting still you cant feel it, except for when you are driving. Last night it fouled my new NGK plugs out just by free revving it. Im stumped. Jonno that dyno looks like the way my car would feel. Its like trying to push the great wall of china out of my way and then it clears up and Im on the rev limiter before I can catch it.

Edited December 31, 2008 by boostedfe3

[JonnoHR31]

just the stock ecu. i put up with it til i got a pfc. could try a safc but it'll still retard the timing

[TAKUSHI]

mmm sorta sounds like the same prob im having but mine will do it from down low till high rpm and only before the car warms up

im smelling raw fuel at some points so im getting some sort of ignition cut or fuel up, im sorta hovering around crank angle sensor

[boostedfe3]

I thought cam angle sensor also. I tried a different one that came off a buddies car and same thing. Stupid stock ecu. Since I have a series II and live in the states, can I just find a series I ecu and have it remapped. Really not looking to go to a standalone ecu at the moment.

Edited December 31, 2008 by boostedfe3

[Adriano]

Cant remap either easily, they are basically the same thing.

[mongrel]

code 21 is no ignition ref, 25det's run internal ignited COP, the coils send back a ref signal to the ecu to say they have fired correctly. code 21 is logged when the a ref signal is not receive for more than a couple of revolutions. the fact that the mis is evident at 5000rpm(probably full boost, high engine load) would indicate that the coils are starting to fail(it's harder to spark at higher cylinder pressures). the engine will probable light load free rev through 5000rpm without missing

failsafe/limp for error 21 may include timing map locking and possible fuel map supplement.

try swapping the coils if you can get hold of another set, or try diagnosing which coil is failing and swap with another cylinder to see if the misfire moves to that cylinder.

[45ULT]

also check your camshaft as the splines for the cas wear out and cause all sorts of timing problems as there is too much play between the cam and cas splines. your prob sounds like rich and retard with a bit of coil pack break down thrown in lol

[boostedfe3]

Thanks guys for all the helpful replies. 45ult I will take a look at the splines on the camshaft and see if I can find any wear. After this I just dont know where to look. An engine coolant sensor couldnt cause this could it?

[MBS206]

New coil packs, plus a new coil pack loom will most likely solve the issue...

[boostedfe3]

you guys think I should try and disable rich and retard and see what happens? and once again thanks for the responses. Also keep in mind I have that the car does this sitting still and free revving with part throttle.

Edited January 2, 2009 by boostedfe3

[Adriano]

How are you planning on disabling R & R, fitting a resister instead of the knock sensor wont do it, all it does is get rid of the safety of knock retard if knock occurrs.

[boostedfe3]

oh ok. I was under the impression that it would disable it, but I understand what you are saying also.

[KiwiRS4T]

oh ok. I was under the impression that it would disable it, but I understand what you are saying also.

If you don't want to get a computer consider getting an Apexi SAFC (an old cheap version will do) and an Apexi SITC both usually available on US ebay. Otherwise you can't really tune your car at all.

[MYRB30]

Have you checked fuel pressure underload????????????????

[boostedfe3]

ok will look into the afc. No I have not checked the fuel pressure yet, although that is next. I almost think that it is running way rich. when the car is warming up I get lots of brown smoke out the exhaust. And Im not getting any codes at all now and I have been driving it for a couple of days.